In demand led operation the control system asks for heating from Boilers or cooling from Chillers. In principle this is quite simple and most control systems do it.

In practice many control systems will keep the boilers and chillers on most of the time during office hours. Often this is caused by minor faults such as mis-calibrated temp sensors, ‘aircon’ faults or a temperature setting error.

A well managed ‘Demand Led’ building will use boilers in midwinter, chillers in midsummer and on temperate days boilers may be required in the morning with chillers in the afternoon. There are some cases where boilers and chillers are required at the same time…for instance sunny days in winter.

Well managed Demand Led systems are very efficient. The energy savings can significantly outweigh the cost of implementation.