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Jones Lang LaSalle Management Services Limited 31st May 2002

Energy Management Guidance 1 Energy Management Programme ......................................................................................4 2 Data Base ...........................................................................................................................4 3 Priorities.............................................................................................................................6 4 Energy Audit ......................................................................................................................6

4.1 Stage I – Historical Data Collection ..................................................................6 4.2 Stage II – The Preliminary Survey.....................................................................7 4.3 Stage III – The Detailed Investigation ...............................................................8 4.4 Analyzing the results..........................................................................................8

5 Best Operation & Manual Procedures ...............................................................................9 5.1 Operation............................................................................................................9

5.1.1 Operating Procedures........................................................................................9 5.1.1.1 General Guide Lines ..........................................................................9 5.1.1.2 Guidelines for Operation of Central Plant .......................................10 5.1.1.3 Operating Guide Lines in Kitchen and Cafeteria Areas...................11

5.1.2 Maintenance Procedures .................................................................................11 5.2 EQUIPMENT ..................................................................................................12

5.2.1 General............................................................................................................12 5.2.2 Prime Movers and Motors ..............................................................................12

5.2.2.1 Motors ..............................................................................................12 5.2.2.2 Engines.............................................................................................13

5.2.3 Fans and Pumps ..............................................................................................13 5.2.3.1 Fans ..................................................................................................13 5.2.3.2 Pumps...............................................................................................13

5.2.4 Heating Equipment .........................................................................................14 5.2.4.1 Boilers ..............................................................................................14 5.2.4.2 Central and Room Heating Units.....................................................15

5.2.5 Refrigerating Equipment.................................................................................16 5.2.5.1 Compressors.....................................................................................16 5.2.5.2 Water Chillers (Evaporators) ...........................................................17 5.2.5.3 Condensers and Heat Rejection Apparatus ......................................17 5.2.5.4 Refrigerant Piping Circuits and Controls.........................................18 5.2.5.5 Unit Air Conditioners.......................................................................19

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5.2.6 Air Handling Equipment .................................................................................19 5.2.7 Humidification and Dehumidification Equipment..........................................19 5.2.8 Air Compressors for Pneumatic Controls .......................................................20

6 Energy Saving Opportunities ...........................................................................................20 6.1 Low Cost/ No Cost Energy Conservation Opportunities.................................20

6.1.1 Review Rate Structures...................................................................................20 6.1.2 Maintenance Modifications ............................................................................21 6.1.3 Ventilation .......................................................................................................21 6.1.4 Infiltration .......................................................................................................22 6.1.5 Operating Practices .........................................................................................22 6.1.6 Hydronic Systems ...........................................................................................23 6.1.7 Steam Systems ................................................................................................24 6.1.8 Air Distribution Systems.................................................................................25 6.1.9 Control Adjustment and Modifications...........................................................25 6.1.10 Transmission .................................................................................................25 6.1.11 Lighting.........................................................................................................25 6.1.12 Domestic Hot and Cold Water ......................................................................26 6.1.13 Elevators and Escalators ...............................................................................26

6.2 Equipment Operation Strategies ......................................................................27 6.2.1 Time-based Optimization................................................................................27

6.2.1.1 Time of Day Operation ....................................................................27 6.2.1.2 Space Temperature Unoccupied Setpoint Adjustment.....................27 6.2.1.3 Start/Stop Optimization....................................................................27

6.2.2 Reset Strategies ...............................................................................................27 6.2.2.1 Load Side Adjustments ....................................................................27 6.2.2.2 Hot/Cold Deck Temperature Reset ..................................................28 6.2.2.3 Discharge Air Temperature Reset ....................................................28 6.2.2.4 Chilled Water Reset .........................................................................28

6.2.3 Ambient Condition Adjustments.....................................................................28 6.2.3.1 Condenser Water Reset ....................................................................28 6.2.3.2 Hot Water Reset ...............................................................................29

6.2.4 KW Demand Limiting ....................................................................................29 6.2.4.1 Equipment Shedding Strategy..........................................................29 6.2.4.2 Temperature Compensated Duty Cycling........................................29

6.2.5 EQUIPMENT LOADING STRATEGIES......................................................30 6.2.5.1 Chiller Sequencing...........................................................................30 6.2.5.2 Boiler Sequencing............................................................................30

6.2.6 SYNERGISTIC OPTIMIZATION STRATEGIES.........................................31

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6.2.6.1 Cooling Generation and Distribution...............................................31 6.2.6.2 Heating Generation and Distribution ...............................................31

6.3 CAPITAL-INTENSIVE ENERGY CONSERVATION OPPORTUNITIES ...31 6.3.1 KW DEMAND LIMITING ............................................................................31

6.3.1.1 Large System Load Reduction.........................................................32 6.3.2 EQUIPMENT LOADING STRATEGIES......................................................32

6.3.2.1 Unoccupied Period...........................................................................32 6.3.3 COOLING SUPPLY OPTIMIZATION (FREE COOLING)..........................32

6.3.3.1 Air-Side Enthalpy Economizer Cycle..............................................33 6.3.3.2 Chilled Water Source Optimization .................................................33

6.3.4 DISTRIBUTION OPTIMIZATION ...............................................................34 6.3.4.1 Air Distribution................................................................................34 6.3.4.2 Water Distribution............................................................................35

6.3.5 HEAT RECOVERY ........................................................................................36 6.3.5.1 Air-to-Air Heat Exchangers .............................................................36 6.3.5.2 Water-to-Water Heat Exchangers.....................................................37 6.3.5.3 Combination Heat Exchangers ........................................................38

6.3.6 EVAPORATIVE RY CLIMATE” COOLING ................................................38 6.3.6.1 Air-Side Strategies ...........................................................................39 6.3.6.2 Condenser Air Precooler ..................................................................39

6.3.7 EQUIPMENT REPLACEMENT ...................................................................39 6.3.7.1 Boilers ..............................................................................................40 6.3.7.2 Chillers.............................................................................................40 6.3.7.3 Motors ..............................................................................................40

6.3.8 POWER FACTOR CORRECTION................................................................40

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1 Energy Management Programme Energy conservation can be defined as more efficient or effective use of energy. As fuel costs rise and environmental concerns grow, more efficient energy conversation and utilization technologies become cost-effective. However, technology alone cannot produce sufficient results without a continuing management effort. Energy management begins with the commitment and support of an organization’s top management. There are five basic stages in implementing an energy management program:

1) Develop a thorough understanding of how energy is used. Also, a data-base of past energy usage and cost should be developed. (Please refer data base to part 2.)

2) Conduct a planned, comprehensive energy audit (part 4) to identify all potential opportunities for energy conservation activities. (Please refer energy-saving-opportunities to part 6 and best practices of operation & manual procedures to part 5.)

3) Identify, acquire, allocate, and prioritize the resources necessary to implement and maintain energy conversation opportunities. (Please refer prioritization to part 3.)

4) Accomplish the energy conservation measures in rational order. This is usually a series of independent activities that take place over a period of years.

5) Monitor and maintain the energy conservation measures that have been taken. Reevaluate them as building functions change over time.

Energy efficiency and/ or energy conservation efforts should not be equated with discomfort, nor should they interfere with the primary function of the organization or facility. Energy conservation activities that disrupt or impede normal functions of workers and/ or processes and adversely affect productivity consequence false economies. 2 Data Base In developing an energy management program, a data-base of past energy usage and cost should be developed. Any reliable utility data that is applicable should be examined. Generally, this is monthly data; it should be analyzed over years. A base year should be established to be used as a reference point for future energy conservation and energy cost avoidance activities. In tabulating such data, the actual dates of meter readings should be recorded; any periods during which consumption was estimated rather than measured should be noted.

