The BEES (Building for Environmental and Economic Sustainability) software can help contractors and designers select cost-effective, environmentally preferable products, promote the use of concrete, and identify environmental “weak links” in their product's life cycle.
BEES was developed by the National Institute of Standards and Technology (NIST) Building and Fire Research Laboratory. It includes data for nearly 200 building products, including concrete. You can download this Windows-based decision support software free at www.bfrl.nist.gov/oae/software/bees.html.
BEES rates products using a life-cycle assessment approach covering 12 environmental impacts. It uses the UNIFORMAT II classification system to compare building elements based on their function regardless of design specifications or materials used. This system, from ASTM E1557, “Standard Classification for Building Elements and Related Site-work,” is based on a three-tier hierarchy: major elements, group elements, and individual elements.
The first step in doing an analysis is to choose one of three alternatives (equal, Harvard, or EPA) to apply different weights to the 12 environmental impact areas, or devise your own weighting system. The program default considers economic and environmental performance equally (50/50), but you can change that, too.
Next select the building elements you are interested in. The major category choices are Building Sitework, Equipment and Furnishings, Interiors, Shell, and Substructure. After a category, a group element, and an individual element have been selected, the program shows the materials on file for that element.
For Roof Coverings, for example, the list of choices depends on whether the installation is in a “Sunbelt climate.” If so, you select one of 16 cities with the type of environment you wish to consider, then choose from generic asphalt shingles in nine colors, red clay tile, and fiber cement shingles in three colors. If not in the Sunbelt, you select from three generic materials with no consideration for color.
For each material you include, you must select from three options how far it is from the point of manufacture to the point of use. Here is where the program can help in comparing the long-term costs of using an environmentally friendly material from a remote source versus a less benign material produced close by.
For example, compare light gray fiber cement shingles with white and black asphalt shingles in two different Sunbelt cities and assume all are made the same distance from the point of use. For our example, we'll use 500 miles and weight the environmental and economic impacts evenly. We'll also assume new construction, electric heating, and cooling with the ductwork in the attic (the defaults). The initial results are reported in impact units per square foot of product over a 50-year use period. These dimensionless potential overall impact ratings are from 0 to 100; lower numbers are better.
For Salt Lake City, BEES gives the fiber cement shingles the highest POI rating, about 40.2, with the black and white asphalt shingles nearly even at 30.1 and 29.7. The incriminating factor for fiber cement is “Criteria Air Pollutants,” specifically, particulates generated during the “raw materials acquisition” stage of production.
Considering the same materials in Las Vegas, however, the black asphalt shingles have the highest POI—38.9—which comes from the “Global Warming” portion of the analysis based on carbon dioxide production during the “use” phase of these shingles. So it will take more energy to cool this building over its service life than if it had light gray fiber cement shingles (35.1) or white asphalt shingles (25.9).
Architects, engineers, contractors and owners can use such data as input when applying for LEED certification and other sustainability accreditation for construction projects.