The influence of insulation styles on the air conditioning load of Japanese multifamily residences

The performance of building envelopes significantly affects the indoor energy consumption, thermal comfort, and durability of a building. Numerous studies have focused on the thickness of insulation materials and considerations for insulation placement (installing insulation inside or outside the wall), however most of the studies have discussed insulation placement in each building's components and form (wall, roof, floor), and very few of them have considered the insulation as an insulation system of the building. In 1999, the Japanese Institute for Building Environment and Energy Conservation issued the standards for residential energy efficiency that specified the standards of building envelope thermal transmittance and overall heat loss coefficients however; the insulation placement was not well explained. Additionally, it is common in Japan to use intermittent air-condition systems rather than having the air conditioning units continuously operating. It is necessary to investigate the performance of insulation taking into consideration the specific life styles of people living and working in Japan. In this research, we will (1) develop new interior insulation to conduct insulation on all of the interior surfaces of building units (walls, ceilings and floors) for environmental building design based on the calculation of heat loss; (2) discuss and demonstrate the effect of high heat capacity on each of the building components and thermal bridge by building environmental simulations; (3) carry out the simulation in different cities in Japan (Sapporo, Hachinohe, Sendai, Toyama, Tokyo, Miyazaki and Naha) and discuss the applicability in these different areas of Japan. Comparing the environmental qualities among three insulation styles (outside insulation on outside walls, inside insulation on outside walls, and interior insulation which is an innovative insulation style in Japan), the energy saving and thermal comfort advantages will be demonstrated. This research will provide an innovative insulation style that could contribute to new generations of energy-saving standards and formulations in Japan.