This is a villa situated about an hour’s rapid train ride from Tokyo in a mountain resort of Karuizawa, Japan. It is basically a wooden structure with the peripheral balconies in steel. The design is adapted from passive energy principles applied in the world-famous Katsura Imperial Villa in Kyoto. The only artificially operated system is the radiant hot-water heating embedded in the floor, running the entire length of the peripheral fenestration with heat pump air conditioning units as supplements just in case.
Legal and binding design guidelines in the area required a roof slope of 1:5 minimum, eave length of 5oo mm minimum, and a limited selection of exterior coloring.
Natural passive energy means include but are not limited to the following: 1) exterior insulation with 2) air circulation paths in between exterior and interior finishes 3) cross ventilation under the groundfloor to protect against humidity 4) overall cross ventilation with openable windows 5) complete fenestration on the south with 6) airtight, high-insulation composite sash with 7) double-pane glass 8) allowing low winter sun penetration and blocking high summer sun 9) use of deciduous trees in the south similarly allowing low winter sun penetration and blocking high summer sun 10) extended eaves to provide shade 11) double floor living space to act as passive solar collector 12) fireplace in the living space to burn trash 13) ceiling fans to circulate warm air 14) highly insulating natural Japanese stucco (with embedded maple leaves) 15) use of laminated bamboo instead of wood for floors, built-in furniture, cabinets, doors, and closets, as bamboo is very fast-growing (and hence more ecological than wood) and profusely abundant in Japan) 16) use of fluorescent and LED lights 17) corrugated metal exterior finish for easy maintenance and sustainability 18) reflective silver roofing for insulation and temperature control