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If energy is available for more than one building and/ or department within the authority of the energy manager, each of these should be tabulated separately. Initial tabulations should include both energy (kJ) and cost per unit area. (in an industrial facility, this may be energy and cost per unit of goods produced.) Available information on variables that may have affected past energy use should also be tabulated. These might include ambient temperature, percent occupancy for a hotel, or quantity of goods produced in a production facility. Since such variables may not be directly proportional to energy use, it is best to plot information separately or to superimpose one plot over another, rather developing values as kilo-joules per square meter. As such data are tabulated, energy accounting procedures for regular collection and use of future data should be developed. Comparing a building’s energy use with many different buildings is a valuable way to check its relative efficiency. ANSI/ASHRAE Standard 105-1984, Standard Methods of Measuring and Expressing Building Energy Performance, contains information that allows uniform, consistent expressions of energy consumption, both in proposed and in existing buildings. Its use is recommended. However, the data presented here are not in accordance with this standard. The quality of published energy consumption data for buildings varies because they are collected for different purposes by people with different levels of technical knowledge of buildings. The data presented here are primarily national data. In some cases, local energy consumption data may be available from local utility companies or state or provincial energy offices. At this point in the development of an energy management of program, it is useful to compile a list of previously accomplished energy conservation measures and the actual energy and/ or cost savings of such measures. These items should be studied during subsequent energy audits to determine their present effectiveness and the effort (s) necessary to maintain and/ or improve them. Since most energy management activities are dictated by economics, it must be understood the utility rates that apply to each facility. Special rates are commonly applied for such variables as interruptible service, on peak/ off peak, summer/ winter, and peak demand, to name a few. It should be worked with local utilities to develop the most cost-effective methods of metering and billing and to enable energy cost avoidance to be calculated effectively.

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3 Priorities Having established a database, priorities should be assigned to future work efforts. If there is more than one building or department under monitoring, the database for energy use and cost for each should be compared on an overall basis and on the basis of energy use and cost per unit area, cost per unit of production, or some other index that demonstrates an acceptable level of accuracy. Comparisons should also be made with realistic energy targets, if they are known. For such comparisons, it is often possible to set priorities that use the available resources most effectively. At this point, a report should be prepared for top management outlining the data collected, the priorities assigned, and plans for continued development of the energy management program and projected budget needs. This should be the beginning of a regular monthly, quarterly, or semiannual reporting procedure. 4 Energy Audit By identifying and minimizing wasted energy through an energy audit, you can achieve the following results:

Conserve non-renewable energy resources which are gradually running out; Protect the environment by burning less fossil fuels, for example, by reducing power

generation requirement, thus lessening carbon dioxide emissions which contribute to global warming;

Save energy and reduce running costs. An energy audit may be conducted over three stages. The first is the historical data collection, which is simply a matter of checking old energy bills. The second is the preliminary survey, a walk-through of your building or plant to identify the most obvious problems. The third, the detailed investigation, calls for in-depth scrutiny of potential areas for improvement as identified by the historical data collection or preliminary survey. 4.1 Stage I – Historical Data Collection You can begin your energy audit with a review of energy consumption – the cost and amount used in your building or plant over the past two to five years.

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This can be done by examining fuel bills and system/ equipment operation log books for the billing periods you are reviewing. Put this data in the form of graphs, showing both energy consumption per month and the corresponding costs for each type of energy consumed. You can then establish a pattern or general trend over a number of years. These graphs may indicate normal seasonal fluctuations in energy consumption. They may also reveal such problems as the incorrect operation of systems and equipment or running times that are longer than necessary. For example, you may find that timers are set to operate air-conditioning and/ or lighting systems outside office hours. After the collection of historical data, the next step is to conduct the preliminary survey. 4.2 Stage II – The Preliminary Survey This is an inspection of a building or plant to identify obvious energy management opportunities – EMOs. It is a simple exercise you can carry out yourselves. All you need to do is to make use of existing data and knowledge of the building or plant to locate major energy consuming areas, obvious energy inefficiencies and wastage, and priority areas for further investigation. In buildings, the installations that need the most attention are air-conditioning systems, lighting, and lifts. Look for the following and other EMOs:

Air-conditioning and lights that remain on when the office is vacant; A single switch controlling a large number of lights; Excessive lighting levels in corridors; Inappropriate setting and positioning of thermostats; Doors and windows that are left open when air-conditioning is operating; Blinds or shades not provided in air-conditioning areas.

Some EMOs may involve changes which you can implement immediately with little or no cost. Others may require a larger investment in capital or resources. To ensure the successful implementation of any energy saving measures, however, it is essential to have all staff fully involves and committed. If a significant investment is required to save energy, you will want to determine whether the cost is justifiable through a detailed investigation.

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4.3 Stage III – The Detailed Investigation To carry out a detailed investigation, you will probably need a technical expert. Large organizations may already have staff who are qualified to make these assessments. Or you may wish to employ an outside energy specialist. The technical expert measures energy consumption levels and recommends changes that should be made. He will also provide an estimate of the capital cost required to implement the EMOs, as well as calculate the energy savings. Detailed investigations may required a larger investment both in time and money terms, so it is vital select areas which are likely to result in significant energy savings. These areas are normally identified during the preliminary survey. Another factor to consider is whether a building is owner-occupied or leased. A detailed investigation carried out by a building owner may identify problems which point is to his tenants or vice versa. It is always useful for both parties to coordinate their efforts in these investigations. Once the results from the detailed investigation are in, they should be analyzed carefully. Improvements and action programs can then be drawn up based on these findings. 4.4 Analyzing the results A written report should be drawn up based on the results of the historical data collection, the preliminary survey and the detailed investigated. It should outline any deficiencies in the collection of energy data and recommend a plan of action. The plan should include details of EMOs that offer significant savings in energy, the capital cost involved, suggested priorities, and a sequence of action to achieve energy savings. Any plan that involves a large investment needs to be financially justified. You will want to work out the payback period for each plan and compare it with the capital cost. For more expensive plans, a life-cycle cost analysis should be used. Some plans or EMOs which are not cost-effective now or have a low priority could be justified if they are implemented during major refurbishment or equipment or replacement. Always ensure that energy-efficient technology is specified when new equipment is ordered. It is also important both to monitor energy saving measures and conduct energy audits on a regular basis. This enables you to update and re-evaluate your energy management policy as part of an on-going energy management program.

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5 Best Operation & Manual Procedures 5.1 Operation 5.1.1 Operating Procedures

Each building is a unique situation and energy conserving operations should be tailored for the building involved, preferably with professional engineering guidance. Significant energy savings may often be achieved by modifying the operating procedures for HVAC systems. These operational savings may cause minor deviations from previously accepted standards of comfort.

5.1.1.1 General Guide Lines

Some or all of the following operational procedures may be implemented to effect energy savings. The temperatures quoted are dry-bulb, as measured by a thermometer, and humidities as measured by a sling psychrometer. These may differ slightly from the temperatures quoted in the CIBSE Guide.

(a) Reduce the use of heating and cooling systems in spaces which are used

infrequently or only for short periods of time. (b) Preheat building so that it just achieves 17° C by the time occupants arrive.

Complete warm-up during the first hour of occupancy (lighting, people and use of equipment will aid this process).

(c) Heat office accommodation to 20°C when occupied and to within the range of 10° C to 13° C when unoccupied. (This does not mean that air should be mechanically cooled if the temperature exceeds 20°C.)

(d) Turn heat off during last hour of occupancy. (e) Cool office accommodation to 24°C when occupied. Do not use mechanical

cooling when unoccupied. (f) Precooling during summer should be avoided where possible. However, if

necessary, precool building so that space is just at 26° C by the time the occupants arrive. Complete cool down during first hour of occupancy.

(g) Allow relative humidity to vary from 30% to 55% in air conditioned occupied spaces.

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(h) Turn off non-critical exhaust fans, i.e. where ventilation is not required for compliance with statutory regulations or for health or safety reasons, or where a process or product will not be impaired.

(i) Turn off reheat in all areas during the summer except where process or equipment requirements necessitate humidity control.

(j) During summer minimise air conditioning loads by use of shading devices at windows.

(k) During the heating season close window shading devices when dark outside to reduce radiation from body to cold window surfaces and the outside.

(l) During the cooling season reduce heat generation from internal sources i.e. lighting, machines, cooking equipment, etc.

(m) Readjust and rebalance system to minimise over-cooling and over-heating which result from poor zoning, poor distribution, improper location of controls, or improper control.

