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             T.E.Manning V.o.f., Schoener 50, 1771 ED Wieringerwerf, Netherlands


        A self-financing project centered on basic hygiene education, on the installation of sustainable
sanitation, distributed clean drinking water, PV lighting for study and the supply of efficient stoves for
cooking, the production of bio-mass to fuel them, and recycling at local level and disposal of non-
organic waste.

        The project includes setting up Community Health Clubs for hygiene education; provides
sustainable toilet and wastewater facilities, wells (wherever necessary), pumps, and water tanks;
establishes local exchange transfer (LETS) systems to promote local exchange of goods and
services; and implements an interest-free revolving micro-credit system to pay in formal currency for
items and services originating outside the local communities.

        The project also refers to PV (photovoltaic) lighting for study and in clinics and PV refrigeration
for medicines. Any PV lighting needed for separate local production initiatives would be included
within their respective micro-credit schemes. PV operated TV sets for education can be included.
Private Solar Home Systems (SHS) may be financed by the Local Bank where users are able to
sustain their obligations under a hire purchase agreement for the SHS as well as meet their
obligations under the project itself.

        High efficiency stoves for cooking will be produced with 100% local value added as will the
bio-mass necessary to fuel them. Recycling centres will be set up to re-cycle non-organic refuse
within the local currency systems. Harvesting rainwater to increase agricultural production and the
general quality of life is promoted. The project cost is about Euro 3,000,000, which can be 100%
financed through an interest free loan with a 10 year repayment time.

          The project will be continued for at least a further 8 years beyond the initial two years' start-up
period.     After the initial two years, further development will be generated by the
communities themselves under the supervision of the Project Coordinator.


This model project is founded on the idea that most people in developing countries are able and
willing to pay for their own hygiene education, water supply, sanitation, rubbish disposal and bio-mass
production structures provided they have the seed money necessary to get started. The seed money
will where possible be interest-free. Although this proposal is essentially self-financing, some
extremely poor communities may need financial aid until their projects become self-sustaining.

There is ample potential to develop the production of goods and services at community level in
developing countries, but development is restricted by a chronic lack of money. Leakage of financial
resources away from local areas makes the problem worse because it artificially limits the people's
basic right to produce and exchange goods and services.

This potential can be exploited by using a combination of advanced financial instruments and modern
technologies, including solar submersible horizontal axis piston pumps, spring rebound inertia hand
pumps, and the "Beosite" technology developed by the Dutch technology developer Eos Advises.
Beosite technology enables many items important to local development projects to be made in low
cost labour-intensive local production units with 100% local value added.

Hygiene training programmes are based on the formation of Community Health Clubs. These have
been successfully developed and introduced by the NGO Zimbabwe A.H.E.A.D.

The project is financed using:

a) A ten year interest-free seed loan for about US$ 60 per person
b) Local currency or LETS (Local Exchange Transfer) systems
c) A Micro-credit system modeled on the successful Grameen banks in Bangladesh, but interest-free
d) Savings on traditional costs of fuel for cooking and, in some cases, of water.

The financial proposals allow funds in both the local currencies and the formal, or ordinary, currency
to be systematically re-circulated - interest free- within the participating communities. Financial
leakage from the project area is discouraged.


The immediate goals of the project are:

a) To carry out a basic hygiene education programme by establishing Community Health Clubs
b) To install technically appropriate sanitation for the people in question
c) To provide a permanent safe drinking water supply in all foreseeable circumstances.
d) To make safe drinking water available within a radius of 150-200 m. from users' homes.
e) To contribute to the fight against water-related diseases through hygiene education, the supply of
appropriate sanitation and clean drinking water systems.
f) To reduce the work load on women
g) To provide for the continuity of health, sanitation and drinking water systems by establishing
appropriate institutional structures.
h) To enable students and others who wish to study in the evening to do so.
i) To avoid the need to import wood into the local system.
j) To introduce efficient bio-mass fuelled means of cooking
k) To create added value through recycling of non-organic waste
l) To keep available financial resources (LETS money and formal money) revolving within the
beneficiary communities.
m) To stimulate on-going local industrial and agricultural development through the use of local
currency (LETS) and micro-credit systems.


The long term goals of the project are:

a) To sustain on-going improvement of the general quality of life wellbeing and health of the local
b) To free more human resources for local production and development.
c) To reduce water-borne diseases so that medical staff and financial resources can be re-directed to
other health objectives such as vaccination programmes and preventive medicine.
d) To decrease infant mortality and promote family planning.
e) To increase literacy levels.
f) To eliminate dependency on fuels imported from outside the project area.
g) To help reduce deforestation and global warming.
h) To create value added from locally recycled non-organic solid waste.
i) To create a "maintenance culture" to conserve the investments made.
j) To increase the local pool of expertise so that local people can improve their sustainable well-being
and development by identifying and solving problems, including erosion, with a minimum of outside


The basic principles behind the project are:
a) The enhancement of self-sufficiency in local economies.
b) Existing social traditions will not suffer.
c) Local expertise, labour and materials will be used.
d) Women will play an active role in the project.
e) The people must be able and willing to take full responsibility for all goods and services
   provided under the project and for its administration.
f) The users must contribute financially to loan repayments, cover on-going costs and accept the
   powers of the elected tank- and well commissions.
g) The project will be self-funding. Savings on traditional fuel costs for cooking and services will
   cover most of the project costs.
h) The supply of traditional natural fertiliser for agricultural purposes will not be compromised.
i) Each individual user will be enabled to meet his financial commitments to the project.
   Household difficulties in meeting monthly quotas can be cushioned either from the monthly
   allowances received by the tank- and well-commissions, or by creating a simple LETS
   system safety net. Members temporarily in difficulty could be allowed to run up a larger than
   usual debit balance. Members permanently in difficulty could perform services within the
   LETS group in exchange for group payment of their outstanding debts.
j) 'Small is beautiful'.
    Small decentralized systems are to be preferred wherever possible. This promotes close
    contact of the people with the installation and running of their own local infrastructure.
j)  Local LETS currencies will complement the use of formal money .
    They will make up for the lack of formal money that would otherwise be needed to expand
    the quantity of local goods and services.
    Economic development within the LETS systems will also stimulate growth in the formal
    economy which will increase its formal tax base.
l) The seed loan capital will be systematically recycled to users as micro-credits.
   The micro-credits will allow goods and services that cannot be locally produced to be bought
   with formal currency outside the project area.
m) Leakage of formal currency out of the project area will be reduced.
   The seed capital will be retained in the local area during the 10 year interest-free loan period.


Hygiene Education Structures

Voluntary Community Health Clubs are set up within the project area. The members of each Health
Club, which can include men, follow a course normally lasting at least six months. During the course,
hygiene-related topics are discussed under the leadership of a specially trained Health Worker.

The Health Clubs will continue to meet regularly after the course has finished. Their role is
fundamental to the project. They serve as a forum for identifying community needs, assisting with
project planning and implementation, and developing the sense of unity and cooperation on which
the success of the project depends.

A system will be set up to provide on-going inspection of the individual sanitation and water supply
systems by local Health workers.

Water quality will be systematically monitored by a local clinic or hospital using testing equipment
supplied under the project.

Sanitation Facilities

These are based on the separation of urine, faeces, and grey water.

In urban areas, urine, grey water and fertiliser can be used in vertical gardens made from Beosite
blocks under the LETS systems.

The number of users for each toilet unit will be decided at the start of the project based on the users'
preferences and customs. Units could be for an individual family or a group of related families.

A typical unit will comprise a small toilet building containing three Beosite  tanks. One tank will be
used for urine. The other two tanks will be used as aerobic composting toilets. Building support
structures, san-plats for urinals and toilet seats will also be supplied by the local Beosite  production
units. The toilet structures will be built by local builders or cooperative groups and paid for using the
LETS local currencies. Use of improved evaporation systems could eliminate one of the composting
toilets. For health reasons we prefer the twin tank method.

Almost the whole sanitation project can be done under local exchange transfer (LETS) systems, with
nearly 100% local value added.

The toilets will be supplied with appropriate washing and cleaning means for personal hygiene.

A small quantity of locally available lime, ash, sawdust or similar would be added to the urine tank
once or twice a day and to the faeces after use. The contents of the urine tank can be emptied
whenever desired. A mixture containing one part urine and ten parts of water can be safely used for
watering plants.
Users not wishing to dispose of the urine themselves will hire local operators to do it for them under
the local LETS currency systems. The development using LETS currencies of a collection system
may be needed in poor urban areas where users have no gardens or are unable to dispose of their

With the double composting dry toilet system, one properly aerated toilet tank is used until it is more
or less full. It is then sealed and allowed to compost for 9-12 months while the second tank is being
used. During that time, the compost in the sealed tank reduces to about one wheelbarrow full of soil
per adult per year. After 9-12 months composting, the soil can be safely and profitably used as soil

With a single tank improved evaporation system, the faeces are dried by circulating relatively warm
air in the system. It produces coagulated pellets that look like dry dogs' food. The residue is light and
small. The tank can be emptied any time at 2-3 year intervals and the contents can be safely used as

Users not able to dispose of the soil conditioner will hire local operators to do so under the local LETS
currency system.

Organic material other than urine and faeces will be composted in simple compost boxes built and
supplied using local LETS currencies.

In rural project areas, grey household water from the kitchen and from household cleaning can be
collected in an appropriate closed container and spread on the family vegetable plot once a day,
avoiding the formation of open or stagnant pools and concentrations of water. It can also be used to
dilute urine. Users not able to dispose of their grey water will hire local operators to do so under the
local LETS currency systems.

In urban project areas, grey water may need to be regularly collected, possibly together with urine,
and taken to the countryside nearby where it can be recycled. This work would be done under the
local LETS currency systems.

Non-organic solid waste products will be recycled in recycling centres operating under the local
currency (LETS) systems, creating more local added value. In larger communities the centres may be
specialised to some extent. Collection charges will depend on the kind of material being recycled.
Environmentally harmful materials will be charged for at a higher rate than other materials.

Local Beosite (R) Production Facilities

The project requires the supply of many water tanks, water containers, well-linings, san-plats, toilet
seats and support structures. Many of these are traditionally made from concrete, using materials that
have be paid for in formal currency and are usually not available locally. Concrete and cement are
environmentally unfriendly and are difficult to dispose of after use. Concrete water tanks can cost up
to Euro 4000 per tank. Concrete products are also subject to production faults and cannot always be
repaired when damaged. They are heavy and difficult to transport.

A practical alternative to concrete is to use a new-age product like "Beosite". Beosite production
units can be established wherever there are local deposits of cheap gypsum (CaSO4 + H2O) or
anhydrite (CaSO4 + 1/2 H2O) which are very common, occurring naturally in most parts of the world..
They can be used to make cheap ecological, hygienic tanks, well-linings, toilets and other products.
"Beosite"  is a state-of-the-art technology originating in the Netherlands. It can easily be transferred
to the project area . The Beosite production units can make a major contribution to the regional
economy after the project has been completed as well as manufacturing the products needed for the
project itself.

 "Beosite"  production units are permanent industrial assets. They can be used to make various
load-bearing structures and other building materials. Beosite can even be used to weather-proof the
mud walls of locally built houses and as a substitute for construction timber, reducing de-forestation.

Beosite will also be used to make high efficiency stoves. The stoves can stand temperatures of up to
500 degrees C. They will recycle heat from smoke circulated around the pot. The stoves can be
safely carried by hand with boiling water in the pot and fire in the stove. Although they will work with
any sort of fuel, mini-briquettes made from bio-mass will be produced locally under the project.

The modest cost of Beosite production units will be funded within the project by interest-free green
loans repayable over a period of 3-5 years. The initial casting moulds for Beosite products can cost
up to Euro 7000. These costs will restrict the initial range of products any single production unit can
make. The top priority will be to service the needs of the project itself. Additional copies of the initial
moulds are, however, very cheap to make.

Water Supply Structures

The water supply systems for the project will be decentralised. Large diameter wells and bore holes
will be dug using local labour, construction methods and materials.

About 6-9 solar submersible horizontal axis piston pumps will be installed in each well. Each of the
pumps will supply water to a dedicated water tank serving a local community. The well is the hub of
the supply system. The water pipelines radiating from it are its spokes.

Schools will each receive one dedicated tank. Clinics, for further safety, will be served by two tanks
each fed by its own pump.

Each well will be equipped with back-up handpumps. The handpumps will provide water during
unusually long periods of bad weather.

Where culturally appropriate, there will be a communal washing area near each well so that women
used to doing their washing in groups can continue to do so. The backup handpumps may also be
used to service the washing areas and in cases of emergency.

The water supply is based on a water consumption of 25 liters per person per day. Since solar energy
is to be used to pump the water, bad weather must be taken into account. For that reason, the tanks
need to have a capacity for three days' use. Each tank will supply about 200 people. The capacity
required to give 25 liters per day to 200 people for three days is 15m3, the planned size of the tanks.

