Dwelling infiltration and heating energy demand in multifamily high-rise and low-energy buildings in Korea

Building energy demand is an important factor in reducing energy consumption and greenhouse gas emissions in the building sector. Current low-energy building design concepts have decreased energy demand mainly by improving the thermal performance. The Korean government has continuously reinforced thermal performance by region and wall. Multifamily high-rise buildings (MFHRBs), a representative residential building type in Korea, have a powerful air-driving force caused by wind and stack interactions in winter. The weather-driven airflow produces (1) outdoor air infiltration across the envelope and (2) interzonal airflow from household entrance doors adjacent to unconditioned corridors. The two factors should be considered depending on weather conditions and airtightness for main airflow paths (such as envelope and household entrance doors) in the total heating energy demand. Nevertheless, airtightness is still not proposed according to regional weather conditions and airflow paths, as has been done for the exterior thermal performance. This study provides information about how and how much airtightness should be determined for MFHRBs to achieve low-energy buildings or to meet existing or new building energy demand standards. The leakage areas for the household envelope and entrance door are suggested by region in Korea for the different satisfaction levels of the passive-house energy demand standard (15 kWh/m2.year). The suggested leakage areas show the uncertainty of the dwelling airtightness metric (such as ACH50) adopted internationally for the energy demand standard. Moreover, the existing limit (0.6 ACH50) is suitable for southern regions but required to be lower elsewhere, especially in the central regions of Korea.