Cool Roofs in Underserved Neighbourhoods in Boston

Prepared by Kim Perrotta

Opportunity Knocks 

In 2022, the City of Boston implemented a Cool Roofs Pilot Project to cool underserved neighbourhoods that experience higher temperatures in the summer months.

“The Cool Roofs Pilot Project was somewhat experimental,” offered Zoe Davis, Senior Climate Resilience Project Manager, with the Office of Climate Resilience at the City of Boston. “It was a huge period of opportunity.  We had just completed Boston’s Heat Plan.  Mayor Wu had recently taken office and was eager to address climate change and inequities in the city.  Additionally, there were many funding opportunities for climate-related projects through the Inflation Reduction Act (IRA) and American Rescue Plan Act (ARPA) provided by the federal administration.”  

“The City had 250 gallons of reflective paint left over from another project and the Heat Plan identified cool roofs as an action that could reduce temperatures in some of our underserved neighbourhoods so we moved forward with a cool roofs pilot project,” said Davis.

Boston’s Equity-Based Heat Plan

In 2022, Boston had just completed a comprehensive Heat Plan,Heat Resilience Solutions for Boston, that included geospatial analyses, community engagement, the identification of a broad range of strategies, and simulation modelling. 

The Heat Plan was designed as an equity-centered framework that would reduce the risks and effects of extreme heat, with particular attention to populations in the city that “can experience greater extreme heat exposure and risk, including communities of color, immigrant communities, communities where English is spoken as a second language, older adults, individuals with chronic health conditions, and youth.”  While it will apply to the whole city, it aims to prioritize overburdened neighbourhoods that are disproportionately impacted by extreme heat. 

The Heat Plan was also developed around the premise that “a better, more resilient Boston can create cooler communities and also support broader benefits for justice, equity, and basic improvements to everyday life.” 

Identifying Priority Neighbourhoods 

Heat data was combined with socio-economic data from several sources for 2015-2019 to identify critical hot spots across Boston where high temperatures coincide with historic disinvestment and “environmental justice communities with minority, low- to no-income, and English-isolation characteristics.”  Five neighbourhoods or “focus areas”were prioritized for action with this process – Chinatown, Dorchester, East Boston, Mattapan and Roxbury.  

With Chinatown, for example, which is the hottest of the five prioritized neighbourhoods, the city-wide heat analysis found that day-time and night-time median temperatures (40.6°C and 31.1°C respectively) are 14.4°C hotter than the city’s median day-time and night-time temperatures (37.5°C and 27.7°C respectively).

The urban form analysis found that Chinatown has less green space, wider streets with fewer street trees, and higher population and building densities than other neighbourhoods in Boston.  Tree canopy and parkland make up only 8% and 3% respectively of the land cover in Chinatown compared with 27% and 23% respectively for the city as a whole.  This is a significant difference and helps to explain the temperature difference between Chinatown and the City as a whole.

The socio-economic analysis found that Chinatown is also home to a greater proportion of people who are susceptible to harm from extreme heat: 

• 15% of its residents are over 65 years of age compared to 12% city-wide;
• 21% live on low incomes compared to 16% city-wide; and 
• 84% of the housing units are renter-occupied compared to 64% city-wide.

Older residents are more sensitive to extreme heat.  The Heat Plan notes that those who live on low incomes or live in rental units are less likely to have control over indoor air temperatures and more likely to have chronic health conditions that make them more susceptible to harm from extreme heat. 

Assessing Strategies and Community Engagement

Community engagement for the Heat Plan included a series of five “listening sessions” in each of the five focus areas to appreciate how heat is affecting the lives of their residents and to hear about the critical needs of residents in those areas.

The strategies identified by staff and the community were assessed according to their heat resilience benefits and co-benefits including those related to heat reduction, heat relief, adaptive capacity, public health, environmental impacts, and environmental justice & equity.  

A simulation model was used to estimate the reduction in surface temperature and in perceived temperature for cooling strategies such as light-colored roads, shade canopy, green roofs, and cool roofs.  

Cool Roofs Program 

One of the 26 strategies included in Boston’s Heat Plan was a Cool Roofs Program:

“The City will launch a cool roofs program, which will provide grants to a nonprofit organization to complete cool roof installations on eligible properties. The City will explore additional near-term opportunities to demonstrate large-scale cool roofs on public buildings.”

“Dark-colored roofs can absorb much more heat than lighter-colored roofs,” explained Davis. “In dense urban spaces, they can contribute substantially to urban heat island impacts.  Modelling demonstrated that light-coloured or “cool” roofs can reduce extreme temperatures in localized areas.”   

The Boston Heat Plan notes that cool roofs were also strongly supported by community members with 45% of respondents indicating that they would like to see more cool roofs in their neighborhoods. 

“In 2022, we put out a Request for Applications for a Cool Roofs Pilot Project,” said Davis.  “We were looking for a non-profit organization to do the work because the City cannot really do work on private property.  We had $120,000 we could direct towards this project.”

“We wanted an organization that could implement the project with an equity lens; that  would prioritize disadvantaged and underserved populations,” explained Davis. “We wanted cool roofs to be applied to community assets such as public housing and non-municipal community facilities that provide essential services to vulnerable populations.”

“We awarded the contract to Local Initiatives Support Corporation (LISC) Boston, a non-profit organization with a lot of experience managing similar projects. In the end, three roofs on sizable subsidized housing projects and a homeless services center were treated with the reflective coating,” said Davis. “The program funded 16,000 square feet of cool roof coating. The three buildings were located in the neighbourhoods of Allston and Dorchester.” 

Challenges Encountered and Lessons Learned

Boston’s Cool Roof Program has met with three major challenges; one related to a trained labour force, one related to the timing of funding and approvals, and one related to funding for cool roofs.

“When we initiated this project three years ago, it was difficult to find roofers who were trained or experienced in the use of reflective paints for flat, dark-coloured roofs,” noted Davis. “Hopefully, that will change over time.”

“We noticed some timing issues,” said Davis. “If roof repairs are needed or additional elements like solar panels are to be added to the project, it’s important to consider the amount of time required for building permit processes. For this grant, the timing of the end of the grant period didn’t align with the permit and installation timeline.” 

“Unfortunately, we have not been able to take this program beyond the pilot stage,” explained Davis. “While there is funding for our work on energy efficiency and carbon mitigation retrofits for buildings in underserved neighbourhoods in the city, there is not currently funding for projects that improve climate resiliency, and cool roofs are not currently recognized in energy efficiency and carbon programs as a retrofit that can address these co-benefits.”

“Some jurisdictions, such as Cambridge, have been able to fold cool roofs into their energy efficiency projects, but in Boston, that type of change has to be made when a program is being developed or re-funded.  We are interested in integrating more resilience solutions including cool roofs into our energy efficiency and carbon mitigation programs in the future,” offered Davis.

White Roofs in Montreal In 2011,Rosemont-La-Petite-Patrie made it mandatory for all new public and private buildings to have a white or green roof.  Four years later, the borough went one step further.  It adopted a new by-law which stipulates that all new flat-roof constructions will be composed of a white, energy-efficient membrane.  This by-law, which was passed “to promote sustainable development, combat heat islands and contribute to public health by improving air quality” prohibits the use of “multi-layer waterproofing systems composed of bitumen, bitumen felt, fiberglass and gravel” on flat roofs for new buildings.  Rosemont-La-Petite-Patrie was the first borough in Montreal, and perhaps the first jurisdiction in Canada, to require white or cool roofs.  Since then, the majority of metropolitan boroughs and municipalities in Montreal have followed its example.  It is estimated that there are nearly 6000 white roofs in Montreal.