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5th A I C Conference, October 1-4 1984, Reno, Nevada, USA




A r c h i t e c t and Energy Consultant
L i ndenhofstrasse 15
CH -      8001 Zurich
S w i t z e r l and

The Swiss performance standard f o r energy conservation in buildings
SIA* 380/1 i s explained. This standard leaves a i r i n f i l t r a t i o n and
other d e t a i l decisions t o planners i f minimum performance levels
are met. Calculation procedures f o r heat balances based on a
standard-occupancy are described. Tools to achieve optimum space
heating and ventilation rates are explained. Instrumentation for
checking the thermal performance of the house in operation i s

*SIA: Swiss Society of Engineers and Architects
1.                                      TNAD

     Different countries have chosen different ways so f a r t o limit
     building energy consumption. Most countries have started w i t h
     component standards, established as a means t o protect the consumer
     against deficient products. The large number of DIN-Standards in
     Germany [ref. I ] and the Californian Energy Conservation Standards
     [ref. 21 are typical examples f o r s e t s of building component
     standards. A f o r quality standards in complex systems as cars,
     bui 1dings or some industrial products (tv-sets e t c . ) another method
     i s equally established: the performance standard of an e n t i r e
     system which i s treated as a black box. Standards f o r the fuel
     consumption of cars are a good example of t h i s method where c l e a r
     testing situations have been established. The advantage of t h i s
     l a t t e r approach i s a larger freedom f o r designers and producers t o
     come up with solutions they find best under given economical and
     technical conditions. The standard serves only as a precisely
     stated goal, where the solution can be freely chosen among a
     multitude of always changing paths. Switzerland has chosen with
     SIA 380/1 [ref. 31 t h i s l a t t e r method t o limit energy consumption
     of buildings a f t e r a period of increasing numbers of component
     standards and responding t o a growing concern of the professional
     community not t o be completly regulated by detailed s t a t e legisla-
     tion. Heating i n the system "HOUSE" i s devided into two subsystems:
     - net heat consumption
     - annual coefficient of performance
     Both have to comply w i t h the respective s e t s of standards. Electric
     consumption, the use of ventilation, a i r conditioning and cooling
     equipment are defined separately.
     The SIA standard 38011 (1984) gives a calculation procedure to
     compute the two s e t s of standards and also allows the use of an
     easier method f o r small buildings below 500 m gross f l o o r area
     which i s based on the older component standards w i t h more stringent
     val ues.
     Air i n f i l t r a t i o n i s therefore not treated in detail in t h i s
     standard. B u t i t i s included in the calculation procedures f o r
     heat l o s s , i t i s specified in the standard-occupancy and i t i s
     also treated in the component standards f o r small buildings
     (window joints etc. ). According t o a s e t of recent simulations on
     t e s t houses the a i r i n f i l t r a t i o n share amounts to some 20 - 40 %
     of the net heat loss [ref. 41, with well insulated houses tending
     to the upper value.
2.    OL

     I t i s obvious t h a t an optimisation of the heat balance of a building
     including losses and gains places great concern on the "optimum"
     ventilation. This means t h a t i n order t o comply with a legal
     standard you may not design a i r t i g h t buildings and prevent people
     from getting a sufficient amount of fresh a i r . Therefore, the
     standard i s divided into three information sets:
     - construction d e t a i l s t o improve airtightness, avoid unnecessary
        hvac equipment, orland t o u t i l i z e heat recuperation ( t a b l e 1 )
     - standard-occupancy defined a s a s e t of a i r change rates depend-
        ing on use; these values have t o be applied i n the calculation
        procedures (tab1e 2)
     - user related a i r i n f i l t r a t i o n of a well designed house should not
        be t o t a l l y dependent on everyday compliance of a l l occupants.
        Advice and training has to be given t o the normal user because
        most s t i l l open windows in wintertime t o "moistenn the dry room
     A f o r meeting the performance standard of a project i n t h e design
     stage only t h i s standard-occupancy i s relevant; construction d e t a i l s
     can be freely chosen according t o local practice*.
     Table 1:            Criteria f o r use of mechanical ventilation and a i r

         -    External influences     . noise
                                      . a i r pollution
                                      . safety
                                      . extreme alpine conditions
         -    Building parameters     . offices with deep spaces      (<    6 m2)
                                      . offices with large spaces ( > 200 m 2 )
                                        internally located and underground areas
                                      . high r i s e ( > 12 s t o r i e s )
         -    Use conditions          . high occupant concentration (< 3 m2/per-
                                      . toxic fumes and smells (smoking) son)
                                      . high internal heat production (>45 W/m2)
     Note: the Swiss climate i s relatively moderate with an average out-
     door temperature in Zurich in January of -1°C and in July of +18OC;
     of course there a r e southern zones with some 3 K higher average
     temperatures and extreme temperatures in the mean summer day of 33°C.

