Concrete Meets Leed’s Need For Heat Island Reduction

New Portland Cement Association (PCA) research on the solar reflectance of concrete and its positive impact on limiting heat island effect can assist

New Portland Cement Association (PCA) research on the solar reflectance of concrete and its positive impact on limiting heat island effect can assist architects and builders involved in urban projects. Announced at November’s 2007 Greenbuild International Conference and Expo in Chicago, research findings will allow projects to accrue points towards (Leadership in Energy & Environmental Design) LEED certification without costly testing of concrete pavement performance. The study marks the first time the solar reflectance of concrete has been examined in relation to LEED points.

PCA is a leader in research on how cement-based applications can play a positive role in sustainable development, says PCA Director of Sustainable Development David Shepherd, AIA. This study shows that concrete, regardless of its ingredients, can help to limit the heat island effect.

A heat island is a local area of elevated temperature in a region of cooler temperatures. Heat islands occur where a preponderance of dark exterior building materials and pavements as well as a lack of vegetation are found, typically in urban areas. Commissioned by PCA and conducted by CTLGroup, the study evaluated the reflective properties of concrete slabs, using the LEED-NC SS Credit 7.1 Heat Island Effect: Non-Roof criteria.

Authored by Martha VanGeem, who was on hand at Greenbuild to discuss the findings, and Medgar Marceau, a research report shows that all 135 specimens from 45 sets of concrete samples representing exterior flatwork Û regardless of the mix design Û met the required criteria. The mixes were created using a number of different components, including recovered materials such as fly ash or slag cement.

The solar reflectance of the cement proved to have more effect on the samples’ net solar reflectance than any other mix constituent. PCA notes this is the first time the solar reflectance of concrete has been examined in relation to LEED points and is the most comprehensive study of its kind to date. The solar reflectance of the supplementary cementitious material (fly ash or slag cement) had the second-greatest effect. In fact, the solar reflectance of fly ash was at times greater than or less than that of ordinary cement. However, slag cement was consistently greater than that of portland cement or fly ash.

The research also indicated that all specimens had a light broom finish, but due to the constituent materials, some specimens have a smoother surface than others. Those with a smoother surface had a higher solar reflectance than those with a rougher finish.


Leading the Greenbuild 2007 presentation of Portland Cement Association’s Solar Reflectance of Concretes for LEED Sustainable Sites Credit: Heat Island Effect research was David Shepherd, AIA, PCA’s director of sustainable development. He is responsible for crafting and integrating the sustainable development message into all U.S. cement market segments, and serves as PCA liaison with national allied associations. He currently chairs the sustainable development committee for the North American Concrete Alliance and is on the Environmental Council of Concrete Organizations board.

Also on hand was one of the report’s co-authors, Martha VanGeem, a principal engineer and group manager of CTL’s Building Science and Sustainability Group, who serves as a project principal investigator and specialized in-house consultant in the areas of sustainability, energy conservation, energy codes, thermal mass, mass concrete, and moisture migration.


As part of its Concrete Thinking for a Sustainable World initiative, Portland Cement Association (PCA) emphasizes the wide range of sustainable benefits made possible by concrete and other cement-based products. The following features illustrate why more green-focused architects, builders and engineers are becoming Concrete Thinkers, PCA asserts, applying concrete solutions to sustainable design.

  • You can hold the loudest parties on the block Û The greater mass of concrete can reduce sound penetrating through walls by more than 80 percent, compared with wood- or steel-frame construction.
  • Concrete keeps on going, and going, and going Û Concrete can be readily recycled and reused as base material for roads, sidewalks and concrete slabs, sparing the use of virgin materials.
  • Cement-producing facilities grow ever greener Û The cement industry has invested in new technologies and equipment to improve energy efficiency at its plants by 33 percent from a 1975 baseline. The Environment and Energy Awards program honors facilities in North America that go beyond local laws and government regulations to improve environmental performance.
  • The Big Bad Wolf can’t blow your concrete house down Û Concrete stands up to nature’s turbulence and will not rust, rot, or burn. The most widely used building material in the world, its structures have withstood the test of time for more than 2,000 years.
  • Decorative concrete provides beauty that lasts a lifetime Û Using decorative concrete limits finishing materials and harmful VOCs (volatile organic compounds), while providing a high-quality, durable, and low-maintenance surface.
  • From sidewalks to symphony halls, concrete makes virtually any design possible Û Concrete is a highly versatile material that can be used to create buildings or homes of any shape or size, from big box retail centers to elegant building spires. The Second Annual PCA Concrete Thinking for a Sustainable World International Design Competition drew nearly 200 contestants worldwide, student teams whose entries pushed the design envelope.
  • With pervious concrete, puddles are a thing of the past Û Pervious concrete allows rainwater to naturally filter through it, preventing deposits of oil, grease and other contaminants from entering storm drains and going directly into the water supply. This technology is recognized by the U.S. EPA as a as a best practice for stormwater management.
  • Concrete keeps buildings warmer in the winter and cooler in the summer Û As energy costs rise, winter threatens to be more costly than ever for consumers. Buildings with exterior concrete walls, also called mass walls, utilize less energy to heat and cool than similarly insulated buildings with wood- or steel-frame walls.
  • All needed information is a few mouse-clicks away Û Created by PCA, is a comprehensive online resource for information on using cement-based materials for sustainable design.
  • Concrete is cool! Û With the urban heat-island effect causing city temperatures to rise, concrete can help neutralize that impact to keep communities cooler. Announced at the 2007 Greenbuild Conference in Chicago, new research conducted by PCA in conjunction with CTLGroup on the solar reflectance of concrete demonstrates its significant impact in curtailing the heat island effect. The study data can support architects and builders involved in urban construction, allowing projects to accrue points towards LEED certification without costly testing of concrete pavement performance.