Goals.  The developer targeted Passive House certification and net zero capable performance as a market differentiator, successfully selling two of the units before construction was even complete.

Solution.  The resulting building with three dwelling units includes a high performance building enclosure, design for passive solar gain, very high efficiency mechanical systems, and grid-tied photovoltaics. These performance attributes helped contribute to both media and buyer appeal.

Enclosure.  The super-insulated air tight building enclosure includes an insulated concrete form wall system that provides continuous insulation yielding an R-50. An R-50 roof assembly combines mineral wool in the cavity and 5” continuous rigid insulation on top of the roof deck. R-20 is under the concrete floor slab with R-33 on the foundation walls, paired with building details to mitigate all thermal bridging. High performance U-0.14 triple pane windows/doors offer a SHGC-glass of 0.50 to capture the sun's energy. Particular care was paid to maintaining a continuous air barrier, yielding a final infiltration rate of only 0.56ACH50.

Systems.  Ducted air source heat pumps provide space conditioning, including heating, cooling, and dehumidifcation. A Zehnder Comfoair ERV completes the package with highly efficient ventilation and energy recovery. Domestic hot water is supplied in each unit by a heat pump hot water heater. 

Renewables.  On the roof a grid tied 4.5kW photovoltaic system for each unit turns the electric meter backwards to offset energy consumption.