HVAC brochure - In the heat of the moment by gyvwpsjkko

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									     In the heat of the moment
     Optimise heating, ventilation and air conditioning

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                                     Contents page
                                  Energy efficient heating, ventilation and air conditioning (HVAC)                               2
                                  1. Introduction                                                                                 2

                                  2. HVAC basics                                                                                  2

                                  3. Heating                                                                                      2
                                     3.1 Heating: opportunities for efficiency improvements                                       3

                                  4. Ventilation systems                                                                          3
                                     4.1 Ventilation systems: opportunities for efficiency and energy saving improvements         3
                                         4.1.1 Replace leaky dampers                                                              4
                                         4.1.2 Use separate make-up air for range hoods                                           4
                                         4.1.3 Use economiser controls                                                            4

                                  5. Air conditioning and refrigeration                                                           4
                                     5.1 Opportunities for improved efficiency: air conditioning and refrigeration equipment      4
                                         5.1.1 Minimise the temperature difference                                                5
                                         5.1.2 Reduce the cooling load                                                            5
                                         5.1.3 Optimise cooling towers                                                            5
                                         5.1.4 Adjust control set points                                                          5
                                         5.1.5 Raise evaporator temperature (suction pressure)                                    5
                                         5.1.6 Lower condensing temperature (discharge pressure)                                  5
                                         5.1.7 Clean heat exchange surfaces                                                       6
                                         5.1.8 Provide cooler air to the condensers                                               6
                                         5.1.9 Regular maintenance and monitoring                                                 6
                                         5.1.10 Recommended maintenance procedures specific to refrigeration                      6

                                  6. General opportunities for energy efficiency which apply across all HVAC systems              6
                                     6.1 Air handling systems                                                                     6
                                     6.2 Fans and pumps                                                                           6
                                     6.3 Hot and chilled water piping                                                             7

                                  7. Energy Efficiency Checklist                                                                  8

                                  8. Support and advice                                                                           9

                                  9. References                                                                                   9

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            Energy efficient heating, ventilation and
            air conditioning (HVAC)
          1. Introduction

          Throughout commercial, industrial and some residential premises, the use of systems to provide a comfortable
          living environment is common practice in South Africa today. These heating, ventilation and air conditioning (HVAC)
          systems consume large quantities of energy, particularly electricity and represent a key target area for improved
          energy efficiency. HVAC systems provide a key opportunity for optimisation. Achieving optimisation also means
          operational costs need not spiral out of control despite the possibility of substantial electricity price escalations.

          In common with most other countries in both the developed and the developing world, South Africa needs more
          generation capacity. The extent to which Eskom is able to supply the country’s demand for electric power has a direct
          impact on economic growth.

          All sectors of the economy can reap major benefits from implementing energy efficiency policies. By optimising
          processes and plant efficiency, electricity users reduce input costs and increase their return on investment. As an
          added benefit, reduced energy consumption means reduced environmental impact, an important part of the “triple
          bottom line”.

          Eskom’s Demand Side Management initiative is helping electricity users to identify various means of reducing their
          electricity consumption without impacting on their business performance.

          This information brochure aims to assist industrial and commercial users of electricity to improve the energy efficiency
          of HVAC systems. It explains the benefits of energy efficient systems and common problems affecting efficiency,
          before describing a number of measures to improve operating efficiency and thereby reduce electricity usage and costs.
          It concludes with a summary checklist and details of free energy efficiency advisory services available from Eskom.

          2. HVAC basics

          A variety of HVAC systems are used in commercial buildings:                        All sectors
          however, most have certain major components in common,
          such as electrical motors (driving pumps, fans or compressors),                 of the economy
          ducting and filters. Proper maintenance of HVAC system
          components keeps the system operating at peak efficiency.
                                                                                          can reap major
          This not only conserves energy and energy costs; it also helps                   benefits from
          maintain comfortable conditions, extends equipment life, and
          prevents costly breakdowns. Maintenance should be performed
          on a regular scheduled basis. A number of simple maintenance                    energy efficiency
          steps can be undertaken in-house. However, more comprehensive
          maintenance can be obtained by relying on qualified service                         policies.

