Saving Advice Air Conditioning

Saving Advice Air Conditioning

Air conditioning is becoming more common in all commercial buildings. Refrigeration plant is used to provide cooling and can be very energy intensive. Broadly there are three types of system:

• Centralised air systems, where all cooling is in a central plant room with conditioned air ducted to point of use.
• Partially centralised, where centrally cooled air is further cooled by chilled water in a cooling coil at point of use.
• Local split unit types with external condenser for comfort cooling of hotspots.

Key Measures

• Avoid excess cooling - air conditioning is rarely needed below 24-26°C.
• Reduce internal and solar heat gains to avoid overheating.
• Use free cooling from night ventilation, exposing building fabric etc.
• Check control system and operational hours match occupancy.
• Ensure chilled pipes and ducts are well insulated and undamaged.
• Ensure filters are cleaned regularly and equipment is regularly serviced.

Practical Tips
Minimise internal heat gains by reducing tungsten lighting use and employing energy saving features of office equipment such as computers and photocopiers.

Improved air movement and ventilation can significantly lower temperatures and improve occupant comfort. Consider switching off air conditioning, and using ceiling fans and opening windows to circulate air and reduce temperatures.

Have your control strategies checked; many systems are poorly controlled to the extent that simultaneous heating and cooling is possible. Widen the dead-band between heating off, say at 20°C, and cooling on, say at 25°C. It may be possible to use free cooling by circulating outside air without running the refrigeration. Some systems have unnecessarily tight control of humidity that significantly increases consumption by chilling to remove humidity then re-heating the air.

Solar gains have a considerable heating effect and can lead to discomfort. Control excessive solar gains using blinds in sunny weather. Consider shading or upgraded insulation to walls subject to solar gains.

Further information on air conditioning

• The Heating and Ventilating Contractors' Association provides information on local contractors. Tel 0207 313 4900 or visit www.hvca.org.uk

• The Market Transformation Programme is developing a database that should enable energy consumption of small air conditioners to be compared at www.mtprog.com/nondomestic/index.html