Passive House Office & Warehouse Facility
EnergySeal Headquarters, located in McCall, Idaho, is a 16,000 sf office and warehouse building designed and built for a high-performance insulation contractor. The goal of the project was to create a modern, ultra-energy efficient building in the harsh climate of Idaho’s central mountains, where winters can exceed 10,000 heating degree days. The entire building (11,000 square feet of warehouse and 5,000 square feet of office space) meets the stringent PHIUS+ Passive House standard. In addition, the office space is designed to be Net-Zero with renewable energy generated onsite by a façade-mounted PV array.
EnergySeal Headquarters is among the most energy-efficient buildings in North America, with a measured energy use intensity (EUI) after the first year of occupancy of 14.85 kBTU/sf/yr before renewable energy production. After the electricity generated by the 14.7 kW solar PV array is accounted for, the EUI becomes 12.0 kBTU/sf/yr, which allows the building to meet the 2030 Challenge 80% reduction from baseline site EUI target. By committing to an aggressive energy target early in the planning stages, even a challenging project type such as a warehouse can result in a cost-effective, ultra-low energy building without relying on overly complex and expensive mechanical and renewable energy systems. The project team achieved aggressive levels of energy efficiency by focusing on a high-performance building enclosure which relies on super-insulation, high levels of air-tightness, and thermal bridge free construction.
All structural components were carefully modeled and designed to ensure that thermal bridging was minimized and accounted for in the energy modeling. The wall and roof systems utilize a combination of HFO low-global warming potential (GWP) polyurethane foam and ultra-low embodied energy plant based cellulose insulation composed of 85% paper fiber. The high-performance R-8 windows utilize R-11 triple-pane glass with low conductivity frames. Motorized external venetian window blinds control solar gain and glare to minimize the cooling load and maximize indoor environmental quality for occupants year-round.
The ultra-efficient building enclosure allowed the building to be heated with a very simple HVAC system. A single 4-ton variable capacity cold-climate air source heat pump serves the entire warehouse space. The office portion of the building is served by a 3-ton heat pump with an integrated intelligent communication system which provides zone control through modulated dampers and smart controllers. The office space is ventilated using an 87% efficient heat recovery ventilator (HRV), controlled by an indoor environmental sensor that modulates the ventilation rate based on real time occupancy and indoor air quality.