Rising out of a hillside, two roofs cover a house organized around a three-story living space that functions as both a spatial nexus and a natural ventilation stack. The volume is divided by an interior south facing cast-in-place concrete heat sink mass wall, which stores light, creating an all season solarium that, in the summer, opens and unfolds into the natural landscape. The exterior surface of the house features solar-responsive cement board siding pattern that transitions from dark to light according to its orientation. Perforations to the interiors walls allow for viewing ports within the house, giving way to a greater sense of openness and better distribution of light within. From the outset, the intention was to minimize the cost of finishes and fixtures and spend the budget on structure and systems. Consequently, the material palette is simple: bamboo, drywall, cement board, and concrete.
The Hsu House was designed to meet LEED Silver guidelines. The architects even used a thermal and daylight simulation software to balance daylighting and thermal performance to create a super-insulated environment. All of the opaque walls contain at least six inches of open cell polyurethane insulation and another two inches of rigid polyisocynaurate underneath the cement board cladding. The house also incorporates a rainwater collection system, a high efficiency forced air heating with HEPA filtered heat recovery ventilation, a TPO high albedo membrane roofing system, Energy Star lighting and appliances, high efficiency plumbing fixtures, and, this summer, a custom thermosymponic solar thermal heating device will be installed. Designed to be naturally ventilated, the house has no cooling systems.