Located in Seattle, CornerStone reinterprets the contemporary office building through a focus on health, material transparency, and carbon reduction. Drawing on the city’s industrial heritage and timber legacy, the five-storey structure explores how commercial development can contribute to environmental restoration.
The building’s massing balances form with measurable performance. Shed roofs, carved façades, and articulated street edges respond to climate, managing rainwater, increasing daylight penetration, and fostering communal activity at ground level.
Mass timber as carbon strategy
At the core of CornerStone’s environmental performance is its hybrid structural system. A glulam structural frame and dowel-laminated timber (DLT) floor panels are paired with concrete elements to create a mass timber–concrete hybrid that significantly reduces embodied carbon compared to conventional steel construction. The timber structure stores carbon while supporting regional forestry economies. In total, the hybrid system saves approximately 1,886 metric tons of CO2e, reducing the building’s structural carbon footprint by 35 percent. Exposed timber surfaces contribute to occupant comfort through visual connection to natural materials.
Daylight, air, and biophilic integration
Façade carvings allow natural daylight to penetrate into the floor plate, reducing reliance on artificial lighting and lowering operational energy demand. Cantilevered balconies wrap each elevation, extending workspace outdoors and strengthening the relationship between occupants and the surrounding neighbourhood.
An exterior stair supports active circulation, reducing elevator dependence. Enlarged landings provide informal meeting zones, framed by a perforated steel scrim that filters light and air. On the roof, a honeybee apiary connects the building to ecological systems, while a honeycomb-inspired timber pergola at the entry references pollinator habitats and the mass timber structure. Together, these elements highlight a workplace culture centred on movement, daylight access, and environmental awareness.
Water stewardship in a rain city
CornerStone’s sloped shed roofs harvest Seattle’s rainfall. Rainwater is directed into a 268,745-gallon cistern, supporting non-potable uses and contributing to a 54 percent reduction in domestic water consumption. This approach positions precipitation as a site resource.
Stormwater strategies are complemented by site-level design interventions that shape pedestrian movement. Small recesses and circulation areas at street level create opportunities for retail spill-out and rest, while referencing the building’s regenerative systems.
Healthy materials and performance standards
Enrolled in Seattle’s Living Building Pilot Program, CornerStone achieved three Petals under the International Living Future Institute’s Living Building Challenge, including the Materials Petal. More than 1,000 building materials were vetted to eliminate Red List chemicals, supporting indoor air quality and occupant health.
Energy efficiency measures, including high-performance glazing, optimised fenestration, and a high-efficiency mechanical system, reduce overall energy use by 30 percent, achieving a projected Energy Use Intensity (EUI) of 33.5 kBtu per square foot.
