The Agenda with Steve Paikin (Audio) - What is Thermal Comfort?

Episode Date: June 26, 2025

Toronto is adapting to climate change with new Thermal Comfort Guidelines, developed after a city-wide study by DIALOG and Buro Happold. With the number of days exceeding 30 C projected to rise from 10 to 55 annually by 2080, we're examining how the city is reimagining public spaces to stay livable throughout the year. Field reporter Jeyan Jeganathan dives into what makes us feel comfortable outdoors-examining the role of wind, humidity, sun, and shade-and how better design can create more resilient, equitable cities. See omnystudio.com/listener for privacy information.

In 2017, it felt like drugs were everywhere in the news. So I started a podcast called On Drugs. We covered a lot of ground over two seasons, but there are still so many more stories to tell. I'm Jeff Turner and I'm back with season three of On Drugs. And this time it's going to get personal. I don't know who Sober Jeff is. I don't even know if I like that guy.

On Drugs is available now wherever you get your podcasts. A forest on wheels. 50 trees rolling through the city in shopping carts. This is Nature in Motion. Created by architects in the Netherlands, the Moving Forest is a playful mobile installation. For eight weeks this summer, the roaming fleet to 50 carts will weave through Toronto, forming spontaneous shade canopies. It's part of the Bentway's summer exhibition, Sun Shade, an exploration of how cities adapt to rising temperatures and design more comfortable

urban spaces. At its core, it explores how we experience public spaces through the lens of thermal comfort. Have you ever crossed the street to get on a shady side of the street on a really hot summer day or just change your route to avoid the windy corner in winter? If you've done that, you've already made a decision based on thermal comfort. Thermal comfort is just how comfortable

you feel in a space. Not too hot, not too cold. And that depends on four key factors. One, it's humidity. Two is wind. Three is air temperature. That's the number you see on your thermometer. And four is radiant temperature. It's the radiation you get from the surrounding area,

whether it's directly from the sun or from the surrounding material. So if you're standing next to a patch of asphalt versus patch of grass, the radiation is going to feel differently. Dorsa Jalalian is an associate and senior urban designer at the Multidisciplinary design practice, Dialogue. She's reshaping the way we think about building cities for a changing climate. Many of us think of Toronto as a winter city. Cold, windy. Many of our planning policies certainly think so because we have so many urban planning policies and guidelines

that talk about maximizing access to sunlight. But Toronto also has hot and humid summers and we are going to get more of those. We used to have about on average 10 days a year that our temperatures exceed 30 degrees Celsius. If the current emissions continue as they are, we are going to get a lot more of them up to 55 days a year that we get over 30 degrees Celsius by 2080. So from 10 days a year to 55 days a year. So how do we think of our city? How do we plan our cities better? So why does thermal comfort matter so much? Just take a walk through Nathan Phillips Square, you'll see why. In recent years, updates like the Peace Garden have helped refresh the space,

changing the way people experience it. But when it comes to staying cool, they're still a challenge. This is one of our most iconic public spaces here in the city. And one of the least comfortable and one of the hottest in a hot summer day. You can see there's very little shade in the summer. And imagine a hot July afternoon. This can be really uncomfortable with all the concrete soaking up the heat. So what we can do about it, imagine flexible shade structures, umbrellas.

You can think of movable chairs and tables that you can move around based on the need, but also those can be easily cleared out when you have a big festival or gathering. These are just strategies to make it more thermally comfortable. Another problem area Torontonians are familiar with, the Bay Street corridor. You can feel the wind here and the reason why is what we call it a wind canyon effect or a wind tunnel effect. When wind gets here, especially when you have tall buildings all packed closely together and facing opposite each other, all lined in a straight line, what happens? The wind gets funneled between the buildings and create a very intense gust at pedestrian level,

at ground level. So to avoid that wind tunnel effect, there are a few things you can do. You can, one is varying your building height. So instead of all the buildings being at the same height, even the difference of two stories can help with breaking that wind sort of flow that's going between the buildings.

The other one is to stagger your tower placement. So instead of all the towers being opposite each other, facing each other, imagine them being lined in a zigzag pattern. As Toronto's climate heats up, city officials, in collaboration with Dialogue, completed a thermal comfort study to update guidelines to better design public spaces to be comfortable for people year-round. Now we have much more data that we can work with. We can undertake thermal comfort studies much more easily.

The cost is less. They're faster to undertake. We wanted to do the update because there's a lot of growth in Toronto. So we want to make sure that as our city is growing that we're building and designing meaningful public spaces that people can enjoy and where communities can flourish and grow. It's an invitation for those shaping the city to think holistically. Who's going to use this space? When? What time of the year? How is it going to feel in July versus February? So for now these guidelines are adopted by City Council earlier this year. Everyone shaping our cities from

the municipality itself to developers, architects, designers, are invited to look at those guidelines and think about designing for thermal comfort in mind. The study helps with organizing streets, entire blocks, and the strategic placement of open spaces and city parks. The City of Toronto is actively using the new thermal comfort guidelines on large-scale projects like the new Etobicoke Civic Centre. That was a whole reconfiguration in that neighborhood and is also a great example of extensive tree planting alongside very wide streets. The findings have been incorporated into the design of the new Civic Centre and the buildings adjacent to it and certainly the streetscapes as well.

Trees are the best, most elegant strategy because deciduous trees, for instance, the ones that lose their leaves in the fall are perfect because they give you shade when you need it the most in the summer and they give you access to sunlight when you also need it in winter you want to feel warmer and they don't have leaves so you have that access to sunlight so they're great tools when it comes to sun and shade. From chilly winter mornings to the heat of summer, the thermal comfort study establishes temperature ranges. Winter it's somewhere between zero degrees to I think nine degrees. The summer is somewhere between nine degrees and 26 degrees so there. So there is a range and a target that we're looking to meet depending on the season.

As Toronto's population continues to grow, and in most cases it's up, the need and access to public spaces is more crucial than ever. The City of Toronto actually has a really cool, interesting tool that they have recently developed. It's called Tree Equity Score Analyzer, which takes all the equity factors and the tree canopy percentage and maps it out in the city so you can see the tree equity score of a neighbourhood. So you can really prioritise a neighbourhood with low tree equity score to plant more trees

there, plant more deciduous trees there. But also the other strategy is to think about those apartment neighborhoods. Not everybody has access to a backyard and a nice, serene, cool space with trees. So really in those neighborhoods it becomes even more important to think about comfortable outdoor spaces. As Toronto's summers grow hotter, the way we design our city will define its future because a livable city isn't just one that withstands change, it's one that embraces it, ensuring that every street, every park and every square remains a place for people no matter the

season. Thinking about thermal comfort means that we are aiming to make our cities more livable, more resilient, and more enjoyable.