Sitting on a small lot of a tight urban street on the outskirts of downtown Halifax, the (s)efficient house overlooks a south-facing garden while keeping the east views of the industrial lands to a minimum.
The retired homeowners wanted to downsize in retirement. With 960 sq. ft. of living space on one level, the house has minimal upkeep and future accessibility potential. An additional 300 sq. ft. of garage space allows for the storage of cars and other items. The living space has the opposite "gull wing" roof shape allowing the main living spaces to have high, vaulted ceilings which make the compact interior feel voluminous.
The house is efficient, but the (S) in the name of the house stands for sufficient. It is not a large house, and the clients wanted a house that was just enough, no extras. It is about having not only less to heat and cool, but less to maintain. We think it is a great precedent because our culture always sells the idea of the "dream home" which tends to have lots of extras and be very expensive. It was a delight to have a client looking for elevated living that was not about excess.
The foyer area between the separate garage and living space creates the entry point to the house. The small footprint was purposely designed with a "divider" closet/dining servery creating a threshold between the front entry hall and the mudroom before meandering and opening into the main public areas of the house.
An important factor for wellness is occupant comfort related to natural daylighting and a comfortable room temperature. The large, south-facing feature window ensures adequate solar gain and natural light in winter. The home's heat pump is set at 18c and stays at 19c to 23c depending on where it's measured and the time of day. With windows in every room, oftentimes with dual aspects, the house requires little lighting, except at night.
Water strategies needed only simple measures involving water-conserving fixtures, thus saving the budget for more pressing issues of envelope design and the photovoltaic array. The water use in the first nine months of operating has been 14 CM for three months, or roughly 140l/day.
The house is double framed to ensure no thermal bridging or puncturing through the vapor barrier and has a ducted heat pump system. It exhibits R48 insulated walls, R88 roof, triple-pane windows, and tight envelope detailing. The garage has a steeply pitched roof to accept the photovoltaic array.
The exterior walls and roof of the house were clad in metal for affordability. It's also low maintenance, long-lasting, and is recyclable at end-of-life. The frame was built of wood for low embodied energy and the benefits and acting as a carbon store. It was designed without using long spans or cantilevers to avoid the need to use steel in the structural design. It also kept both embodied energy and cost down. Drywall and wood flooring were used for the simple interior.
The house effectively operates as a Net Zero Energy Home with slightly net positive energy consumption (producing more than it's using). The energy target for Passive House is 15 kWh/m2/year.
The rated capacity of the photovoltaic array is 6.88kw but the project has only seen a max of about 5.2kw. The home has averaged about 18.6kwh with a peak day of 35+. The reduction is mainly shading losses from an oak tree to the south/west, especially when in full leaf, which slightly shades the solar panels at certain times and due to the low slope in the winter.
The home's power usage is monitored by an 'Emporia Energy' Smart Home Energy Monitoring device. The device allows homeowners to gauge certain appliances or circuits on an app on their phone to ensure their home is operating efficiently in real-time.
With closed-cell, spray foam insulation, the (S) Efficient House needed balanced ventilation to bring fresh air inside when necessary. The team at Tate Engineering decided the Fantech FIT® 120E Fresh Air Appliance with Energy Recovery and the ECO-Touch® AUTO IAQ wall control would be an ideal fit for this project.
With 70% total energy recovery, the FIT 120E retains heat from the outgoing air and transfers it to the incoming air to offset the load on the heat pump. The wall control increases the fresh air appliance’s airflow capacity based on the total VOC levels and the percentage of indoor relative humidity within the space, and user preferences. This keeps the fresh air appliance from "overworking" while still bringing in the right amount of outdoor air. This process aids in keeping power consumption low.
The largest power consumers have been the heat pump followed by the fresh air appliance and the water heater. There was a learning curve on how best to operate the heat pump and fresh air appliance in the first year and the owners anticipate improvements in efficiency in the coming year.
Retirement goals are often associated with owning a "big house" and perhaps retreating to the countryside. This project looks at retirement goals differently, focusing on a "right-sized" house nested into a community close to amenities of a downtown core. The design focused on attributes such as having a bright, airy space and a low-maintenance home free from concerns of electric inflation. The design satisfies the goals of rethinking housing and retirement while fully serving the needs of the owners.
MAEGAN MURRINS AND RAYLEEN HILL ARE WITH RHAD ARCHITECTS.
See the original article in SABMag/Atlantic Focus
https://issuu.com/sabmagazine/docs/digital_atlanticspring2024/26
