'Roughly one out of seven newly built houses in Japan is a prefabricated house'
In 2008, a total of 1,093,485 houses were newly built in Japan. Among them, 154,271 houses (14.1%, or one in seven) were prefabricated.
Japan launched a 70,000 PV-roof market incentive program between 1994 and 2006 that initially covered 50% of PV installation costs, becoming the first country to introduce federal subsidies for residential PV systems. This strategy catapulted Japan to be world leader in installed PV capacity and PV cell manufacturing. These incentives were gradually phased out, leaving behind a thriving industry, with the cost of PV reduced by over 75% during the course of the program. As of 2010, Japan was third in the world for installed PV power, behind Germany and Spain, and second in the production of photovoltaic cells globally. The majority of the production, at 55%, is destined for the local market. Of the local market, the residential sector has the greatest share at 85%. This programme has since been replaced with the Subsidy for Residential PV Systems.
Nuclear power has a central role in Japanese energy policy, both in terms of energy supply and climate change, supplying 30% of Japan's total electricity generation. However, given the 2011 Japanese earthquake and subsequent nuclear emergency, the prominence of nuclear energy is likely to be revaluated. As of 2005, renewable energy accounts for 8.4% of Japan's final energy consumption. The long-term goal is ultimately to reduce CO2 emissions by 60% – 80% by 2050.
Laketown 'Miwa no Mori'
Koshigaya City, Saitama Prefecture
The Miwa no Mori housing development is a group of 132 prefabricated housing units located on the outskirts of Tokyo. The project was built with the intention of reducing CO2 emissions by 20% in the district when compared with standard housing developments. Completed in 2008, the project received the highest rating possible under CASBEE-Home (Detached House) 2007 edition.
The steel frames of each home are surrounded (internally and externally) with high density glass wool insulation boards, to achieve high energy efficiency. Each house includes high efficiency water heaters and air conditioners. Simulations were conducted prior to construction to determine wind direction and speed to best position windows, skylights, fanlights and balconies in order to maximise natural ventilation. There are also external roll-up screens on the low-e double glazed windows, which can minimise solar gain, (preventing up to 70% of heat from sunlight from entering the home, and effectively countering the need for cooling energy during very hot weather)An important consideration of each unit was their high seismic resistance, given the high number of earthquakes in Japan.
Under the Kyoto protocol, Japan has committed to reducing CO2 emissions by 6% between 2008-2012 based on 1990 levels. Japan has developed an impressive range of policies to address rising emissions. These include the 'Top-Runner' Programme for end-use products, energy efficiency labelling, new technologies (e.g. energy management systems) and portfolio standards for renewables.
The most recent version of the Strategic Energy Plan of Japan was released in June 2010 and sets out energy targets for 2030. These include the goal to halve CO2 emissions from the residential sector and raising the zero-emission power source ratio by 70% (it is approximately 34% at present). The plan also sets out goals to make net-zero houses available by 2020 and to establish them as standard practice by 2030.
Energy efficiency standards for new dwellings were first introduced in 1979, with the Act of the Rational Use of Energy (also known as the Energy Conservation Act) with numerous subsequent revisions. The 2009 amendment strengthens energy regulations for buildings and now requires buildings with 300 square meters of floor space or more to report individual energy conservation measures to the designated authority.
The Basic Program for Housing: Energy Efficiency Standards was released in 2006 in an effort to improve housing standards over the following decade. Targets include the installation of energy saving measures (i.e. double-glazed windows) in 40% of housing by 2016 and to increase the life span of homes to approximately 40 years (as of 2003, the average life span was 30 years).
The voluntary environmental building standard in Japan is CASBEE (Comprehensive Assessment System for Built Environment Efficiency) in conjunction with Japan's Green Building Council. For the residential sector, there is CASBEE-Home (Detached House) v.2007.9. CASBEE is defined by Building Environmental Efficiency (BEE), which rates the relationship between Q (environmental quality) and L (environmental load).
Launched in 2009, the Housing Eco-Point Scheme provides 'points' for eco-friendly renovation or new renovation of eco-houses. Eligible renovations include the insulation of windows, walls, ceilings and floors, as well as solar power systems and water saving toilets. Earned points are then exchangeable with a variety of products and services.
The Subsidy for Residential PV Systems was launched in 2009, providing subsidies of JPY 70,000 per kW installed. However, the subsidy is limited to installations with costs less than JPY 650,000 per kW with a maximum output of 10 kW. Last year, the 2010 budget allocated JPY 40.15 billion to the programme. There are also significant savings on taxes, with certain energy-saving renovations providing relief of annual income tax for up to five years. There are also potential savings on fixed property taxes and taxes associated with construction.