The Influence of Insulation Styles on the Building Energy Consumption and Indoor Thermal Comfort of Multi-Family Residences

The properties of building envelopes significantly affect indoor building energy consumption, indoor thermal comfort, and building durability. In the current standards for Japanese residential energy efficiency, insulation placement is not well regulated. Meanwhile, it is common in Japan to use air-conditioning intermittently, rather than having the units operate continuously. Therefore, considering specific Japanese lifestyles, we investigated insulation performance. In this research, we: (1) developed the interior insulation to include insulation on walls, ceilings and floors of building units (all of the interior surfaces) to achieve building energy savings by avoiding heat loss through thermal bridges; (2) discussed and demonstrated the effects of high heat capacitance for each of the building components and the thermal bridge by conducting building environmental simulations; (3) conducted simulations in seven cities in Japan and discussed the applicability of these different weather conditions; and (4) compared temperature distributions to investigate differences in indoor comfort with partial heating on winter nights. We demonstrated the energy saving and thermal comfort advantages of interior insulation. This research provides an innovative insulation style based on Japanese lifestyles that contributes to new energy-saving standards and formulations.