Thoughtful green restoration achieves LEED Platinum

The roof garden on the new third-storey addition is irrigated through grey water recovery

With a 65sq.m addition on the roof, and the excavation of the 74sq.m basement, the owner/builder, a green building consultant, almost doubled the floor area of this two- storey, semi-derelict 1907 property, converting it into a contemporary triplex that now houses three generations of his family within this single green restoration project.
The heritage designation of the neighbourhood required the restoration of exterior finishes and details that had been removed during a previous renovation in the 1960s. These included slate roofs and turret, new windows, decorative metal trim and woodwork, all of which required traditional trade skills that were costly and difficult to come by. However, the neighbourhood character also contributed to a perfect LEED score in the ‘Location and Linkages’ category, providing all the amenities and transportation options necessary for a fully pedestrian lifestyle.
The interior layout and mechanical services were designed to enable flexibility according to the needs of the family. The design also anticipates further densification of the site with the future addition of a five-storey, 465sq.m second phase.
With rainwater used for irrigating the garden and green roof, conservation and recovery strategies [rather than rainwater harvesting] are used to achieve water efficiency goals. Low flow fixtures and dual flush toilets are supplemented by a custom grey water system, designed to recover water from bathing, showering and clothes washing in order to treat it and reuse it for toilet flushing and irrigation.
Water is treated biologically in primary and secondary sedimentation tanks that lead to a sand filter, covering roughly 3sq.m in the basement utility room. A 2,045 litre subsurface reservoir holds the water before it is pumped into the non-potable water lines.
Upgrading the building envelope required a number of different strategies and insulation types. The original masonry exterior walls contained no insulation, so these, together with the new basement walls, were filled with recycled urethane foam to achieve approximately R30. The rooftop extension combines EPS panels on the exterior, with mineral wool and reflective foil insulation to achieve more than R34.
A geothermal system located in the basement utility room provides heating and cooling. The unit also provides hot water, drawing from two 99m wells. Heating distribution is via hydronic radiant floors and walls as well as the original cast-iron radiators. In order to provide these two distinct water circuits as well as two-thirds of domestic hot water needs, the geothermal heat pump sends heated water to a triple heat exchange reservoir. Cooling and backup heating is done through a forced air distribution system.
Grey water heat-recovery units were installed on drain lines, and a final recovery phase transfers residual heat to a coil in the grey water recycling unit that preheats domestic hot water.
The lighting strategy includes tube skylights, compact fluorescent [CFL], LED and task oriented fixtures that seek to minimize overall energy consumption.
When energy cost savings are factored in, the overall cost of this green restoration was less than that of a conventionally designed alternative.

jury comments

The project uses geothermal heating, recycled materials and a green roof and garden, and overall represents smart, compact living space that could even support a “back to the future” style of multi-generational living. At approximately $100/sf, the green restoration is remarkably affordable, especially for a LEED Platinum rating [under the US LEED Homes], partly achieved through careful selection of a limited variety of materials.

Watch a video of the jury commenting on the project on youtube:


  • Architect: Angéline Spino, Architect, Montreal
  • Owner/Builder: Emmanuel Cosgrove, Montreal
  • Designer: Carina Rose, Montreal
  • Structural Engineer: Donald Arsenault, Montreal


  • Structure: Wood-frame construction; also used materials found at city waste/recycling drop-off points that accounts
    for three-quarters of materials introduced to the site.
  • Exterior: Soy/recycled PETE green spray urethane foam by Demilec, cellulose insulation, Tyvek air barrier, 2×6 studs, EPS panels on third-storey addition, sheet metal cladding; Integrity windows by Marvin; intensive green roof by Green Innovations/MODI, Soprema roofing membrane.
  • Interior: Salvaged slate and wood flooring, recycled paint by Boomerang, and low VOC paint, soya-based Purebond poplar-core plywood for cabinetry.
  • HVAC, Water: Four-ton geothermal system with triple heat exchange reservoir, hydronic radiant floors and walls and use made of original iron radiators, Lifebreath heat recovery ventilator [HRV] and HEPA air filter by Nutech fed by an earth tube that pre-heats or cools incoming air; custom greywater recovery system using sedimentation tanks, sand filter and 2,045 litre cistern, low flow fixtures and dual-flush toilets.
  • Building gross area: 307 sq.m

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