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Light Reflectivity-Sustainability
 

 

 

Albedo Numbers Streetscene

   
Asphalt Parking Lot Concrete Parking Lot
   
 
   

 

 

                          "Which do you want your family walking to their car on?"

                                Concrete:  Safety increased, Lighting Expenses decreased, Energy savings.

   
   
ALBEDO OF CONCRETE AND SELECT OTHER MATERIALS
   

Table 1 Solar reflectance (albedo) of select material surfaces - l,2,3,4

 

Material surface

Solar Reflectance

Black acrylic paint 0.05
New asphalt 0.05
Aged asphalt 0.1
"White" asphalt shingle 0.2
Aged concrete 0.2 to 0.3
New concrete (traditional) 0.4 to 0.5
New concrete with white portland cement          0.7 to 0.8
White acrylic paint 0.8
   

LEED Sustainable Sites Credit 7.1 (1 point): Landscape and Exterior Design to Reduce Heat Islands. One option in this requirement is to "use light-colored/high-albedo materials (reflectance of at least 0.3) for 30% of the site's non-roof impervious surfaces." This re­quirement can be met by using portland cement concrete rather than asphalt concrete for 30% of all sidewalks, parking lots, drives and other non-roof impervious surfaces. Albedo, which in this case is synonymous with solar reflectance, is the ratio of the amount of solar radiation reflected from a material to the amount shone on the material. Solar radiation includes the ultraviolet as well as the visible spectrum. Generally surfaces that look light colored have a high albedo, but this is not always the case. Surfaces with lower albedos absorb more solar radiation. This is then converted into heat and the surface gets hotter. Pavements with higher albedos absorb less energy and are thus cooler. Where paved surfaces are required, using ma­terials with higher albedos will reduce the heat island effect, and thereby save energy by re­ducing the demand for air conditioning and improve air quality.

Traditional portland cement concrete generally has an albedo or solar reflectance of ap­proximately 0.35 although values can vary. Measured values are reported in the range of 0.4 to 0.5. For "white" Portland cement, values are reported in the range of 0.7 to 0.8.5 New as­phalt concrete generally has a reflectance of approximately 0.05 and asphalt concrete five or more years old has a reflectance of approximately 0.10 to 0.15. More information on urban heat islands is available from the Lawrence Berkeley National Laboratory website on Urban Heat Islands http://eetd.lbl.gov/Heatlsland/

   
 

 1Levinson, Ronnen and Akbari, Hashem, "Effects of Composition and Exposure on the Solar Reflectance of Portland Cement Concrete," Lawrence Berkeley National Laboratory, Publication No. LBNL-48334, 2001, 39 pages.

2 Pomerantz, M., Pon, B., and Akbari, H., "The Effect of Pavements' Temperatures on Air Temperatures in Large Cities," Lawrence Berkeley National Laboratory, Publication No. LBNL-43442, 2000, 20 pages.

3 Berdahl, P. and Bretz, S, "Spectral Solar Reflectance of Various Roof Materials", Cool Building and Paving Materials Workshop, Gaithersburg, Maryland, July 1994 14 pages.

4 Pomerantz, M., Akbari, H., et al, "Examples of Cooler Reflective Streets for Urban Heat Islands: Cement Concrete and Chip Seals," DRAFT, Lawrence Berkeley National Laboratory.

5 Levinson, R. and Akbari, H., "Effects of Composition and Exposure on the Solar Reflectance of Portland Cement Concrete," Lawrence Berkeley National Laboratory, Publication No. LBNL-48334, December 2001, 39 pages.

   
         M VanGeem MV1VanGeem(a-.CTLzroup.com Construction Technology Laboratories, Inc
 
  Solar Reflectance Index (SRI)

 

In relation to Pervious Concrete

29 or greater     =     Acceptance level for achieving SRI levels acceptable for LEED

Pervious because of its uneven surface (with hills & valleys) creates shadows.  This makes it appear somewhat darker than traditional concrete pavement. 

Tests on pervious concrete pavement have delivered SRI numbers both higher and lower than 29. 

Pervious concrete pavements with 25% slag replacement for cement have consistently tested above the 29 mark.

White Portland Cement also significantly raises the SRI numbers.

The soybean cure for pervious concrete has also successfully been seeded with a color agent when sprayed on the surface leaves a white film.  It can be sprayed on a pervious pavement at any time for color addition or a refresher.  More information can be attained from Jim Miller, (317) 758-4777, C2 Products, Inc.

Portland Cement Association (847) 966-6200.

CTL  (847) 965-7500

 

 

Pervious Links & Resources: 

www.nrmca.org National Ready Mixed Concrete Association

www.perviouspavement.org also National Ready Mixed Concrete Association

www.cement.org Portland Cement Association

www.concrete.org American Concrete Institute (Committee 522 Pervious Concrete)

John Kevern is a great Pervious Resource:

John T. Kevern Ph. D. E. I. T.  (used to be at Iowa State Univ., did research on Pervious Concrete)

Assistant Professor

UMKC School of Computing & Engineering

(816) 235-5977 office phone

(816) 235-1260 fax

370H Robert H. Flarsheim Hall

5100 Rockhill Rd.

Kansas City, MO  64110-2499

KevernJ@umkc.edu