July 14, 2021

Heat Wave in Metro Vancouver: How Do We Cool Hot Cities?

 

Metro Vancouver went through a deathly hot heat event at the end of June  in this area that is usually temperate in the summer. While there are estimated to be about 34 percent of homes in British Columbia that have air conditioning according to B.C. Hydro,  that has not been something that is standard in Metro Vancouver with its moderate oceanic climate.

But the need and demand for cooling dramatically changed at the end of June 2021.

The heat wave was supposedly a one in one thousand year event that would have been a one in 150,000 year event if it was not for global warming according to the Environmental Change Institute of Oxford University in this article by Ryan Flanagan of CTV News.

The truth is that no one saw these high temperatures coming and staying, and researchers that model climate and weather are suggesting that an increase of 2 degrees celsius in global warming will mean that “extreme heat” will be in Metro Vancouver every five years.

Seattle has already seen an increase in 90 degree fahrenheit (32 degree celsius) days. Between 1971 and 2000 there were on average three 90 degree days a summer. Between 2015 and 2018, there were an average of ten 90 degree days a summer.

In the 2015 census, 33 percent of Seattle homes were air conditioned. In 2019 that number had risen to 44 percent of homes that were air conditioned. I could not find any statistics on Metro Vancouver homes that are air conditioned, but with Vancouver’s more moderate climate the numbers would be much lower.

During the heat wave many people that were in glass towers went to stay elsewhere to avoid the heat.  Many people passed away in the province during the heat wave, 719 people, triple that which would be normally expected.

What can cities do?

Cities that already experience extreme heat provide some answers.

There are two main ways to approach this:  by planting trees,  and by covering surfaces with non absorbent materials.

Cities are often ten  degrees celsius hotter than surrounding areas because of the urban “heat island” effect. There is also an  increase in mortality and strokes when the temperature is above 25 celsius.

In 2007  there was a tragic event in Chicago where an annual running  marathon was conducted when temperatures soared above 26 degrees celsius. One person died and 185 people were hospitalized. As a result of that race organizers planted myriads of trees along the running route to counter the urban heat sinks and to mitigate high temperatures.

The Nature Conservancy notes that trees can cool down city streets by as much as two degrees celsius on the hottest days. That does not sound like much but each degree increase in temperature leads to a  a three  percent or more increase in mortality.

In Sydney Australia adding water features and cool coatings on roads and sidewalk reduces air temperature by 1.5 degrees celsius. Asphalt paving creates a heat sink, absorbing 95 percent of the sun’s exposure. Painting white coloured sealant on paving can reduce road temperatures by 23 degrees fahrenheit according to NASA in New York City applications.

The same cool coatings can be applied to facades and roofs to reflect solar energy away instead of absorbing it.

Singapore has a Landscaping for Urban Spaces and High rises policy called LUSH which insures plantable and planted balconies, rooftop gardens and green walls which can reduce temperatures by up to three degrees celsius. This same impact in reducing temperature was done in Seoul Korea with the daylighting of the Cheongyyecheon Stream through the centre of the city, which provides a flood valve, a walkable urban space, and reduces day time temperatures by three degrees celsius.

Some things, like large canopies at street level on commercial streets provide shelter in the winter and cooler sidewalks in summer heat.  Bus shelter roofs can be redesigned to provide more shade. Chongqing China on the Yangtze river delta has water misters at bus stops with water chilled to cool the air and passengers.

Community Centres and libraries  can be cooling centres, and ubiquitous public washrooms and water bottle stations  can allow people to be on the street, comfortable and hydrated. Vancouver was one of many municipalities that quickly established misting stations and a list of cooling stations.

We already have some existing networks to set up a system to check on the vulnerable and the elderly through Canada post, newspaper deliveries, and libraries. I have already written about the City of Toronto library that contacted pandemic isolated seniors to find out how they were doing and to see whether the library could co-ordinate any services for them.

This is by no means a complete list, and you can add to it in the comments. Even today heat waves in the United States kill more people than natural disasters, and the United Kingdom is estimating a 257 percent in heat related deaths by 2050.

This is about creating cities that are canopied and cooler, and using surface coating that reflect and not absorb heat. It is also about co-ordinating services that can reach out to isolated seniors and others that can be offered alternatives to remaining home in overheated environs. Two videos below show the cooling impact of Seoul’s Cheonggyecheon Stream, and some suggestions to cool cities.

And once again, the simple tree which exhales 6,000 pounds of oxygen over a lifetime, improves air quality and lowers temperatures on the hottest days needs to be centred and championed. We should be embracing planting more trees on every  city streets and in parks and spaces.

Our future depends on it.

 

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Comments

  1. What I find astonishing is that many of these new ‘green’ buildings don’t come with blackout blinds, so they let all the heat in, magnified by the glass. So, you either have to replace them at about $600 per blind or invest in an air conditioner or other cooling method.

  2. Traditionally hot cities have generally developed a “shade culture” over time. Vancouver doesn’t have a shade culture because the number of days per year that people have looked for shade here is low. Vancouver has barely developed a “shelter culture” for rain even though it seems to rain for months at a time. One option for shopping streets would be for the City to have a standard modular shelter that can be erected over seating areas reclaimed from parking spaces for restaurants. These could be for both shade and rain and cantilever both out over the seating area and back over the sidewalk. I’m envisioning a restaurant leasing the shelter and the parking space for some nominal amount. The tops of the shelters could be a light colour to reflect the sun.

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