Institutional Developments

Permanent on-going procedures to maintain and administer the system will be worked out between
the project coordinator, the tanks and wells commissions, maintenance and inspection staff, and the
local private bank that administers the micro-credit loans.

The purpose is to create a "maintenance culture".
Multiple re-cycled interest-free micro-credits will provide formal money needed to develop local
production capacity. The rest of the development will be done with the LETS systems.

The capital available for recycling in the form of micro-credits is made of :
a) Part of the initial seed money until it is needed for the project
b) Seed loan repayments
c) Micro-credit repayments
d) The long term maintenance fund
e) System capital replacement fund which will be built up after the ten years' seed loan has been
   fully repaid

For instance, a woman may need a sewing machine to be able to make clothes. She will need
"formal" currency to buy the sewing machine. That money will be available in the form of an interest-
free micro credit. She will sell outside the local LETS system some of the clothes she makes to earn
the "formal" money she needs to repay her loan. The rest of the clothes can be sold within the local
currency LETS system.

As she repays her loan, the repaid capital can be loaned again for another interest free micro-credit
project, so the available seed money repeatedly re-circulates within the local economy.

Establishing local exchange transfer (LETS) systems to overcome the chronic lack of "formal" money
in the project area is fundamental to the project. LETS systems create local currency units to
exchange goods and services. They eliminate common complaints concerning the operation of
development projects, such as:

                    "There's no money to pay people to write out the water bills"
                      "There's no money to collect the monthly contributions"
                         "The people can't afford san-plats for their toilets"

Very often , all that is needed is a way to transfer goods and services within the community without
having to use formal money.

We propose to make participation in the LETS systems compulsory for all people of working age
involved because everybody will benefit from and participate in some of the community level
initiatives undertaken within the project. For instance, PV lighting for study will be financed at local
tank commission level and its costs written off against the users in that tank area only. Others, such
as tree-planting or road building may benefit the whole community and every member will be charged
for his share. Compulsory membership is also needed where common assets are being used or sold
or when goods and services for the project have to be supplied in the local currencies.

Nearly all LETS transactions are open to normal "free market" negotiation between the parties.

Many goods and services like those provided by the Community Health Clubs, and those needed to
build the sanitation and water supply services can be paid for using the LETS systems. We have
included formal currency estimates for these goods and services so that enough micro-credit loan
money is available to start developing local production.

PV Lighting, Television And Refrigeration

A PV lighting system for study can be installed in each tank area once a study area has been built
there using the local LETS currency. The cost of the study area would be equally debited to all LETS
members in the tank area.
Enough money is set aside in the project to cover 200 PV lighting systems.

Payments and On-Going Costs

The users will pay a monthly fee to be decided during phase 2 of the project. It is expected to be
approximately Euros3-3.5 per month for a family of 5. This sum will be used:

-    to repay the loan itself. This money will be re-cycled interest-free for use as micro-credits to
     develop local production capacity.

-    on going administration and maintenance costs. This money pays the monthly fees of the
     project coordinator and the salaries and transport costs of maintenance and inspection personnel
     and of the well and tank commissions.

-    long term maintenance and reserves. These funds will also be re-cycled for micro-credits but
     managed so that the capital is available when it is needed.

Once the original seed money has been repaid, the monthly payments will create a large fund for use
to extend of the basic services provided under this project.

The whole cost of the "Beosite" production units will be covered by interest-free loans repayable over
3-5 years. This capital can also be re-cycled as it is repaid.

There will be large savings in the traditional cost of fuel for cooking. The savings will come from using
high efficiency Beosite stoves and local production of bio-mass for fuel.

Provision of drinking water under the project will avoid the need to purchase expensive water from
vendors especially in poor urban areas.

Waste re-cycling under the project will produce savings by creating value added from resources
currently unused and because payments for collection and handling of the waste will be kept inside
the local economy.


The following drawings and diagrams are supplied as an integral part of this paper:

a)   Diagram   showing institutional structures with cash flows
b)   Diagram   showing waste disposal structures
c)   Diagram   showing suggested structures for the LETSsystems
d)   Diagram   of the proposed water distribution systems


Useful references for further information on dry sanitation are:

a) Winblad Uno et al, Ecological Sanitation, SIDA (Swedish International Development Cooperation
    Agency). Stockholm 1998. ISBN 91 586 76 12 0.
b) Del Porto David * Steinfeld Carol, The composting toilet system book, CEPP (Center for
   Ecological Pollution Prevention), Concord Massachusetts, 1999. ISBN 0-9666783-0-3.
Technical information on the project and on the technologies used is available together with a full list
of key words at:


Cooperation, role in development; Local Exchange Transfer (LETS) systems; Micro-credit systems;
Poverty alleviation; Self-financing development projects; Sustainable development

                                    AAP de Alwis
                    Department of Chemical and Process Engineering
                                University of Moratuwa
                                  Moratuwa, Sri Lanka


      The paper shows that there had been a different approach by developed and
developing countries in the area of biogas energy. This difference is argued to be highly
unproductive. The immediate need to have a different approach is stressed and a
possible strategy is elucidated so as to realise the optimal benefits from the biogas


       1973 was crucial in making the world realise for the first time the impact of an
energy crisis brought about by an organised group pushing up the price of an essential
commodity. It was not the resource limitation that caused the immediate problem but the
organised curtailment of a supply and the significant price hike. However, there was
immediate realisation of the resource limitation factor by all the affected parties. The
world, which was used to cheap energy and the resultant comforts, had to adjust to this
new situation quite rapidly. By this time the world clearly showed heterogeneity in it’s
economic order by way of having developed and developing country groups, first and third
world countries, North and South divisions etc. The adjustment to these energy price
shocks took place in different ways in these two groupings. While the developed world did
not abandon the physical benefits and associated lifestyles, they adjusted by way of
immediately improving on energy utilization efficiencies and embarking on developing
renewable energy technologies for the future. Their pace of development continued
unabated and the economies in addition became all the more efficient as well. Developing
countries already burdened with many economic weaknesses this was to be a problem
seriously compounding all other problems. The developing countries thus did not react in
the same manner as the developed group, and as a result the economies still suffer from
gross inefficiencies and the much sought after development is still an elusive dream. As
energy is a vital factor in development, the type of remedies suggested to resolve the
energy problems, have been the use of appropriate technologies.                Renewable
technologies were identified to play a major role and for example a program of the United
Nations adopted the ‘Colombo Declaration’ in April 1974 resolving that one of the most
urgent priorities is Energy. A regional project for the development anaerobic digestion
(biogas) throughout Asia was approved in November 1974. ESCAP became active in
promoting anaerobic digestion as a result [1,2 ]. Much of Asia had not benefited from
developments in this area and energy shortages are quite common within the region.

         However, as with the general approach in handling the energy crisis, in the case of
utilization of biogas, North followed a different approach to that of us in the South.

                              BIOGAS ENERGY SYSTEMS
       Biogas systems can help in solving the problems facing the societies of present and
future. This can only happen if the "Systems Approach" is adopted in utilization of
technology. The Biogas utilization can happen professionally only if the subject had been
taught, understood and applied systematically and if the advocates look at the technology
in an objective manner. The images such as biogas is from waste, the energy is for rural
etc. needs to be discarded. Biogas technology has a poor image ("Biogas plants are built
by dreamers for poor people"). If you do not want to seem one of the poor, you do not buy
a biogas plant. This is the current perception of biogas in the South. The image of the
biogas plant must be improved.

       To emphasis on the acceptability of Biogas - on which the whole success of its
potential contribution lies - one cannot do better than quote from Sasse, [3] even though
he is still considering the rural folk in his statement.

         " A technology is appropriate if it gains acceptance. Biogas plants have hitherto
gained little acceptance. Simple biogas plants have up to now presumably been
inappropriate: Bicycles are appropriate: If a person buys a bicycle, he is proud. It is a sign
of his advance, his personal progress. The bicycle is appropriate to the need for social
recognition. If the person mounts the bicycle and falls off because he does not know how
to ride it, it is not appropriate to the abilities of its owner. The person learns to ride and
thus adapts himself to his cherished bicycle. It is appropriate to his need for convenience
and low cost transport. The bicycle breaks down. The person has no money to spare to
have it mended. He saves on other expenditure, because the bicycle is important for his
pride and his convenience. He walks long distances to the repairer. He adapts to the
needs of the bicycle. The person can afford this expenditure without getting into economic
difficulties. The bicycle is appropriate to his economic capacity. A biogas plant is correctly
operated and maintained if it satisfies the user's need for recognition and convenience.
He for his part is then prepared to adapt to the needs of the biogas plant.” Sasse’s view
however, could be extrapolated to that of the society in general accepting a technology for
its general use.

       The statement that Biogas plants are appropriate to the technical abilities and
economic capacity of third world farmers is heard all too frequently. Unfortunately the
trend has been to fit in a technology at a level suitable for an existing situation than trying
to implement technology into a developing framework. The societies are expected to
stagnate and the needs to be quite basic. These assumptions are unacceptable from a
development scenario. South should consider the limitations such thinking bring in while
simultaneously trying to address the general aspirations of the masses. The biogas plant
must also be a symbol of advancement with features of superior technology as in with
information technologies.

       Thus there is a need for a change in making this technology into a sustainable
success. Sasse, concentrates on rural settings and on small-scale energy and fertilizer
supply systems. There is also the need to emphasis the large-scale potentialities.
Department of Trade and Industry (UK) in a report [4] mentions the electricity generating
potential of 400 MWe by the use of biodegradable wastes from industries with anaerobic
digestion processes. This shows the large-scale opportunities in industries, large-scale
community systems, town’s etc which the Biogas offers.

Industrial Development Board (IDB) was the first government institution to have initiated a
program in biogas. This was in the seventies and took place as a response to the oil
crisis. However, the scale of activities apparently had been very limited in Sri Lanka as a
survey is reported in [5] which had revealed only two working units. IDB started the Sri
Lankan biogas program by introducing the Indian (floating barrel) type digester unit. In a
bid to disseminate technology to a younger and a more receptive group (i.e. School
Students) IDB setup about 45 units in schools across the island. However, this failed with
schools authorities not pursuing the idea nor maintaining the units provided to them. None
of the school units were found to be functional after a while.

Wijesinghe and Chandrani (1986) were perhaps the first ever-detailed study conducted on
Biogas in Sri Lanka [6] . The study period has been over 6 months (August 1984 -
January 1985). However in that period they have been able to determine the existence of
303 units only. Out of these 280 units, 170 (61%) were functioning satisfactorily or at
lower levels of production. The most common type of digester had been found to be the
6m3 capacity, fixed dome Chinese type, with cattle dung being the most common raw
material. Another detailed survey was carried out in 1996 [7]. The results (Table 1)
indicate the lower success of biogas units.
            Table 1 Cumulative Summary of Biogas Survey 1996, Sri Lanka
               Total units surveyed                        - 369
               Under construction (observed)               - 04
               Systems surveyed (complete)                 - 365
               Functioning units                           - 104
               Functioning rate                            - 28.5%
               No. of units abandoned after successful use - 16
               Success rate                                - 32.9%

Type of digester            % of Total    functional units   Efficiency

No. of Chinese units        - 313         85.8%       95           30.4%
No. of Drybatch units       - 23          6.3%        06           26.1%
No. of Indian units         - 27          2.7%        00           0%
No. of other units (UASB)   - 02          0.55%       02           100%

Digester setting     % of Total      functional systems      Efficiency

No. of Home systems          - 278        76.2%       81           29.1%
No. of Farm systems          - 22         6.03%       7            31.8%
No. of Institutional systems - 65         24.5%       16           24.6%

One significant reason for the failure had been that this technology had been promoted
without imparting the knowledge on why you are doing it and how you should manage it
[8]. In addition even the basic appliances were missing or of very poor quality and at
replacement time of any item usually meant the end of the unit.

Biogas systems in other countries in the region has also been promoted with a similar view
and the general mandate of many promoters had been that this is a technology which
could develop rural communities to a higher level of existence by fulfilling some of their
basic requirements. Traditional low cost-low efficiency digester systems have been in
general prescribed as the energy solution for the rural poor from the third world and these
still find favour from many aid and charity donors. These activities also reinforces the
wrong concepts held by the society in general and succeeds in marginalising a technology
which can said to have triple advantages

 An energy management tool
 An environmental management tool
 Ability provide a soil conditioner (An agro enterprise management tool)
The developing countries by and large suffer from a lack of clear policy directives on
renewable energy issues (all types including biogas) from their respective governments.
This also hampers developing focused approaches to solving the energy problem.


   Biogas extraction and use has become a vibrant industrial technology in developed
 economies and is now finding applications due to variety of reasons. Some of these are;

   Uncontrolled methane emissions – as emitted from solid and liquid wastes of organic
    composition under anaerobic condition – are not acceptable today as methane is a
  powerful greenhouse gas (GHG). Thus control of these emissions are essential from a
 climate change point of view. The solution that has been forwarded is the capture of this
    gas and utilisation it via combustion thus converting it to CO2 and obtaining energy.

