The effect of room temperature control by air- or operative temperature on thermal comfort and energy use

The most commonly used thermostat control variable in heating, ventilating and air-conditioning systems is air temperature. The requirement for thermal comfort in international standards are however based on operative temperature. Will the adoption of operative temperature based control lead to better thermal comfort and how will this affect the energy use? The position and type of thermostat may also influence the comfort in the occupied zone.

These questions were studied by simulations of three heating and cooling systems, fan-coil system (convective system) and two radiant systems: floor heating/cooling system and radiant ceiling heating/cooling panel system in three different geographical locations (Copenhagen, Paris and Rome). Besides the simulations, the influence of the position was tested in an experimental room with a convective and a radiant heating/cooling system.