HVAC systems are designed to heat on the coldest day in winter and cool on the hottest day in summer…with a bit to spare.

The design around maximum load means settings are set high and often maintained permanently. Boiler temps are hot, chiller temps are cold, pumps are ‘revved’ high, fans blow hard.

An example a site we work on has a maximum cooling power of 600kW. The average measured actual cooling demand ranges between 50 and 200kW.

British climate is temperate. Usually the temperature is between 5 and 20 deg…:-(

Turning everything down or even off when demand is low, can make the whole system more efficient and much cheaper to run. Heat exchangers are more efficient if they operate above the dew point, pumps use a lot less energy and the chiller is used less.

As an example our plant system operating at maximum uses 200kW of electricity operating at full specification with no load. Varying the capacity using a demand led strategy of all plant elements allows it to use just 12kW or 6% as a mimimum.

As an example of how this is done please see our blog ‘Hidden Energy Savings…pumps’.