Project Details:

Personal Comfort System: Energy Impacts

Technical Background

PEC Energy Saving Diagram

Explanation of Diagram

Our energy simulation studies suggest that using Personal Comfort Systems to expand the range of temperatures at which occupants are comfortable (the comfort zone) can reduce building’s heating and cooling energy by up to 30%, depending on climate. The horizontal axis of this graph shows a range of possible interior setpoints (the temperatures at which the thermostat tells the HVAC system to add heat or cooling.) Conventional buildings assume people are comfortable only in the narrow range between about 22 and 24 degrees C, so outside this range the system operates and consumes energy. Expanding the comfort zone means increasing the deadband, the times at which the HVAC system does not need to operate. The vertical axis of the graph indicates the annual energy savings achieved for each degree we expand that narrow range—either by lowering the heating set point or raising the cooling setpoint or both—in various climates. Low-energy PCSs help realize these results by consuming only a negligible amount of electricity while ensuring that occupants remain comfortable across this broader range of temperatures.

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