5.1.1.2 Guidelines for Operation of Central Plant

Operational changes may be accomplished by manual control or through the use of automatic systems and the efficiency and cost of both methods should be compared before implementation. The complexity, cost, and importance of central plant and machinery demands that operational changes should only be carried out by fully experienced personnel.

It is essential for the plant operator to maintain daily operational logs so that proper checks can be kept on plant operating conditions and times, and so that the worth of any energy conserving measures which are introduced can be properly evaluated.

Some of the basic operating adjustment which can be carried out are as follows:

(a) Shut down central HVAC equipment during unoccupied periods whilst assuring

that any frost or condensation protection or other safety requirements are satisfied-

(b) Consider operation of boilers at lower pressures and temperatures in accordance with demand, taking adequate safeguards, e.g. to prevent 'back- end' corrosion.

(c) Consider elimination of hot stand-by boilers (often boiler failure will not cause serious hardship).

(d) Operate only the heating water pumps necessary-

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(e) On multiple boiler plants examine operating procedures and operate one boiler at full load rather than two or more at Dart loads.

(f) Check flue gas analysis and adjust burners to achieve most efficient flue gas temperatures, CO2, O2 and excess air settings.

(g) Where multiple chillers are available, operate one compressor at full load rather than two or more at part loads.

(h) Operate condenser water system at lower temperatures and/or lower flow rates as appropriate to design of system.

(i) Operate only the chilled water pumps and cooling tower fans as necessary (j) Raise chilled water temperatures when humidity or load conditions permit.

5.1.1.3 Operating Guide Lines in Kitchen and Cafeteria Areas

Various measures are available to make more efficient use of energy in kitchen, Cafeteria and other food handling areas:

(a) Turn off infra-red food warmers when no food is being warmed. (b) Keep refrigerator doors closed and ensure seals are properly maintained. (c) Ensure refrigerator condensers have sufficient air circulation and that dust is

cleaned off coils. Ensure that condensers are sited away from heat producing equipment.

(d) Keep refrigeration coils free of frost build-up. (e) Clean and maintain refrigeration on chilled drinking water equipment. (f) Reduce temperature or turn off items not required during non-peak periods. (g) Minimise use of ovens for pre-heating. (h) Operate equipment such as dishwashers and ~ ovens only with full loads. (i) Cook with lids in place on pots and kettles. (j) Consider using micro-wave ovens for thawing and fast food preparation where

they can reduce power requirements. (k) Train employees in conservation of hot water. Fit timers to equipment. (I) Install heat reclaim equipment, particularly on dishwashers.

5.1.2Maintenance Procedures

Good maintenance is one of the most important items in ensuring the success of any programme of energy conservation and management. Effective maintenance will ensure efficient operation of systems and equipment and prolong usable life.

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With proper maintenance most equipment will operate at a better efficiency and consume less fuel or energy. Maintenance guidelines for items of equipment in common use are set out in Section 5.2.

5.2 EQUIPMENT 5.2.1General

Energy conserving management requires implementation of the correct operating and maintenance procedures so all equipment operates at best efficiency and with least possible energy consumption. The timing and frequency of maintenance procedures is vital to the efficient running of equipment. This is investigated in detail in BS 5720 published by the British Standards Institution. Monitoring equipment performance will help identify malfunctions which can then be referred to maintenance manuals.

5.2.2Prime Movers and Motors

Proper maintenance of motors and engines helps conserve energy by keeping operational efficiencies at their best levels.

5.2.2.1 Motors

Check:

(a) Electricity supply voltage is correct. (b) Loads are balanced across three phases of electrical supply. (c) Motor is correctly sized to suit application. (d) Power factor at varying loads is acceptable; correct if necessary. (e) Electrical circuits and attend to loose connections or bad contacts. (I) Motors for proper cleanliness. (f) Motor ventilation/cooling to ensure overheating does not occur. (g) Lubrication of motor and drive bearings. Inadequate lubrication results in

excessive friction and torque leading to overheating and power losses. (h) Motor drive, and where necessary tighten belts/ pulleys, replace worn bearings,

and ensure correct drive alignment.

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5.2.2.2 Engines

Check:

(a) Engine performance by recording cooling fluid temperatures and comparing with manufacturers' data and ensure temperature controls are set correctly.

(b) Fuel consumption and compare with design figures. (c) Load and demand pattern and consider waste heat recovery. (d) Maintenance procedures are carried out in accordance with instruction manuals.

5.2.3 Fans and Pumps

5.2.3.1 Fans

Check:

(a) Cleanliness of fan blades and interior fan casing. (b) Lubrication of bearings. (c) Fan drive, and where necessary tighten belts/ pulleys, replace worn bearings,

and ensure correct drive alignment. Proper tensioning of belts is critical. (d) Operation of volume control devices, i.e. speed control, dampers etc. (e) Fan noise/vibration is not abnormal. If excessive, determine cause and correct. (f) Maintenance procedures are carried out in accordance with instruction manual. (g) Motors as 5.2.2.1.

5.2.3.2 Pumps

Check:

(a) Lubrication of bearings. (b) Pump drive, and where necessary tighten belts/ pulleys, replace worn bearings,

and ensure correct drive alignment. (c) Proper tensioning of belts is critical. (d) Pump noise/vibration is not abnormal. If excessive determine cause and

correct. (e) Maintenance procedures are carried out in accordance with instruction

manuals. (f) Motors as 5.2.2.1.

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5.2.4Heating Equipment

5.2.4.1 Boilers

(i) Boilers (General)

Check:

(a) Boiler performance by recording operating pressures, temperatures and fuel consumption, monitoring combustion efficiency, noting variations from normal and taking corrective action as necessary. The use of recently calibrated portable equipment is recommended.

(b) Boiler water-side to ensure cleanliness of heat transfer surfaces (freedom from scale deposits, sediment, or boiler compounds). Where chemical cleaning is required this should be carried out by a specialist.

(c) Boiler fire-side to ensure cleanliness of heat transfer surfaces (freedom from deposits of soot, fly-ash, slag etc.).

(d) Boiler firing period. Abnormal operation may indicate faulty controls or incorrect plant selection.

(e) Flue temperature is not excessive (typically not more than 100° C above water or steam temperature).

(f) Boiler insulation, boiler casing, refractory and brickwork for unwanted hot spots or air leakage.

(g) Monitor effectiveness or water treatment.

(ii) Oil-Fired Boilers

Check: (a) Oil burners; inspect nozzles or cups, clean as necessary. (b) Oil line strainers; clean or replace if dirty. (c) Oil heaters to ensure oil maintained at correct temperatures. Consider thermal

insulation of tanks, particularly if tanks are outside building. (d) Oil pipe lines for absence of leaks. (e) Oil pumps operate properly and maintained in accordance with instruction

manuals.

(iii) Gas-Fired Boilers

Check:

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(a) Gas burners; clean as necessary and examine for wear. (b) Burner gas pressure. (c) Gas lines for absence of leaks. (d) Gas boosters operate properly and maintained in accordance with instruction

manuals. (e) Governors and control valves are operating correctly. (f) Heat exchanger is clean.

(iv) Coal- Fired Boilers

Check:

(a) Automatic stokers, grates, controls for efficient operation. Excessive unburned coal contained in the ashes indicates inefficient operation/ combustion.

(b) That for kindling condition, the minimum rate for effective continuous combustion is used.

(v) Electric Boilers

Check:

(a) Heater elements for cleanliness and/or electrodes for cleanliness, wear, alignment and spacing.

(b) Electrical supply voltage correct. (c) Electrical circuits; attend to loose connections or bad contacts. (d) Relays properly maintained. (e) Controls for proper operation.

5.2.4.2 Central and Room Heating Units

(i) Radiators, Convectors. Skirting (Baseboard) and Finned- Tube Units

Check:

(a) Cleanliness of all heat transfer surfaces and unit casings. (b) Heating units properly air-vented and hot water circulating correctly. (c) Air movement across heat transfer surfaces not obstructed.

