Indoor Environmental Controls for Improving Occupant Thermal Comfort in Perimeter Spaces : Focusing on the Thermal Environment due to Solar Radiation during the Heating Season

Purpose: Solar radiation during the winter daytime can cause horizontal stratification of indoor temperatures in perimeter spaces. Window-side spaces in perimeter spaces often experience high temperatures of 30 degrees or more in winter, and the horizontal radiant temperature imbalance from solar radiation forms simultaneous cooling and heating loads in the perimeter spaces. As a result, the thermal comfort difference between window-side and hallway-side occupants increases within the same space. Method: Short-term monitoring of indoor temperature on clear days was conducted in a university classroom in Busan during winter. Considering the operating conditions of the HVAC system in winter, local temperature differences and unmet load hours in the indoor space were investigated under 1) no heating and ventilation, 2) heating only, and 3) heating and ventilation operating conditions, and the thermal comfort and dissatisfaction of the occupants were evaluated. Result: The results of the study showed that the window-side space would experience high cooling loads in winter, and the duration may vary depending on the orientation and the window designs. Therefore, it should consider HVAC system design and operation to respond to the simultaneous heating and cooling demands in the same perimeter spaces in winter.