Numerical investigations on the effects of envelope thermal loads on energy utilization potential and thermal non-uniformity in sleeping environments

Due to the variation of outdoor environment, the building envelope thermal load undergoes obviously corresponding variation. Therefore, it's previously reported that building envelope had a deep effect on the indoor thermal environment at daytime and nighttime. In subtropics, the higher energy consumption of air conditioning system makes it necessary to study the task/ambient air conditioning system, not only in commercial buildings, but also in residential buildings. At the same time, the effects of the envelope thermal load on these task/ambient air conditioning systems should also be investigated. In this study, a bedroom with a task air conditioning (TAC) system was established and the influences of the building envelope thermal load on indoor thermal comfort level and the energy utilization potential of the TAC system were numerically investigated. Firstly, EUC (energy utilization coefficient) was used to evaluate the energy utilization potential. The EUC values were found growing from 1.0 to around 1.2 with an obvious increase, indicating higher energy utilization potential. Secondly, PMV was used to evaluate the thermal comfort. It was found that the PMV values were increased with a growth rate of 0.051 per W/m² at t_s of 20 °C, 0.036 per W/m² at t_s of 23 °C, and 0.027 per W/m² at t_s of 26 °C. Thirdly, the air temperature non-uniformity in three directions was evaluated. It was found that the increase in envelope thermal load enhanced the air temperature non-uniformity.