(ii) Warm Air Fan Units (Furnaces) and Unit Heaters

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Check: (a) Cleanliness of all heat transfer surfaces and unit casings. (b) Air movement across heat transfer surfaces not obstructed. (c) Fuel burners for correct operation. (d) Unit insulation and casings for hot spots or air leakage. (a) Repair and seal as necessary. (e) Fans, motors and drives for proper operation as 5.2.3.1. and 5.2.2.1.

respectively. (f) Air Filters are clean.

(iii) Direct Electric Heaters

Check:

(a) Cleanliness of all heat transfer surfaces and unit casings. (b) Air movement across heat transfer surfaces not obstructed. (c) Electrical supply voltage correct. (d) Electrical circuits, and attend to loose connections or bad contacts. (e) Controls for proper operation.

(iv) Off-Peak Storage Heaters

Check:

(a) As (iii) above. (b) Charging period and tariff is appropriate to pattern of use. (c) Charging controls are correctly set for building insulation standards.

5.2.5 Refrigerating Equipment

5.2.5.1 Compressors

Check:

(a) Compressor operating pressure and temperatures are in accordance with operating instructions, particularly suction pressure, discharge pressure and oil pressure.

(b) Compressor operates normally. Frequent starting/stopping or continuous running may indicate inefficient operation.

(c) Compressor noise level is not abnormal. Excessive noise or vibration may indicate drive needs attention.

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(d) Compressor joints and shaft seals (open machines only) to ensure leakage is not occurring.

(e) Motors as 5.2.2.1. 5.2.5.2 Water Chillers (Evaporators)

Check:

(a) Chiller performance by recording water inlet and outlet temperatures and flow rate (or water-side pressure drop).

(b) Chillers to ensure cleanliness of water-side heat transfer surfaces is maintained. Where chemical cleaning is required this should be carried out by a specialist.

(c) Monitor effectiveness of water treatment. 5.2.5.3 Condensers and Heat Rejection Apparatus

(i) Water-Cooled Condensers

Check:

(a) Condenser performance by recording water inlet and outlet temperatures and flow rate (or water-side pressure drop).

(b) Condensers to ensure cleanliness of water- side heat transfer surfaces.

Where chemical cleaning is required this should be carried out by a specialist.

(a) Associated cooling towers as 5.2.5.4. (b) Monitor effectiveness of water treatment.

(ii) Evaporative Condensers

Check:

(a) Condenser performance by ensuring refrigerant pressures and water temperatures are in accordance with operating instructions

(b) Condenser to ensure cleanliness of heat transfer surfaces. (c) Water piping circuits free from leakage, and spray nozzles/water distribution

system clean, including pump screen/strainer. (d) Refrigerant piping circuits free from leakage. (e) Fan and pump working in accordance with operating instructions, see also 5.2.3. (f) Air inlet filters/screens clean.

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(g) Monitor effectiveness of water treatment.

(iii) Air-Cooled Condensers

Check: (a) Condenser performance by ensuring refrigerant pressures, and air flow rates

and temperatures are in accordance with operating instructions, and that control for energy conservation as recommended in 3.8 is being maintained.

(b) Condenser to ensure cleanliness of heat transfer surfaces. (c) Refrigerant piping circuits free from leakage. (d) Fans working in accordance with operating instructions, see also 5.2.3.1. (e) Air flow not being by-passed from fan outlet to coil inlet.

(iv) Cooling Towers

Check:

(a) Tower performance by recording ambient wet-bulb temperature, water inlet and outlet temperatures and flow rate, and that control for energy conservation as recommended in 3.8 is being maintained.

(b) Tower cleanliness to minimise air-side and water-side resistances including tower-fill or packing, nozzles/water distribution system, tower basin, water intake screens/ strainers, air intake screens etc.

(c) Water piping circuits free from leakage. (d) Water levels correct and 'bleed-off properly controlled. (e) Fans working in accordance with operating instructions, see also 5.2.3.1. (f) Air flow not being by-passed from tower outlet back to inlet. (g) Monitor effectiveness of water treatment.

5.2.5.4 Refrigerant Piping Circuits and Controls

Check:

(a) Operating pressures and temperatures are correct around the system. (b) Piping, equipment and components to ensure freedom from refrigerant and oil

leaks, paying particular attention to pipe joints on equipment, valves and instrumentation and around flanges, flare connections and condenser relief valves.

(c) System is free of moisture by inspection of moisture-liquid indicator . (d) Refrigerant charge is correct.

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Bubbles in sight glass may indicate system is short of refrigerant. (e) Expansion valves correctly set. (f) Insulation on suction and liquid lines.

5.2.5.5 Unit Air Conditioners

This includes window-box and through-the-wall type room air conditioners and room heat pumps.

Check:

(a) Unit to ensure cleanliness of heat transfer surfaces, e.g. evaporator and condenser coils, heating elements etc.

(b) Filters and intake / discharge louvres are clean. (c) Air flows not obstructed. (d) Electrical supply voltage correct. (e) Window and wall frames around units to ensure no unwanted air leakage. (f) Unit is properly maintained;

compressors (5.2.5.1.) condensers (5.2.5.4.) refrigerant piping (5.2.5.5.) and fans (5.2.3.1.).

5.2.6 Air Handling Equipment

Check:

(a) Equipment components for cleanliness and ensure pressure drops are in accordance with manufacturers' data e.g. heating and cooling coils, filters, casing interior etc.

(b) Fans as 5.2.3.1. (c) Humidification and dehumidification equipment as 5.2.7. (d) Damper blades and linkages for proper operation and for tight shut-off where

required. (e) Unit casings and around coils and components for freedom from air leakage. (f) Insulation; repair or replace where necessary.

5.2.7 Humidification and Dehumidification Equipment

Check:

(a) Equipment components for cleanliness, e.g. spray nozzles, eliminators, strainers, water tanks, casing interiors etc.

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(b) Fans and pumps as 5.2.3. (c) Equipment operation to ensure absence of moisture carry-over. (d) Monitor effectiveness of water treatment.

5.2.8 Air Compressors for Pneumatic Controls

Check:

(a) Compressor operates normally. Excessive running may indicate air leakage/ pressure loss in the pneumatic piping system or at the controls.

(b) Air pressure in storage vessel at correct level, pressure switches correctly set and all pressure regulating valves functioning properly.

(c) Air intake filters clean. (d) Moisture removal/drying equipment working properly. (e) Maintenance procedures are carried out in accordance with instruction manuals. (f) Motors as 5.2.2.1.

6 Energy Saving Opportunities 6.1 Low Cost/ No Cost Energy Conservation Opportunities 6.1.1Review Rate Structures

Many electric utilities have ten or more different services, each often subject to one or more riders. Contact an appropriate utility representative to find out what different rates, services, schedules, and riders are available. Most have customer service representatives who can explain utility operations and go over yours to suggest ways of economizing. Once you are familiar with utility materials, determine for every separate service location:

Rate schedule and riders used Maximum demand and period of occurrence Power factor Monthly and annual energy consumption Average cost per Kwh Service voltage level and secondary use level Transformer and equipment ownership

Make a complete and careful review of at least one current bill for each service and ask yourself: "Am I getting the appropriate rate?" "Is the bill computed properly?" "Why am I on

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this rate?" "How can I qualify for a better rate?" Seek a satisfactory answer to each question. Contact utility representatives for help and work with them to develop a program and rate which best meets your needs and conditions. Have them come in to review each service. Ask them if other rates apply or could be made applicable. Determine advantages and disadvantages of each. Check figures. Your utility representative will tell you about the alternatives if you ask, but it's up to you to make a decision. If you do decide to change rates, determine what the impact will be, if any, on building systems, and what savings will be generated.

6.1.2 Maintenance Modifications

The importance of good maintenance to a program of energy management cannot be overemphasized. Not only will effective maintenance help ensure efficient operation of equipment and systems but also will help prolong the useful life of equipment.

6.1.3 Ventilation

Inspect all outdoor air dampers. They should be as air-tight as possible when closed.

Check operation of actuators and positive positioners for accuracy. Install, repair, or replace as needed.

