Hot Roofs Above Bedrooms Cause Sleep Deprivation—Can You Solve the Cool Roof Puzzle?

By Will Driscoll

People who sleep in a top-floor bedroom under a black asphalt roof are likely to lose sleep on summer nights due to heat from the roof, with serious consequences.  Technically, the fix is simple—coat every black asphalt roof with a white coating—but progress toward that goal is slow.  Can you advise on how to make it happen, in the comments section below?

The issue: black asphalt roofs get really hot, keeping people from sleeping well, and causing real problems

Black asphalt roofs, which are common on Northeast urban row houses (townhouses), “can reach temperatures of 150°F or more in the summer sun,” reports the U.S. Department of Energy.  With or without air conditioning, a roof that hot above your bedroom will radiate heat at you all night long.

And people can’t sleep well when it’s too hot.  A research study using data reported by 765,000 people over 10 years found that “increases in nighttime temperatures amplify self-reported nights of insufficient sleep.”

Losing sleep is far worse than a nuisance.  “People make cognitive errors that matter when they sleep badly, whether crashing vehicles or making poor decisions in the workplace,” said UC Berkeley professor Solomon Hsiang in response to the study, as reported by Bloomberg.  He added, “Students learn poorly when they don’t sleep, and consistent lack of sleep harms people’s health.”

The technically easy solution:  white roof coating of asphalt roofs

Any roofing firm can apply an “elastomeric” white roof coating to a black asphalt roof, which can reduce a roof’s temperature on a 90-degree day from 150°F to 95°F.  (“Elastomeric” means the coating will stretch with the roof as it expands when it’s warm, and contract with the roof as it contracts when it’s cold.)  A homeowner who can safely get up on their own roof, with tools and supplies, can also do the job.  The cost is modest, since the job is relatively small: clean, patch, prime, and apply the finish coat.

But progress in getting black asphalt roofs coated white is slow.  For example in Philadelphia, where people have been talking for a decade about this issue, look closely at the Google Maps satellite view of the city and you will see mostly black roofs, while the roofs that aren’t black are generally gray—a color that provides only about half the cooling benefit of a white roof.

The puzzle:  How to persuade landlords and homeowners to apply white roof coating to black asphalt roofs?

This section offers some possible solutions to the white roof puzzle.  Please share your ideas in the comment section below.

Community group involvement:  People who have black asphalt roofs may not know that their roof gets as hot as 150°F in the summer, or that a simple white roof coating would fix the problem.  Community leaders could work with roofing companies to advertise the benefits of white roof coating—soliciting testimonials from those who already have a white roof—and its modest cost.  By aggregating the orders of a number of homeowners at a time, a community group could request bids from roofing companies and obtain a lower price for the work.  The challenge here is that community leaders are already busy pursuing other initiatives.

Residential “PACE” financing:  As states and cities gain experience with commercial PACE financing (i.e., “property-assessed clean energy” financing to fund energy-saving measures on commercial buildings), more states and cities are now adding residential PACE financing, to allow homeowners to borrow money for approved energy-saving expenses.  In a PACE program, a building owner’s loan repayments are billed via their property tax bill.  PACE financing could help homeowners who don’t have adequate savings to pay for white roof coating.  By making financing easier, it could also expand the market for white roof coating, and with a larger market, roofing companies might be more inclined to advertise the service.  The challenges are that some states have not yet enabled residential PACE financing, and in states that have done so, launching a city PACE program takes time and energy.

Leapfrogging to rooftop solar:  As the cost of rooftop solar installations decline, this solution becomes economical in more locations every year.  A rooftop solar system that effectively shade the roof, and does not radiate much heat to the roof, would effectively keep the roof cool.  In some locations the electricity cost savings provided by a solar panel system could pay for the system and its financing costs.  The challenge is the same as the basic challenge for white roof coating: how to persuade homeowners and landlords to take this step.

A new public health law:  Landlords who don’t pay their tenants’ air conditioning bills are under no pressure to apply a white roof coating to their properties and thus improve their tenants’ health.  Cities could institute a public health measure requiring white roof coating.  Then, if a landlord failed to comply, the city could coat the roof white and bill the landlord via the property tax bill.  (In my suburban town, letting your grass grow tall is considered a public health problem, and if you don’t cut your grass the city may cut it for you, and bill you for the work.)  The challenge is that to my knowledge no city has yet recognized hot roofs over bedrooms as a public health issue.

Other ideas:  What is missing here?  What are your ideas?  Please share them in the comments section below.