The White Black Box House is factory prefabricated in five transportable modules. The house system uses conventional building materials carefully selected for cost-effectiveness, yet provides bright, spacious, indoor/outdoor living spaces on tight, semi-urban infill sites attractive to young families. The design for this very tight site maximizes outdoor living space, with roof top terraces, courtyards and private garden spaces at grade. The house is available in many variants for various site conditions and individual homeowner requirements, and is available as net-zero energy capable, with high insulation values and options for photovoltaic energy production and other energy conserving and energy producing design components. This house was constructed at a factory in Salem Oregon, complete with all fixtures, appliances, systems and surfaces, trucked to a site in Menlo Park, California, with all modules installed on previously site-built foundations in a six hour period. After this initial day of crane work and joining of the modules, final completion of the house on site includes a limited amount of work joining utility and electrical junctions at module lines, and infilling surface components along module lines. The approach is designed to significantly reduce cost, resource consumption, construction time and complexity for new homeowners, while still providing wide latitude for personalization of the design, and high-quality construction. The house is constructed on a compact lot in a developed neighborhood, with an existing poor-quality house on the site needing to be demolished. One of the main challenges was that the client requested to have the shortest time possible for onsite construction of the new house, so that once they had moved out of the old house, they could be back in their new home on the same site within just a few months. With the house designed and built in modular prefabrication, it was possible to have the demolition and onsite work shortened to only about 4 months, with the bulk of the house constructed off site in a factory at the same time the site work was underway. This construction approach substantially saves on energy and natural resources, as well as minimizing neighborhood disturbance and reducing the construction finance costs. With most construction systems installed in the factory, a higher quality and predictability of construction costs and schedule is possible, without weather damage and other common limitations of building on site.