          3. Heating

          Heating is necessary where industrial or business activity takes place in temperatures that are unsuitably low for
          workers or for the processes being conducted by the business. In most instances the same units that provide air


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         conditioning, provide heating; reflecting the fact that changing seasons have an effect on whether air in the workplace
         needs to be heated or cooled to deliver comfortable conditions.

         In more specialised applications, where large-scale heating is required, boilers may be employed which generate heat
         for dispersal by boiling water. Additionally, electrical heaters can be found in many business settings.

         3.1 Heating: opportunities for efficiency improvements

         Where boilers are used, simple interventions that support improved operation of equipment also contribute
         to better reliability. Such interventions should include:

         •	 Inspect	boilers	for	scale	deposits,	accumulation	of	sediment	or	boiler	compounds	on	water	side	surfaces.
         •	 Inspect	electrical	contacts	and	working	parts	of	relays	in	order	to	maintain	good	working	order.
         •	 Check	heater	elements	for	cleanliness	and	replace	as	necessary.
         •	 Check	instrumentation	and	controls	for	proper	operation,	and	repair	and	adjust	as	necessary.

         Where zonal electric heating equipment is being used, the following maintenance activities will support
         improved efficiency:

         •	 Ensure	heat	transfer	surfaces	of	all	units	are	kept	clean	and	unobstructed.
         •	 Make	sure	that	air	movement	in	and	out	of	the	units	is	unobstructed.
         •	 	nspect	heating	elements,	controls	and,	as	applicable,	fans	periodically	to	ensure	proper	functioning	and	cleanliness.
         •	 Determine	if	electric	heating	equipment	is	operating	at	rated	voltage.

         4.Ventilation systems

         Mechanical ventilation systems allow fresh air into buildings
         mainly to control odours typically caused by smoking, cooking
         or industrial activity. Ventilation has a significant impact
         on a building’s total energy consumption. The rate of
         ventilation, and the difference between outside and indoor
         temperatures, have a direct bearing on the energy consumed
         by the heating or cooling system to compensate for the heat
         gain or heat loss.

         A properly functioning ventilation system is essential to the
         operation of any commercial building. Nonetheless, experience
         indicates that many buildings are using more ventilation than is
         minimally necessary. Another concern is that building owners are not
         taking full advantage of the various control and heat recovery devices
         that, when applied to the ventilation system, can reduce the energy consumed
         for heating and cooling. As a result, a substantial amount of energy is being wasted.

         4.1 Ventilation systems: opportunities for efficiency and energy saving improvements

         Since ventilation systems are driven by fans or pumps and deliver air through ducts, most opportunities for improved
         performance and reduced electricity consumption relate to optimising these components. This is discussed in more
         detail in the general opportunities section on page 6.


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            4.1.1 Replace leaky dampers
            Many ventilation systems have low quality outdoor air dampers that do not permit accurate control of airflow.
            Even when dampers are fully closed, the quantity of air leaking in may exceed minimum outdoor air requirements.
            Leaky outdoor air dampers can be replaced with high-quality, opposed-blade dampers that have air spats at the
            blade edges and ends.

            4.1.2 Use separate make-up air for range hoods
            Kitchen equipment exhaust hoods and other process equipment hoods that frequently remove large quantities
            of conditioned air from a building must be replaced by introducing outside make-up air. To reduce the quantity
            of energy wasted in pre-conditioning supply air to exhaust hoods it is often possible to install a supply air system
            that is completely or partially separated from the rest of the building HVAC system.

            4.1.3 Use economiser controls
            Mechanical cooling is often used when outside temperatures are relatively acceptable.

          5. Air conditioning and refrigeration

          The purpose of refrigeration or air conditioning systems is to move heat from a cooler space to a warmer space.
          In very simple terms, these systems move heat against its natural direction of flow.

          The energy required moving the heat uphill from colder to warmer depends on two things:
          •	 the	temperature	difference	from	cold	to	warm,	and;
          •	 the	amount	of	heat	the	system	has	to	move	(the	cooling	load).

                                                              Fan axle
                                                      Compressor            Condenser coils
                                                                                       Hot air

                                                                                     Outdoor air


                                                                                Expansion valve
                                      Cooling coils   Temperature
                                                      sensing bulbs             Indoor air

                                           Figure 1: Typical air conditioning unit

          5.1 Opportunities for improved efficiency: air conditioning and refrigeration equipment

          One attractive characteristic of many air conditioning systems is that the system will deliver the cooling effect required
          over a wide range of conditions. Unfortunately, the energy consumed in extreme conditions is likely to be more than
          double that of normal conditions.

