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The New Growth Strategy announced by the Japanese government in 2010 sets a long-term target of cutting greenhouse gas emissions by 25 percent from 1990 levels by 2020. However, carbon dioxide (CO2) emissions from residential sector in Japan continued to rise in spite of the progress of heat insulation and air tight in houses and the spread of efficient housing equipments.
In order to achieve the long-term target above, it is critical to reduce CO2 emissions from the residential sector through promoting the further energy conservation in houses.
In such a background, the concept of an LCCM (Life Cycle Carbon Minus) house was proposed as a house which has a long service life, emits the least amount of CO2 for constructing the house, using the house and disposing of the wastes, creates recyclable energy by using solar power generation, etc., and results in a negative life-cycle CO2 emission balance even with the CO2 emission during the construction included.
The LCCM (Life Cycle Carbon Minus) Demonstration House
Specifically, considerable reduction of energy consumption at the stage of operation and introduction of solar power generation exceeding the consumption make it possible to counterbalance the CO2 emissions from construction. (Fig.1)
However, drastic reduction of energy consumption for operation will degrade health, safety, comfort and convenience. For the widespread use of LCCM house, it is necessary to retain these elements to the maximum degree.
ConceptsAs is shown in Fig.2, CO2 emissions from conventional houses continue to increase the longer they are operated. In contrast, CO2 emissions from LCCM houses decrease with the surplus energy for operation and fall below zero after a period of years, although they rise slightly at the time of renovation.
Conceptual diagram of a Life Cycle Carbon Minus houseAlthough the concern for LCCM or zero energy houses has risen worldwide, the research on those technologies is insufficient yet and it is necessary to clarify the technological potential etc. For this reason, the Building Research Institute (BRI) started a joint research project titled "Study on Zero Energy Housing" in 2009 in cooperation with the National Institute for Infrastructure and Land Management (NILIM) and the Japan Sustainable Building Consortium (JSBC).
In parallel, the Life Cycle Carbon Minus House Research and Development Committee (chair: Dr. Shuzo Murakami, Chief Executive of Institute for Building Environment and Energy Conservation) was set up at JSBC and a three-year R & D project regarding LCCM housing was started in fiscal 2009 with the support of the Housing Bureau of the Ministry of Land, Transport and Tourism.
"New Growth Strategy" (the Cabinet decision on June 18, 2010) requires a step-by-step introduction of obligations to meet the energy-conservation standards for net zero energy/zero emission of housing/building in order to achieve the target of cutting greenhouse gas emissions by 25 percent from 1990 levels by 2020, and expects that ZEH (zero energy house/zero emission house) will be made as a standard newly-built house and ZEB (zero energy building/zero emission building) will be achieved in public buildings by 2020. BRI will be conducting research to reflect in creating technological standards necessary to achieve those goals using the study of LCCM houses.
In addition, The Ministry of Land, Infrastructure, Transport and Tourism, the Ministry of Economy, Trade and Industry, and the Ministry of the Environment jointly proposed a plan on November 12, 2010 to require all newly-built buildings to meet the energy-conservation standards by fiscal year 2020. BRI will also conduct research to reflect in developing the new technological standards.