Tips for Energy Conservation in Heating, Ventilation & Air Conditioning

1. Adjust compressor, air and water quantities to obtain maximum output.

2. Use heat reclaiming equipment in air conditioning plant.

The heat of cooling is rejected through cooling tower to the atmosphere. This hot water can be used for the guest room, laundry and kitchen if continuous cold water is available for condenser.

3. Do not employ reheating for comfort applications.

4. Air quantities can be reduced if the return air is passed though fixtures.

5. Avoid sealing or fouling of heat exchangers.

6. Location of cooling tower should be such that should prevent boiler and generator flue gases, kitchen & laundry exhaust from entering cool­ing tower air intake.

7. Where high dry bulb temperature and low humidity is available, use evaporative cooling. This calls for additional capital investment but operating costs during summer will be low.

8. Reduce air handling unit speed and air quantity.

9. Chillers should be operated at the highest leaving water temperature which consumes less brake horse power per tonne of refrigeration.

10. Chiller operating at half load consumes less energy as compared to one at full load.

11. Duct air leakage, water leakage should be avoided. Ineffective and dam­aged insulation should be changed as early as possible.

12. Heat exchanger, cooling tower, condenser, cooling coils are thoroughly cleaned.

13. Ensure constant water temperature in cooling tower which will reduce brake horse power consumption.

14. Filters should be cleaned regularly.

15. Instalment boiler in the diesel generator exhaust gas chimney.

16. Recover heat from the diesel generator jacket cooling water system.

17. All the clarifiers in the hot water system should be decided period- ally and an effective condensate return system should be installed and passed through the clarifier before being led into the hot well tank.

18. Hot water pipes should be insulated.

19. The addition of a small percentage of water with furnace oil gives com­plete combustion.

20. The boiler may accumulate soot, scale, slag, or ash, which can be re­moved by scraping, brushing, or vacuuming. Boilers using water heat transfer may benefit if the water side of the heating surfaces is cleaned with chemicals.

21. As far heat distribution system is concerned the cleaning of finned coils, radiators, and convectors will allow heat to flow more easily.

22. Strainers on hot water or steam lines and air vents, if regularly inspected and cleaned, will allow the free flow of water, steam, or air, respectively.

23. The air cooling equipment can also benefit from cleanliness.

24. Condenser coil surfaces can be washed or brushed, and the removal of dirt or leaves, which can obstruct air flow, from air-cooled condensers with outside outlets, will help to maintain efficient operation. Deposits from hard water sprayed on coil fins can be prevented by treating the water.

25. The prevention of various kinds of leaks in the HVAC system may also be a useful way to conserve energy. Boiler combustion chambers may eventually crack, allowing air to leak in and decreasing combustion efficiency.

Similarly, sectional boilers may not be sealed according to the manufacturer’s specifications; flue connection seals also require checking and repair.

When steam heat delivery is used, steam trap or condensate tank leaks should be of concern. In the air cooling system, chillers must be inspected for refrigerant leaks wherever refrigerant pipes join. A system with too little refrigerant will be overworked and ineffi­cient.

26. In the HVAC setting, protective coating refers mainly to insulation of pipes or ducts. Effective, intact insulation of heating pipes (including return pipes), heat exchangers, and condensate tank will save loss of heat energy and money. Once installed, the insulation must occasion­ally be inspected and renewed.

Opportunities fall into the following major categories: » Building characteristics energy-conservation factors designed into fabric; retrofitting energy conservation measures;

Matching source to load flexible systems which are efficient across the range of operating conditions (number of customers, climate etc.): heating systems may be 70-80 percent efficient at full-load but only 30 percent efficient at one-third load.

The hotel may operate at full load for only a few days of a year, for example in the most extreme climatic conditions and with full occupancy. Sophisticated con­trol systems, linked to computer logging facilities can opitomize heating systems.

Decreasing loads, reducing lighting consumption, decreasing number of air changes, peak demand control.

i. Increasing efficiency- improving efficiency of plant across the range of oper­ating conditions.

ii. Reducing costs- cheapest utility source and best available tariff.

iii. Recovery of waste energy recovers the energy normally lost to the atmos­phere or drains from exhaust systems, swimming pools condense heat recov­ery, boiler flue heat recovery.

iv. Use of alternative energy- solar energy, co-generation refuse burning.

v. Sources- geothermal energy, wind energy, water energy.

The fabric of the building, particularly in the case of old ones, should be investigated to assess the extent of heat loss through walk, windows, roofs and draughts. If these are excessive, the potential of energy savings should be investi­gated. A quick and cheap way of doing this is by monitoring the rate of snow and frost melt in winter months.

The temperature of all public areas and guest rooms should be investigated, ensure that these are not set at too high temperature.

Simple measures, like the replacement of conventional radiator valves with Thermostatic Radiator Valves (TVRs), can save money and allow guests to adjust the room temperature accord­ing to their personal preference. In hotels there may be a build-up of heat in upper floors due to lights and heating, exacerbated by the fact that warm air rises.

Old boilers will generally have lower efficiencies than their newer equiva­lents and in addition, are more suitable for sophisticated control. Audits of exist- in” hotels should include measures of boiler efficiency in order to determine any potential for savings.

For small hotels, a condensing boiler is more efficient in use than a conventional one. In the condensing boiler heat is extracted from the water vapour which is entrained in the fit gases through the use of extra heat exchange area.

The latent heat trapped in this moisture vapour can represent 10 percent of the total energy content of the fuel. Condensing boilers can increase boiler effi­ciency from 80 percent to 90 percent.

Building energy management systems (BEMS) are sophisticated computer- based systems. BEMS can optimize boiler performance and can be used to provide sophisticated management to remote locations through the use of auto-dial mod­ern system.

In this way management support can be provided by head office personnel or through the use of contract companies. Replacement of the boiler and the use of modern BEMS can save large amounts of energy.

BEMS can be used to control heating zones within a hotel. Each part of the hotel can be operated as a separate heating zone with each zone having its own pumped circulation.

Each zone can also have its own heating programme and this can be related to operational factors, such as level of occupancy. At quiet periods, rooms can be let in a single zone, with other areas receiving only background heating. As occupancy increases, more zones can be switched from background to full heating.

Occupancy-linked controls can allow energy consumption to be targeted only on those rooms that are occupied. A number of different systems have been used.

In one, a key-link panel in reception activated the system and is linked to two-stage thermostatic radiator valves (TVRs) in the guest’s room. When the key is present on the rack & the room temperature is held at a ‘set-back’ temperature.