Spend a summer day in Phoenix, Arizona and you might want to put on your highest grade sunblock…
Unrelenting heat bears down on Phoenix as the temperature shoots towards a record breaking 120.
These are the kind of temperatures that are detrimental to your health.
Phoenix hit 110F today for the second straight day. And there’s more where that came from.
…or perhaps just stay indoors.
Phoenix is America’s hottest city right now and not in a good way. In 2020,
it hit 43C degrees on 53 days . That’s 20 more days than the year before. Now it’s
a desert. So things are always going to be warm.But Phoenix is particularly prone to
overheating thanks all of its concrete, asphalt and car parks.
These temperatures aren't merely uncomfortable. They can be deadly.
Nearly 200 people died from extreme heat in Phoenix in 2020- a 60% increase from
2019. And climatologists fear this trend will only get worse.
The government of Phoenix wants to be
cool and is doing something few cities has done before – using
innovative construction materials and urban design to cut the heat.
Phoenix has always been scorching. Thanks to its latitude, high temperature,
and low elevation - it's a bit of a target for hot weather.
But the location isn’t the only factor contributing to the heat.
Over the past decade, the city’s population has been rapidly growing - in fact it’s one of the
fastest in the US. Today, nearly 1.7M people live in Phoenix - a 16% increase since the last census.
This growth has created a phenomenon known as the urban heat island effect.
That’s where a metropolitan area gets much hotter than its surrounding typically rural areas.
More people means more construction for things like buildings, car parks, and roads - and less
room for greenery which can be key for shade and lower temps as it typically reflects heat.
Some of the artificial surfaces found in
cities - like concrete - tend to retain more heat from the sun.
And unlike open spaces where hot air can be widely dispersed densely
packed buildings typically disrupt airflow and can make it hotter.
It might not surprise you to learn that nearly 100% of Phoenix residents
use AirCon. But while that keeps people cool indoors, it also transfers heat back outside.
As if you weren’t already getting hot under the collar, these heat waves are also very expensive.
According to a study, the people of Phoenix spend around $7.3M in heat related hospital
visits every year. government agencies spend upwards of $100M maintaining roadways that
crumble in extreme temperatures. Now That particularly impacts low
income neighbourhoods. People here have less access to resources to cool down.
Half of the deaths in 2020 occured outdoors where people may not have
had access to shelter. As for the deaths indoors,
faulty AirCon was typically the culprit. Some people may not have been able afford the fix.
With rising deaths and temperatures, in 2021, Phoenix created the Office of Heat Response
and Mitigation with a goal of reducing these numbers.These guys are seriously cool and their
team is led by head cool dude Dr. David Hondula - a former professor at Arizona State University.
To our knowledge, it's the first publicly funded office sitting in local government
structures in at least the United States, maybe North America, maybe the world. Of course it’s
really hard to know whats happening in every community across the world.
In 2022, Hondula’s team submitted a response to the city with a
range of ideas to work with other departments to meet their goals.
First and foremost we divide our thinking into
two to broad categories. heat response activities, or those we describe as short term strategies
that help keep people safe and comfortable when it is hot. And here we're talking more in the
emergency management realm strategies like cooling centres, public warning messages, communication,
certain laws and protections about heat safety.…And then the other half of our thinking
is heat mitigation and longer term strategies to cool the city and increase quality of life.
One of these strategies is to plant more trees. But because Phoenix is
in the middle of a desert - only certain drought-resistant species can survive.
In 2010, Phoenix set out to plant a tree canopy that would cover 25% of the city by 2030.
But as of now, the city is not on track to meet this goal by 2030 and
the plan has yet to be revised. There are other challenges in maintaining trees
in the urban environment. A number of our trees will get uprooted by storms every year. They'll
get hit by vehicles in the streetscape. There certainly is occasional vandalism that happens.
Branching out, other cooling solutions technologies, Phoenix has been testing is cooling
pavement. This is a layer of grey-coloured paint sprayed on top of asphalt with a product called
CoolSeal. It’s a water-based asphalt emulsion. darker colour pavement absorbs heat from the
sun and then releases it at night, leading to higher temperatures and more energy consumption.
The grey pavement instead reflects sunlight and Phoenix hopes this can help ease temperatures.
We got a cool pavement product inside the machine. And at the back of the machine,
we actually have spray nozzles - so it provides an even thorough application on the pavement of
the cool pavement material. Cooling pavement is currently
being tested in a few select neighbourhoods and the results are looking promising. Surface
temperatures on cooling pavement are consistently 5° to 6°C cooler than traditional asphalt.
The surrounding neighbourhoods as a whole experienced a drop in temperature by a
fraction of a degree throughout the day as well. And the benefits didn’t end there.
there will be less thermal strain on the asphalt itself, which should increase the longevity,
which would mean we can lengthen the repaving cycle for streets that have the cool pavement,
and that is absolutely money saving. Now this all pretty cool , the department
doesn’t expect this technology to be the definitive solution and a few more
options are still on their very cool office table. We believe they'll be rolling out an incentive
program for cool roofs on residential properties in the near future. Cool roofs. Same idea as cool
pavement…And then, yes, attention to a zoning ordinance, redevelopment cases. Redevelopment
is really one of the few opportunities the city has to shape what our city looks like,
what's on the ground? How tall is it? What colour is it? How much vegetation is there?
Changes to any building codes or architecture will take time. And feeling the impact of any
positive effects from that might take even longer. All of what we're talking about could be perceived
as unattractive to the development community if we are not presenting a comprehensive narrative
and explaining from our perspective why we think these are good, good investments to
make and why they can be beneficial not only to residents, but also to true developers.
Progress is set to be measured in statistics like death and illness numbers and calls to emergency
services. But it may take a few years to truly understand what the key performance measures are.
Urbanisation is a factor driving this regional climate change. as
our shifting environment begins to brings stronger storms, wildfires,
and droughts across the world, cities far beyond Phoenix will have to act.
The city’s action today could serve as useful learning for others tomorrow. And
proof that global change often has to start at local level.
Stay cool guys and If you enjoyed this video make sure you’re subscribed to Tomorrow’s Build.