  Conventional energy sources are depleting - The world has realised that there is only a
 finite time and that the time available is also short before conventional fuel resource base
is depleted. Thus the need to develop renewable energy resources have intensified and it
   is important to have proven, reliable and commercially viable energy systems available
                                    when the crunch occurs

      As a tool for sustainable development - Today the emphasis is on sustainable
 development and both the way energy is used and the management of the environment
have been given equal consideration. In satisfying this twin needs, biogas option provides
                           a neat clean development mechanism.

Nynes and Thomas [9] offers a comprehensive review of all aspects of biogas technology
from a European Union perspective. This detailed review is an eye-opener to the scale in
which the technology is practiced in EU countries and elsewhere.

Hence it is evident that a clear strategy is required in realising the true potential of this
technology. Thus in the South we should adopt a strategy similar to the outline provided
for Sri Lanka in Table 2 [10]

        Table 2: A Possible Strategy for the Development of Biogas Systems

 A Biogas system’s value as an environmental management technique is a key factor in
utilising the technique across sectors such as the urban environment, industrial waste
treatment and livestock management facilities. The utilisation of a biogas system within
these sectors will remove these places at least partially from the main energy supply
chain. One could plan for this partial displacement initially.

 The promotion of biogas systems, based on raw materials such as animal waste and
straw, has been largely targeted towards the rural household sector. Though being
practiced since the 70’s the success rate of these ventures has been low. In developed
countries, the emphasis has been different [10].

Hence, to realise the biogas potential, several important additions are necessary to what is
currently available. These should form essential steps in an overall strategy.

a) Awareness of the problem (in terms of both energy and environment) and the
   consequent need for innovative solutions is necessary. However, the awareness
   should be developed into more focused and detailed information. One should move
   away from introducing basics (they will definitely cannot be totally phased out) to more
   specific and detailed introductions. Most of the time, at present we are not going
   beyond simple introductions - What? How and why? Advantages and disadvantages

b) Adoption of biogas systems in sewage handling (in the urban sector) should be
   promoted. Integrating functionally and aesthetically biogas systems into waste
   management and energy generation to household systems is necessary. Wherever
   installing sewerage systems anaerobic digestion should form part of the overall
   objective of such systems.

c) Development of appropriate end-use mechanisms at both individual and institutional
   levels (since the use of biogas for cooking may not meet with everyone’s satisfaction in
   the urban/rural environments).

d) Development of convenient digestion systems (the concrete/ brick masonry types are
   inappropriate as flexible or convenient systems). At household level one should look at
   incorporating a biogas system into the initial architectural planning. This type of
   popularization using different materials is quite important in developing flexible systems
   for use. The manufacturing and fabricating capability should exist within the country.
   The necessary controls and instrumentation capabilities should also be built into these
   units designed for various utilisation contexts.

e) Development of national standards for biogas systems at various levels of utilisation is
   important. Quality Assurance of units and appliances and across the whole system is
   an important element for long-term success.

f) Emergence of private entrepreneurs with the ability to install and support biogas
   systems. For industrial systems it is possible to look at making the technology currently
   available externally, such as BIOENERGY (from Biomechanics), CLEAR (Clear),
   ANAMET (AC-Biotechnics), BIOMASS (Biomass Int.), BIOFAR (Degremont), HYAN
   (Gore & Storrie), under license to the local market. The market and monitoring
   mechanisms practiced in Nepal are of interest for small systems in Sri Lanka.

g) Since food and agro industries have the potential to dominate the Sri Lankan production
   and manufacturing sector, one can always envisage that if successful use of biogas
   systems is demonstrated, our emerging industries will stand to benefit from the
   knowledge base that will be readily available within the country. Successes at the
   industrial sector level may in turn encourage the small-scale use of low-rate systems at
   societal level. However, the pace of application and acceptance need to be accelerated
   and industrial energy goals from the biomethanation mechanism should be established.
f) More enlightened financing schemes should be set in place. Indian IREDA is an
   example. Indians are utilising GEF (Global Environmental Facility) funds quite
   effectively in the promotion of biogas. Local banks should be more enterprising and
   adopt different schemes for funding projects. It is important to realise that the present
   climate for renewable development is not exactly even a one of transition as the oil
   prices are at quite low levels and thus the technologies that have been developed have
   the edge over the developing technologies. However, the critical need for development
   cannot be decided solely on the basis of a cost in Rupees and cents and the
   government together with banks should realise this.

  j) Funding and technology development for market acceptability should be supported
       internally: As can be seen there are many technical options though falling into few
    select categories. Most projects –if not all- today are guided by the conventional Cost-
      Benefit (CCB) analysis to guide investment decisions. The simple logic being, if the
     benefits of a project exceed the costs, the investments should be undertaken. As can
       be seen some thrust in development of biogas has occurred due to environmental
    reasons. These aspects are difficult if not impossible to identify and quantified and nor
       do they have proper market values. Though non-market Environmental valuation
       Techniques are (EVT) are available to carry out an extended benefit cost analysis
     perhaps it is much easier to utilise common sense and national policies of importance
        to devise mechanisms for development of these technologies. Thus government
     intervention is necessary. This is true and applicable in developed countries such as
                         United Kingdom, Australia and European Union.


       The proposed strategy is to promote biogas systems from a top down approach, i.e.
from large/medium scale units to small scale units or from industrial/institutional systems to
individual units. The biogas can and will be successful if there is enough emphasis on
commercialization and with the promotion of technologies through market mechanisms.
The steps indicated should be the essential elements in the implementation strategy and
should be in place to serve all levels of users.

        Of the regional countries India is moving away from the earlier low-rate systems to
more advanced commercial systems for institutions and industries. Indian Ministry of non-
conventional energy systems is actively pursuing the development and dissemination of
these biogas systems supported by organisations such as IREDA. It was in Colombo in
1977 that a conclusion was reached that small is not so beautiful in respect to biogas
systems [11]. However, the concept of small-scale individual biogas units should not be
totally discarded as that has a role to play in some areas. However, in these small-scale
low-rate digester systems, the aspect of aesthetics should be introduced for greater
acceptance. In some times when pushing technologies through, this aspect gets totally
ignored or the importance is not realised at all.

       It is possible to conclude when looking at developments taking place in the
developed countries and viewing the potential for this technology in the Asian sub-
continent that this relegation of biogas as a rural technology had to be abandoned. In
some economies as in Sri Lanka still the impression is biogas was a failed energy
technology and a one that is more suitable for giving ‘organic fertilizer’. Forgetting these
aspects and relegating biogas to a ‘tried and did not really succeed’ is unjustifiable in
terms of science and common sense!

1. A. Barnett, L. Pyle. and S K Subramanian, Biogas Technology in the Third World: A
      multidisciplinary review, IDRC Publication, 1978.
2.    M Amaratunga, Biogas in an Integrated Farming System, Agricultural Engineering, Vol.
      1, No. 1, University of Peradeniya, 1977.
3.    L. Sasse, Biogas plants, GATE/Vieweg, Braunschweig FRG, 1984.
4.    DTI, Anaerobic Digestion of industrial wastewater: A survey of potential applications in
      the United Kingdom Industry; ETSU B 1294, 1993.
5.    Gosling, New Scientist, 11th October, 1979
6.    L C A de S Wijesinghe, A quantitative study of the direct use of kerosene for lighting in
      Sri Lanka households, J. Natn. Sci. Council, Sri Lanka, 1983.
7.    A A P de Alwis, National Survey of Biogas Systems in Sri Lanka, Energy Forum Vols.
      1-3, 1997.
8.    A A P de Alwis, Biogas as an energy resource: Learning from past mistakes, OUR
      Engineering Technology Vol. 3, No. 1 pp 5-12, 1997.
9.    Nynes and S. Thomas, Biogas from waste and wastewater treatment, CD from James
      & James UK, 1998.
10.   A A P de Alwis, Renewable Energy Options in Sri Lanka : Study on the Potential of
      Bio-gas in Sri Lanka, Energy Forum SL, 2000
11.   New Scientist, 6th January, 1977
                       ENERGY EFFICIENT BUILDINGS


                                  Solar Energy Unit
                              Sri Aurobindo Ashram
                               Pondicherry 605002


    Amongst the six principles of the newly emerging trends of Green Architecture,
first three concern with energy namely conserving energy, working with climate
and minimizing consumption of resources without compromising building quality in
terms of its durability and liveability. Energy is a major factor right from predesign
choices through the complete life cycle of buildings. As such energy constants of
building materials must be reduced drastically and the design, planning of
buildings and their layout have to make fuller use of natural resources of energy
for comfort and reduce demands on transportation energy. This paper is a non-
comprehensive overview of this fast growing area at research and pioneering
design levels. Ecorating of building materials, fittings and appliances are meant to
address the problem of energy content and efficiency of buildings at engineering
level. Design integration to ensure coupling of knowledge base with conceptual
and strategic choices for evolving functional buildings is still not main stream
practice but is gaining momentum. This paper touches some of these aspects and
postulates that a reduction by a factor of 2 in non-conditioned buildings and by a
factor of 4 in airconditioned buildings is an achievable target within the first
decade of the new millenium.


   Inspite of the fact that quality of buildings is a definitive marker of
development and almost quarter of the national energy budget is spent in
production of materials of construction in Developing Economies, systematic
studies of energy in buildings and its impact in design practice has lagged behind
the corresponding advances in agriculture and industry. Factor 4 in industry and
factor 3 in agriculture are the accepted reduction targets in industrialised countries
on a life cycle basis. Factor 2 reduction in buildings is a reasonable target
without involving major
investments in newer technologies of manufacture or construction. Energy
conservation, working with climate and reducing Resource intensity per unit area
of building are still very essential [1]. These have to become the watchwords of
Energy efficiency in the mainstream design of buildings, neighbourhoods and


   Energy is expended in five stages in buildings :
 Embodied energy in materials of construction.
 Energy during construction depending upon layout, structural system, site
   organisation and project programming.
 Operating energy for services like environment control, lighting, hot water
   depending upon appliances efficiency and life style.
 Maintenance and replacement energy depending upon quality of construction
   and care in handling.
 Energy for demolition, recycle and salvage value.
   Each one of these factors have to be looked at and cannot be attended upon
by professionals or technology alone. A culture has to be created involving users,
managers and builders as well.


   Energy in buildings has been studied and sought to be applied in design in the following
five ways over the last fifty years. A broad review of the concepts has been described by
Sodha etal [2] and an overview of the principles and realisations on the ground has been
detailed by Gupta [3]. The approaches are:

   Solar architecture using or excluding Sun’s radiation with the help of devices
    such as porous screens with dripping water on fenestration or roof deck, sun
    control louvres or domestic solar water heaters or SPV lights requiring no
   Energy conscious buildings using materials of construction with lower energy
    constants, lowering of operating energy by proper orientation and envelope
    parameters such as insulation, window design, ceiling height, exterior finishes
    and microclimate modification by landscaping, clustering, radiation shielding
    and outdoor sprays or earth berming.
   Solar passive buildings using sun and wind caused temperature difference
    across the façade as driving potential to collect, store and distribute energy in
    internal spaces through conduction, convection, radiation or evaporation.
    Trombe wall, attached green houses, skytherm system, night ventilation and
    passive down draft cooling towers are some of the design options.
   Smart buildings are comparatively new arrivals and use climate actuated
    controls for adjusting daylight and comfort temperatures primarily in public
    buildings so far.
   Green buildings use all the above and onsite power generation, waste
    recycling, water harvesting and appliance efficiency primarily for group housing
    or eco-communities [4].


    Traditional solutions in terms of low rise, low density heavy buildings are no
longer valid because of land costs, increasing population and shortage of building
materials. However, traditional respect for environment coupled with newer
scientific developments in building materials, structural design, comfort studies,
public transportation, decentralised utilities and energy efficient appliances are
going to generate newer and more sustainable solutions. Energy supplies per
capita cannot go on increasing because of serious implications for pollution,
climate change and resource depletion. Ecorating of building materials, fittings and
appliances are meant to address the problem of energy content/demands in the
context of buildings at engineering level. Design integration to ensure coupling of
knowledge base with conceptual and strategic choices for evolving functional
buildings has yet to be mainstream practice. This is not easy either as is shown in
the matrix of interacting factors for sustainability[Fig.1], wherein energy is only
one aspect of a formidable list of paramters to be considered for a useable


       Low energy building materials

Compressed earth stabilised bricks or fired bricks produced in efficient vertical
kilns along with MCR tiles, ferrocement channels or stone slabs cut down costs as
well as embodied Energy of buildings. Tables I & II show the case of fired bricks and
energy content of a house in Auroville [5]. The basis for ecorating of materials is
derived by Geeta V.etal in [6].

