Portland residents in search of an energy-efficient home need look no further than Lightbox 23, the new net-zero project from Lightbox Portland and Steelhead Architecture. A speculative development project in northeast Portland, Lightbox 23 has two units and numerous sustainable features, including super-insulated walls, high-performance ventilation systems, and two 10-kW solar arrays. But sustainablity isn’t the project’s only draw – it also boasts beautiful design and stunning views of Mt. St. Helens’ and Mt. Adams’ snow-capped peaks.
A set of floating stairs, which provides access from each floor to the half-levels above and below, serves as the duplex’s backbone. A deck on the building’s north side can be accessed from the exterior. From this deck, residents can enjoy the open air and, on a clear day, the distant peaks of the two mountains.
While the solar array on top of the building provides the building with its energy, part of making the project net-zero included finding ways to reduce the energy load overall. To tackle this problem, Steelhead Architecture turned to affordable super-insulation. Each unit has two-by-eight walls filled with blown-in cellulose, along with two inches of rigid insulation affixed to the exterior of the plywood. The concrete slabs have 3 more inches of rigid insulation. The roof construction has a similar mix of insulation, which eliminates the need for any vents.
The home’s mechanical system further supports the unit’s net-zero goals. All-electric ducted heat pumps, which are much more efficient than gas systems, provide heat for the apartments. Furthermore, nothing on the project uses gas at all. A heat recovery ventilator with its own ducts effectively controls air exchanges with zero energy loss. To ensure a low heat/cooling loss, the architects sought out leaks and used repetitive joint sealing, further reducing the project’s energy use.
Lightbox 23 is an exploratory project of Lightbox Portland, which is devoted to high performance, high-density modern progress. There are three additional Lightbox Portland/Steelhead Architecture projects presently underway.
Images via Josh Partee Photography