The Danforth Deep Energy Retrofit
The Beechwood Project is the evolution of a post-World War II bungalow into a super efficient two-storey home: a retrofit that exceeds Passive House air tightness requirement for new construction. The project underwent an integrated design process involving the architect, sustainability consultant, mechanical engineer, builder, and other professionals from the high-performance building industry. Through this process, the home’s geometry, glazing, insulation, mechanical system, air barrier detailing and constructability were optimized for energy efficiency, high indoor air quality and low water consumption. The builder designed the air barrier system as well as selected materials to achieve these excellent results. Non-standard materials included expanding foam tape and U-shims used during window installation and a fluid-applied air barrier on the interior of the existing masonry walls.
Key details for this project include:
Performance: 0.44 ACH at 50Pa Insulation levels (original house without insulation): above-grade walls – R40, below-grade walls – R30, Roof – R60, windows – R7, sub-slab – R20 4” of continuous exterior insulation for thermal-bridge free construction Design heating load of 28W/m2 Mechanical ventilation with 76% heat recovery for the total system (via new ERV)
Air Barrier Detailing: A continuous air barrier was created around the entire house – from below the basement slab to the 2nd floor ceiling: 10mil poly sub-slab; Fluid-applied air barrier on existing masonry walls. The existing joists embedded in masonry; each joist carefully detailed with air barrier putty and reinforcing mesh; Self-sealing membrane used to transition between existing masonry walls and new 2nd storey addition; On the new second storey, nail base (polyisocyanurate insulation with an OSB skin) was used as the air barrier. All seams and fasteners were carefully taped to ensure continuity. Nail base was also used for the air barrier on the ceiling; All penetrations were carefully sealed with sealant, neoprene boots, or flexible flashing tape depending on their size
Systems: Water-to-water reversible heat pump using multiple heat sources and sinks. A shallow geothermal loop buried below the sub-slab insulation acts as a heat source/sink Heating and cooling delivered hydronically via radiant ceiling panels and slab A hydronic coil conditions ventilation air before it is distributed to the house and provides additional dehumidification in the summer ERV: RenewAire EV200 Drain water heat recovery Rainwater ready: Non-potable uses (laundry, toilets, irrigation, exterior hose bibs) have been separately plumbed for future connection to a rainwater cistern Solar ready: will receive hybrid solar thermal/PV panels in 2015
Materials: FSC framing lumber Lead free brass fittings Durable sloped cool metal roof, SRI 30; Cool flat roof, SRI 87 Triple pane, argon-filled, fibreglass windows 40% SCM content concrete Watersense certified low-flow toilets High recycled content drywall Green Seal Standard GS-11 compliant paints Recycled denim batt sound insulation Quebec-sourced maple wood for stair and flooring LED lighting throughout Hard surface flooring throughout, including finished concrete slab Organic linseed oil wood finish
Waste: Existing masonry and original floor joists retained Appliances, doors, boiler and radiators donated 80% waste diversion achieved during construction