CityLinks Featured Innovator: White Roof Project

ARTICLE | Apr 6, 2016

Thanks to what can only be described as a fortuitous misquote from Bill Clinton one evening on The Daily Show, founder Juan Carlos and his collaborators at White Roof Project were able to harness the power of an idea and turn it into a global movement. The idea is simple, and the payoff is huge. Paint roofs white, and watch urban temperatures drop.

Through advocacy, organizing volunteers, and consulting, White Roof Project gets black tar rooftops in urban centers painted white and promotes this type of sustainable market around the world. It is one of the only non-profits out there today that has been able to effectively create a volunteer ecosystem to accomplish this.

In 2010, an Earth Day event inspired Carlos and some friends to paint a New York City rooftop white. To raise funds, Carlos created a website and dubbed their endeavor a white roof project. Coincidentally, President Clinton had just released his mandate for collectively affecting climate change and it included painting black tar roofs white across the nation. He was working closely with Al Gore at the time who was working with the New York City government Cool Roofs initiative.

Clinton appeared on The Daily Show to advocate for his cause. Carlos speculates that Clinton mistook his project for the city’s efforts, because during his appearance on the show, Clinton proceeded to name drop “White Roof Project” rather than “Cool Roofs Project” a number of times.

Thanks to this, White Roof Project received a lot of attention. When the time came to paint the first rooftop, 150 volunteers showed up and sparked a movement. What started as a white roof project became the White Roof Project. Since then, they’ve painted over 496,000 square feet of rooftops, organized over 1,150 volunteers, and have amassed 175 community partners across 22 cities.

So how does it work? If you don’t have the time to visit the Project’s Do It Yourself page, here are the basics.


Volunteers painting a roof white.

You’ll need:  two warm days of sunshine, a can of spray paint to grid off 100 sq. feet sections, two buckets of paint for each section, and a group of willing people to lay down two coats.

What does this achieve? In many cases on a summer day when it’s 90 degrees outside, the surface of a black tar roof will double in temperature to 180 degrees, turning the building into a 125 degree oven. If that same building were to have a white rooftop, the surface temperature will only be 10 degrees hotter than the outside air and the interior of that building will actually be about 10 degrees cooler than the outside air. “So, on a 90 degree day you walk into your home, it’s going to be about 80 degrees.  And then to cool that down to say 72, is much quicker, much more energy efficient, and you don’t have to cool for as long at as high of a setting,” said Carlos.

The obvious benefit from painting rooftops white is that it saves electricity – and the amount in savings is staggering. On a micro-level, one individual can save 15% to 30% on electricity costs. At the city level, it has been “forecasted [in 11 metropolitan cities] that the energy savings from implementing a large size program of this sort, where you’re able to paint all of these black tar rooftops white, we would have 7 GW of savings, which equals the same amount as 14 power plants, which is $750,000,000 saved off the grid,” said Carlos.

The more square footage covered, the stronger the effect. The center of a contiguous group of white roofs will see a greater temperature reduction than those on the outskirts. This essentially converts an urban heat island into a cooling island by creating a reflective surface across the entire city.

“We put up temperature monitors and receive that data over time. We’re able to analyze the difference that a white roof has made vs that black tar roof that we covered up. It’s one of the other pieces of value that we share with our stakeholders and specifically with those folks that live in that home, that residential building, or that commercial building. It helps them understand what it means to have a white roof. Because one of the really great things, as you may or may not know, is that a white roof project is low cost, is energy efficient, and overtime you save money while curbing climate change as a result of just painting this dark surface a light color,”  said Carlos.

White roofs also help reduce smog. “Heat trapping raises ambient air temperatures and causes additional smog to become stuck in our cities. This lowers air quality and causes the summer smog domes that can be observed around American metropolises. White rooftops can help alleviate some of that heat trapping, and if implemented on a large scale could lower air temperatures and reduce smog in our cities. A black rooftop keeps smog in and makes it harder for us all to breathe,” said Carlos.


EPA, 2008


In addition to smog, city summers come with much hotter rainwater. “That's because black rooftops are really hot, and when rain hits them they get cooled down. What do you think absorbs that heat? The rainwater that is going straight down into sewers and directly back into our waterways. In fact a black rooftop can actually make storm water up to 30 degrees Fahrenheit hotter! A temperature reading of a river on the surface of the water shows that it can be up to 8 degrees Fahrenheit warmer right after a storm. Heating up our waters is bad and destructive,” said Carlos. White roofs minimize the amount of heat rainwater absorbs.

Today, White Roof Project functions in a number of different ways. They help companies host corporate events, where employees can spend a day or two volunteering their time to give back to the community. They have a history of partnering with city governments and community groups to mobilize large numbers of volunteers.

It’s important to note that there has never been a lack of interest from volunteers. The willingness of people to get behind this mission speaks to its simplicity and efficacy. There are few things you can do which have such immediate results with so little effort. It makes it a satisfying experience and it begs the question: Why isn’t this happening everywhere?

“There is a vision for the earth in 2035. We know that two thirds of that population will live in urban settings.  If we were to paint 5% of the rooftops white in the US every year for 20 years, by 2035 we’d be done.  What would that save us?  The total savings in CO2 emissions offsets would be 24 billion metric tons. That is the exact same amount of CO2 that was emitted in 2010. So essentially, if we are successful in our mission, which needs to be cumulative, needs to be all of us working together, it would be like turning off the world for one entire year. Or, at least like turning off the United States for one entire year.” 

If you’re interested in implementing a white roof project in your city, company founder Juan Carlos, has graciously provided his email here and together with the Global Cool Cities Alliance will help you to get up and running. Or you can check out the Do It Yourself instructions available to help individuals or groups manage their own projects. You can learn more about White Roof Project from its website.


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