This Project is a wooden office building in the forest at the foot of Yatsugatake. The client spent over a decade selecting this suitable site to ensure symbiosis with nature. An “energy-saving system” using passive methods (natural ventilation, direct solar gain, natural lighting), an “energy-making system” comprising a heat and power generator using renewable energy (solar power, wooden biomass resources) and a micro-grid system with a lithium-ion rechargeable battery are adopted to achieve ZEB. This building has been properly operated by environmentally conscious staff and has achieved a year-round PEB (Positive Energy Building).