Toronto Residential Building Is Our New Poster Child for Sustainable Design

A new rental apartment building, 1925 Victoria Park in Toronto, is being proposed by Well Grounded Real Estate, a company founded by Harry Diamond in the 1950s, and no relation to the more well-known Eph Diamond, who cofounded Cadillac-Fairview. Well Grounded Real Estate has been quietly managing its own rental buildings for years but is about to make a very big splash.

Vice-president Jonathan Diamond walked Treehugger through the concept. It is unlike almost any apartment building in North America; it is more like a master class in sustainable design. The developers summarize it in a mind-blowing paragraph:

"The first feature is the massing, which promotes daylighting to the central courtyard while mitigating heat gain to units. The second is the exterior, single-loaded corridor that promotes natural daylighting on two sides of the units and cross-ventilation. The third is the prefabricated hybrid-timber building system that enables rapid and non-disruptive 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, low embodied carbon, healthier for the tenants, and incredibly cost-effective to operate, maintain, and repair." 

We usually get excited about one or two features in a building, but this is a whole textbook of them. The company has put together a remarkable team of consultants. The architects, Partisans, are talented designers known to Treehugger for their wood that wows; Integral Group is known for its deep green mechanical engineering; and Transsolar Klima Engineering is famous for reinventing natural ventilation. (The latter two have both been previously on Treehugger.) Landscape architecture is by Janet Rosenberg & Studio, and structural engineering is by Aspect.

Courtyard Massing and Exterior Corridor

In a previous post on how to build a sustainable apartment building, I noted that "trends I see are more exterior single-loaded corridors to improve ventilation and reduce the need for shared enclosed spaces where airborne contaminants can linger." 

In another post, I wrote that the era of the double-loaded corridor should be over. In most apartment buildings, occupants have pressurized corridor systems where "fresh" air comes in under the apartment door from the corridor. I always thought this was a terrible system, with the air almost filtered through dirty carpeting and all that dust, poop, and pollen getting pushed in. Post-pandemic, it's a disgusting idea.

Here, instead of an enclosed corridor, there is an exterior corridor wrapping around a central courtyard, providing access to the elevators and two stairs that are part of the taller tower. It is generous in width, wide enough that kids can play and adults can have a coffee, although the Toronto Fire Department will no doubt complain about the furniture.

This single-loaded corridor design is common in Europe but unusual in colder parts of North America. But the benefits are many, including much more interesting apartment layouts, where you can get habitable rooms facing both the interior and the exterior. The brief explains how it is healthier, too:

"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 interior spaces is dilution through maximizing ventilation. The units are designed to optimize natural ventilation to improve air quality without negatively impacting energy use or occupant comfort." 

Having the walkways on one side and balconies on the other provides solar shading, which reduces the need for mechanical cooling. The "green mesh" of planting will help cool the walkway and increase shading. 

Hybrid Wood and Concrete Slabs

The building is constructed of prefabricated panels using the CREE system, a hybrid of concrete slabs and Glue-Laminated (Glulam) beams. It uses a lot less concrete because of the wood beams, making it much lighter and with a lower carbon footprint. These slabs will sit on prefabricated structural facades with integrated Glulam columns. CREE promises 80% lower embodied carbon emissions and 50% lower carbon lifecycle emissions.

The balconies and walkways are structurally and thermally decoupled from the building to optimize performance and make maintenance easier. It seems more complex, but Diamond tells Treehugger that it's not hard and can be done by any precast company.

Decoupling Mechanical Systems

Here is where it gets complicated and exciting. Heating and cooling are via radiant ceilings, with pipes cast into the concrete slabs. Yes, radiant heating works from above because it is radiant, not convective. Radiant heating is well understood, though mostly when it is underfoot. But radiant cooling has rarely been done in Canada, and no doubt people have images of water dripping from the ceiling. This doesn't happen because there is a dewpoint sensor that turns off the cooling should the space approach the condensation point.

Meanwhile, fresh ventilation air is provided through a separate system. "A damper at each suite will control the ventilation air provided to each suite based on the fresh air and dehumidification needs of the space. The ventilation air will be provided to each occupied space via ducts located under the raised access floor, keeping the overhead free for maximum radiant ceiling coverage."

Of course, the hot and cold water comes from a geo-exchange (ground source heat pump) system under the parking level. 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 cannot think of anything they missed other than having the water pumped by wind turbines on the roof—joking, it wouldn't work—but, of course, the roof is covered with solar panels.

In the introduction, the developers write: "This project presents a unique opportunity to advance the development of prefab heavy timber construction and affordable housing in Toronto. It will be a pilot development to prove that highest standards for 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 Toronto zoning meat grinder, where every building has to step down expensively to the rear so as not to offend the neighbors in their single-family houses. This building is already lower at the rear, but those little bungalows have great power.

This is a very big challenge. It helps that the owner is in for the long haul, noting, "We are long-term owners and operators. As such we understand that every design decision has downstream consequences on the livability for our tenants and the operations of the building." I suspect that other architects and developers will be admiring it and learning from it for a very long time.