Inspect filters carefully. Utilize high-efficiency, low-cost filters Reduce exhaust air quantities where practical. Establish a ventilation operation schedule so

the exhaust system operates only when needed. Add a warm-up cycle to air handling units with outdoor air intake. Keep outdoor air

dampers closed during morning warm-up or cool-down cycles so that only existing building air is conditioned.

Add controls to shut down the ventilation system whenever the building is unoccupied for an extended period of time.

Reduce volume of toilet exhausts in buildings which have multiple toilet exhaust fans having a total fan capacity in excess of outdoor air requirements.

Install baffles to prevent wind from blowing directly into an outdoor air intake. Install enthalpy economizer controls to air handling units. Enthalpy control will determine

the most economical source of supply air, outdoor air vs. return air, thus maximizing "free cooling" opportunities.

Check if backdraft dampers are operating correctly, motorized and gravity-type. Verify through temperature calculation that the minimum outdoor air dampers are set

properly. A 10% crack can actually allow approximately 30% air flow.

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6.1.4 Infiltration

Replace broken or cracked window panes. Replace worn or failed weatherstripping around operable windows. If possible, install

weatherstripping where none was installed previously. Consider instructing occupants not to open windows while the building is being heated or

cooled. Replace any worn or broken weatherstripping or caulking around doors. Inspect gasketing on garage and other overhead doors. Repair, replace, or install as

necessary. Consider installing automatic door closers on all doors leading to the exterior or

unconditioned spaces. Consider installation of an air curtain, especially in delivery areas. In locations where strong winds occur for long durations, consider installing wind screens

to protect external doors from direct blasts of prevailing winds. When heating areas with strong infiltration rates, avoid using convection heating systems.

Use radiant heating systems where possible. Radiant heaters do not waste energy by heating the fast moving air, instead they heat people and objects only.

Caulk, gasket, or otherwise weatherstrip all openings, such as those provided for entrance of electrical conduits, piping, through-the-wall cooling and other units, outside air louvers, etc.

6.1.5 Operating Practices

Reduce use of heating and cooling systems in spaces which are used infrequently or only for short periods of time.

During cooling season after hours, flush the building with outdoor air if the enthalpy is lower than the present indoor air.

When appropriate, consider closing supply registers and radiators and reducing thermostat settings or turning off the electric heaters in lobbies, corridors, and vestibules.

Turn off all non-critical exhaust fans. Develop an after-hours equipment operation checklist for use by custodial and other

building personnel as well as by occupants who may use various spaces after normal periods of occupancy.

Adjust and balance system to minimize overcooling and overheating which result from improper zoning, distribution, sensor location, sensor calibration and control sequences.

Shut down central and distributed heating, ventilating, and air conditioning equipment during unoccupied periods.

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Operate one of multiple compressors and chillers or boilers at full load, rather than two or more at part loads.

Operate the condenser water system at optimal temperatures for the equipment receiving condenser water.

Operate only the chilled and hot water pumps and cooling tower fans necessary. Increase chilled water supply temperatures when humidity and load conditions permit. Operate boilers at lower pressures and temperatures in accordance with space heating

demand. Consider elimination of hot standby boilers since, in many cases, a boiler failure will not

cause serious hardship. Check flue gas analysis on periodic basis: the efficient combustion of fuel in a boiler

requires burner adjustment to achieve proper stack temperature, CO2, and excess air

settings. Check settings to provide stack temperatures of no more than 150o above steam or water temperature. There should be no carbon monoxide. For a gas fired unit, CO2

should be present at 9 or 10%. For #2 oil, 11.5-12.8%; for #6 oil, 13-13.8%. Adjust air/fuel ratios of firing equipment. Most fuel service companies will test your

units for a token fee and provide specific recommendations. Use automatic viscosity controllers to achieve better oil combustion atomization. Automatic viscosity controllers also permit mixing or using different grades of oil. Intelligently question the operation of each piece of equipment and eliminate their

operation if unnecessary. Adjust tenants expectation of service to coincide with lease operating hours and adjust

operating hours accordingly.

6.1.6 Hydronic Systems

Install insulation on all hot and chilled water pipes, fittings, and valves passing through unconditioned spaces to minimize heat losses and gains.

Balance hydronic systems to attain satisfactory temperature and water flow. Trim impeller to actual size required on pump curve after terminal unit flows are reduced to the minimum. This will enable reductions of power requirements of actual load.

Check sizing of valves, filters, and pipe sections. All those which are undersized should be replaced.

Blowdown energy losses can be minimized by installing automatic blowdown control. Automatic blowdown controls monitor the conductivity and Ph of the boiler water and only release water necessary to maintain acceptable water quality.

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6.1.7 Steam Systems

Install insulation on all steam mains, risers and branches, economizers, water heaters, and

condensate receiver tanks where none now exists. Add additional shut-off valves for more efficient zone control. Check that shut-off valves are operating properly and are not allowing steam to escape into

the system piping. Modify equipment as necessary to recover heat now going to the sewer. Such reclaimed

heat from condensate can be used for boiler feedwater heating, to heat a portion of the building, to preheat water being supplied to the domestic hot water heater, or can be returned to the boilers.

Check for proper operation of all steam traps and replace where necessary.

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6.1.8 Air Distribution Systems

Test, adjust, and balance entire air distribution system in accordance with methodology

suggested by ASHRAE. Insulate all ductwork carrying conditioned air through unoccupied spaces with at least

11/2" of fibrous insulation or its thermal equivalent. Reduce system resistance to air flow to a minimum by replacing those duct sections and

fittings which impose unnecessary resistance on the systems Reduce fan power input requirements by reducing air volume.

Install turning vanes in all square 90o ductwork transitions.

6.1.9 Control Adjustment and Modifications

Adjust controls at the time of testing, adjusting, and balancing of all heating and cooling

systems. Adjust controls where applicable to prevent simultaneous operation of heating and cooling

systems to achieve desired temperature. Add controls to enable up to 100% shut-down of air and water to unoccupied space. Consider installation of night set-back and morning start-up controls. Consider adding a step-controller to electric heating systems with resistance elements to

permit staging, resulting in more effective heat control and demand management. Calibrate controls as per manufacturers requirements.

6.1.10 Transmission

Keep indoor shading devices clean and in good repair. During the heating season, close all interior shading devices before leaving space to reduce night-time heat losses.

Install indoor shading devices where none now exist, even if exterior shading devices are used. They should be light-colored and opaque.

Add or improve insulation under floors that are over garages or other unconditioned areas. Refer to ASHRAE Standard 90 for insulation guidelines.

6.1.11 Lighting

Establish an effective lighting usage program. Reduce exit lighting consumption to 10 watts per fixture maximum. Consider replacing present lamps with those of lower wattage which provide the same

amount of illumination.

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Remove unnecessary lamps if the required illumination levels can be attained. Replace existing lamps with more efficient version of the same type of lamp. Replace existing mercury vapor lamps with more efficient metal halide or high pressure

sodium lamps designed specifically for the purpose. Consider use of light-reducing fluorescent lamps when reduced light output is consistent

with needs in the space, such as stairwells and storage rooms. Use occupancy sensors wherever possible. When natural light is available in a building, consider the use of photocell switching to turn

off banks of lighting in areas where the natural light is sufficient for the task. Use photocell and/or time clock controls for outdoor lighting whenever feasible. Shut off lights during unoccupied hours. Re-circuit lights to allow for unoccupied shutdown of mixed use space. Use alternate switching or dimmer controls when spaces are used for multiple purposes and

require different amounts of illumination for the various activities.

6.1.12 Domestic Hot and Cold Water

Inspect water supply system and repair all leaks, including those at the faucets. Install water saving flush valves where not presently installed. Inspect insulation on water storage tanks and piping. Repair or replace as needed. Reduce generating and storage temperature levels to the minimum required for washing

hands, usually about 105oF (40.56 oC). If you have an electric domestic water heater, consider load shedding to avoid adding water

heating load to the building during periods of peak electrical demand. If hot water is distributed through forced circulation, turn off the pump when the building

is unoccupied. Install aquastats on forced circulation systems. Disconnect all refrigerated water fountains after hours and during the day if acceptable to

building occupants. Change all faucets to metered type and if existing, adjust on time to less than 30 seconds.