     Change of Set Temperatures

        Simple strategy of changing Set Temperatures in conditioned buildings can
        offset plant capacities and peak demands by 15 to 20 percent. Variable comfort
        standards can still be met by increasing air movement through use of efficient
        fans during summer in airconditioned buildings and increasing of clothing in
        winter. These have significant energy saving implications for commercial
        buildings in tropics. Fig.2 due to Sozkolay shows the comfort zone as a
        function of climate based on the Aulicieum Equation [7] along with control
        Potential Zones for various climates.

     Solar Passive Systems

        Use of solar passive heating /cooling technologies can reduce design loads in
        conditioned buildings. Considerable amelioration of discomfort in
        nonconditioned buildings can be achieved by efficient design without
        increase of energy as shown in Table III by S.Prakash [8]. Range of climatic
        conditions that can be handled by various passive technologies is shown in
      Networking

Networking of near energy autonomous eco-communities reduce energy demands
   for services and intracity transportation. For urban type of satellite cities or new
   campus communities, this can be the new paradigm of planning as it can save
   upto 25 percent of energy normally spent In intracity commuting.

                                CONCLUDING REMARKS

   In conclusion we can see that there is no limit to fostering sustainable solutions specific
to sites and needs, which by definition would be low cost, low energy conscious designs.
Energy for full life cycle of a building can be reduced by a factor of `2’ without major
investments just by conscious design and by a factor of `3’ to `4’ with change in
technologies of manufacture, construction, management and increased enduse efficiency.
To give a preview of pioneering developments, Fig.3 from [9] and [10] show what is
current for domestic and commercial buildings in India. Fig.4 shows the latest building
plan for London which gives a factor `2’ reduction from the current best practice and of
factor`4’ from normally designed buildings [11]. Existing byelaws with reference to energy
aspect of buildings have been reviewed by Prajapati etal [12]. This is a prerequisite to
widescale practice which is now long overdue. The earliest energy efficient building in
modern idiom was in 1940 (Golconde in Pondicherry) but it did not create a movement
inspite of Chandigarh and India International Centre.


1. Brenda and Robert Vale, Green Architecture, 2nd Ed., Thames and Hudson,
2. M.S.Sodha,R.L.Sawhney and N.K.Bansal, Passive heating and cooling
   Energy Technologies,1-27,U.K.High Commission, New Delhi,1997.
3. C.L.Gupta, Solar passive buildings for developing countries, Engg. Sc. Trans. of
   Indian Academy of Sciences, Sadhna 18 (1), 77-104, 1993.
4. Anupama Kundoo, Eco-community planning, chapter 5, in Renewable Energy
    Basics and Technology, supplementary vol.,Solar Agni, Pondicherry,1999.
5. A.Kumar,V.Geeta and K.R. Lakshmikanthan, Cleaner brick production in India,
    a cross sectoral initiative, Basin News,18, 11-14,1999.
6. A.Kumar and V.Geeta, Reversing the downward spiral, Development
    Alternative Monograph, pp.85, 1999.
7. S.V.Sozkolay, Climate analysis based on the psychometric chart, Ambient
    Energy,7(4), 171-82,1986.
8. S.Prakash, Life style and energy conservation, Renewable Energy
    Technologies, pp.85, U.K. High Commission, New Delhi, 1997.
9. Cdr.Sharma, Ease, (Pvt.Communication).
10. Abhikram and U.Chauhan, Rites of Initiation (Torrents Research Centre),
    Indian Architect and Builder, 11(11),22-30,1998.
11. Anon. A news item in Spectrum, British Council, New Delhi,1999.
12. J.Prajapati, R.Hazra and J.K.Nayak, A review of the building byelaws of a few
    selected cities in Western India vis a vis solar passive effects, SESI Journal,9

                                          1                        2       3
 Energy MJ Brick                        5-11                      4.2      2.0
 Tons Co2                                565                    290(226)   113
 10 Bricks
 Rs./GJ of Energy Product                120                      400      600

1. RK - Rural Kiln (clamps)
2. BK - Bulls Trench kiln
3. VK - Vertical Shaft kiln (adapted from Chinese Technology)
4. ( ) - Best Practice

                             Wire Cut Bricks      Country Fired      Compressed Earth       Rammed
                                 (WCB)               Bricks               Block              Earth
                                                        (CFB)              (CEB)              (RE)
    Weight of Brick(cm) +     23X11X7.3 =        20.5 x 10 x 6.3 –   24 x 24 x 9 = 5.18   (Cast in situ)
    Volume                      1.95 lt.              1.29 lt.               lt.
    Weight of Brick           3.4 kg = 1750       2.2 kg = 1700        9.6 kg = 1850       1850 kg/m3
                                  kg/m3               kg/m3                kg/m3
    Utilization                    Fire                 Fire            5% Cement                 -
    Per Unit on site             Rs.2.00             Rs.1.05              Rs.3.90
    Percentage                     4%                   15%                 5%                    4%
    As per m (raw                  513                  774                 193                   -

    Tar used                 1 Cement 6 Sand     1 Cement 6 Sand     1 Cement 6 Sand 6            -

    Of Mortar / m2 of Wall      61 lt./m2            72lt./m2            26 lt./m2                -
    As per m of wall         87 (with 1.5 cm     112 (with 1.5 cm    40 (1 cm mortar)             -
                                 mortar)             mortar)
    Output per team          350 B = 3.65 m2      500B = 4.46m2       170B = 4.25 m2          8 m2
    Pointing Output (m2            4m2                  4m2                 5m2                   -

    Of 1m3 of raw material     Rs.1065/m3           Rs.935/m3             790/m3           Rs.790/m3
    including the waste
    Of mortar per m3           Rs.1220/m3          Rs.1220/m3           Rs.645/m3                 -
                    3                       3                   3                    3
    Of wall per m              R.1740/m            Rs.1395/m            Rs.1105/m          Rs.790/m3
    Of wall per m2             Rs.400/m2            Rs.286/m2           Rs.265/m2          Rs.185/m2
                              (23 cm. Thick)     (20.5 cm. Thick)      (24 cm.thick)      (24 cm. Thick)

    Emission (CO2)*             39 Kg/m2            126 Kg/m2            16 kg /m2          16 kg/m2
    Energy Consumption         539 MJ/m2           1657 MJ /m2          110 MJ/m2          110 MJ/m2
    Energy Crushing            (±) 90-120           (±) 30-40        (±) 40-60 kg/cm2       (±) 40-60
    Strength                     kg/cm2              kg/cm2                                  kg/cm2
    Water Absorption             9 –11%             10 – 14%              9 –11%            8 – 10%


 Source: Development alternatives, New Delhi – 1998               Value August 1999: 1 US $ =
± 42.5 RS.
Dry fired brick is also called village brick                      Wire cut brick is also called
kiln-fired brick.
Materials cost includes the delivery on site. The CEB price is the production cost on site. All
the costs are cost price.

700 Rs./4.5m3 lorry      Mason        = 110         Team for bricklaying = 1 mason, 1 helper,
175 Rs./m3 sieved sand   Rs./day                    1amma
                         Helper       = 55          Team for rammed earth = 5 coolies
Rs. 40 m2 dug & sieved   Amma         = 40          Team for CEB making = 9 block makers
soil                     Rs./day
Cement = 177 Rs./bag     Coolie       = 60          Team for pointing = 1helper
(T – 53 Grades)          RE Coolie   = 65 Rs/day
                         Block maker = 65 Rs./day

        Building Type                      A                     B                  C
                              Fully conditioned building   Hybrid building     Unconditioned
                                   Today  Target          Today  Target        building
                                                                              Today  Target
 Peak diversified installed
 electrical load (W/m2)               150  50                30  10             10  4

 Average electrical energy
 consumed (kWh/m2 year)               300  75                 60  8              84

B: Hybrid building – e.g. Having evaporative cooling

      Ideal is to upgrade comfort without increasing energy e.g. Type C today can become
Type B target.

                                        F.D. Heidt

              Group for Building Physics & Solar Energy, Dept. of Physics
                     University of Siegen, 57068 Siegen, Germany

KEY WORDS: Low energy architecture, passive-solar architecture, software tools, multimedia
presentation, thermal simulations, energetic retrofit of buildings.

      This paper emphasizes the importance of high-quality software to improve the efficiency
and quality of energy-related planning for new buildings and the energetic renovation of
existing buildings as well. Two software products are presented in more detail which are
especially designed for these applications. NESA stands for “Niedrig-Energie-Solar-
Architektur” (which means “Low-Energy-Solar-Architecture”) and aims at the widespread
dissemination of knowledge on the energy-related and solar design of new buildings. RESA
is an acronym for “Ratgeber für Energetische Sanierungen” and describes a software tool
which was developed to give sound advice for the energetic renovation of existing buildings.


      Low energy solar architecture and the energetic retrofit of buildings are equally
important issues to reduce the thermally required energy consumption and thus the
environmental impact of buildings. For this reason software is developed to advise architects
and civil engineers on energy and building related issues. Two programs shall be presented
      The database NESA describes in a multimedia way low energy and solar architecture in
Germany. NESA aims at improving the dissemination of knowledge about passive solar and
energy conscious design. The amount of presented information and its easy handling make
NESA equally useful for both consulting and education.
      RESA aims at the very important and huge potential of energy saving by renovation
measures in existing buildings. It is intended to advise people how to choose and
coordinate the best actions from the large variety of possibilities. RESA offers maximum
support in the whole process of energetic retrofit even for inexperienced users.
      Both programs refer mainly to cold or moderate climatic conditions as they prevail in
Mid-Europe where heating of buildings is the major task ad cooling is required for a couple
of days only. These climatic conditions, however, are responsible for the most important
contribution of the world´s energy consumption in buildings.
      Independently from this observation, the main emphasis of this paper lays on the
importance of software which is - together with its multimedia facilities – an almost
universal tool for information, education, training, design, planning and evaluation.


Purpose of NESA

      The effective use of solar energy and energy saving measures can drastically reduce
the demand of heating, cooling and lighting energy required for conditioning buildings.
Experiences on passive solar and energy conscious design are well-known but not at all
widespread. In almost every country, however, there are many examples of diverse
buildings - residential, commercial or institutional - where energy saving and solar
concepts have successfully been realized. It is the purpose of this work to improve the
dissemination of related knowledge by means of modern multimedia software.
                                                                    In this context indication of
                                                              the building´s energy per-
                                                              formance is a sectional aspect
                                                              only. It must be put in relation to
                                                              the whole architectural concept
                                                              including visual aesthetics,
                                                              integration into surroundings
                                                              and landscape, functions of
                                                              rooms, constructional details,
                                                              material selection, techniques of
                                                              building services and many
                                                              others. The multimedia program
                                                              NESA compiles information
                                                              related to these different aspects
                                                              of a building under the
                                                              development environment Tool-
Figure 1.       Photos give a first impression of the               Up to now twenty German
described houses.                                             houses are included in the
                                                              database. Much more examples
- residential, commercial and institutional buildings - shall be added so that finally a repre-
sentative electronic picture-book of passive solar and low energy architecture will exist.
Additionally the example buildings can be modified within the program. Hereby it is
possible to generate own projects, compare them to given ones and perform several
related analysis tasks such as energy analysis and shading calculation.
      The goal of NESA is to assist
architects, engineers and energy
consultants, specialized workmen and
potential building clients to get a
comprehensive survey and better
understanding of concepts and
practice of passive solar and low
energy buildings.
      NESA was developed at the Uni-
versity of Siegen in close cooperation
with Prof. Willi Weber ad his team at
CUEPE1, University of Geneva. They
created almost simultaneously the
analogous program DIAS (Données
Interactives d´Architecture Solaire) for
regions in Switzerland [1, 2, 3, 4].
                                           Figure 2.    The embedded plans give ideas for
Description of NESA
                                           own projects and serve as guides to activate
                                           further photos of a building by simply clicking with
     NESA uses photos, drawings,
                                           the mouse.
computer animated sequences and
hyperlinked text for the presentation of
exemplary buildings, visualization of information and dissemination of knowledge.
    Objects
     NESA visualizes twenty low energy and solar houses in Germany with detailed
explanations by means of photos (see Figure 1), ground plans for each level (see Figure
2), elevations, conceptual and detail drawings. These examples show passive solar
                                                         energy use, solar heating systems
                                                         and systems for heat recovery.
                                                         Also buildings with photovoltaic
                                                         equipment for electricity supply and
                                                         a single family house with
                                                         complete and exclusive solar
                                                         energy supply are demonstrated.
                                                              Maps
                                                               A survey map shows the
                                                         geographical positions of the
                                                         included buildings. Details of city
                                                         maps illustrate the urban space
                                                         where these buildings are situated.
                                                         Climatic maps present the regional
                                                         distribution of solar radiation and
                                                         ambient temperature in Germany
Figure 3.     Solar potential of distinct regions of (see Figure 3) for summer and
Germany is highlighted on a climatic map. A survey winter conditions. Moreover, the
map shows the sites of all buildings included in the program NESA includes the
database.                                                corresponding data bases.

