Study on the modification of heat balance model by observed mean radiant temperature and mean skin temperature

This study proposed a applied heat balance model customized to Korea's climate and physiological characteristic. Our model based on heat balance model proposed by Huang (2007) and ASHRAE (2005), but with improvements that, reflect observed data such as mean radiation temperature and mean skin temperature. The proposed model calculates the expected temperature for thermal comfort, depending on changes in relative humidity, wind speed, mean radiant temperature, metabolic rates, and clothing insulation. The earlier model assumed the same outdoor temperature and mean radiant temperature but we found that the difference between the two temperature by observation. Changes in expected temperature according to changes in mean radiant temperature were examined. It was found that, as outdoor exposure grows longer, the outdoor temperature needs to be lowered to maintain thermal comfort. The expected temperature for thermal comfort was lower at a metabolic rate of 4 Met than at 1 Met. In terms of wind speed, the expected temperature is not affected by a rise in wind speed when mean radiant temperature is low. However, as mean radiant temperature rises higher, the expected temperature varies more according to different wind speeds. And the discrepancy in expected temperatures was measured between calculations of skin temperature according to the formula of the model and mean skin temperature as measured in this study. The results showed that the latter case yielded higher expected temperatures. As examined thus far, this study considered only mean radiant temperature and mean skin temperature among the diverse variables of the model, and showed the discrepancy in expected temperatures by the difference in the two variables. A variety of heat balance models developed in previous studies, both at home and abroad, have been introduced in Korea, and they need to be tested and improved with actual experiments to yield more accurate outcomes, tailored to Korea's particular environment.

Acknowledgements : This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2013-065891).