6.1.13 Elevators and Escalators

Turn off unnecessary elevator systems after hours. Perform a traffic review to determine if a building is properly elevatored or over or

under-elevatored in light of use during different periods of the day. If properly elevatored or over-elevatored, take one or more elevators out of operation at least during periods of light traffic

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6.2 Equipment Operation Strategies 6.2.1 Time-based Optimization

The following optimization strategies are initiated and terminated during a specifically determined time of the day where the operational level of equipment can be altered without adversely affecting occupant comfort levels.

6.2.1.1 Time of Day Operation

Timed operation functions consist of starting and stopping various systems based on the time of day. Most sophisticated control systems include holiday settings and daylight savings features, thus eliminating the need to reset settings periodically.

6.2.1.2 Space Temperature Unoccupied Setpoint Adjustment

The energy required to maintain space conditions during the unoccupied hours can be reduced by adjusting the temperature set point for the space. The amount of setback is limited by the ability of the equipment to regain temperature control and not allow equipment to fail (pipes freezing) during the unoccupied periods.

6.2.1.3 Start/Stop Optimization

Optimized start/stop is a program to start and stop the system based on the thermal inertia of a structure, the capacity of the system to either increase or decrease temperatures during the facility start-up and shut-down times, and weather conditions.

6.2.2 Reset Strategies

The following include strategies that allow the resetting of setpoint temperatures based on changing conditions.

6.2.2.1 Load Side Adjustments

Reset of the setpoints is determined by changes in the quantity of heating or cooling required for the specific operation.

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6.2.2.2 Hot/Cold Deck Temperature Reset

The system selects individual areas with the greatest heating and cooling requirements and adjusts the hot and cold deck temperature accordingly, minimizing the inefficiency of the system by reducing the difference between the hot and cold deck temperatures.

Note: In many instances where both cooling and heating are occurring simultaneously, the best choice is the elimination of one or the other or both. Re-heat (mixing) type systems can be successfully converted to variable air volume systems, creating a substantial energy savings. This option of conversion should ultimately be the first consideration when dealing with the optimization of re-heat systems.

6.2.2.3 Discharge Air Temperature Reset

Only variable temperature heat systems will be able to take advantage of the discharge air temperature reset strategy. This function adjusts the cooling coil discharge temperature upward until the zone with greatest demand for cooling has closed its reheat coil valve.

6.2.2.4 Chilled Water Reset

Depending on several factors, energy can be saved be resetting the chilled water temperature, allowing it to rise no further than the zone with the greatest cooling demand. Specific control schemes depend on system configuration. For example, operating chillers at elevated chilled water temperature leaving the evaporator causes an increased refrigerant temperature and enthalpy entering the compressor. This, in turn, increases the cycle of efficiency (coefficient of performance) of the chillers. For the compression refrigeration cycle, the following rule of thumb is used: a 1oF increase results in a 1% savings in energy input.

6.2.3Ambient Condition Adjustments

Changing external conditions allow for reset of certain setpoint temperatures, enabling further energy savings.

6.2.3.1 Condenser Water Reset

Overall energy consumption of refrigeration equipment can typically be decreased by reducing the condenser water setpoint temperature. Specific control schemes depend on the system configuration and type of refrigeration equipment.

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For example, operating chillers at reduced condenser water temperatures decreases the enthalpy of refrigerant exiting the compressor. This increases the coefficient of performance and thus reduces the energy consumption. Typically, a 1% increase in efficiency can be expected by a 1oF or 0.56 oC decrease in condenser water temperature. In order to attain maximum energy savings, the manufacturer part load data and control recommendations should be attained before any condenser water reset strategy is implemented.

Note: Excessive condenser water temperature reduction can have adverse effects on the operation and efficiency of certain refrigeration equipment, especially centrifugal equipment. Pressure differentials below the design point (condenser water temperatures below approximately 65oF or 18.33 oC) begin to erode previous efficiency gains and can cause several operational problems, including oil loss and refrigerant old up” in the condenser section.

6.2.3.2 Hot Water Reset

In a reduced load condition, boiler outlet water temperature can be reduced by mixing the outlet water with boiler inlet water to create a mixture determined by the outside air temperature and the boiler water temperature difference. This unloads the boiler and decreases fuel consumption. As the boiler unloads, flue gas temperature decreases but still remains high enough to not precipitate corrosive substances inside the boiler stack.

6.2.4 KW Demand Limiting

The following strategies reduce the overall kW maximum electrical demand. These strategies are especially beneficial in areas where the utility company charges an increased rate for kWh consumption based on the maximum kW demand consumed in the measured period of time.

6.2.4.1 Equipment Shedding Strategy

The shedding strategy disables non-critical electrical loads to prevent a predetermined maximum electrical demand from being exceeded. Additional secondary loads are turned off on a priority basis if the initial load shedding action does not reduce the predicted demand to a level low enough to satisfy the function requirements.

6.2.4.2 Temperature Compensated Duty Cycling

Temperature compensated demand limiting is used primarily on refrigeration equipment. At a

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predetermined kW demand level, the operating setpoint of equipment will be adjusted, thus either decreasing the runtime of the equipment or reducing the load on the associated equipment.

6.2.5 EQUIPMENT LOADING STRATEGIES

The following strategies maximize plant efficiency by assuring that the existing equipment is allowed to reach full load efficiency before additional equipment is enabled.

6.2.5.1 Chiller Sequencing

Substantial electrical cost savings are achievable by operating the most efficiency combination of lead and lag chillers. In multiple chiller plants, optimum scheduling can often be accomplished with no investment and, at other times, with adding a nominal amount of piping and control equipment that will allow for the automatic starting/stopping, monitoring, and unloading of the associated equipment. A lag chiller should only be started when two chillers can operate more efficiently than one. The majority of the time, it will always be more efficient to run one chiller fully loaded as opposed to two or multiple chillers partially loaded. Knowing the optimum loading point of a specific chiller is critical in optimizing operating efficiency. Because it is not always easy to determine a chiller part load performance curve for a specific set of conditions, this comparison should be based on efficiency ratings at constant condenser water temperature, not the ARI chiller curve.

6.2.5.2 Boiler Sequencing

Light heating loads on a multiple boiler installation are often met by one boiler on line with the remaining boilers idling on standby. Idling boilers consume energy to meet standby losses. In many cases, these losses are increased by a continuous induced flow of air through the idling boilers and up the chimney. Unless a boiler is about to be used to meet an expected increase in load, it should be secured and isolated from the heating system (by closing valves) and from the stack and chimney (by closing dampers). A large boiler can be fitted with bypass valves and regulating orifice to allow the minimum flow required to keep it warm and avoid thermal stress when it is brought online again. If a boiler waterside is isolated, it is important to prevent backflow of cold air through the stack which could cause the boiler to freeze.

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6.2.6 SYNERGISTIC OPTIMIZATION STRATEGIES

These strategies take a holistic approach to energy consumption reduction. Instead of focusing on individual pieces of equipment, synergistic optimization strategies emphasize complete systems.

6.2.6.1 Cooling Generation and Distribution

Before optimizing a system component, the effect on the entire system needs to be analyzed. Many times, one optimization strategy can eliminate the savings generated by another strategy. Unfortunately, there are no hard and fast rules to make the process of integration easier. In fact, in many cases, the only way to verify the most efficient way of operating installed equipment is through diligent comparison tracking. Meters may need to be installed to measure both the output of conditioned capacity and the input of energy to the associated systems. Here is an example of competing optimization strategies. If a cooling system is equipped with a VFD on the distribution pump and the chiller has chilled water reset capacity, which one of the two or both strategies should be implemented? For instance, if the space load requirements decrease and the flow is decreased, the chilled water temperature will remain constant, and no possible savings from a chilled water reset strategy would be realized. Should the temperature of the chilled water be reset before the flow of chilled water is reduced by the VFD? The answer depends on the specific type of refrigeration equipment, capacity, unloading curve, size of the distribution pump, and quantity of reduced load.

