Little Mountain Cohousing

Little Mountain Cohousing, a Passive House project that started construction in early 2019, will include 25 residential units plus a range of common house facilities. The building’s opening date is set for early 2021.

The six-storey building’s massing was designed to conform to tight rezoning requirements while creating units that responded to the needs of the individual cohousing group members. Common spaces—kitchen and dining, children’s playroom, laundry, a central courtyard, and more—were a primary concern. Cornerstone Architecture structured the main common spaces so that they open onto a southwest-facing court at the corner of the lot, which is also overlooked by the common circulation at each building level. Topping the building is a common accessible green-roof area with roof decks and urban farming beds.

The superstructure is mainly wood-frame construction with a double exterior wall to achieve high insulation and airtightness. The concrete ground floor over the parkade is sandwiched between layers of insulation to minimize thermal bridging around the perimeter and thermal bridging caused by structural members. Roof insulation is installed both in the joist cavity and continuously above the structure. The project incorporates high-performance windows with glazing characteristics varied by orientation and surrounding shading objects to minimize summer heat gain.

Convective heat loss through plumbing stacks is substantially reduced by using exterior air-admittance valves with positive air pressure attenuators. For ventilation, high-efficiency HRVs are located in each residential unit and in common areas. CO2-based heat pumps provide the primary source of hot water, and electric baseboard heaters provide additional heat should it be required in the mild Vancouver climate. The project is designed without a gas service connection and will be virtually greenhouse-gas-free in operation.