          Often, extreme conditions result from inadequate or deficient operation and maintenance practices. Therefore, a
          simple but effective strategy for minimising energy cost involves attention to operation and maintenance procedures.


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         These include:

            5.1.1 Minimise the temperature difference
            •	 Clean	heat	exchange	surfaces.
            •	 Check	and	reset	–	if	possible,	evaporating	and	condensing	temperatures.
            •	 Avoid	non-condensable	items	in	the	refrigerant.	

            5.1.2 Reduce the cooling load
            •	 Insulate	the	cooled	space	and	refrigeration/chilled	water	lines.
            •	 Reduce	warm	air	infiltration	to	the	cooled	space	(especially	moist	air).
            •	 	 inimise	excess	energy	consumption	loads	which	add	to	the	cooling	requirement,	
               such as open kettles in the kitchen.

            5.1.3 Optimise cooling towers
            •	 	 erform	chemical	treatment	tests	to	determine	if	solid	concentrations	are	
               being maintained at an acceptable level.
            •	 Keep	the	tower	clean	to	minimise	both	air	and	water	pressure	drop.
            •	 Clean	intake	strainer.
            •	 	 heck	fans	by	listening	for	any	unusual	noise	or	vibration.	Inspect	the	
               condition of the V-belt and align the fan and motor as necessary.

            5.1.4 Adjust control set points
            Proper control maintenance is essential in operating air conditioning
            systems optimally. Situations may prevail where the existing controls are
            not appropriate or are not capable of controlling the systems properly.
            The symptom of this may be as simple as a thermostat that fails to effectively
            control comfort levels in an occupied space.

            5.1.5 Raise evaporator temperature (suction pressure)
            The amount of power demanded by an air conditioning compressor
            is determined by the difference between the evaporator and condenser
            temperature (or pressure). Therefore, if the system requiring cooling can
            tolerate a small increase in temperature at the evaporator, an opportunity
            to reduce compressor power may exist. In order to determine if such a change
            is possible, and will not damage the compressor, one should consult an air
            conditioning expert. Since compressors are finely tuned systems, caution should
            always be exercised when considering adjustments to operating conditions.

            5.1.6 Lower condensing temperature (discharge pressure)
            The amount of power demanded by an air conditioning compressor
            is determined by the difference between the evaporator and condenser
            temperature (or pressure). Therefore, if the compressor can tolerate a small
            reduction in temperature at the condenser, an opportunity to reduce compressor
            power may exist. In order to determine if such a change is possible and will not
            damage the compressor, one should consult an air conditioning expert. Since
            compressors are finely tuned systems, caution should always be exercised when
            considering adjustments to operating conditions.

            5.1.7 Clean heat exchange surfaces
            If the heat exchanging surfaces of the evaporator or air handling unit (AHU) in an air
            conditioning	system	of	any	size	is	not	clean,	the	evaporator/AHU	is	forced	to	operate
            at a lower temperature than necessary, increasing compressor power. In smaller systems, air, dust
            and other contaminants accumulate, while in large liquid systems regular maintenance is required
            to avoid excessive fouling of exchange surfaces.


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            5.1.8 Provide cooler air to the condensers
            Cooler air may allow the compressors to operate more efficiently.
            •	 	 ooftop	cooling	units	containing	compressors	and	condensers	generally	draw	air	from	close	to	the	rooftop.	
               Cooler	air	may	be	available	–	as	close	as	1.2	to	1.5	metres	high	off	the	roof.	
            •	 Condenser	units	run	cooler	when	installed	on	the	southern	side	of	a	building.
            •	 Avoid	direct	sunlight	to	shine	on	condenser	units	anytime	during	the	day.
            •	 Ensure	sufficient	natural	cross	ventilation	over	the	condenser	unit	to	remove	any	hot	air	efficiently.
            •	 	 void	installing	condenser	in	closed	confined	rooms	where	hot	air	might	accumulate.	Provide	enough	vents
               for hot air to escape or install whirley birds to remove hot air efficiently.

