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Victorian home on UofT campus gets a radical, engineering-heavy makeover

The not-so-simple scheme: A box within a box

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A sign outside the home at 31 Sussex Ave. near the University of Toronto campus. Architect Michael McClelland calls it “Gemini House” and along with University of Toronto’s Kim Pressnail and Ryerson University’s Russell Richman, he has succeeded in bringing a 19th Century home up to 21st Century standards of energy efficiency. The renovation scheme centred on a deceptively simple plan - a box inside a box, or as the designers termed them, ‘periphery’ and ‘core’

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The home relies on a radiant floor system for its heat source and it has state-of-the-art, triple-glazed, German windows everywhere but on its handsome heritage face (original windows were retained). As well, it has a pair of energy recovery ventilators in the newly-insulated basement crawlspace. Eventually, the home will house visiting professors in disciplines such as architecture, engineering or building science, plus be opened up periodically for tours and teaching purposes. Professor Pressnail says the traditional way to insulate an old home is to spray foam right onto the brick, but his team worried about the brick drying too much. Instead, they created a vented air-space by adding tiny holes to the masonry outside, and by ‘hanging’ the foam on a custom mesh screen to create an air-space between the foam and the brick.

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The box-within-a-box concept meant creating a shell within the old home by significantly pulling in all of the interior walls in order to add gobs of insulation. Within this new building, there is a core zone and a periphery zone, each insulated from the other and controlled by their own thermostats. On the main floor, the core contains the daily-use spaces, such as kitchen, living and dining rooms, while the periphery contains non-essential spaces, such as the vestibule and the ballroom. This dual personality – hence the Gemini moniker – allows the occupant to heat only those spaces he or she needs.

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The new interior almost “floats” independently of the old home; indeed, the gap between the two is so pronounced, there are two sets of windows at each opening and a person can stand in the space between them. The entire staircase had to be raised to allow for new, super-insulated floors.

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Slots on the floors of the window areas control solar heat gain. 'So if it overheats out there we can pump it in here, or we can vent it,' Prof. Pressnail says. 'Usually when you have solar designs you get it when you don’t want it and you don’t get it when you need it.' The new interior is also equipped with a passive heat chimney. Cutting away the part of the second floor over the vestibule allowed for a remote-controlled hatch that allows hot air to escape when necessary. Also, a tube from the roof now carries natural light into the formerly dark stairwell.

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The Ballroom, being in the 'periphery', needs to be quarantined from the 'core' when not in use, so there are double doors that can be shut.

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In order to preserve the home’s original plaster ceiling, insulation of the ballroom had to be done by removing flooring from the second floor and adding it from above. Also, since the interior walls had to come in a great deal to put insulation in there, ERA Architects had to remove the intricate moldings and reinstall them once the new room dimensions were known to ensure for original symmetry.

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The solar tube brings light to the stairwell. The team is hoping that when the house is in full energy-efficient mode, savings will be around 60 - 70 percent versus a conventional house. While this first Gemini House has been an expensive endeavour, to turn a new build into a Gemini could be done with only a 10 – 15 percent increase in the construction budget.

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The original ceiling plasterwork in the front room.

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Mr. McClelland’s team from ERA Architects Inc included fellow principal Edwin Rowse and associates Graeme Stewart and Max Berg.

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