Cool Roofs: A Solution for Urban Heat Islands

Cool Roofs: A Solution for Urban Heat Islands

Eliana Linder

Climate change has been one of the biggest global issues for years and even with numerous climate change summits and attempts to reverse the effects of global warming we are barely making a difference. A big factor of climate change is urban heat islands which are when cities have a higher temperature than surrounding areas due to heat getting absorbed from urban surfaces such as roofs. During the daytime urban areas can reach 1-7℃ higher than outlying areas according to The United States Environmental Protection Associations, although this may not seem like a big difference with the number of urban areas increasing, the number of urban heat islands is also increasing.

Fortunately, there are solutions to battling these urban heat bubbles such as cool roofs. Cool roofs are a specific type of roof that has a very high reflectivity and will reflect the heat back into space instead of absorbing the heat. There are multiple different types of cool roofs and each of them has pros and cons; white reflective paint, green roofs, and solar tiles. Green roofs are a viable solution although it implies a lot of work and doesn’t reflect as much heat as others. Solar roofs, although turning sunlight into energy, can be very expensive and are harder to manage and control. 

This leaves one solution left: white reflective roofs. These roofs have a higher albedo than other types of roofs which allows them to reflect the most amount of sunlight. Generally, these paints are made from titanium dioxide which reflects certain types of wavelengths. These are affordable and easy to install no matter what type of roof that you have currently. 

There are lots of cooling paints that are on the market but recently Purdue University developed the whitest paint yet. This paint reflects 98.1% of sun rays compared to commercial paints which generally reflect about 80% of the sunlight. After much testing, it was decided that barium sulfate was the most effective material at reflecting the sunlight. Not only did they use barium sulfate but they used a high concentration and different sized particles in the paint. 

It is said that this paint could be revolutionary because it could replace air conditioning. If the house is only absorbing 1.9% of the sunlight it will make the house significantly cooler. One of the lead researchers at the university, Ruan says it can, “potentially cut up to 80 percent of conditioning costs.” This is not only environmentally beneficial because it uses less energy day to day but also economically beneficial because it lowers your electricity bill astronomically especially over the summer.

This paint is very versatile and can go on “building roofs, food storage units, warehouses, data centers, outdoor equipment, automobiles, etc.,” according to Xiagyu Lu, another researcher at Purdue University. Many tests have been performed and when the paint was put in a temperature of 43 degrees Fahrenheit while the sample was only 18 degrees Fahrenheit. This could be truly revolutionary if it is applied correctly, potentially eliminating the need for air conditioning entirely in all buildings. The one problem, it isn’t available to the public yet. Ruan says, “We are currently partnering with a large corporation towards commercializing the paint, and hopefully it will hit the market in a couple of years.” Although this is not an ideal situation once it becomes available to the public many are encouraged to use this paint on any type of roof that they have.

Ideally, it will revolutionize the cooling industry and if used properly could eliminate the need for air conditioning completely! Changing to a type of white reflective paint on the market currently is also beneficial economically and environmentally. Your local Home Depot or even Lowe’s will have a type of reflective paint and although it isn’t the whitest paint it can still make a huge impact. Make sure to look out for the release of the whitest paint in the next couple of years! I urge you to look at different options for your room and what would be the most beneficial for the specific climate and type of roof but no matter what there is definitely a cool roof out there for you.