6.2.6.2 Heating Generation and Distribution

As in the cooling generation and distribution example, conflicts in optimization strategies can be created. Hot water reset strategies and distribution optimization strategies can at times counteract each other. Once again, careful analysis of the energy consumption of the associated equipment should be determined before an optimum overall strategy can effectively be implemented between the hot water distribution flow reduction and hot water reset.

6.3 CAPITAL-INTENSIVE ENERGY CONSERVATION OPPORTUNITIES 6.3.1 KW DEMAND LIMITING

The following strategies reduce the overall KW maximum electrical demand. These strategies

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are especially beneficial in areas where the utility company charges an increased rate for KWH consumption based on the maximum KW demand consumed in the monitored period of time.

6.3.1.1 Large System Load Reduction

Most utility companies offer a discounted KWH rate during off hours and may not even charge a demand penalty during these same off hours. Therefore, there exists a large incentive to adjust peak loads to these off hours. All of the following load reduction strategies are typically complemented by the installation of an overall equipment KW demand load shedding system.

Thermal Storage Load Shifting Thermal storage technology shifts all or part of the building's air conditioning requirements from peak to off-peak hours. Refrigeration equipment typically is operated at night producing ice or chilled water which is subsequently stored in insulated tanks and used the next day to meet all or part of the building's cooling requirements. Thermal storage is most cost effective in office, retail, and health facilities. Generally speaking, thermal storage is not cost effective in buildings with small cooling loads, peak loads occurring during off hours, or where the utility rate does not have a substantial rate reduction during off-peak hours.

6.3.2 EQUIPMENT LOADING STRATEGIES

The following strategies maximize plant efficiency by assuring that the existing equipment is allowed to reach full load efficiency before additional equipment is enabled.

6.3.2.1 Unoccupied Period

During unoccupied periods or in extreme part load conditions in chiller plants that are never fully loaded, a smaller, more efficient chiller that would operate more hours at its optimum loading point may be cost justified.

6.3.3 COOLING SUPPLY OPTIMIZATION (FREE COOLING)

These strategies take advantage of moderate weather conditions, low wet bulb temperatures, that will allow for the elimination of relatively expensive compression refrigeration when the facility still maintains a substantial cooling requirement. These strategies are often referred to

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as free cooling opportunities. 6.3.3.1 Air-Side Enthalpy Economizer Cycle

An air side enthalpy economizer cycle compares the total heat content, enthalpy, of two air streams, return air and outdoor air, and chooses the most economical source. Dry bulb economizers attempt to mimic the aforementioned strategy though fail to maximize savings and in certain conditions may actually make the wrong control decision.

Note: Enthalpy monitoring equipment is extremely sensitive and should be carefully maintained. The humidity measurement component may need to be replaced as often as every three years.

6.3.3.2 Chilled Water Source Optimization

In most cooling plants the chiller uses by far the most energy in the system. As a result, the greatest possible energy savings would accrue from turning off the chiller. Under suitable conditions of weather and cooling load, the cooling tower can act as the source of chilled water.

Direct Free Cooling This is the simplest and most thermally effective use of cooling tower water. With direct free cooling a bypass system physically interconnects the condenser water and chilled water loops into one common water path between the load and the cooling tower. This direct interconnection of the two water loops permits the load to benefit from the cooling tower's full capacity. This direct system, often called a strainer cycle, is usually least recommended because of numerous problems associated with its operation and maintenance. Intermixing the two water streams contaminates the "clean" chilled water with "dirty" condenser water. Besides the real possibility of fouling the relatively small heat exchanger passages in the chilled water loop, mixing water from the two loops creates a challenge for water treatment of both systems.

Indirect Free Cooling

The addition of a heat exchanger piped in a parallel bypass circuit with the chiller maintains complete isolation of the chilled water and condenser water loops during the free cooling

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cycle. While some free cooling opportunity is lost because of the need for colder water from the cooling tower, the indirect free cooling system offers the clear advantage of separate water circuits. It also permits the isolation of the chiller for seasonal cleaning and maintenance. Plate-and-frame heat exchangers are usually acceptable for the moderate temperatures and low pressures occurring in the water circuits. Also, because the plate exchanger can function properly with only a small temperature difference they are the most common means of indirect free cooling. Because of its operating advantages and relatively low costs, the indirect free cooling system is the most commonly used.

Refrigerant Migration

Many chiller manufacturers offer an accessory package that can enable this free cooling method to be used. In this arrangement, as the compressor shuts down, valves open to permit the free migration of refrigerant vapor from the evaporator to the condenser and the flow of liquid refrigerant from the condenser to the evaporator.

Because heat transfer is essentially limited to refrigerant phase-change, the capability of these systems rarely exceeds about 25 percent, a very small portion of the year. A requirement for full-load operation would completely preclude the use of a refrigerant migration system.

6.3.4 DISTRIBUTION OPTIMIZATION

The following strategies attempt to reduce energy consumption by modulating the flow of the controlled medium as the demand and load of the controlled system changes. As less medium is circulated the energy necessary to condition the medium is also reduced.

6.3.4.1 Air Distribution

These strategies have become very popular with the advent of variable air volume systems. The following methods provide better control and greater energy savings as compared to traditional static discharge control or the re-direction of the supply air.

Inlet Vane Dampers

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Adjustable dampers installed on the inlet side of centrifugal fans modulate in order to adjust the quantity of air supplied to the system. Inlet vane dampers, depending on their design, for the most part unload the motor evenly. For example if the flow is reduced to 80% capacity the motor will only consume approximately 75% of the design flow energy. At 50% capacity the motor will now only draw 60% of the original energy consumption.

Variable Frequency Drives A variable frequency drive (VFD) varies motor speed by changing the voltage and frequency of the output to the motor. In the case of centrifugal fans, energy savings result from the fact that the power to operate the device varies with the cube of the speed in applications where the system pressure drop depends on flow. Therefore if the system and the load allow a fan to slow down to 75% of its design speed, the theoretical power to do the job will be only 42% of the design input power.

VFD's not only provide substantial savings but also allow for more stable control of the system as compared to other alternatives. VFD's provide a means of ramping up induction motors slowly thus alleviating the stress associated with starting and stopping. VFD's also help eliminate the degrading effect induction motors have on the electrical systems power factor. VFD's have several applications including, variable air volume systems, cooling tower fans, exhaust fans, etc.

6.3.4.2 Water Distribution

Similar to the air distribution strategy, pumping power can be reduced in systems where a decrease in flow is possible or entire portions of the distribution system can be decoupled without any negative effect on the operation of the system.

Primary/Secondary Pumping In primary/secondary pumping systems the production flow, chiller plant or boiler plant, is hydraulically isolated from the distribution flow, cooling coils or radiators. The advantages to primary/secondary pumping systems-decoupled systems are numerous. Portions of the system can be isolated without affecting the operation of the rest of the system. Problems associated with reduced flow through generating equipment, chillers and boilers are

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eliminated.

With the reduction of load and the reduction in generating equipment, secondary pumps may also be disabled.

Variable Frequency Drives The power input to centrifugal pumps, like centrifugal fans, varies with the cube of the pump speed. Variable speed pumping can be applied only on variable flow water systems. These include domestic water booster pumps and hydronic heating and cooling systems where the loads are controlled with two-way valves. When reducing flow through conditioning equipment care should be taken. Boilers and chillers have minimum flow requirements that must be met to ensure proper operation.

6.3.5 HEAT RECOVERY

The following strategies attempt to recover the energy available in waste heat. All processes, whether the consumption of natural resources to create heat or the conversion of electrical energy into work create waste heat. The keys to reclaiming this waste heat are two fold. First, there needs to be another ongoing process that can use this waste heat. Second, the waste heat needs to be at a high enough temperature so that it can be useful.

6.3.5.1 Air-to-Air Heat Exchangers

Air-to-air exchangers transfer heat directly from one air-stream to another through direct contact on either side of a metal heat transfer surface. Air-to-air heat exchangers may be purchased as packaged units or can be custom made. They transfer sensible heat only unless treated with special materials. Size is limited only by the physical dimensions of the space available. Although efficiencies of air-to-air heat exchangers generally are below 50%, it must be recognized that they are relatively inexpensive, have low resistance to air flow, in most cases require no motive power input, and are trouble-free and durable.

