Effect of thermostat time constant on temperature control and energy consumption

The objective of this study is to compare the temperature control, occupant comfort, and energy usage for four thermostats with different time constants installed on a wall in a real building zone equipped with a commercial variable air volume (VAV) unit with hydronic reheat coil and a direct digital control (DDC) system. This study was performed using experiments on a VAV system controlled by thermostats with different time constants. The experimental results verify that a sluggish thermostat causes higher energy consumption, less occupant comfort, and a lack of temperature control.