                                                                  Calculation Tools

    CUEPE : Centre universitaire d´étude des problèmes de l´énergie
      NESA calculates for
the described buildings or
for user-defined projects
e.g. heat transfer
coefficients (U-values),
the risk for and amount of
water condensation in
walls, detailed monthly
energy analyses
presented by bar-charts
or as a seasonal Sankey
diagram for all heat gains
and losses. Input of data
into NESA is supported
by intuitive graphical
schemes (see Figure 4).
The program determines
further the heating
demand according to the        Figure 4.    Intuitive graphical schemes support the input of
German WSVO from               data. Data from buildings included in the database may be
1995 as well as fuel           loaded and edited.
demand. Even the effects
of shading by external overhangs can be presented by animated graphical illustrations as
well as by tables.
           Encyclopedia
      An encyclopedia contains keywords and terms related to solar architecture, low
energy houses, heating demand and technical equipment for buildings. It includes
definitions, equations, units, drawings, descriptions and references. All of these
information packages serve as a help for program users leading them to better
understanding as well as to topics for further reading and investigation.
                                 RETROFIT ADVISOR RESA
Purpose of RESA

      For a long time to come, the major part of the total energy requirements for space
heating will be consumed in buildings that already exist today, not in those to be erected in
the future: For existing buildings in Germany, the mean specific heating energy demand is
something more than about 200 kWh/(m² a), and most of them will still be occupied for many
years. New buildings constructed according to the German WSVO from the year 1995 are
supposed to require less than half of this heating energy. Progress in energy efficient
buildings is going strong, so newly constructed buildings are about to use only a small share
of the country's total heating energy demand. Energetic retrofit is therefore an important

  WSVO stands for “Wärmeschutzverordnung” and means the thermal standard of
buildings which is required by law.
      The potential of energy saving measures in existing buildings is considerable. Insulating
walls and replacing leaky windows does not only save energy, it improves the occupants'
comfort, too. Many retrofit measures are even economically reasonable.
                                                            For home owners, private as well
                                                      as public, it is difficult to assess the
                                                      possibilities for energetically renovating
                                                      their buildings. Usually, they will need
                                                      professional help, e.g. from specialized
                                                      engineers. Working out a set of
                                                      appropriate retrofit measures for a
                                                      specific object takes some time and thus
                                                      may quickly become expensive.
                                                            The aim of RESA is to offer support
                                                      in respect to this matter. With RESA, it
                                                      will be possible to determine an overview
                                                      of sensible retrofit measures for a
                                                      particular building within less than two
                                                      hours. The program output includes a set
                                                      of retrofit measures, the determination of
                                                      related costs and the energy savings to
                                                      be expected.
                                                            RESA has the ability to calculate
                                                      the heating energy demand of a given
                                                      building according to the Swiss SIA3
Figure 5.        Drawing the ground plan and the 380/1 or, optionally, to the German
elevation creates the 3D-building. All surfaces WSVO from 1995. It knows the heat
can be selected with a mouse-click and its transfer properties and the costs of
properties can be loaded from an appropriate renovation measures from an attached
data base.                                            database and is able to determine a
                                                      ranking of these measures. The program
is easy-to-use; no special training is required except for a basic knowledge about energetic
retrofit [5, 6, 7].
Building input

      The first step of planning an energetic retrofit is to enter the building in its current state,
i.e. walls, windows, roofs, floors and heating system together with their relevant properties.
The dimensions of the building must still be taken from a plan or from direct measurements,
but RESA offers considerable support in determining the other data required: Areas of walls,
ground floor, ceiling, roof parts as well as the building´s volume are calculated automatically
whenever the drawing of the building on the PC-screen has been completed (given by
ground plan and elevation). Then the building is presented as 3D-body which can be rotated
arbitrarily in space. For Germany, the climate of the building site can be derived from the
post-code or a climatic map. All building components (walls, windows, floors, ceilings, roofs)
and the heating system are chooseable from corresponding databases with common
constructions or technical performances. The relevant properties are transferred to the input
forms of the program by means of a mouse-click only (see Figure 5). By this way the required
input of data to run the program RESA is done in a very fast and effective manner.

 SIA is the abbreviation of “Schweizerischer Ingenieur- und Architekten-Verein” which
means “Swiss Association of Engineers and Architects”.
 Retrofit suggestions

       Once the input process is finished, the
 energy demand for heating the existing
 house is calculated within a few seconds,
 and results can be presented in various
 forms and diagrams. One of them is a
 seasonal Sankey diagram (see Figure 6)
 showing energy gains and heat losses
 through different possible paths.
       RESA is now able to figure out
 automatically the best set of energy-related
 renovation measures depending on several
 optimization criteria. Examples for them are
 maximum energy savings with a given
 amount of money, minimum costs for a
 postulated amount of energy savings,
 maximum cost efficiency for a given number      Figure 6.      A Sankey diagram displays all
 of operation years, maximum energy              kinds of energy supply and energy losses for
 savings obtainable without any financial        the investigated building.
 restriction For every building component,
 RESA searches in another database for ap-
 propriate renovation measures, calculates the respective costs and the amount of saved
 energy and determines the best of the variants. Similarly as for the existing building, results
                                                            for every renovation measure are
                                                            presented by diagrams, They
                                                            compare with the status quo.
                                                            Together with the corresponding
                                                            financial informations this makes it
                                                            easier to estimate and rate the
                                                            suggested measures (see Figure
                                                            Other aspects

                                                                       To a large extent, the
                                                                 determination of retrofit sug-
                                                                 gestions can be influenced by the
                                                                 user of RESA: If, e.g. for reasons
                                                                 of protection of monuments, the
                                                                 façade of a building must not be
                                                                 changed, a corresponding option
                                                                 can be activated. Building compo-
                                                                 nents that one wishes to preserve
Figure 7.      Comparison of energy balances between
                                                                 may totally be excluded from the
the existing building and a planned renovation measure
                                                                 process. Renovation suggestions
by means of seasonal bar charts illustrate the
                                                                 can be selected manually as well,
relevance of this measure.
                                                                 starting either from the original
                                                                 building or from the automatically
 generated renovation suggestions. To this aim, RESA places its retrofit database at the
 user's disposal.
       The relatively complex process of energetic retrofit may lead to a diversity of solutions.
 In order to facilitate the choice of the best solution in each individual case, a means to store
and compare several different variants of retrofitting the same building is integrated. Reports
containing a description of the existing building, the suggestions for retrofits, energy savings
and other informations can be printed out as well.
                                 SUMMARY AND OUTLOOK

      The multimedia database on passive solar and low energy architecture in Germany
NESA is well suited to give a comprehensive survey and better conceptual understanding
of this field of architecture, building physics and engineering [8]. NESA includes illustrative
examples of buildings, contains a broad range of related information and allows the user to
perform many types of calculations for built-in examples and own projects. The integration
of further building examples within an European context is planned and under preparation
[9]. NESA is easy to use and therefore adapted to broad-range application as information
and instruction tool [10].
      The adviser for energetic retrofit RESA is intended to support people concerned with
the renovation of existing buildings. Help is offered in the survey of the existing building, the
determination of the heating energy demand and the choice of appropriate renovation
measures. User-defined optimization criteria for the automatic determination of a ranking of
retrofit measures and the possibility to manually adapt the results to the circumstances of the
individual case give the program enough flexibility for practical use; nonetheless the user
needs only a basic knowledge about energetic retrofit in order to handle the program.
Currently, RESA is tested by a large housing company under the conditions of practice.
Feedbacks from there will be incorporated into the program. Final results and experiences
will be disseminated by professional further education.
      In conclusion: Modern software has become – especially in combination with
interactive multimedia facilities – a very powerful tool to educate, train and qualify people
which are working in this field. Moreover, this software can significantly contribute to the
enhancement of quality assurance and working efficiency.


      The author wishes to thank the Ministry of Science and Technology of North Rhine-
Westphalia, Germany, for the support of this project under Contract No. 253-011-91 (AG-
Solar NRW). He is further indebted to Prof. W. Weber and P. Haefeli at CUEPE, University
of Geneva, and to all the builders and architects who readily let their buildings be
presented in the NESA program. He also thanks Dr. H. Drexler for his continuous
contributions to develop NESA, Dipl.-Phys.-Ing. J. Groß for his part in programming the
first RESA code as well as his group members Dipl.-Phys. S. Benkert, Dipl.-Ing. K.P.
Büchler and Dipl.-Phys. A. Eicker for their steady work to further develop ad improve the
existing software.

[1] W. Weber, H. Drexler, P. Gallinelli, P. Haefeli, B. Lachal, D. Gonzalez: DIAS
    Interactive Database on Solar Architecture - PEM Pascool Electronic Metahandbook,
    Conference Proceedings, Solar Energy in Architecture and Urban Planning, 4th
    European Conference (1996), Berlin, pp. 201…204.
[2] F.D. Heidt, T. Braeske, H. Drexler: NESA - an innovative multimedia software
    presenting examples of passive and low energy architecture in Germany, Conference
    Proceedings, Solar Energy in Architecture and Urban Planning, 4th European Confe-
    rence (1996), Berlin, pp. 193…196.
[3] T. Braeske, F.D. Heidt: Innovative software for education and visualization of passive
    solar and low energy concepts, Proceedings PLEA 96, 13th International Conference
    on Passive and Low Energy Architecture, July 16th...18th 1996, Louvain-la-Neuve,
    Belgium, pp. 51…56.
[4] S. Benkert, T. Braeske and F.D. Heidt: Presentation of passive solar and low energy
    architecture in Germany by multimedia software. Proceedings EuroSun '96, Sept.
    16th...19th 1996, Freiburg, Germany, pp. 964...969.
[5] J. Groß:Bilanzierung und Optimierung der Wärmeflüsse in einem Gebäude mit einem
    Computermodell. Diploma thesis, Fachbereich Physik, Universität-GH Duisburg and
    Fachgebiet Bauphysik und Solarenergie, Universität-GH Siegen, 1995.
[6] T. Braeske, F.D. Heidt and J. Schnieders: Software to assess energy performance and
    energy savings economy in buildings. Proceedings EuroSun '96, Sept. 16th...19th 1996,
    Freiburg, Germany, pp. 976...982.
[7] A. Eicker, K.P. Büchler and F.D. Heidt. RESA - An advisor to retrofit buildings.
    Proceedings of CISBAT´99, Sept. 22 - 23, 1999, Lausanne, Schweiz, pp. 419-422.
    Laboratoire d´Énergie Solaire et de Physique du Bâtiment, EPFL, CH - 1015 Lausan-
[8] S. Benkert and F.D. Heidt.: Knowledge Transfer for Low Energy and Solar Architecture
    by Software. Proceedings of CISBAT´99, Sept. 22 - 23, 1999, Lausanne, Schweiz, pp.
    423-428. Laboratoire d´Énergie Solaire et de Physique du Bâtiment, EPFL, CH - 1015
[9] S. Benkert and F.D. Heidt: The European project IDEA for dissemination of knowledge
    on low energy and solar architecture. Environmentally Friendly Cities, Proceedings of
    15th International PLEA Conference, May 31 - June 3, 1998, Lisbon, Portugal, pp. 645-
    648. E. Maldonado and S. Yannas (Editors), James & James Science Publishers Ltd.,
    London.Error! Bookmark not defined.
[10]S. Benkert und F.D. Heidt: Software für die Wissensvermittlung zur Niedrigenergie-
    und Solararchitektur. In: U. Beck und W. Sommer (Hrsg.): LEARNTEC 99, 7.
    Europäischer Kongreß und Fachmesse für Bildungs- und Informationstechnologie,
    Tagungsband, 1999, S. 313 - 318. Schriftenreihe Karlsruher Kongreß- und
    Ausstellungs GmbH, Postfach 1208, 76002 Karlsruhe.
                              ADMINISATRATION BUILDINGS

               *Institute for Energy– and Environmental Process Engineering,
                                  Technical University Munich
                        Boltzmannstr. 15, D-85747 Garching, Germany
                     Tel. 0049(0)89-28915713, Fax: 0049(0)89-28915714
                e-mail: /


The subject of the lecture are buildings with double-skin-facades which are mainly used
   for high rise buildings such as the planned administrative building of the National
   Bank in Bratislava and the most important head quarters in Germany. Due to a
   second facade layer with optimal air in- and outlets in front of the primary facade, this
   type of facade construction enables natural ventilation by means of opening the
   windows even for high rises which are in general completely air-conditioned because
   of extremely high wind loads on the building. By using renewable energies such as
   solar and wind energy the total energy consumption for heating and cooling may be
   reduced up to 30 %. The most suitable geographical regions for the realization of
   these double facade systems are e.g. Scandinavia and Central Europe or in general
   areas north of the 45 th northern parallel. A classification of typical double-skin
   facade constructions is given as well as a short overview about the possibilities to
   integrate solar energy using components such as solar air heaters and photovoltaic
   devices for air conditioning and ventilation. Furthermore the advantages and
   disadvantages of the different double-facade systems are discussed. The results of
   an ongoing experimental study of several facade systems will be presented at the
   end of the lecture.

