Impact of external insulation and internal thermal density upon energy consumption of buildings in a temperate climate with four distinct seasons

Most of the building codes for energy saving are focused on strengthening the insulation and airtightness of the building envelope. Insulation and air tightness of the building envelope reduces heat loss during the healing season, but can lead to overheating in the cooling season according to the building types owing to the internal heat gain levels. This study reviewed the effect of strengthening the external insulation level on energy consumption for heating and cooling in buildings with various internal heat gain levels. The reference building was located in a temperature climate with four distinct seasons in Seoul, South Korea. The variation of annual heating and cooling energy consumption was analyzed in regard to diverse internal heat gain levels and envelope properties using parametric simulation methods. Less total energy was required for heating and cooling by enforcing the insulation level in buildings with low internal heat gain levels, while more energy was required in large office buildings with high internal heat gain levels. The present prescriptive envelope design standards of Korea are ineffective in high internal heat gain buildings. Actually, the current U-value envelope standard may increase the annual energy consumption in commercial buildings in Korea. The standard for external thermal insulation should depend on whether the building is envelope-dominated or internally dominated to reduce the building healing and cooling energy demands.