A novel thermal comfort and energy saving evaluation model for radiative cooling and heating textiles

Personal thermal management (PTM) techniques, which establish local thermal envelopes around the human body instead of cooling/heating the entire building space, have great potential for thermal comfort satisfaction and building energy saving. As a promising technique for PTM, novel radiative cooling/heating textiles have been investigated by many researchers. However, there lacks good evaluation method for such novel radiative cooling and heating textiles to verify their thermal performance. The objective of this work is to build a comprehensive thermal comfort and energy saving evaluation model for novel textiles. Firstly, a naked human body model is built and validated by experimental data. After that, the clothing model is added and the heat loss of the human body at different ambient temperatures is analyzed and compared with experimental results. All experimental data for validation are obtained from the literature. Then, the thermal comfort model and the energy saving model are used to obtain the effectiveness of novel textiles. In addition, the effect of air gap thickness on thermal comfort and energy saving is also thoroughly discussed. It is concluded that the thermal comfort HVAC temperature setpoint would increase 0.2 ∼ 2.8 °C (cooling) and decrease 0.8 ∼ 4.4 °C (heating) at air gap thickness δ = 5 mm (compared to HVAC cooling setpoint of 23.0 °C, and heating setpoint of 22.0 °C). More importantly, the use of novel radiative cooling/heating textile could reduce up to 39.4%/44.2% building energy consumption.