   Famous architects like Sir Norman Foster, Ian Peterson, Horst Ingenhoven and
   Günther Henn, but also the investors of high rise office-buildings and even HVAC-
   engineers (heating, ventilation and air-conditioning) recently are taking into account
   more often the application of so called double-skin facades in high-rises claiming to
   fulfill ecological and corporate-identical demands.
   This type of facade is characterized by a second translucent glass facade layer
   („second skin“) in front of the building protecting it against bad weather conditions
   such as strong wind, rain, hail and last but not least against noise. The development
of these facade systems was initiated by the dissatisfaction of the users of fully air
conditioned office buildings complaining about headache, nausea, tiredness and
allergies caused by the well-known “sick-building syndrom”. Installing a second
facade layer beeing partly air permeable by means of different gaps and openings
between the panes of glass or at the bottom or at the top of the building (compare
chapter 2), natural or free ventilation by opening the windows can be made possible
due to reduced wind pressure even in high-rises. This was the starting point for the
development of several double-skin-facade systems during the last 10 years
described in the following section.
In Germany many office buildings with double skin facades have been erected during
the nineties. Most of them near highly frequented urban highways such as in Berlin,
Düsseldorf, Cologne, Essen and Frankfurt because another reason for their
application is the positive noise reduction performance (compare chapter 3). The first
building in Slovakia probably using this new facade-technology (Box-window or
twinface system) will be the National Bank in Bratislava (see figure 1).

The different constructions of double-skin facades which were developed during the
last ten years can be classified into 5 main-systems. The distance between the
primary (inner) facade and the secondary (outer) facade in general varies from 0,3 m
to 2 m. Apart from system (b) all systems are only using natural forces to induce the
air flow in the gap like the stack effect (free convection) due to solar radiation and the
pressure difference at the building due to wind effects:

      Figure 1: General view and ground plan of the National Bank in Bratislava

    (a) Unsegmented curtain wall facade
This type of double-skin facade is the most simple one. It may be identified by an air
gap between primary and secondary facade without showing any vertical or
horizontal subdivisions. The air in- and outlet for ventilating the spacing are locate at
the bottom and at the top of the building. The second skin itself does not have any
additional gaps for air infiltration. In some cases the air in- and outlets can be closed
to create a „air cushion“ of preheated air around the building in winter. Figure 2
   illustrates a schematic view of this type. The administrative building of the assurance
   company „Deutscher Ring“ in Hamburg, Germany (see figure 3) was one of the first
   buildings applying this kind of double-skin-facade.

   Figure 2: Scheme of a            Figure 3: Administrative building of the assurance
   unseg-mented        curtain      company „Deut-scher Ring“ in Hamburg.
   wall facade
(b) Circulation-facade
   This system of a double-skin-facade is characterized by horizontal subdivisions
   occuring every second storey of the building with controllable in- and outlets for the
   air at the bottom as well as at the top of each section that can be closed (winter) or
   opened (summer). To force a horizontal air-circulation in the gap around the whole
   building there are several ventilators installed at each corner of the building. By
   means of an intelligent control system adjusting the air mass flow, the temperature
   difference between the south-orientated and the northern facade can be limited down
   to 3-5°C. Figure 4 shows a schematic view of this system which until today was only
   realized at the Headquarter building of the Götz GmbH in Würzburg (figure. 5) – a
   good example where the double-skin-facade was integrated in the HVAC-concept of
   the building.

       Figure 4:                    Figure 5: Headquarter of the Götz GmbH, Würzburg,
   Circulation-facade               Germany

(c) Corridor-facade:
   This double-skin-facade is quite similar to the above mentioned Circulation-facade.
   The horizontal separations occure after each storey so that a kind of corridor is
   created with air entrances and outlets on the bottom and on the top of the floor.
   Starting the development of this type the air entrances and outlets were arranged on
   top of each other so that the exhaust air of one floor was the „fresh air“ for the storey
   above (recirculation). In the meantime they are staggered in such a way that the
   recirculation-rate can be reduced to 30 % (so called diagonal ventilation). Figure 6
   illustrates the fundamental functioning of this system and the principle air-movements
   . The Citygate (Stadttor) of Duesseldorf (see figure 7) and the office building at the
   Halensee street in Berlin (Fig. 8), both situated next to busy urban highways, are
   some of the most famous double-skin-facade buildings recently finished in Germany
   applying the corridor-system.

(d) Box-window-facade:
   This double-skin-facade system is characterized by a separation of the cavity in both
   directions. By means of horizontal subdivisions after each floor and vertical glass-
   lisens in each window axis the cavity is divided into socalled „box-windows“. This
   system is ideal to be realized by a cheap modular element construction. Each box-
   window is provided with an air entrance and outlet at the bottom and at the top of the
   floor. Combining two of such units enables to realize „diagonal ventilation“ of the
   cavity as mentioned above and shown in figure 9. Not only because it is cut out to be
   realized by an easy and cheap element construction this system is the most common
   one. Compared with the systems mentioned before its big advantage is the reduction
   of sound and smell transmission from one office to another. This system was also
   applied at the Headquarter of the RWE in Essen (figure 10) and of the Victoria
   Assurance in Duesseldorf (see figure 11). Latter one using vertical air inlets on both
   sides of the box-window and a horizontal outlet minimizing the recirculation-rate
   down to 25 %.

   Figure    6:    Corridor-        Figure 7: Model of the       Figure 8: Office building
                                                                    at Halen-see street in
   facade with (right side )        Dues-seldorfer
   diagonal ventilation             Stadttor (City gate),

   Figure 9: Scheme of a            Figure             10:         Figure     11:    Victoria
   box-window-facade                Headquarter building           Assurance                ,
                                    of the RWE, Essen              Duesseldorf

(e) Twinface-facade4:
   The last and most complex double-skin-facade system consits of so-called vertical
   „ventilation ducts“ with an air in- and outlet at the bottom and at its top. For low rise
   buildings these ducts run the height of the building, whereas for high rise they only

    Twinface is a registered trademark protected Europe-wide by a patent (EP 0 467 876 A2) of
   P. Jordan
   run for several storeys (up to ten). On both sides of the ventilation ducts seperate
   box-windows are situated. Assuming high solar radiation the box-windows showing
   socalled „overflow openings“ on both sides may be vented by the duct because of the
   stack effect. The air supply of each box-window is realized by a horizontal small vent
   at the bottom, to allow the entrance of fresh air. Figure 12 illustrates the principle
   diagram and the idealized air-movements of a Twinface-facade. The Headquarter of
   the Building Society in Schwaebisch Hall (Bausparkasse Schwaebisch Hall) in figure
   13 is the highest building (35m) where the duct/box-window system was applied
   whereas the „Temple“ of the ALCO company in Muenster (fig. 14) represents the first
   building ever using this kind of double-skin-facade.

   Figure 12: Scheme of            Figure 13: Building           Figure 14: „Temple“ of
   the Twinface-facade             society                       ALCO           Systems,
                                   Schwaebisch Hall              Muenster

Among all presented systems the last one shows the highest potential for further
   development but is also the most complicated in design. Until today unfortunately
   most of the time double-skin-facades are only an additional feature of hight-tech
   buildings, which are still equipped with ordinary HVAC-Technique (fully air-
   conditioned). In future double-skin facades should be a part of the whole HVAC-
   concept of the building. Especially the last type is predestined to be used for example
   as a part of the air ductsystem where even solar air heaters may be installed (see
   chapter 4).
The application of double-skin-facades is not only limited to corporate identity
   administrative buidlings shown above but also for the refurbishment of residential
   buildings. By the installation of a second transparent facade layer the overall heat
   transfer coefficient of the building may be improved up to 30 %. The austrian facade
   manufacturer ALU-SOMMER for example has developed a double-skin-construction
   that may be installed in front of a building without interrupting the operation of the
   building. Figure 15 shows a picture of an administrative wing of the ALU-SOMMER
   plant where a conventional facade was turned into a double-skin-facade to
   demonstrate the new system.
     Figure 15: Double-skin testing facade (Twinface) of ALU-SOMMER, Stoob, Austria


All double-skin-facade systems presented above are showing to a different extent the
    following advantages, depending on the geometric design of the air in- and outlets:
1.      Natural ventilation gets possible to some extent even in high rises due to
     reduction of the wind pressure by installing a second transparent facade-layer (up
     to 60% of the operating time of office buildings). As a result the runtime of the unit for
     ventilation and air conditioning may be reduced to 40%.
2.      Improvement of the noise reduction features of the facade. Using double-skin-
     facades the sound reduction index can be improved from 28 dB (conventional
     facade) up to 47 dB. - equivalent to a reduction of two sound reduction categories.
     Even when the windows of the primary facade are open values of 30 dB could be
3.      Reduction of the energy consumption of the building in winter. Because of the
     „green-house effect“ in the additional air gap the heat losses due to transmission
     (reduced temperature difference between in- and outside) and ventilation (pre-heated
     incoming air) may be reduced up to 30%.
4.      Weather protected installation of shading devices in the gap between primary
     and secondary facade followed by reduced investment and lower expenditures for
     maintenance (Protection against mechanical demolition by storm and hail).
5.      Reduction of the cooling load of the building in summer compared with
     buildings showing shading devices which are installed inside the office (avoiding
     secondary heat gain).
6.     Natural cooling of the building during night-time by opening the windows
   because of
7.     Improved protection against burglary. The secondary facade in general consits
   of a burglar-proof 10 to 12 mm single thickness security glass
8.     Decentral or central heat recovery in combination with natural ventilation
     (central heat recovery especially for type e of the double-skin-facade systems)

     On the other side double-skin-facades are faceing the following problems:
1.      Extremely high temperatures of the air in the gap between primary and
     secondary facade in summer so that natural ventilation gets impossible and
     secondary heat gains of the office are increasing due to a heat flux from the outside
2.      Low temperatures of the air in the gap between primary and secondary facade
     in winter so that natural ventilation gets uncomfortable (draft appearance and cold air
     section in the office)
3.      No possibility for cleaning the incoming air (if working with natural convection
     and stack effect only) which is extremely relevant at highly frequented city highways
4.      Higher cost for facade cleaning (factor 2 to 3)
5.      Higher capital expenditure for installation(factor1,5 – 2 ) compared to
     conventional facades

     Half year ago the austrian facade manufacturer ALU-SOMMER (Stoob) started a
     project in cooperation with the Technical University of Munich to gain more
     knowledge about the function principles of the complex Twinface-facade. One goal of
     the theoretical and experimental studies is to compare the effects on the indoor
     climate of a conventional facade and a double skin facade The testing facade itself
     (fig. 15) and the offices behind were equipped with metrology recording above all air-
     and surface temperatures, humidity, air-mass flow rate and the outdoor climate.
     Furthermore the Twinface-system is going to be improved by analysing the systems
     performance in a forced convection mode in combination with the installation of solar
     components (air heaters etc.). First results are showing that the thermal and hygienic
     problems described above may be solved or minimized by using ventilators within the

   Installing a transparent second facade in front of a building already means to turn the
   shell of the building into a kind of air heater (greenhouse effect, radiation trap).
   Therefore the gap and the secondary facade itself are cut out for the integration of
   solar energy using components like photovoltaic (PV) modules for electricity
   production (secondary facade) as well as solar thermal components such as air
   heaters (i.e selective absorbers) or different kind of water-collectors for solar heating
   and cooling purposes. The installation of solar energy using components makes it
   possible to reduce the conventional energy input for heating and air conditioning of
   the entire building by one third at least.
   Special air heaters such as matrix collectors consisting of blackened metal wire mesh
   can heat up the air to such an extent that this preheated ambient air can be used as
   air supply for the building in wintertime (figure 16). In summer this matrix absorber
   may be used as a shading device in front of the windows. By means of three different
   layers the transparency can be easily adjusted by the user (figure 17)
Even PV-modules may be used not only for electricity production but for shading (see
   semitransparent modules in figure 17) or for preheating the ambient air
   (hybridmoduls). Furthermore ordinary absorbers may be installed in the
   nontransparent sections of the building to improve the stack effect and to heat up the
   air that may be led to a heat exchanger in summer (hot water production) or may be
   used for a central or decentral air supply of the building in winter. If a stationary
   shading device is required even these components may fulfill this purpose.

   Figure     16:    Single     functional
   application of solar energy using
   Figure 17: Multifunctional application
   of solar energy using components
By means of special vacuum-tube collectors in the secondary facade, replacing the air
inlets and partly the glass panes, hot water of about 110°C may be produced. In winter this
water may be used for a hot water heating system whereas in summer it may serve to run
decentral absorption cooling units of about 4kW cooling capacity installed in the offices.
At the moment the energy potential of all these components and some of their technical
and architectural possibilities of integration are determined by the authors at the Technical
University in Munich. First results will be presented in summer 1999.
Double-skin-facade constructions are showing a lot of advantages but should not be
applied for each office building. Especially for high rise and administrative buildings near
busy urban highways they are often the best solution. Considering the enormous technical
potential double-skin facades should be integrated in the HVAC concept of the buildings in
future. There is still a big demand on further research activities to understand the complex
3-dimensional unsteady thermofluiddynamic processes within the air gap to design these
facade systems properly.

