Toronto’s new Thermal Comfort Guidelines (TCG) provide a blueprint for adapting urban spaces to meet the challenges of climate change.
Aimed at helping ensure outdoor public spaces are habitable through the four seasons, the guidelines will help shift how the design community thinks about the impact of future developments on their surroundings at a time when urban intensification is on the rise.
One of the first cities in the world to adopt four-season comfort criteria, the guidelines were developed by the city in collaboration with DIALOG and Buro Happold.
They provide acceptable ranges of the Universal Thermal Comfort Index (UTCI), a globally-recognized standard for measuring the thermal comfort ranges of various periods in a year, says Kristina Reinders, program manager in urban design for the city of Toronto.
The UTCI combines wind, humidity, air temperature and radiant temperature to determine thermal comfort.
“It is what the temperature feels like, not what is registered on the thermometer,” says Reinders.
A mandatory requirement for city-led initiatives, the TCG are recommended for privately-led developments exceeding five hectares and involving buildings taller than six storeys, such as the new Toronto waterfront developments, Downsview development and Etobicoke Centre, she says.
The guidelines cover a wide range of ideas, from how a building’s site orientation and design shape can mitigate wind to where and what type of tree canopy can offer shading in summer and solar penetration in winter, says Dorsa Jalalian, an associate and senior urban designer at DIALOG.
Too often in Toronto developments have fallen short of these objectives.
“The way we are designing now our regard for the climate context is minimized. Thinking holistically about a space and how it is going to feel in July versus February hasn’t been thought of,” Jalalian says.
“Within a larger space or public square we can make sure we have a variety of microclimates, a spot in the sun and a place to cool off. That’s what really good design does.”
The TCG also offers an “equity lens,” identifying neighbourhoods and areas of the city where thermal comfort design should be prioritized.
As an example, Toronto’s tree canopy map shows lower income neighbourhoods tend to have less green space and fewer parks and areas to cool off on hot summer days.
The guidelines are based on performance, offering a flexible design route, rather than a prescriptive-based solution that can result in repetitive building forms, says Jalalian.
“We have a target for thermal comfort. If you are achieving, you are good to go, but if you are not we’re not going to tell you what to do. You can see in the design toolbox what works best for you to improve thermal comfort.”
Jalalian says thermal comfort designs don’t come at a high cost.
“A lot of it is about being mindful in your design.”
Reinders cites the stretch of Bay Street in downtown Toronto’s financial district as an example of where inhospitable winds might have been mitigated through designs that took a different approach. Sometimes reoriented tall buildings on their sites and creating five or six storey stepbacks or podiums at grade are enough to minimize the impacts of wind.
Optimistic that the design community will take to the guidelines, Reinders says there are some thermal comfort studies underway now in Toronto, including one around the Kennedy TTC Station that is nearing completion.
“There is a lot of interest in low carbon design…and I think this goes along side with that.”
She suggests the development community will be on side as long as the guidelines remain voluntary and thermal comfort studies can be done early in the development process.
“We have a lot of good developers that want to build meaningful communities that optimize the quality of life of the residents.”
While the guidelines are “Toronto specific,” Reinders adds other four-season cities in Canada, the northern U.S. and northern Europe could “easily take the approach we’ve taken and make adjustments. We’ve shown a lot of leadership.”
