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The Urban Heat Island - Action Needed

Northern Light

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Many of us with, let alone those without air conditioning have been suffering through the latest heat wave.

For most people it is less the heat along than its combination with humidity that makes the temperature outside difficult and inside (without good air conditioning) intolerable.

But that is all exacerbated but one notable effect, the urban heat island.

If one looks at graphs on the Weather Network's website, one can clearly see that while daytime temps are slightly above normal; its the warm temperatures at night that lead to poor sleeping, and mean no real respite from the discomfort of the day.

The number of days over 20 degrees C at night has jumped alarmingly.

That is not a function of climate change or an anomalous warm summer.

Its a function of urban sprawl, too much pavement and too little shade.

Black surfaces, notably roads and parking lots, but many building roof systems as well, radiate heat after dark, after having absorbed sun during the day.

This is something Toronto has to address to preserve its livability

I'll put a few ideas out for discussion, but invite others, as well as how to get buy-in to tackle the problem.

1) Major roads are a huge source of the heat island effect. They are difficult to shade properly due to width.

The action plan required is that 'turning lanes' (not at lights, but the on-going ones down the middle of many suburban roads) need to come out in favour of islands with shade trees and perennial plants.

Further that boulevards must be green, provide good tree growing conditions and canopy-forming trees (no fruit trees or other short species).

2) We need to ultimately eliminate as much surface parking as possible, but in the interim, we need to create canopy over parking lots. This may mean removing up to 20% of parking spots in a large mall lot. A clear action plan is needed that addresses alternative transportation to such places and that encourages ride-sharing, carsharing, cycling, walking and transit.

3) We need to consider alternative surfaces for side streets and parking lots. The use of light-coloured interlocking pavers or compacted limestone screening would reduce the heat island effect.

4) We need to consider narrowing side streets that have ROWs greater than 7M, even if this means eliminating parking on one-side of the street. The reduced width, if replaced with a tree-lined boulevard would substantially reduce temperatures.

5) Flat roofs have to go green or cool, not just on new buildings, but existing ones, no more black.

6) Even shingles need to be re-thought, my instinct is that dark colours need to go unless there is a historical reason to preserved them.

*****

Finally, notwithstanding all of the above, I think its very important that we help people cope by increasing access to air conditioning.

In rental apartments that could mean compelling a landlord to provide at least one window unit to provide one livable room during a heat wave; or it might mean merely upgrading electrical, as I know many older apartments have only 60-amp electrical service which severely limits one's ability to install a/c even if you can afford it.

The above needs to apply to public housing as well.

We also need to adapt public swimming hours/season length to reflect the warmer weather were getting giving people a way to cool down; and complete air conditioning in public buildings, most notably schools.

Thoughts?
 

SunriseChampion

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2) We need to ultimately eliminate as much surface parking as possible, but in the interim, we need to create canopy over parking lots. This may mean removing up to 20% of parking spots in a large mall lot. A clear action plan is needed that addresses alternative transportation to such places and that encourages ride-sharing, carsharing, cycling, walking and transit.


5) Flat roofs have to go green or cool, not just on new buildings, but existing ones, no more black.

6) Even shingles need to be re-thought, my instinct is that dark colours need to go unless there is a historical reason to preserved them.

*****

Thoughts?
Oh yeah, do I ever. ;)

2. Surface parking is one of the biggest wastes of space that humanity has ever come up with, in my opinion. It's an egregious waste of land. Surface lots at retail centres should be completely replaced with either underground or stacked car parks, freeing up some land for more efficient development. I don't have any tattoos and have some ideas on some I might want to get and to be honest, "I hate surface parking lots" could be one of them.

5. It blows my mind when clients ask for dark membrane for flat roofs. Why the hell do you want to cook your house? There are amazing light-reflective finishes available but people still mostly choose dark ones. No idea why as most flat roofs are not visible except from in the air so aesthetic reasons don't make sense.

6. Sloped roof finishes are tough. The best ones absorb heat like mad (ie, copper, slate). The materials heat up so much that they burn skin through clothing! It's not a joke when I say that it gets to 60C on a roof in the summer. Some of the cheaper (and shorter-lasting) roofing materials also absorb heat like mad (ie, asphalt shingles) and these are widely used because of cost. A shingle roof is less than a quarter the price of a slate roof. Though, as with anything, you get what you pay for.
Cedar is good for light-reflection and non-absorption of heat but while being expensive does not last very long (~25 years or about the same as asphalt shingles) so it's not a very good option, though it is a great renewable resource. Clay tiles also absorb less heat than slate and metal roofs but not by much and are not functionally useful in our climate. Then there are recycled plastic and rubber materials that are pretty cost-efficient while having a decent life (~50 years) but their heat absorption is close to that of the natural stone and metal finishes.
The closest thing to an ideal solution, in my experience, might be zinc paneling. Pre-oxidised grey zinc is a bit cooler than some other metals and has a great life. Of course, you are not getting this put on the vast majority of middle and lower income houses because of cost and ain't nobody got time to offer discounts to people who can't afford it.
 

narduch

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With Ford in power now I doubt we make any moves on this front.

I think the Toronto Green Standard is in jeopardy
 

SunriseChampion

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Because in the next few years it will become very onerous on new construction in the city.

