Implications of room air motion on control of thermal comfort in rooms with natural convection heat sources

Electric and hydronic baseboard heating systems rely on natural-convection-driven air motion to distribute energy throughout a space to maintain thermal comfort. For electric baseboard heating systems employing an on/off control scherne, the room air motion and consequent room temperature distributions are time-dependent. The thermostat cycling rate and location play a significant role in determining the air temperature swings, changes in room air velocity, and possibly in the mixing of ventilation air to dilute indoor air pollutants. Current thermostat design practices and the placement of thermostats on a wall do not take into consideration the airflow pattems and changes in air motion. This paper describes the model and the simulation results of using computational fluid dynamics software to investigate the implications of room air motion on thermal comfort control in natural convection heating situations. The simulations provide transient room air motion and temperature profiles in a simple two-dimensional room during on/off cycling of a base board heater by a thermostat. These results can then be used to determine an optimal thermostat location within a room and for improving thermostat design.