Rotary The rotary heat exchanger uses a heat transfer medium in the form of a cylindrical drum or wheel. When rotated slowly between the supply air stream and the exhausted air stream, it

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absorbs heat from the warmer air stream and delivers heat to the cooler air stream.

In addition to sensible heat transfer, the wheel can be treated with a desiccant, drying agent, which transfers water vapor from the humid air stream to the drier air stream. Non-hygroscopic - non-absorbing - wheels transfer water vapor when the temperature of one air stream is below the dew point temperature of the other and there is direct condensation of water vapor.

Convoluted Plate This type of heat exchanger acquires its name from the irregular shaped heat transfer surface. It is typically used for low temperature heat transfer in conditioned air processes.

Heat Pipe

A heat pipe is a possible heat exchanger which involves a closed fluid cycle within a sealed tube. Cool air passing over one end of the tube is heated when it condenses the fluid enclosed in the tube. The warmer air stream passing over the other end of the tube is cooled when it evaporates the fluid contained in the tube. The action is reversible and operates whenever there is a temperature difference between either end of the tube. Because they contain no moving parts, there is minimal leakage between air streams. Mechanical energy is not used except in the form of increased fan horsepower to overcome static pressure losses. Note that the two ducts transferring the energy must be brought into close proximity to each other.

6.3.5.2 Water-to-Water Heat Exchangers

Shell and tube heat exchangers are the most common and can be used to exchange heat in liquid-to-liquid, steam-to-liquid, and gas-to-liquid configurations. All three configurations are commercially available in a wide range of sizes and outputs and with reliable heat exchange data. Heat exchangers should be insulated to prevent unnecessary heat loss and should be constructed of materials to suit the application.

Condensate Recovery This waste heat is typically used to preheat feed boiler water or for heating domestic hot water. Condensate generation is non-linear, therefore they may be coupled with storage tanks

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to ensure that most of the heat is captured for later use. When the temperature of disposal of hot condensate is regulated, the use of a condensate recovery system can also eliminate the use of domestic cold water for cooling the condensate before disposal.

Double Bundle Condenser A double-bundle condenser is constructed with two entirely separate water circuits enclosed in the same shell. Hot refrigerant gas from the compressor is discharged into the condenser shell where its heat is absorbed by either one of the water circuits or by both simultaneously depending on the requirements of the system at a given time. One of the circuits is called the building water circuit and the other the cooling tower circuit. The condenser is split into two independent hydronic circuits to prevent contamination of the building water and its associated pipes, coils, pumps, and valves with cooling tower water, which may contain dirt and corrosive chemicals. When a double-bundle condenser is added to a standard refrigeration machine, the heat rejected by the compressor is made available to the building water circuit.

Miscellaneous Hot Water Waste Recovery As the title suggests anywhere that substantial waste heat is available a heat exchanger could be commissioned to reclaim and re-use that surplus energy. The number of possibilities is limited by the return on investment and imagination of the engineer.

6.3.5.3 Combination Heat Exchangers

Run-around System The run-around system consists of finned-tube water coils located in the exhaust and supply air stream, and a pump circulating water or a water/ anti-freeze solution between the coils. In this form, the system is for sensible heat recovery only. It is seasonably reversible, preheating in the winter and precooling in the summer. If latent recovery is necessary, the system can be modified by replacing the water coils with a cooling tower surface. Therefore, an additional solution pump is needed to complete the system. This provides total heat or enthalpy transfer as the solution absorbs heat and water vapor from the air streams and also acts as an air washer or scrubber.

6.3.6 EVAPORATIVE RY CLIMATE” COOLING

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In parts of the country where the summers are very dry, translating into low wet-bulb temperatures, evaporative cooling can substantially reduce the cooling requirement placed on refrigeration equipment. In short, the evaporation of water in very dry air can substantially decrease the temperature of the air.

6.3.6.1 Air-Side Strategies

The following strategies affect the supply air to the space directly.

Direct Water is distributed directly into the supply air stream through the use of various mechanisms, including spray nozzles and baffles. The water evaporates in the dry air, thus reducing the sensible temperature of the air. Although this is the most efficient form of evaporative cooling, the direct method creates an environment that is suitable for the growth of disease-causing micro-organisms. For this reason, the direct method is presently not the most popular form of evaporative cooling.

Indirect Instead of introducing water directly into the air, the indirect method uses a separate loop for the heat transfer mechanism. Water is pumped to a cooling tower and then to a cooling coil in the supply air stream. The indirect method alleviates many of the health issues associated with the direct method, although it has greater first and operating costs.

6.3.6.2 Condenser Air Precooler

These systems reduce the temperature of the air used by the condenser section of the air cooled refrigeration equipment. This cooler air not only increases the efficiency of the refrigeration equipment but also increases the capacity of the system. The only operational costs associated with this type of retrofit is the cost of the evaporated water and the increased air flow resistance the condenser fans must overcome.

6.3.7 EQUIPMENT REPLACEMENT

Since newer equipment is typically engineered to operate at higher efficiencies, replacement of existing equipment often results in attractive financial returns. Evaluations should be made from a "system" or "total central plant" perspective.

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6.3.7.1 Boilers

In most cases, new boilers on the market can obtain 80% efficiency. Even greater efficiencies can be obtained by specifying multiple modular boilers and/or air-atomizing burners. The replacement of any boiler system should be modular. A modular boiler system comprised of two or more small capacity boiler units will increase seasonal efficiency. Each module is fired at 100% of its capacity only when required. Fluctuations of load are met by firing more or less boilers.

6.3.7.2 Chillers

New chillers can operate at efficiencies as low as 0.55 kw/ton and should be evaluated as an alternative to the machines currently installed. Depending on the location and the cost to install the equipment, the possible new auxiliary equipment required, and any utility company rebates, the installation of new more efficient chillers may be justified.

Furthermore, certain chillers such as screw machines are designed to operate more efficiently at part loads and can be used to augment or replace your current mix of equipment. Again, the analysis should be based on the total cost to operate the central plant.

6.3.7.3 Motors

Consideration should be given to replace any old motor that is over 5 hp and operates for more than 1000 hours with a new high efficiency motor. Combined with utility rebates, these measures are almost always cost justified.

6.3.8 POWER FACTOR CORRECTION

The power which must be supplied to any induction load such as induction motor, transformer, fluorescent lamp, etc., is made up of real and reactive power. Real power, or the working power, is measured in kilowatts (KW). The reactive, or magnetizing current, is required to produce the flux necessary for the operation of any induction equipment. Without magnetizing current, energy could not flow through the core of a transformer or across the gap of an induction motor. The unit used to measure reactive power is the kilovar or kVAR. The vector sum--not the arithmetical sum--of the real power and the

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reactive power is the apparent power, measured in kilovolt-amperes or kVA. Power factor is a ratio of real power (KW) to apparent power (kVA) or,

Power Factor = Real Power (KW) Apparent Power (kVA)

Electric utilities must provide both real and reactive power for their customers. Reactive power does not register on a kilowatt-hour meter but producing it still requires the utility to put additional investment into generating and distribution facilities. Many utilities make up for the expense of producing reactive power by including power factor provisions in their rates. As it so happens, many utilities are defining low power factor as anything less than 0.9.

A power factor improvement or at least a review of power factor economics is indicated for any building that purchases at primary level or on a large commercial power rate or which maintains one or more of its own electric substations. More specifically, some power factor improvement will prove worthwhile if your electric use meets one or more of the following conditions:

Power demand is recorded on bill (in kVA) Electric rate has a kVAR or power factor penalty clause There are problems with voltage regulation or chronic low voltage Load growth limits spare capacity and you need more capacity

Causes for lower power factor typically are lightly loaded motors which draw excessive amounts of reactive power and increase energy losses in the overall distribution system. Power factor correction can be made through the installation of capacitors at utilization equipment locations. Costs of equipment and installation usually can be paid back quickly, if (and only if) the utility charges for reactive power supplied. It is advisable to review the need for and amount of power factor correction on specific types of loads with either the utility, equipment manufacturer, or your consultant if that fails, try zapping them with electricity.

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