[1] J. Blumenberg, A. Zoellner:
„Doppelfassadenkonzepte in der modernen TGA/HLK- Fassadenpower nicht nur für High-
Tech-Tower.“ In: Clima Com-merce International (CCI), Offprint of Issue 4/1998, Promotor
Verlag, Karlsruhe, 1998.

[2] J. Blumenberg, A. Zoellner:
„Strom und Wärme aus der zweiten Haut-Nutzung von Regenerativenergien bei
Doppelfassaden-Gebäuden.“ In: Clima Commerce International(CCI), Special Issue for the
Constructec in Hannover, 28. Oct. 1996, Promotor Verlag, Karlsruhe.

[3] A. Kolb:
„Theoretische und experimentelle Untersuchungen an einem neuen solaren Luftkollektor
mit durchströmtem Absorber“.
Ph.D.-Thesis at the Technical University Munich, Institute C for Thermodynamics, Munich
                                   Ashvini Kumar5 and T.C. Tripathi
                                           Solar Energy Centre,
                              Ministry of Non-Conventional Energy Sources,
                                 Block-14, C.G.O. Complex, Lodhi Road,
                                           New Delhi - 110003.


      This paper discusses the solar passive programme at the Solar Energy Centre (SEC). The basic
elements of the programme are i) construction of SEC's own buildings based on solar passive
concepts, ii) monitoring and evaluation of thermal performance of these buildings, iii) carrying out R&D
to enhance utilization of solar passive concepts, and iv) providing technical consultancy for
incorporation of these concepts into the building design. Preliminary monitoring results of roof surface
evaporative cooling system installed on the roof of technical blocks are also presented. Thermal
performance of guesthouse building, which is the only residential building in the campus, is discussed
in the paper. Simulation results of a study carried out at SEC for assessing the potential of energy
savings through the use of energy efficient windows in the country are also presented in the paper.


     Weather and climate influence human health and longevity. The history of shelter engineering
reveals an unremitting effort by mankind to provide itself with an indoor climate to which man is best
adapted. Man’s preference for appropriate and controlled thermal environment is the main reason for
constructing buildings. It is well known that the buildings account for a large proportion of the overall
energy consumption of a society. With the pace of development becoming faster, the demand of
energy in new buildings that are constructed today is increasing further. The situation in developing
countries is reaching serious proportions, as the energy needs are to be met of the fast growing
population and also to sustain development. In this background, use of solar passive concepts into
the building design provides a legitimate choice to

    Fax No. 011-4363546, /
meet the occupants’ need for thermal comfort and effecting savings of conventional energy to
a significant extent.

      A quick glance at the ancient architecture reveals that it had many characteristics, which
led to thermal comfort inside the buildings. The Greeks appreciated the importance of south;
whereas the Iranian Architecture developed the concept of wind tower utilizing earth’s
coolness and water evaporation, and also exploited the concepts of clustering and thick walls.
The various forts and domes in India presents a fine example of buildings responsive to the
climate. The modern architecture, however, ignored the use of these special architectural
characteristics, till the global interests grew in the control and supply of energy. Presently,
numerous buildings [1-2] have been constructed all around the world and proved the
effectiveness and energy saving potential of these concepts, which are now called as solar
passive concepts.

       This paper discusses the solar passive programme at the Solar Energy Centre including
a discussion on the designing of its own buildings based on solar passive concepts. The
paper presents preliminary monitoring results of roof surface evaporative cooling system
installed on the roof of technical blocks and a simulated performance of the guesthouse
building. The paper also presents results of a study carried out for potential assessment for
saving of conventional energy.


     In India, the Ministry of Non-Conventional Energy Sources (MNES) initiated wide-ranging
programmes in the last two decades for the promotion of solar passive architecture. A number
of R&D projects were sponsored to various premier institutions wherein solar passive buildings
were designed, constructed and studied in different climatic zones in the country. The present
research efforts sponsored by MNES include analysis of weather data and formulation of
design guidelines, and survey of energy conscious buildings in the country. The Ministry has
also got carried out a study on the assessment of existing building bye laws with a view to
examine possibilities of incorporation of solar passive concepts into the building design.

      Training programmes are supported by MNES at various levels through out the country.
The financial incentives are provided to encourage use of solar passive concepts in public
sector buildings. The main aim of the various programmes of the Ministry is to provide training
and education, and publicity and demonstration. As a result, a number of buildings utilizing
solar passive concepts are being designed and constructed in the country. Himachal Pradesh
has taken a lead in this as a number of buildings have already been constructed in the State
and many more are in the pipeline.

       The Solar Energy Centre, which is a division in the Ministry, has also undertaken various
activities in the area of solar passive buildings. The activities include construction of SEC's
own buildings based on solar passive concepts, monitoring and evaluation of thermal
performance of these buildings, carrying out R&D to establish these concepts, and also
providing technical consultancy for incorporation of these concepts into the building design.
Besides, the Centre has also been organizing training programmes/ workshops in focused
areas and is engaged in publishing technical literature. The presently on-going interactive
R&D projects undertaken at SEC in collaboration with other premier institutions in the country
include the following specific projects:

   Performance Evaluation of SEC Guest House
    Jointly with Tata Energy Research Institute, Delhi.
   Development of Tools for Architectural Design and Simulation (TADSIM) for Solar Passive
    Jointly with IIT Bombay, Mumbai.

     A manual has also been prepared on solar passive architecture in collaboration with IIT
Bombay for use of practicing architects and building designers. Broadly, the manual
addresses to the following topics:

 Historical over view and contemporary trends
 Climatic factors, climatic zones, comfort conditions and climate wise requirements of
  architecture for thermal comfort
 Principles of solar passive architecture
 Design guidelines for various climatic zones in the country
 Techniques for estimation of thermal performance
 Appendices containing useful data required for designing and simulation


     The campus of Solar Energy Centre is located at village Gwalpahari in Haryana on
Gurgaon - Faridabad Road, and is about 20 Kms. from Qutub Minar in Mehrauli, New Delhi.
The climate of the site is classified as composite, and is characterized by hot summer (April-
June), cold winters (November - February) and monsoons (July - September). The important
weather parameters are given in Table 1.

The SEC buildings are constructed using solar passive concepts. These may be divided in
three categories viz. Technical/ Administrative Blocks, Guesthouse and Mechanical Workshop.
A site plan of the buildings is shown in Figure 1. The salient design features of the buildings
are as follows:

 Orientation: The buildings have been designed elongated in east-west direction, so as to
  provide longer southern exposure for maximum gain of solar radiation during winters. The
  guesthouse building is 20° off to east from due south.

 Direct gain windows: The windows with adequately designed sun shades are provided on
  southern walls to provide entry of direct sun light into the buildings during winter months
  and at the same time providing shade from sun light during daytime in summer months.

 Day lighting: The windows are split into two parts, one located at the normal height, and
  the other just below the vault. The lower windows provide ventilation and view and some
  daylighting close to the window. The upper windows ensure daylighting deep inside the
  workspace. The workshop building has an interesting system of daylighting. The building
  has a stepped cross-section with a reflective finish on the roof surfaces. Daylight is
  reflected from the lower roofs into the building providing glare-free even lighting. The
  drawing offices have deeply recessed windows with baffles, which cut out glare. . It is
  possible to use this building without any artificial lighting during the daylight hours.

 Evaporative cooling: The roof of technical and administrative blocks are specially designed
  in the shape of cylindrical shells of RCC for facilitating use of evaporative cooling concept.
  The thickness of roofs is kept low to provide better thermal conductance to remove heat
  from inside of the building to outside environment due to evaporation of water.

 Use of hollow concrete blocks: These blocks have less thermal conductance because of
  air cavity present within them, and reduce ingress of heat. These blocks have been used
  for exterior walls of technical blocks, administrative blocks and workshop building.
 Reflective roof surface: Wherever possible, the roof finish has been provided with glazed
  ceramic white tiles. Such a finish reflects incident solar radiation and therefore results in
  the reduction of cooling load through the roof. as the position of sun in the sky is high during
  summer and horizontal surfaces receive high amount of solar radiation.

 Earth berming: The exterior walls of the Guest House have been provided with earth
  berming up to window sill level, so as to reduce the exposed area of the walls for reducing
  cooling load and also to increase heat capacity for smoothening temperature fluctuations in
  the indoor environment.


      This is a method of indirect evaporative cooling where the humidity level of the inside air
is not affected. The method is particularly effective in hot and dry climates. For best effects,
the roof surface should be kept wet round the clock and thermal conductance of roof should be

      In order to meet the requirements mentioned above, a thin uniform organic material lining
was used on the roof surfaces of administrative block building of SEC. The water was
sprinkled using spray nozzles. The water flow was controlled using solenoid valves actuated
by a timer device. The cooling system was operated in the summer of 1997, and monitoring of
indoor air temperatures of the various office rooms was carried out. One of the indicative
results, which correspond to 2.7.1997 is presented in Figure 2. It may be mentioned here that
all the rooms were in use and there was no check on the ventilation. Even the fans were in
use inside the rooms. One of the rooms, A-6, however, remained closed during the monitoring
period. The performance of this room, therefore, provides the best indication of the
performance of roof surface evaporative cooling system in SEC buildings. Evidently, a
temperature difference of the order of 4-5°C is observed, which is quite significant. The
detailed monitoring, however, is underway.


      The guesthouse building is the only residential building in the SEC campus, and
therefore has been chosen for simulation of its thermal performance. The floor plan of the
building is shown in Figure 3. Basically, it is a single storey building having six guest suites
and a dining hall, kitchen, lobby, etc. In order to have an idea of the thermal performance of
this building, Mishra and Heidt (1997) has carried out a detailed thermal simulation. For this
purpose, the building has been divided in three thermal zones viz.

 East zone consisting of three suites on eastern side
 West zone consisting of three suites on western side
 Third zone consisting of the remaining areas.

     A plot of the zone temperatures for the complete year is shown in Figure 4. It may be
seen that the maximum temperature in summer reaches about 33C in various suites,
whereas the inside temperature in winter months remains generally in the comfort range.


      It is well appreciated that the energy performance of buildings is controlled by the
performance of its various elements, notably the windows. The windows in a building are
important for aesthetics and also for providing a direct link of the occupants with the outside
environment. Basically, these account for large amount of heat transfer between indoor and
outdoor environments, and if not properly designed, may lead to unacceptable indoor thermal
inside the buildings.

      In order to appreciate the impact of window specifications, a simulation study has been
carried out on a typical air-conditioned office building. The building, which has been
considered in the study, has a three-storey structure having other details as given below. It
may be mentioned that four variations of window designs have been used in the present study
       Single glazed window with metal frame
       Single glazed window with wooden frame
       Double glazed window with metal frame, and
       Double-glazed window with wooden frame.

The U values for these design variations of the windows are also given below, as taken from
Sodha et al. [2].

                             ITEM                         SPECIFICATION
          Number of floors                            3
          Height                                      8.4 m
          Floor area on each floor                    245 m²
          Total floor area                            735 m²
          Total wall area                             586 m²
          Total roof area                             245 m²
          Window area                                 220 m²
          Total envelop area                          831 m²
          U value of roof/walls                       1.48 W/m² K
          U value of windows
          - Single glazed with metal frame            5.6 W/m² K
          - Single glazed with wooden frame           4.3 W/m² K
          - Double glazed with metal frame            3.2 W/m² K
          - Double glazed with wooden frame.          2.5 W/m² K

      The method of calculation has been chosen to be "Degree-day method", which offers
quick results for the assessment of heating/cooling loads. The method is based on the
calculation of degree-days as the product of number of days in a month with the difference of
daily average ambient temperature from the base temperature. As suggested in [5], the base
temperature for heating period is taken to be 18.3°C, which is able to accommodate heating
requirements when the inside temperature is intended to be maintained at 24°C. This rise in
the value of indoor temperature is presumed as an outcome of the heat gains from occupants
of the building, their activity level and the electrical appliances used in the building. By a
simple extension of the argument, a base temperature of 22.3°C has been taken for evaluating
cooling loads.
      The results of numerical calculations are presented in Table 2, which gives annual
demand of heating and cooling loads for five different indian cities viz. Allahabad, Jaipur,
Srinagar, Okha and Dibrugarh. These five cities, as can be seen from the data of degree-days
given in the table, represent different climatic zones in the country. The values of heating and
cooling load are presented in GJ; the values in bold typefaces represent heating load. It is
clear from the table that substantial savings are accrued, if normal single glazed windows with
metal frame are replaced with double glazed windows with wooden frame. The savings in the
cooling/ heating load could be of the order of 30-40%. Though the results are only indicative
of the impact of window performance on the overall thermal performance of a particular
building, yet an inference could be drawn safely from the study that the windows and all other
elements of the building need to be designed properly for optimum performance.

