Energy efficiency and comfort level of floor-based air-conditioning in residential buildings

To investigate the feasibility of locating the air-conditioner at low level in residential buildings, contrastive experiments were carried out in laboratory. The air temperature fields and the velocity fields were tested in a bedroom-type chamber equipped with ceiling-based air-conditioning (CAC) and floor-based air-conditioning (FAC) respectively. Furthermore, the air diffusion performance index (ADPI) was used to evaluate the thermal comfort level of the room, while energy efficiencies of the systems were compared by the power consumption and the COP. It is indicated that the supply air temperature of FAC is 2.6-8.3°C higher than that of CAC, while the ADPI of FAC can also meet the thermal comfort level recommended by ASHRAE in most conditions, although it is a little lower than CAC sometimes. The results of power measurement show that the average power consumption of FAC can save 14.9% than that of CAC, while the average COP increases by 29.6% from 2.5 to 3.25.