내단열 vs 외단열, 외단열 공동주택의 에너지절약 효과

Due to greenhouse gas emissions and global warming problems, many countries have endeavored to construct more energy-efficient buildings. In Korea, the building sector accounts for over 24% of the total national energy consumption, and the energy consumption in apartment buildings, which are the most common type of residential buildings, is about 36% of the total energy consumption in the building sector. Compared to commercial buildings, apartment buildings are envelope-load-dominated buildings with low internal heat gains from occupants, lighting, and equipment. Therefore, the heating load is much larger than the cooling load in the Korean climate, and thermal insulation plays a key role in reducing energy consumption. In addition, the conductive heat transfer through the envelope should be reduced because the hot water pipes used for radiant heating are installed in the floor structures of Korean apartment buildings. An internal insulation system has been applied to the outer walls of most Korean apartment buildings since the first modern apartment building was built in the early 1960s. Consequently, there are many cases in which the layer of insulation is disconnected due to structural components at the wall-slab and wall-wall joints in the envelope. These joints become thermal bridges in which heat transfer increases. In particular, the amount of heat loss is large at the wall-slab joints adjacent to hot water heating pipes. Conversely, an external insulation and finish system (EIFS) can eliminate the thermal bridge by continuing the layer of insulation at these joints. Also, an EIFS can improve the heating efficiency because a thermal mass with high heat capacity, such as a concrete wall, is located on the warm side. Therefore, it is urgently needed to secure cost-effective construction technologies for EIFS because energy saving potentials of externally insulated apartment buildings are substantial. In addition, it is necessary to make insulation regulations to enforce a removal of thermal bridges.