            5.1.9 Regular maintenance and monitoring
            •	 Use	the	sight	glass	to	spot	problems	–	bubbles	indicate	problems.
            •	 Check	lubricants	frequently	–	this	will	also	prolong	the	compressor	life.
            •	 Log	the	operating	parameters	such	as	motor	currents	to	spot	abnormalities.

            5.1.10 Specific to refrigeration, the following maintenance procedures are recommended:
            •	 	 isten	for	unusual	compressor	operation	such	as	continuous	running	or	frequent	stopping	and	starting,	either
               of which may indicate inefficient operation. Determine the cause and, if necessary rectify the problem.
            •	 	nspect	instrumentation	frequently	to	ensure	that	the	operating	oil	pressure	and	temperature	comply	with	the	
               manufacturer’s specifications.
            •	 Inspect	the	tension	and	alignment	of	all	belts	and	adjust	as	necessary.
            •	 Lubricate	the	motor	bearings	and	all	moving	parts	according	to	the	manufacturer’s	recommendations.
            •	 Inspect	the	insulation	on	suction	and	liquid	lines.
            •	 Inspect	all	heat	exchanger	surfaces	and	clean	as	necessary.
            •	 Inspect	compressor	joints	and	piping	connections	for	leaks	and	repair	as	necessary.

          6. General opportunities for energy efficiency which apply across all HVAC systems

          With commonalities in the air handling equipment such as ducting and intakes, electrical components such as fans,
          pumps, compressors and piping systems, there are a number of maintenance areas that are applicable to all HVAC
          systems. These include:

          6.1 Air handling systems

          Simple maintenance procedures include:
          •	   Inspecting	ductwork	for	air	leakage.	Seal	all	leaks	by	taping	or	caulking.
          •	   Inspect	ductwork	insulation	and	repair	or	replace	as	necessary.
          •	   Inspect	damper	blades	and	linkages.	 Clean	the	oil	and	adjust	these	on	a	regular	basis.
          •	   Inspect	mixing	dampers	for	proper	operation.
          •	   Clean	or	replace	air	filters	on	a	regular	basis.
          •	   Inspect	air	heating,	cooling,	and	dehumidification	coils	for	cleanliness.
          •	   Inspect	for	leakage	around	coils	or	out	of	the	casing	and	seal	all	leaks.
          •	   	nspect	all	room	air	outlets	and	inlets	(diffusers,	registers,	and	grilles).	These	should	be	kept	clean	and	free	of	all	dirt	
               and obstructions.

          6.2 Fans and pumps

          Simple maintenance procedures include:
          •	 	 heck	the	alignment	of	the	motor,	fan	or	pump.	Align	and	tighten	as	necessary.


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         •	 Lubricate	motor	and	drive	bearings	on	a	regular	basis.
         •	 Check	for	overvoltage	or	low	voltage	condition	on	motors.
         •	 	 heck	for	excessive	noise	and	vibration.	Determine	cause	and	correct	
            as necessary.
         •	 Keep	fan	blades	clean.
         •	 	nspect	drive	belts.	 Adjust	or	replace	as	necessary	to	ensure	proper	
            operation. Proper tensioning of belts is critical.
         •	 	nspect	inlet	and	discharge	screens	on	fans.	They	should	be	kept	
            free of dirt and debris at all times.

         6.3 Hot and chilled water piping

         Simple maintenance procedures include:
         •	 Inspect	all	piping	for	leakage	at	joints.	Repair	as	necessary.
         •	 Inspect	strainers	and	clean	regularly.
         •	 	nspect	vents	and	remove	all	clogs.	Clogged	vents	retard	efficient	air	elimination	
            and reduce efficiency of the system.
         •	 	nspect	insulation	of	hot	and	chilled	water	pipes	and	repair	or	replace
            as necessary.
         •	 	 heck	flow	measurement	instrumentation	for	accuracy	and	adjust,	repair,
            or replace as necessary.

         Effective maintenance programmes support the goals of strategic conservation,
         in that waste is reduced whenever the equipment is operative. Because HVAC
         equipment is used mostly during daytime hours, the benefits of effective
         maintenance are most pronounced during on-peak hours.