     * Many of the d e t a i l s in the AIC-handbook of 1983 will probably be
             rejected by the average Swiss craftsmen because the d e t a i l s
             involve elaborate f i t t i n g , which a r e infeasible as on-site work.
    Air change r a t e s i n t a b l e 2 i n t h e standard-occupancy a r e defined
    a s minimum - maximum values. T h i s means t h a t without s p e c i f i c
    technical i n s t a l l a t i o n s they cannot be reduced and they should not
    be increased. Of course t h e a i r change r a t e s can be reduced during
    non-occupied times ( n i g h t s , weekends, hol idays) t o a minimum of
    some 0.2 h'l according t o necessary humidity l e v e l s ( f i g u r e 1 ) .
    With t h e introduction of heat-recuperators and controlled venti-
    l a t i o n t h e net a i r change r a t e can be reduced. Due t o the minimum
    a i r flow and additional r e s i s t a n c e of f i l t e r s i n used conditions,
    the a i r change r a t e s cannot be very f a r below t h e r a t e s s t i p u l a t e d
    in the standard-occupancy.
    Table 2:            Standard-occupancy: a i r change r a t e s (annual mean

        One family housing                                             0.4 h-1
        M 1 t i family housing                                         0.6
        Offices , commerci a1                                          0.8

        Air t i g h t n e s s of e n t i r e building*                 0.2

    *     With a l l doors, windows and o t h e r openings closed.

        Figure 1 :        Air change r a t e (one day cycle)
        (Example f o r mu1 t y family housing)
A i r Change Rate
      The main issue i s t o achieve superior indoor temperature control
      in order t o use the available f r e e heat from solar and indoor
      sources t o the maximum. This will prevent ill-advised users from
      opening windows excessively t o control overheating (figure 2 ) .
      Therefore, i t i s not only a question of educating users, but of
      giving them the proper tools t o get the amount of heat they really
      want [ref. 51. An additional feedback to users i s cost-sharing
      according t o the amount of heat consumed. This will of course
      dramatize t h i s e f f e c t in a positive way.
      Figure 2:       Room temperature (one day cycle) [ref. 61
      (Example f o r one family housing)

Room Air Temperature

                                           12                  1 8 hours         24

      On the other hand i t should be emphasized, that any quick change
      during the day in the desired room a i r temperature will n o t bring
      large heat savings due t o the i n e r t i a involved in well insulated
      and t i g h t l y f i t t e d houses (figure 3 ) . This i s especially true in
      the relatively heavy structures (over 600 kilograms per square
      meter) common in Switzerland and Central Europe. Such houses have
      a time constant of 150 t o 250 hours, which leads to a temperature
      reduction due to night setback in normal winter conditions of only
      1 K during night hours.
    Figure 3:      Night setback: cooling effect of a i r temperature
                                                             [ref. 61
Room Air Temperature

   00 start            06              1 2 hours       18 cooling time   24

    Any heating system depending solely on north oriented external
    temperature sensors and a fixed linear relationsship with heating
    system-temperatures cannot satisfy the stated objective of superior
    i nternal temperature control s.
    The other central issue i s to minimize heat loss due t o infiltra-
    tion which i s generally not synonimous to minimal a i r change rates.
    Good room temperature controls of the heating system invite users
    naturally t o a energy conscious behavior. The "synergetic link"
    [ref. 51 increases the effect of energy savings: good insulation
    and tight joints plus indoor sensitive room a i r temperature controls
    improves comfort conditions for the user - reduces energy consump-
    tion a t the same time.
 E S RN           O S M TO

I n order t o assess the process of designing, building and occupy-
ing an energy efficient building the ultimate performance check
i s only possible with measuring techniques. Therefore, a minimum
set of measuring instruments i s defined for a heating system
(table 3 ) . With these instruments every owner or control 1 ing board
can check, after a starting period of 2 years, the actual energy
consumption and compare i t to the design values according t o the
following formula:
                       Eh   =   - (MJ/mZSa)
    : annual specific end-heat use (MJ/mZSa)
      computed annual specific net heating demand (MJ/mZ.a)
eta: mean annual COP (-)

