Located in Toronto’s Roncesvalles Village neighbourhood, this 3,000 sq. ft. house was conceived as an urban home with a bold emphasis on natural materials, sustainable design and contemporary living. The home was constructed on the site of an existing residence typical of Toronto’s older neighbourhoods, and just steps from Roncesvalles Village. While renovation was considered, rebuilding was the most cost-effective way to achieve the project goals and create a free-flowing open concept with natural daylighting, passive ventilation, and a high-performance building enclosure.A green roof system helps to mitigate stormwater runoff, while the property’s landscaping was planned to require minimal irrigation with design features arranged to collect and store it on site. Water conservation was considered throughout the selection of efficient plumbing fixtures. The design implemented a passive solar strategy that takes advantage of the sun’s daily cycle and the movement of air through the seasons. In summer, the overhangs limit heat gain to the south-facing rooms, while operable windows are orientated at the north and south ends of the building to utilize natural cross-ventilation through large operable patio doors. Two main vertical cavities (above the dining table and above the stair) bring light into the middle of the house year-round and especially in the summer. This naturally ventilates the spaces by applying the stack effect to vent hot, stale air above and draw cool, fresh air in through lower openings.In winter, the sun is able to penetrate the building and heat up the concrete flooring, taking advantage of their thermal mass. Highly efficient, radiant in-floor heating and a wood burning fireplace are used to supplement heating. The heat in summer and the cool in winter are kept out through a very effective enclosure with walls of R-30 insulation, roof of R-40, and insulated concrete form (ICF) foundations. These passive strategies reduce energy loads and enhance comfort to minimize the demand on the mechanical system. The use of energy-efficient appliances, LED and compact fluorescent lamps minimize the electrical loads.