I could see Ford meddling in Toronto"s affairs due to that.
True. It does add costs to building which would be of interest to the government. Only they are allowed to add costs, apparently.
 

44 North

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Its a function of urban sprawl, too much pavement and too little shade.

Black surfaces, notably roads and parking lots, but many building roof systems as well, radiate heat after dark, after having absorbed sun during the day.
I already think transitioning to more concrete roads has its merits. Chalk-up surface reflectance and higher albedo as another reason. Lasts longer, doesn't warp, and reduces blistering heat pockets rising above roads/highways/parking lots like we have with asphalt. That's "global warming" right there. Literally, you can feel the +20C deg temp diff when walking across roads or parking lots. Thousands of micro-climate alterations add-up. It changes weather patterns for a large area. Ignore GHGs - changing the landscape and altering surface reflectance is huge.

Then there are recycled plastic and rubber materials that are pretty cost-efficient while having a decent life (~50 years) but their heat absorption is close to that of the natural stone and metal finishes.
The closest thing to an ideal solution, in my experience, might be zinc paneling. Pre-oxidised grey zinc is a bit cooler than some other metals and has a great life. Of course, you are not getting this put on the vast majority of middle and lower income houses because of cost and ain't nobody got time to offer discounts to people who can't afford it.
Wonder how wild or left-wing it would be to incentivize homeowners to use more reflective materials for their roofs. TO does have the greenroof thing, but we could expand on it within the GTA. Hmm, I don't like the sound of putting a thick wad of plastic over people's roofs, exposed to UV and dissolving into a toxic aerosol of micro and nanoplastics. Then again vinyl siding is already prevalent. Feel like a global push away from widespread plastic will occur sometime this century.
 

Johnny Au

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The heat island effect is so pronounced that Downtown Toronto is in a different climatic region from the rest of the city based on the Köppen climate classification system. Downtown Toronto is in Dfa, while the rest of the city (including the Toronto Islands) is in Dfb.

The main difference between the two is that Dfa has the daily mean temperature be 22°C or higher on the hottest month (i.e., July in Toronto's case), while Dfb has the daily mean temperature be lower than 22°C on the hottest month.
 

Northern Light

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I already think transitioning to more concrete roads has its merits. Chalk-up surface reflectance and higher albedo as another reason. Lasts longer, doesn't warp, and reduces blistering heat pockets rising above roads/highways/parking lots like we have with asphalt. That's "global warming" right there. Literally, you can feel the +20C deg temp diff when walking across roads or parking lots. Thousands of micro-climate alterations add-up. It changes weather patterns for a large area. Ignore GHGs - changing the landscape and altering surface reflectance is huge.



Wonder how wild or left-wing it would be to incentivize homeowners to use more reflective materials for their roofs. TO does have the greenroof thing, but we could expand on it within the GTA. Hmm, I don't like the sound of putting a thick wad of plastic over people's roofs, exposed to UV and dissolving into a toxic aerosol of micro and nanoplastics. Then again vinyl siding is already prevalent. Feel like a global push away from widespread plastic will occur sometime this century.
Let's start w/outlawing the worst options before we get to bribing people to do the right thing.

We can lower the cost of better products by growing those market segments by ditching some of the worst offenders.

***

I'm all for alternate road surfaces, but I think shading is also key. There are practicality problems w/that on a 16-lane highway, (putting the highway on a diet appeals to me here, but I'm not completely unrealistic), but as much as possible shade is a savior. It works on roof materials too. Shade the roof it gets a lot less hot.
 

Northern Light

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Hmmm, I just had a peek at the current forecast, nighttime lows, for Toronto, Caledon, Uxbridge, and Shelburne.

They also show night lows of 2, 3 or 4 degrees cooler than Toronto in their current 7-day models.

In terms of where Toronto is at, compared to historic norms, its about 4 degrees above the historical average at night.

If we could get that back, or even mostly back, I think that would be hugely beneficial.

Southern comparisons are iffy as the south is warmer be a degree or 2 to begin with.
 

TrickyRicky

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Northern Light, as someone who is a Landlord and also interested in architecture I think you have some good points but the problem is we are a four season climate and if we are looking at policy or building standards and practices it’s difficult to plan for peak performance all year round. For much of the year the heat island effect can be frankly advantageous from a building owner’s perspective.

If we keep getting hotter weather your suggestion about mandatory A/C in rental units has some merits and personally it’s crept up the list of considerations I make in retrofitting and renovating units. It’s very site and situation specific though with some units just really needing some electrical upgrades, new windows that you can actually open etc.

That said cold weather, snow and ice are still far more important in Toronto from a build performance perspective and the heat island helps not hurts.
 

someMidTowner

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Very cool video from a Youtube channel perfect for UT members. I hadn't heard about LA and Chicago's white roads pilot programs. Toronto's roof program gets a mention, of course.
 

Northern Light

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Very cool video from a Youtube channel perfect for UT members. I hadn't heard about LA and Chicago's white roads pilot programs. Toronto's roof program gets a mention, of course.
Excellent post!

I think it makes a good case for targeting some of Toronto's hottest areas with a combination approach.

White coating on roads, additional parks space, green roof(s), and green decks over sections of highway and/or surface parking.

If we could take an inordinately hot area of the City and reduce its daytime temp in summer heat by 1 degree, but its nighttime temp by 3, we would achieving something very substantial and beneficial.
 
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