Table 3:      Measuring instruments

 -   Counter of operation hours
 -   Start impulse counter
 -   Fuel consumption measurement ( o i l , gas, electricity etc. )
 -   Thermometer for temperatures of the exhaust stack
 -   Meter for domestic h o t water

There i s a tendency t o include all these instruments in a package
in the standard heating p l a n t and t o install performance meters
t h a t show an annual mean COP on a LCD.
O course there will be a large band of deviations between calcu-
lated and measured values that can be divided into the following
four categories:
- design changes (macro of detail) after the energy calculations
   have been made
- bad in situ details due t o bad s i t e supervision
- unnormal cl imate conditions (severe winter etc. )
- unnormal user behaviour (higher temperatures or ventilation
   rates etc.)
Initial drying-out and wood-shrinking periods have to be monitored
and can generally be excluded from an analysis after the f i r s t two
years of normal operation. First year of operation problems with
regulation and optimisation efforts have t o be taken into account,
     also. The band of deviation t h a t generally i s accepted with
     standard climate data a r e deviations of -10 % t o +20 % of the
     annual energy consumption. Larger deviations have to be investi-
     gated and causes identified.
     For t h i s procedure i t i s necessary t o s t i p u l a t e the duty of house
     owners t o keep energy consumption records and t o o f f e r them f o r
     public checks annually. For larger buildings monthly records a r e
     recommended. For the safe hand1 ing of possibly pol 1uting fuel s
     t h i s r u l e has long been established in Switzerland. The data of
     gas, e l e c t r i c i t y and d i s t r i c t heat consumption on the other hand
     are readily stored in s u f f i c i e n t l y accessible data bases.
     Such a measuring procedure i s the new and final check of the build-
     ing qua1 i t y t h a t should be included in every builder's contract.


     The administrative boards can control one s e t of standards t h a t
     characterize the e n t i r e energy system o r can go back and t r y t o
     check a l l the detail components t h a t have been regulated so f a r .
     A c e r t a i n resistance to change from component t o performance
     standard e x i s t s also in Switzerland, even i f the new system seems
     easier t o handle and less time consuming with limited manpower.
     Due t o intervention of the local s t a t e s the formal legal introduc-
     tion of SIA 380/1 will be granted only a f t e r an i n i t i a l t e s t i n g
     period of some 2 years wherein a1 1 pub1 i c buildings will have to
     comply a1 ready with the new standard.
     The Swiss building stock has tended towards more e f f i c i e n t energy
     use since 1975 as can be shown in figure 4. This i n i t i a l success
     will continue in the future w i t h the introduction of SIA 380/1.
             Figure 4:                 Specific heat consumption in housing [ref. 7 , 8)

Relative Frequency
Number of Cases          R         L
                             1     I
                             1     I

              new one-


                                          one-family houses
                                          after retrofit



      0           200            400       600       800         1000        1200        1400           1600    1800
                                        specific annual energy consumption for space heating    E h [MJ/

I wish t o thank the SIA, the Swiss Department of Energy BEW and
the Swiss National Energy Research Fund NEFF f o r supporting t h i s
work and a l s o m collaborator mainly Miklos Kiss and the chairman
of the SIA 380/1 Committee Kurt Meier f o r t h e i r valuable contri-


[I]                                                  I
      German I n s t i t u t e f o r Normalisation: DN Catalogue,
      Berl in 1980

[2]   California Energy Commission: Regulations establishing energy
      conservation standards, 1978

[3]   Swiss Society f o r Engineers and Architects (SIA): Energy in
      buildings, Recommendation SIA 380/1, Zurich 1984
      ( f i n a l d r a f t version)

[4]   Brunner C.U., Kiss M. e t a l : Energy Consumption, simulation
      on t e s t houses, Zurich 1982 (unpubl ished)

[5]   Brunner C.U.: Potential and l i m i t s of energy savings in the
      Swiss building stock, 4th AIC Conference, Elm Switzerland

[6]   Swiss Department of the Interior: Energy savings in new
      buildings, Bern 1981

[7]   Brunner C.U., Muller E.A.: Strategies f o r energy conservation:
      Development of specific heat consumption in the building stock,
      in SI+A Nr. 30, Zurich 1983

[8]   Brunner C.U., Muller E.A.: Changes in the structure of energy
      consumption in buildings [SVEG], Zurich 1984 ( d r a f t ,

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