– [Narrator] 2017 was thethird hottest year on record.
And based on recent trends, it’s not getting cooler any time soon.
Some researchers are asking,how can we stay cool?
Especially in our cities.
They’re typically hotter than rural areas.
You can thank the urbanheat island effect.
暑天 屋顶 建筑
On hot summer days, roofs, buildings
and other urban surfaces can heat up to 90 degrees hotter than the air.
This creates islands of heat.
One of the biggest contributors to those islands, dark surfaces.
Dark surfaces absorball wavelengths of light
and converts them to heat.
So the surface gets warm.
It’s why your mom told you not to wear black during a heatwave.
Surface temperatures canreach up to 150 degrees.
And since asphalt is an insulator,
it traps that heat overthe course of the day.
Then at night when the air is cooler,
the heat radiates away.
Lighter surfaces, on the other hand,
absorb fewer wavelengths and reflect the rest.
That way, all that energy isn’t absorbed.
And surface temperatureswon’t rise as much. So,
would coating our streets white
help cool dowm our cities?
Enter Jeff Luzar, he’s theVice President of Sales for GuardTop,
a pavementcompany looking to cool off LA.
Coat the streets white.
We’re seeing temperature difference right now of about,
anywhere from about nine to 10 degrees, but again,
the temperatures are prettycool outside right now.
When it’s hotter though,
Jeff says the pavement could be up to 30 degrees cooler with the white coat.
Some of the pilot programsthat we’ve done last year
with the Bureau of Streetsand Services LA City,
I know they are, as well as we are,
taking a look at the surfaces, making sure they’re
holding up, making sure they’re still doing
what we said they were gonna do.
And they are.
And some of the neighbors are saying
they do feel a littledifference and this and that.
If we can lower the temperaturesby the ambient temperature
outside by degree or two, it means a lot.
That may not seem
like a lot but a report by the Environmental Protection Agency
suggests that a one and half degree change
could make a huge difference.
Los Angeles could save over $100 million per year in energy savings and smog reductions.
But what is the coating made of?
Most other pavements use coal tar.
Some studies have been doneand that where it’s showing
that it could have somecarcinogenic effects.
But GuardTop says that its coating is made
from recycled materials that don’t have carcinogenic additives.
Of course LA isn’t the onlywarm city in the world.
Other US cities arealso considering coating
their streets like Las Vegas.
But officials thereworry that it won’t stick
due to an oily road mix it uses to combat dry climate.
And in New York City,volunteers have painted
seven million squarefeet of rooftops white,
but that’s only 1% ofthe potential roof area.
It’s clear that there’s still a lot of work to be done.
I was never a big climate climate guy until we started getting
into this product but when you see what differences one degree can make
in climate change, it makesquite a bit of difference.