A new rental building, 1925 Victoria Park in Toronto, is offered by Well Grounded Real Estate, a company founded by Harry Diamond in the 1950s, and unrelated to the better-known Eph Diamond, who co-founded Cadillac-Fairview. Well Grounded Real Estate has been quietly running its own rental properties for years, but is poised to make a splash.
Vice President Jonathan Diamond explained the concept to Treehugger. It is unlike almost any apartment building in North America; it’s more of a master class in sustainable design. The developers summarize it in a mind-blowing paragraph:
“The first feature is the massing, which favors natural lighting of the central courtyard while attenuating the heat gain to the units. The second is the single-load exterior corridor which favors natural daylighting on both sides of the units. and cross-ventilation.The third is the pre-engineered wood hybrid building system that enables rapid, disturbance-free construction and forms the high-performance building envelope.The fourth is a mechanical system that decouples heating/cooling from ventilation The resulting system is highly energy efficient and low in embodied carbon, healthier for tenants and incredibly cost effective to operate, maintain and repair.”
We’re usually excited about one or two features of a building, but this is quite a textbook of them. The company has set up a remarkable team of consultants. The architects, Partisans, are talented designers known to Treehugger for their stunning wood; Integral Group is known for its deep green mechanical engineering; and Transsolar Klima Engineering is famous for reinventing natural ventilation. (The latter two have been on Treehugger before.) Landscape architecture is by Janet Rosenberg & Studio, and structural engineering is by Aspect.
Mass of the courtyard and exterior corridor
In a previous post about building a sustainable apartment building, I noted that “the trends I see are more single-load exterior hallways to improve ventilation and reduce the need for shared enclosed spaces where airborne contaminants may persist”.
In another post, I wrote that the era of the double-charge hallway should be over. In most apartment buildings, occupants have pressurized aisle systems where “fresh” air enters under the apartment door from the hallway. I always thought it was a terrible system, with the air almost filtering through dirty carpets and all that dust, poop and pollen getting into it. After the pandemic, it’s a disgusting idea.
Here, instead of an enclosed hallway, there is an exterior hallway winding around a central courtyard, providing access to elevators and two staircases that are part of the tallest tower. It’s generous in width, wide enough for kids to play in and adults to grab a coffee, though the Toronto Fire Department will no doubt complain about the furniture.
This single-load corridor design is common in Europe, but unusual in colder parts of North America. But the advantages are many, including much more interesting apartment layouts, where you can get habitable rooms looking both inside and outside. The brief explains how it’s also healthier:
“According to the EPA, indoor air pollutants are often two to five times higher than outdoor levels. The pandemic has also taught us that the best defense against airborne pathogens in indoor spaces is dilution by maximizing ventilation. Units are designed to optimize natural ventilation to improve air quality without negatively impacting energy consumption or occupant comfort.”
Having the walkways on one side and the balconies on the other provides sun protection, reducing the need for mechanical cooling. The “green mesh” of planting will help cool the walkway and increase shade.
Hybrid wood and concrete slabs
The building is constructed from precast panels using the CREE system, a hybrid of concrete slabs and glued laminated beams (Glulam). It uses a lot less concrete because of the wooden beams, which makes it much lighter and with a lower carbon footprint. These slabs will rest on prefabricated structural facades with integrated glulam columns. CREE promises 80% lower embodied carbon emissions and 50% lower life cycle carbon emissions.
The balconies and walkways are structurally and thermally decoupled from the building to optimize performance and facilitate maintenance. It sounds more complex, but Diamond tells Treehugger it’s not difficult and any precast company can do it.
Decoupling of mechanical systems
This is where it gets complicated and exciting. Heating and cooling is via radiant ceilings, with pipes cast into the concrete slabs. Yes, radiant heating works from above because it is radiant and not convective. Radiant heating is well understood, but especially when it’s underfoot. But radiant cooling has rarely been done in Canada, and no doubt people have images of water dripping from the ceiling. This does not happen because there is a dew point sensor which stops the cooling if the space approaches the dew point.
During this time, fresh ventilation air is supplied by a separate system. “A damper at each suite will control the ventilation air supplied to each suite based on the fresh air and dehumidification needs of the space. Ventilation air will be supplied to each occupied space through ducts located under the false -floor, keeping the ceiling clear, for maximum coverage of the radiant ceiling.”
Of course, the hot and cold water comes from a geothermal system (geothermal heat pump) below the level of the parking lot. Rainwater is harvested and filtered for non-potable uses; there is heat recovery on all the exhaust ventilation; and there is a sewer heat recovery system to preheat domestic hot water. I can’t think of anything they missed other than having the water pumped by wind turbines on the roof—just kidding, that wouldn’t work—but, of course, the roof is covered in panels solar.
In the introduction, the developers write, “This project presents a unique opportunity to advance the development of pre-engineered log construction and affordable housing in Toronto. This will be a pilot development to prove that the highest standards in sustainability and design are not only possible, but financially viable in the city.
It will be interesting to see how it works its way through the meat grinder of Toronto zoning, where each building must retreat to the rear so as not to offend neighbors in their single-family homes. This building is already lower in the back, but these small bungalows have great power.
It is a very big challenge. It helps if the owner is for the long term, noting, “We are long-term owners and operators. As such, we understand that every design decision has downstream consequences on our tenants’ livability and building operations. I suspect other architects and developers will admire it and learn from it for a very long time.