​Cool Roofs Are Heating Up

16 December

Have you heard of cool roofs? These specially designed roofs help protect a building’s occupants from the heat. Once considered a novelty, they’re starting to make waves by providing solutions to real urban challenges.

More than one city is looking at the relationship between the cool roof and the urban heat island, and how the former can help diminish the effects of the latter.

First, the problem. The EPA has a handy explainer on the urban heat island effect:

“The term ‘heat island’ describes built up areas that are hotter than nearby rural areas. The annual mean air temperature of a city with 1 million people or more can be 1.8–5.4°F (1–3°C) warmer than its surroundings. In the evening, the difference can be as high as 22°F (12°C).”

Why is this significant? Heat islands can have a great many deleterious effects.

First and foremost, they increase the energy consumption in an area. It gets unreasonably hot; people turn up their air conditioning as a response. Heat islands increase this reaction to the point that the demand for power can sometimes exceed the ability of a city’s power grid to provide.

The increased level of energy consumption leads to increased levels of emissions. In areas where air pollutants are byproducts of energy production, this can have adverse health outcomes for residents.

Furthermore, the overall comfort level and quality of life for inhabitants in these areas are diminished. They have to deal with unbearable heat, air pollution, and runoff that can decrease the quality of their water. Hardly an ideal situation.

The EPA is tackling the situation the best they can through their Heat Island Reduction Program (HIRP), but there is only so much they can do. They urge communities to become proactive in solving this problem.

Cool roofs have a higher degree of solar reflection. This means that they bounce light and heat away from the buildings they are installed on. The result is less heat transference to the buildings and a cooler overall environment.

There are many ways to create a cool roof. Manufacturers can apply a reflective paint to shingles, allowing them to reflect more light and heat. The could install a sheet covering over some roofs to achieve a similar effect. Creating roofs from specially painted metals can also create the desired cooling effect.

The particular methodology may vary slightly. They all operate on more-or-less the same principle, though. Less light and heat absorbed makes everything cooler. See where we’re going with this?

Cool roofs present themselves as a possible counter to the effect of heat islands. The reduction in temperatures leads to a nullification of all the negative effects associated with heat islands.

No increased power consumption. No buildup of pollutants. No runoff. No irate, uncomfortable residents.

Depending on the type of cool roof installed, the upfront costs may actually be no higher than an average roof. This makes them both short, and long term cost effective measures. It seems like a worthwhile strategy to implement, no?

Several locales reasoned along similar lines, and have encouraged residents to make use of cool roofs to fight the effects of their urban heat islands.

Louisville, Kentucky, is one such area. Taking a look at their Urban Heat Island Project page, you can see that they’ve had a significant problem. The effect has caused discrepancies as high as “10 degrees higher than in other parts of the city.”

They note all the expected problems the increase in temperatures would cause, and suggest that residents install heat roofs as part of the solution:

“Property owners can install cool roofs that reflect heat. Commercial and industrial buildings typically have black or dark roofs. But businesses can instead have white or light roofs, which reflect heat, installed the next time their structure needs a new roof. Meanwhile, Louisville homeowners can help by using shingles of lighter colors the next time roofing is needed.”

Los Angeles undertook more drastic measures. In 2013, they mandated cool roofs for homes in the city. The ordinance is now in full swing. Even articles critical of what they see as poor planning and government overreach admit that cool roofs do have an effect on temperatures in Urban Heat Islands.

The previous examples were just two early instances in which cool roofs took center stage. Now, in 2016, the trend seems to be heading into full swing. Article after article are singing the praises of cool roofs, and detailing how the demand is heating up.

Take this piece from The Cooperator. It talks about New York City’s cool roof initiative. Note that while the original plan was to cover 1 million square feet of rooftop, the project has now covered 6 million square feet.

Here’s another article from Construction Drive, titled, Reducing Peak Energy Demand: A Hidden Benefit Of Cool Roofs. It states that:

“Few heat reduction strategies can match the energy-savings potential of modern cool roofing technology.”

The article expounds on the benefits, noting that:

“An analysis of the effect of cool or highly reflective roofs in reducing peak demand charges suggests that peak demand charges may account for a significant portion of monthly electric bills across the United States and that cool roofs may provide an equally significant opportunity to reduce these charges when installed on air-conditioned buildings.”

Talk about saving energy. The idea is even taking hold in other countries. An Australian outlet ran this article, which details the satellite data showing the apparent effectiveness of cool roofs. Near the end, they mention that:

“Further investigations in Sydney, Melbourne, Adelaide and Perth with measurements through satellites techniques will help to develop a better understanding of the urban climate situation under different climate conditions for several roof colours.”

Conclusion

It seems that cool roofs are having precisely the effect they were intended to have. Communities across the world are using them more and more to combat the effects of heat islands, and the trend is showing no signs of slowing.

Perhaps this will spur the implementation of other smart building design features that can increase energy efficiency and overall functionality.

To learn more about the scourge of heat islands, make sure you check out the EPA’s Compendium here.

If you want to learn more about sustainable and green building design, make sure you take a look at the U.S. Green Building Council and their wealth of data on the topic.