Performance of stratum ventilated heating for sleeping environment

Occupants show different thermal requirements in the sleeping environment in comparison with the activity environment. A new sleeping environment created by stratum ventilation (SV) is proposed to satisfy the requirements on indoor air quality, thermal comfort and energy efficiency. This study comprehensively investigates the effects of operation parameters on heating performances of SV for the sleeping environment, using validated Computational Fluid Dynamics (CFD) simulations. The operation parameters include the supply vane angle, supply airflow rate and supply air temperature, and outdoor weather conditions. The ventilation performance parameters include the operative temperature, local partial thermal sensation (PTS), local mean age of air (LMAA), air change efficiency (ACE) and energy utilization coefficient (EUC). It is found that stratum ventilated heating creates an operative temperature distribution satisfying the occupants’ local thermal requirement in the sleeping environment, i.e., a warmer head zone relative to the body zone. Moreover, stratum ventilated heating also performs outstanding in terms of indoor air quality and energy utilization coefficient. Among which, the maximal bed zone air change efficiency (BACE) and room zone air change efficiency (RACE) are 0.80 and 0.57 respectively, which is larger than the value of 0.5 in a conventional environment (i.e., a uniform environment). The maximum EUC of stratum ventilated heating reaches 1.45, outperforming the conventional environment with a EUC of unity. Lastly, to facilitate stratum ventilated heating, the optimal parameters of the supply airflow rate, supply vane angle and supply air temperature are proposed with the consideration of thermal comfort, indoor air quality and energy utilization efficiency.