         Various computer programmes are available to facilitate simple but
         comprehensive maintenance scheduling. Depending on the needs of a specific
         facility, some of these can provide weekly schedules along with specific ‘how-to’
         instructions. More complex systems rely on monitoring devices to report service
         requirements as a result of excessive noise or vibration.

         By targeting HVAC systems as a component of an overall energy management
         strategy, smart companies can ensure the continued comfort and safety of their
         workers without experiencing dramatic increases in energy costs.


                                                                                    Savings lost without        Sustained level of     Intelligent
                 100%                                                               control maintenance         efficient energy use
                  90%             Efficient                                         and monitoring*             without control,       management of
                                  devices                                                                       ongoing monitoring
                  70%             and                                                                           and maintenance        energy end use:
                                  installation   Optimisation                                                   programme
                                                 of usage                               Sustained level of
                  50%                                                                   efficient energy use                           Efficent end use devices
                                                                Monitoring              with control, ongoing                          + automation and
                                                                and                     monitoring and
                                                                maintenance             maintenance programme                          control system
                                                                                                                                       + monitoring,
                   0%                                                                                                                  measurement and
                                                         Figure 2: Sustaining energy savings


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          7. Energy Efficiency Checklist
          Good housekeeping and regular maintenance of heating, ventilation and air conditioning systems makes perfect energy
          sense, saving breakdowns and money. Shown below is a summary of relatively simple actions that you can take to use
          electricity efficiently:

          Checklist for the most important energy efficient options:

                  Check                                                                                                 Date

                  Where boilers are used check for scale deposits, electrical contacts, heater elements and
                  control instrumentation.
                  For compressors for cooling regularly listen for unusual sounds or vibrations and check for
                  signs of wear.
             3    Regularly lubricate fan bearings and clean fan components.
             4    Regularly replace loaded air filters, replace leaky dampers and use economiser controls.
             5    Insulate thermal surfaces such as coolant and hot water pipe work.
             6    Inspect ductwork for air leaks.
                  Optimise the performance of fans and pumps (see separate Eskom Energy Efficiency brochures
                  on fans and pumps).
                  For cooling equipment, ensure heat exchanger surfaces are clean and reset evaporation and
                  condensation temperature particularly under extreme operating conditions.
             9    Take full advantage of various control and heat recovery devices on the ventilation system.
            10    Ensure electrical equipment is working at the rated voltage.
                  Establish and follow a regular maintenance programme, ensure staff are trained accordingly and
                  take advantage of a computer programme to facilitate maintenance scheduling.
                  When fitting new equipment ensure that your supplier conducts a proper needs analysis,
            12    replaces oversized motors, new units are sized at optimum efficiency; and that your ventilation
                  system is properly balanced by an experienced specialist.
            13    Reduce HVAC operating hours to reduce electrical, heating and cooling requirements.
            14    Eliminate HVAC usage in vestibules and unoccupied space.
                  Minimize direct cooling of unoccupied areas by turning off fan coil units and unit heaters and
                  by closing the vent or supply air diffuser.
            16    Adjust thermostat settings for a change in seasons.
            17    Reduce fan speeds and adjust belt drives.
                  Check the combustion efficiency by measuring carbon dioxide and oxygen concentrations and
                  the temperature of stack gases; make any necessary adjustments.
            19    Close outdoor air dampers.
                  Install heat recovery ventilators that exchange between 50 and 70 percent of the energy
                  between the incoming fresh air and the outgoing return (conditioned) air.

                  Be sure to switch off air conditioners when leaving the office after a day’s work or install timers
                  to switch air conditioners off to prevent them from running over night or over weekends.


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         8. Support and advice

         Advice on the many techniques and technologies that
         are available for the purpose of saving energy can be
         obtained from independent technical consultants or
         Eskom’s energy advisory service. Interested persons
         can call the Eskom Contact Centre on
         08600 Eskom (08600 37566) and arrange for
         an Eskom Energy Advisor in their area
         to contact them, or visit the website on

         9. References

         1. Energy Efficiency in Industrial HVAC
            Systems	–	2003
         2.	 	 ttp://en.wikipedia.org/wiki/
         3.	 	 ttp://en.wikipedia.org/wiki/


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                                          Issued by Eskom Demand Side Management Mach 2010
                                   Issued by Eskom Demand Side Management August 2010
                                   Eskom Holdings Limited Reg No 2002/015527/06

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