Abstracts:The non-uniform distribution of vertical air temperature helps stratum ventilation and displacement ventilation to save energy compared with mixing ventilation. To reasonably predict the vertical distribution of the non-uniform air temperature, the multi-node (nodal) model requires an in-depth understanding of the airflow pattern and is specific for different designs of ventilation, which challenges engineers/designers in practice. To be more practical, this study proposes a heat removal efficiency (HRE) based multi-node model. The proposed model employs HRE to conveniently represent the airflow pattern, requiring little understanding of the airflow pattern. Moreover, the proposed model is general for both stratum ventilation and displacement ventilation, and flexible to include heating/cooling devices. Experimental case studies show that compared with the conventional model, the proposed model is more accurate and robust. The proposed model reduces the overall mean absolute error in the temperature predictions of the nodes of the air and inner surfaces of the enclosure by 0.1$°$C (from 0.94$°$C to 0.84$°$C) for stratum ventilation, and by 0.08$°$C (from 0.33$°$C to 0.25$°$C) for displacement ventilation with floor heating; and reduces the associated overall standard deviation of errors by 0.14$°$C (from 0.55$°$C to 0.41$°$C) and 0.02$°$C (from 0.19$°$C to 0.17$°$C) respectively. Benefiting from its convenience, generality, flexibility, accuracy and robustness, the proposed model is practical and would contribute to the practical applications of the energy-efficient stratum/displacement ventilation strategies.

Abstracts:There is great potential to apply personalized heating for saving energy and enhancing individual thermal comfort in buildings during cold weather. This study investigated the enhancement of thermal comfort of occupants using personalized heating systems at low indoor temperatures. Three personalized heating systems are chosen for this work, i.e., a radiant heating panel with a heated table pad (denoted as HB1), a heated chair with a heated floor mattress (denoted as HB2), and electrical heating clothing (a heated jacket and trousers, denoted as EHC). The effectiveness of three selected heating systems on overall/local body thermal comfort of female occupants under two indoor temperatures of 15 and 18 °C has been investigated. Total energy consumption of these heating systems has also been examined and compared. Thermal acceptability of EHC was better than HB1 and HB2 at both two temperatures. Overall thermal sensation vote (TSV) in EHC was significantly better than that in HB1. Mean skin temperature remained within the thermal comfort range (32–34 °C). In order to achieve thermal comfort on 70% and 80% of the inhabitants at various body parts, local body TSVs should be within −0.43 to 1.87 and −0.36 to 1.87, respectively. Further, EHC consumed <15 W power, which accounts for only 4.4% and 14.8% of the total power consumed by HB1 and HB2, respectively. Based on the evidenced thermal comfort improvement potential and low power consumption in EHC, it is thus recommended to use EHC for the thermal comfort enhancement of inhabitants under low indoor temperatures.