Renewable Energy and Energy Efficiency

Central HVAC (heating, ventilation and air conditioning systems) can use either water cooled or air cooled chillers. In general, water cooled chillers are more efficient particularly for large installations. Other factors that influence costs are the use of centrifugal compressors and variable frequency drives. The costs of the HVAC system will also be influenced by the operating considerations such as cooling load, system load and cooling hours.

In India, often water cooled systems cannot be used because water is not available. Careful design which allows reuse of sewage treated water for chillers can help in cases where water availability is not adequate.

A good way to improve the efficiency of heating and cooling systems is to incorporate control strategies that ensure systems are used only when necessary. Common control strategies include programmable thermostats, multiple zones, and CO2 demand sensors. These products can be used in new installations but can be retrofitted on existing installations as well.

Air Conditioner thermostats help in regulating the temperature of the room. The thermostats usually include manual overrides to ensure comfort. The entire facility can be divided into multiple zones so that the system can deliver more efficient heating and cooling by eliminating inaccuracies from a central sensor point. Air conditioning sensors include motion sensors in the room as well as carbon dioxide sensors for the room air.

Some architectural designs can also help in ventilation and increase the efficiency of the air conditioning system. These designs include the use of solar chimneys (solar power heats air inside a chimney creating an upward draft of air increasing the ventilation) or earth air tunnels (where a wind tower is connected to an underground tunnel and air is cooled as it passes through the tunnel).