1.     R.P. Sromberg, and S.O. Woodall, Passive Solar Buildings: A Compilation of Data and Results,
       Report No. SAND-77-1204, Sandia National Laboratory, USA, 1977.

2.     M.S.Sodha, N.K. Bansal, P.K. Bansal, Ashvini Kumar, and M.A.S. Malik, Solar Passive
       Building Science & Design, Pergamon Press Ltd., UK, 1986.

3.     Anil Mishra and F.D. Heidt, Validation of Building Simulation Programs, Final Project
       Report, Tata Energy Research Institute (India) and University of Siegen (Germany),

4.     N.K. Bansal and Ashvini Kumar in Energy Efficient Windows, Proceedings of the
       Workshop organized at Solar Energy Centre jointly by SEC and IIT Delhi, 1996.

5.     J.A. Duffie and W.A. Beckman, Solar Engineering of Thermal Processes, John Wiley
       and Sons, New York, 1991.
                                                     Variations of Temperatures
                                                          on July 2nd, 1997.



  Temperature (deg C)







                             10.5   11   11.5   12      12.5   13      13.5       14   14.5    15    15.5   16   16.5
                                                                    Time (hour)

                                     Head's P.A. Room          A.O. Room                      Reception Room
                                     Series4                   Series5                        Verandah

Figure 2                        Thermal performance of roof surface evaporative cooling system at

                                       Brian.C. Hageman
                                           Deluge, Inc.
                                 4116 E. Superior Ave., Suite 4-D
                                  Phoenix, Arizona 85040, U.S.A

                                      Carmo Fernandez
                                        Deluge India Ltd.
                              4116 East Superior Avenue, Suite 4-D
                                 Phoenix, Arizona 85040, U.S.A.


Keywords: water pump, alternative cycle, solar thermal energy

       The newly patented solar water pump offers the potential for utilizing relatively low-
temperature solar thermal energy to do useful work. The engine's operation is based on exploiting
the natural propensity of a fluid to expand as it is heated, and to contract upon cooling. Somewhat
similar to previously described air-based engines that are heated by contact with combustion gases,
the present engine instead uses solar thermal energy as the heat source, and the body of water to be
pumped as the heat sink. The working fluid is supercritical CO 2. As the heated water comes in
thermal contact with the O2 in a heat exchanger, the CO2 expands and pushes a piston. Upon
reaching the end of the piston's stroke, valving is activated which closes the hot water intake and
opens the cold water intake, thus cooling the CO2 and causing it to contract. This process is
repeated in a total of 4 cylinders, allowing water to be continuously pumped.
    A review is provided of similar engines discussed in the literature, and preliminary estimates are
made of the thermal efficiency of the water pumping system.


CO2 Carbon Dioxide
R-23 Refrigerant number 23


     The newly-patented thermal hydraulic engine offers the potential for utilizing relatively
low-temperature solar thermal energy to do useful work. These engines are a new
application of existing technology. The primary application of the engine is the pumping of
fluids. [1]

   The design is simple, using off-the-shelf components and machinable parts.
Maintenance is simple and does not require advanced technical training. The design is
robust, allowing for a long functional life, with easy repairs and parts replacement. The
unit is self contained, allowing for off-grid and remote applications. The working fluid,
supercritical carbon dioxide, is a safe heat exchange fluid, since the accidental discharge
of CO2 is not toxic to the environment. And lastly, this technology is potentially
economical, since solar energy is readily available in many parts of the world.


Thermal Hydraulic Engine

   Referring to figures 1 and 2, the solar-powered water pump operates in the following manner. The pump
is powered using the thermal expansion of supercritical carbon dioxide. Solar collectors focus the sun’s
energy on receiver pipes with water circulating through from the storage tank. This energy heats the water,
and the water is stored in a storage tank. This storage tank functions as a reservoir of hot water, a buffer
between the solar collectors and the engine. This keeps the systems slightly separated for better operation
of both sides. Presently, the hot water tank is maintained at a temperature of about 82C.

    A heat exchanger and piston assembly filled with the compressed carbon dioxide at 172 bar, is heated
from the temperature of the CO2 at the cold state (varies depending on the local climate and temperature of
the water being pumped) to about 82C using the hot water. The heat exchanger is a simple finned shell-
and-tube heat exchanger. The piston is constructed such that the supercritical carbon dioxide is on one side
of the piston, and compressed air is on the other. Heating the carbon dioxide results in increased pressure
on the carbon dioxide side of the piston. When the pressure of the carbon dioxide exceeds that of the
compressed air, the piston moves outward. The shaft extending from this piston is connected to another
piston filled with oil. When the first piston moves outward, it pushes in the second piston, compressing the
oil. The compressed oil is used to run a hydraulic pump. When the first piston has fully extended, cold water
is sent through the heat exchanger. The cold water is supplied from the water being pumped. As the
temperature decreases, the pressure of the carbon dioxide decreases. When the carbon dioxide pressure is
less than that of the compressed air, the compressed air acts as a spring and pulls the piston back in. Four
piston-and-heat-exchanger assemblies are utilized (i.e. four heat exchangers, eight pistons), and they are
timed to run at staggered intervals. Valves that direct either the hot water or cold water to flow through the
heat exchanger are timed using the four pistons. When the piston moves to a certain point, a peg mounted
on the piston opens or closes the valves. Electric motors that run the pumps that supply the hot water to the
system are run off of photovoltaic solar cells. Cold water is run off of energy produced by the hydraulic pump

                                       Selection of the Working Fluid

   Harry W. Parker, Ph.D., P.E. conducted a study of the Deluge engine in 1997. [2] The
temperature differential of the hot and cold water is about 60ºC. For a system using water
or oil as the working fluid, the thermal expansion is not sufficient to generate a large
enough pressure differential to operate the system efficiently. A fluid under very high

pressure is required to get the needed pressure differential. The best fluids considered
were R-23 and CO2. Both fluids have sufficient thermal expansion properties at pressures
of 100 bar or higher. CO2 was selected based upon cost, safety criteria, and
environmental concerns. In addition, CO2, if accidentally released, does not pollute the

Solar collectors

    At issue is the selection of either flat-plate solar collectors or concave solar collectors
for the production of hot water. There is no conclusion on the collector type to be used
yet. This will depend on the necessary hot water temperature for the engine. Flat-plate
collectors are the cheapest alternative. However, the concave collectors raise the water to
a higher temperature, but have more moving parts and higher maintenance and cost. If
the new engine operates in a smaller temperature range, then flat-plate collectors will be
used since there are less moving parts and a simpler operation. The solar technology will
be selected once appropriate testing has been conducted.


Qualitative Pressure versus Volume Diagram

   A qualitative analysis of the CO2 cycle in the heat exchanger – piston assembly is presented in figure 3.
From 1 to 2, hot water is flowing through the heat exchanger. As the heat is transferred to the CO 2, the
pressure of the CO2 increases. However, the pressure of the CO2 is not enough to overcome the pressure of
the compressed air plus frictional forces. At state 2, the pressure overcomes frictional forces and begins
piston movement. As the piston moves, the pressure increases slightly, while the volume also increases
until it reaches state 3. At state 3, the piston has reached its maximum stroke.

    After state 3, cold water is run through the heat exchanger, causing the pressure in the piston to
decrease. Initially, volume is constant because the pressure does not decrease enough to counteract
frictional forces. At state 4, the CO2 pressure is low enough to allow the compressed air pressure to act as a
“spring” in pushing the piston back. From state 4 to state 1, the piston is pushed back to its starting position.
Pressure and volume continue to decrease until returning to state 1.


                                     Rider Ericsson engine

   The Rider Ericsson engine is a hot air Stirling engine constructed of one piston. [3]
When the air in the cylinder is heated, the piston moves up; when it cools, the piston
moves down. A displacer is located inside the cylinder. The purpose of the displacer is to
move air from the hot side of the cylinder to the cold side, and vice versa. Cooling water is
used to cool one side of the cylinder, and any source of heat can be used to heat the other
side of the cylinder.

    As air at the hot side of the cylinder is heated, it expands and forces the piston upward.
When the piston is extended, the displacer is driven down into the hot side of the cylinder.
The hot air rushes around the displacer to the cool end of the cylinder. When the air cools,
it contracts, sucking the piston downward. Then, the displacer moves up into the cool end
of the cylinder, forcing the cool air back down into the hot end of the cylinder. The air is
heated again, and the cycle repeats.

   This is much like the Deluge engine. Like the Deluge engine, the Rider-Ericsson
engine utilizes an external heat source and a working fluid. Also, like Deluge, the volume
increases as heat is added to the air in the cylinder, and volume decreases as heat is
transferred from the air in the cylinder. Like the Deluge engine, the thermal expansion of
the working fluid is used to drive the engine.

   Whereas the thermodynamic cycles for the Deluge and Rider-Ericsson engines are
very similar, the difference lies in the actual construction of the engines and choice of
working fluid. The Rider Ericsson employs a displacer to move the air between essentially
two heat exchangers. One heat exchanger heats up the air, while the other cools it down.
Deluge employs one heat exchanger to take care of both duties, using valves to run either
cold or hot water through the heat exchanger.

Thermal Lag Engine

   The thermal lag engine is a valveless, external-combustion closed-cycle engine having
a cooled piston and cylinder connected to a heated chamber. [4] Air is used as the
working fluid. The air in the cylinder is cooled, causing its pressure to drop. The piston
forces the cool air into the heated chamber, which compresses it. In the heated chamber,
the temperature and pressure of the air rise. When the pressure is sufficient, it pushes the
piston out again. Then, the cycle repeats itself. Since there is adiabatic compression and
expansion and constant volume heating and cooling, the engine theoretically operates on
the Otto cycle.

    This engine is similar to the Deluge engine. For the Deluge engine, there are constant-
volume cooling and heating processes. However, compression and expansion are not
adiabatic. Instead, heat is transferred to the CO2 during the expansion, and heat is
transferred from the CO2 during the compression. In addition, the pressure of the CO2
continues to rise throughout the expansion, and decreases during the compression. This
is the opposite of what happens during the Otto cycle. [5]


   In conclusion, the Deluge Solar Powered Pump has potential in applications calling for an off-grid self-
contained unit. It also has the potential to be a clean, environmentally friendly technology.


   P.E.P. gratefully acknowledges the support of the National Science Foundation through
a CAREER Award (Grant No. CTS-9696003), with matching funds from Deluge, Inc.
(administered by the Industry Network Corporation).


[1]   Deluge, Inc. Deluge, Inc. : Pumping Water for Tomorrow. Online. Available: 29 October. 1999.

[2]   Correspondence from Harry W. Parker, Ph.D., P.E. to Deluge Corp. June 2, 5, and 30, 1997.

[3]   Rusty Iron Workshop. Rider Ericsson Hot Air Pumping Engine. Online.
      Available: 28 October 1999.

[4]   Tailer, Peter L. (1995): “Thermal Lag Test Engines Evaluated and Compared to
      Equivalent Stirling Engines,” 1995 30th Intersociety Energy Conversion Engineering
      Conference 3, 353-357.

[5]   Çengel, Yunus A. and Michael A. Boles (1998): Thermodynamics: An Engineering
      Approach, third edition, WCB/McGraw Hill, New York.


      Hot Water   Cold Water
       Supply       Supply                                    Hot Water Return

                                          Heat Exchanger #1

                                          Heat Exchanger #2

                                          Heat Exchanger #3

                                          Heat Exchanger #4

                  Temperature Indicator       Ball Valve

                                                                    Cold Water Drain
                  Flow Meter                  Reducer

                  Figure 1 – Schematic of Hot and Cold Water System

                                                                    CO2 Piston           Oil Piston
                Heat Exchanger #1                                                                          Reservoir
                                                                    CO2                         Oil

                Heat Exchanger #2
                                                                    CO2                         Oil

                Heat Exchanger #3
                                                                    CO2                         Oil

                Heat Exchanger #4
                                                                    CO2                         Oil
The expansion of the carbon dioxide causes the pistons to push
the oil through the hydraulic motor, thereby powering the pump.                 2500 psi

         Check Valve

         Pressure Indicator                                                                           Hydraulic
                                                                                                      Motor and
          Ball Valve                                                  Air

                              Figure 2 – Schematic of CO2 and Oil System


                                                Q in
                        3                                                          3
           Q in


                                                                                         Otto Cycle

                        2                                                        4
                                                                                              Q out

                 1                      Q out

                                        Cycle for Deluge's Engine

Figure 3 – Pressure versus Volume for the working fluid, CO2 in Deluge’s engine; the Otto
cycle        for       the      thermal         lag        engine         superimposed.


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