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Cooling Down the Metro Mayors Region: the Basics & Benefits of Cool Roofs

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Cooling Down the Metro Mayors Region: the Basics & Benefits of Cool Roofs

Written by Colleen Shortell, Clean Energy and Climate Planning Intern, and Julia Nassar, Clean Energy and Climate Planner II

Pictured: Cool roofs at the Annie E. Fales Elementary School in Westborough, MA. Source: HMFH Architects

June 21, 2024 - As the Metro Boston region experiences longer and hotter summers due to climate change, there is increasing interest in using rooftops and other surfaces to combat the Urban Heat Island effect.

Extreme heat not only poses serious risks to our health and well-being, but also places pressure on our energy systems, infrastructure, and economic productivity. Neighborhoods covered by dark-colored surfaces absorb and retain more heat than light-colored or reflective surfaces. Cool roofs are a “low-hanging fruit” strategy to lower building temperatures and reduce energy consumption during summer months.

 

The Basics

Cool roofs, also known as white roofs or reflective roofs, are roofs designed to reflect more sunlight than conventional roofs. By reflecting more sunlight, cool roofs absorb less heat and keep buildings and surrounding areas cooler and energy costs lower.

A drawing that shows two roofs - one dark that reflects 20% of sunlight and one lighter that reflects 80% of sunlight.

Cool Roof Types & Materials

Cool roofs are versatile and available in various colors and types to suit most buildings. They can be applied as reflective paint (coating) or installed as specialized roofing materials (covering).

  • Cool Roof Coating: A reflective coating or paint is applied over an existing structure. Cool roof coatings are easy to apply (e.g., acrylic coating can be done with a brush, roller, or spray), versatile, and relatively inexpensive, but may require more maintenance.
  • Cool Roof Covering: Coverings are specially designed and typically installed as a replacement for an existing roof. Cool roof coatings are more labor-intensive, require more expensive materials, and professional installation but tend to be more durable than coatings.

Source: Monica Kelly, Natural Resources Committee

While cool roofs are typically white or light-colored to reflect maximum sunlight, they do not have to be white. Cool roofs come in a variety of colors and materials (e.g., energy star rated reflective shingles) that can fit your aesthetic preferences.

Though demand is growing, the market for cool roof vendors and materials is still nascent in the Metro Boston region, especially for residential customers. Ask your roofer if they have experience applying a cool roof coating or installing a cool roof covering.

For more information on cool roofs, visit our Cool Roofs FAQs page: mapc.ma/cool-roofs

Cool Roof Suitability

Buildings with the following characteristics typically see the greatest benefits from cool roof installation:

  • Dark colored roofs that absorb more heat
  • Roofs in direct sunlight
  • Flat or low-sloped roofs that are ideal surfaces for cool roof coatings
  • Buildings that do not have air conditioning or are poorly insulated
  • Buildings with high cooling demand

These characteristics increase indoor temperatures, cooling costs, and energy inefficiency. Explore the Cool Roof Suitability Tool (beta) and Self-Assessment to assess if a cool roof is feasible and beneficial for your building. While the mapping tool is only available for buildings in the Metro Mayors region1, the Self-Assessment is available for any building.

The Benefits

Cool roofs can provide economic, environmental, and health benefits for residents, property owners, and the broader community:

Economic

 
  • Reduces energy costs by reflecting sunlight and limiting AC use, leading to savings on electricity bills.
  • Extends roof lifespan by reducing thermal stress and degradation, limiting needs for replacement.
  • Preserves rooftop equipment such as solar or HVAC by lowering temperatures and thermal stress.
Environmental

 
  • Lowers carbon emissions by reducing cooling demand on fossil fuel services.
  • Promotes cooler, cleaner neighborhoods by reducing overall temperatures, which improves air quality and reduces the formation of pollutants.
Health and Well-being

 
  • Increases comfort with cooler indoor temperatures, creating a more productive environment for dwellers.
  • Reduces heat-related illness like heat rash, stroke, and exhaustion. Cooler temperatures and improved air quality reduce respiratory illnesses, like asthma.

 

As a relatively low-cost and accessible energy efficiency measure, cool roofs can play an important role in the just energy transition. The benefits of cool roofs are even more significant in environmental justice neighborhoods, which typically have less tree canopy and households that spend a larger portion of their income on energy bills.

For more information on the basics and benefits of cool roofs, check out the MAPC Cool Roofs webpage (mapc.ma/cool-roofs) and watch our webinar (Webinar: The Basics and Benefits of Cool Roofs (youtube.com).

1Arlington, Boston, Braintree, Brookline, Cambridge, Chelsea, Everett, Malden, Medford, Melrose, Newton, Quincy, Revere, Somerville, Watertown, and Winthrop.