Tag Archives: Washington DC

American Institute of Architects Recognizes the Benefits of Cool Roofs

In April of this year, GCCA Board Member Greg Kats published a study of the health benefits of cool roofs on Washington DC-owned buildings. After the District retrofitted many of its buildings with white roofs, green roofs, and / or solar collectors the city started saving money. This study turns things on its head by showing that using the old technology of conventional dark roofs is a policy failure that costs cities and building owners money.

Robert Ivy, chief executive of the American Institute of Architects discusses this study, along with other cool roof benefits in this Washington Post guest column. In it, he notes that the highly reflective surfaces of white roofs cut energy bills and can help improve the health of residents and cool cities.

“We’ve known for years that smart roofs save energy, and we’ve been able to come up with methodologies to quantify those savings. However, the health benefits of such design choices have been harder to figure out. The authors of this report, Greg Kats and Keith Glassbrook, have addressed this complex question, and their findings could have an impact on improving the health of residents in urban areas across the nation.

Roofs typically make up 15 to 25 percent of most cities’ surface areas. And because roofs can typically be replaced or retrofitted more frequently than entire buildings, they represent an opportunity for developers and building owners to dramatically cut the “heat island effect” in urban environments …

Use of such techniques, in turn, can have public health benefits, particularly for low-income and elderly residents who tend to be more vulnerable to illnesses related to extreme heat and poor air quality. Moreover, heat mitigation through adoption of cool and green roofs can help ameliorate the effects of heat stress.

The report will prove to be relevant reading for designers, architects or city officials trying to battle the pernicious health effects of urban heat islands. These new methodologies suggest ways for cities to quantify the benefits of their building codes, policies and incentive programs.”

You can read the full report here:
Washington, DC Smart Roof Cost – Benefit Report

Study Links Climate Change to Hotter Urban Heat Islands

Cities are hot and getting hotter, thanks to global warming and the urban heat island effect. With urbanization on the rise globally, extreme heat threatens human health, strains energy grids, and impacts global economies around the world.

Extreme heat is now ranked as the number one weather-related killer in the United States. With over eighty percent of Americans now living in cities, urban heat islands and record high temperatures could cause serious health problems for hundreds of millions of people during the hottest months of the year.

Climate Central just released an analysis of government records for summer temperatures in 60 U.S. cities (1970 to date). This study found that single-day heat island differences reached 27 degrees F in some cities, and that since 2004, at least 12 cities experienced 20 additional days a year above 90°F than surrounding rural areas.

This study also ranks the top ten urban heat islands in the United States. Washington, DC ranks number 6 on this hit parade of urban heat.

Climate Central has prepared a useful interactive tool to help you learn more.

You can read more about the study here.

You can also read GCCA studies on heat health problems in Washington DC, and learn about strategies to lower urban temperatures and save lives.

GCCA Executive Director Kurt Shickman on WAMU’s Metro Connection

Johnathan Wilson, environmental reporter for WAMU (a public radio station in Washington, DC) recently spoke with GCCA Executive Director, Kurt Shickman about rising global temperatures. Kurt talked about the dangers urban heat islands present to people living in cities like Washington, DC, and explained how reflective surfaces and increased vegetation help save lives in extreme heat events.

He also demonstrated how dark surfaces (black roofs) can be as much as 65 degrees hotter than lighter surfaces (white roofs).

You can listen to this WAMU broadcast here, and read a recent GCCA report about how urban heat island heat reduction strategies can help reduce mortality in cities like Washington, DC.

Assessing the Health Impacts of Urban Heat Island Strategies in the District of Columbia

The District of Columbia is susceptible to extreme heat events whose health impacts are exacerbated by the fact that the city is often significantly warmer than surrounding rural areas during the summer. The study found that a 10-percentage point increase in urban surface reflectivity could reduce the number of deaths during heat events by an average of 6%. Adding a 10% increase vegetative cover to the increases in reflectivity yielded an average 7% reduction in mortality during heat events. During the decades between 1948 and 2011, an average of 285 people died of heat-related causes. A 6-7% decrease in mortality would save approximately 20 lives per decade. In addition, an even larger reduction would be expected in hospital admissions from heat-related illness, although this was not a specific finding of this analysis. Changes in temperature and humidity (as measured by dew point temperature) in both scenarios were relatively minor, yet were significant enough to contribute to the reduction of deaths.

The District, given its current policy landscape and development, could achieve the increases in reflectivity and vegetation used in this study. Increasing District-wide roof reflectivity by 10 percentage points is achievable by converting dark grey roofs to white roofs on approximately 25 percent of the District’s buildings. Assuming the average roof lasts 20 years, the District could achieve this with end-of-life roof replacements in slightly more than 5 years. Achieving the same increase in reflectivity for pavements would require the conversion of 50 percent of District pavements from dark asphalt to a slightly lighter option like grey concrete. A significantly smaller percentage of pavements would need to be converted if cool coatings were applied where feasible.

Get the full study on our Cool Roofs and Cool Pavements ToolKit here.