Extending the use of adaptive thermal comfort to air-conditioning: The case study of a local Japanese comfort model in present and future scenarios

The use of setpoint temperatures based on adaptive thermal comfort models has been identified as an efficient energy saving measure in the latest years. The recent studies applying adaptive setpoint temperatures consider ASHRAE and EN16798-1 international models. However, this study has considered a local Japanese adaptive comfort model instead. Therefore, this study analyses the energy demand resulting from the application of a local Japanese comfort model and compares it with the energy demand resulting from the use of the worldwide ASHRAE Standard 55 adaptive model and other fixed setpoint temperatures. Building energy simulations have been performed considering all different climate zones in the territory of Japan, and also considering full air-conditioning and mixed-mode building operation modes, as well as present and future scenarios under the influence of climate change, namely Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5 for years 2050 and 2100. Results show that energy savings ranging between 29 and 52% and 33 and 78% could be achieved by using setpoint temperatures based on the Japanese local adaptive comfort model respectively in full air-conditioning mode and mixed-mode. These results were obtained using the adaptive model for free running buildings, therefore assuming high levels of adaptation. In the context of climate change, the total energy demand decreases in cold climates between 14 and 65% and 18 and 91% for full air-conditioning mode and mixed mode respectively, while in warm climates, it increases between 8 and 36% and 17 and 51%, again respectively for full air-conditioning mode and mixed-mode. Therefore, the use of setpoint temperatures based on the Japanese local adaptive comfort model is identified as a very efficient energy saving strategy.