Heat is a multi-billion dollar challenge for the world’s cities. By 2100, urban heat and local climate change will cost the average city 5.6% of their economic output.

Urban heat, if left unchecked, will increase the cost of climate change for cities by 260% by 2100.  One study of 1,700 cities found that local climate change and urban heat will cost the median city approximately 5.6% of their GDP — a price tag measured in hundreds of billions or even trillions of dollars globally.  This is a nearly 6% tax on citizens for which they will get nothing in return.  For the hardest hit cities, the climate change will cost nearly 11% of their GDP — that is, $1 out of every $10 generated by the city will be lost to the effects of urban heat and climate change.  Higher urban temperatures create a number of problems for city economies including the cost of more energy for cooling, the health costs of polluted air, poor water quality and workers who are less productive.

Cool roofs, even at moderate levels of deployment can deliver energy savings, peak electricity demand reductions, improvements to health and air quality and other benefits accruing from city-scale cool roof installations that are worth billions of dollars to local economies.

The study in the Journal Nature Climate Change cited above also found that changing only 20% of a city’s roofs and half of its pavements to ‘cool’ forms could save up to 12 times what they cost to install and maintain, and reduce air temperatures by about 1.5°F (0.8°C). For the average city, such an outcome would generate over a $1 billion in net economic benefits and is a very realistic target if existing urban heat island mitigation policy best practices are adopted.

Another cost benefit analysis of urban heat island mitigation strategies in Washington finds similar results. At a cost of $0.76 per square foot ($8.26 per square meter), a cool roof delivers over $5 a square foot ($54 per square meter) in net benefits. Many of these benefits, like health cost reductions, are not directly accruing to the person buying the roof. Good policy is needed to shift some of the societal benefits to the decision maker and/or to require cool roofs.

For building owners, an investment in cool roofs typically pays back in 2–5 years, with some roofs paying for themselves immediately.

The installed costs of a roof can vary depending on several factors, including its type, size, complexity, method of attachment, and building location.

1. If the roof needs to be replaced anyway

In cases where new roof surfaces need to be installed, cool roof options are usually similar in cost or slightly more expensive than similar non-cool alternatives. Slightly higher upfront costs occur mostly in colored roofs that require specialty reflective pigments. But the labor required to install or coat cool roofs is about the same as for non-cool roofs.

2. For a roof that is in good condition

Converting a roof that is in good condition into a cool roof has a higher incremental cost than if the roof needs to be replaced anyway. For instance, if you want to coat your new dark roof just to make it a cool roof, the additional cost can be significant. The cost of coating a roof cool depends on the existing roof’s surface. Rough surfaced roofs, like those covered in granules, have more surface area, and require slightly more coating material to achieve the desired thickness.

Typical, approximate installed roof cost premiums for different cool roof options are given in the tables on the following pages. The premiums equal the additional cost you can expect to pay for a cool product. For example, if you are planning to install a mineral-surfaced modified bitumen roof, the table indicates you might expect to pay $0.50 per square foot ($5.43 per square meter) more for a cool roof with the same kind of surface. Since costs vary widely by location, check with your roofing contractor or estimator for more accurate cost comparisons.

Some cities are successfully using cool roof installation programs to prepare their citizens for good, green jobs.

Cool roofs, particularly cool coatings, have been used by cities like New York City, Philadelphia, and Baltimore as an opportunity to provide job readiness and skill training services to populations that may be struggling to find steady work.  New York’s program is graduating about 70 workers a year and many are finding and keeping employment.

This is not just an American phenomenon.  In South Africa, using cool coatings to cool informal dwellings and structures has created new business and employment opportunities across the entire supply chain from manufacturing, mixing and application, sales, and maintenance.  This has been a boon to both rural and urban economies that have long struggled to produce steady economic opportunities.