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Achieving LEED Water-Use-Reduction Credits

November, 2013

By Emily B. Lorenz, P.E., LEED AP BD+C

The latest version of Leadership in Energy and Environmental Design (LEED), called LEED v4, went through six public comment periods before being approved in a membership vote in June 2013. With this approval, the U.S. Green Building Council (USGBC) is keeping with its mission of market transformation through the use of its LEED green building program. As with other iterations of LEED, the USGBC has increased the stringency of the credit requirements of LEED v4. This article focuses on the water efficiency (WE) credits of the LEED rating system that relate to water-use reduction for building design and construction.

Water Efficiency, Use

In LEED v4, there are two WE prerequisites and two WE credits related to water-use reduction. The intent of all of these credits is simply “to reduce water consumption.” The requirements of each prerequisite and credit will be further detailed in the following sections.

BD+C WE Prerequisite 1 (WEp1): Outdoor Water Use Reduction

This new prerequisite requires that the outdoor water use on the project be reduced by 30 percent from a baseline, or by showing that no permanent irrigation is required after two years (the establishment period). Baseline values are calculated from the Environmental Protection Agency’s (EPA) WaterSense Water Budget Tool.

BD+C WE Prerequisite 2 (WEp2): Indoor Water Use Reduction

Formerly the Water Use Reduction prerequisite in LEED 2009, LEED v4’s WE Prerequisite 2 requires that the aggregate indoor water consumption be reduced by 20 percent from a baseline. Table 1 shows the baseline water consumption to be used for different fixtures and fittings when calculating the building’s baseline indoor water use. LEED v4 requires EPA WaterSense labels for product types that are eligible for those labels.

Table 1. Baseline water consumption of fixtures and fittings.
 Fixtures and fittings  Current baseline
 Water closet (toilet)**  1.6 gallons/flush
 Urinal*  1.0 gallons/flush
 Public lavatory (restroom) faucet  0.5 gallons/minute at 60 psi
 Private lavatory faucet*  2.2 gallons/minute at 60 psi
 Kitchen faucet  2.2 gallons/minute at 60 psi
 Showerhead*  2.5 gallons/minute at 80 psi per shower stall
*WaterSense label available for this product type.
**WaterSense currently has a standard only for tank-type toilets. The program intends to develop standards for commercial toilets in the future.

BD+C WE Credit 1 (WEc1): Outdoor Water Use Reduction

The outdoor water use reduction credit requires reduction of the project’s landscape water requirements by 50 percent (for 1 point) or 100 percent (for 2 points). This credit was called Water Efficient Landscaping in previous versions of LEED. In LEED v4, reductions in water use must first be achieved due to plant selection and irrigation efficiency, then by alternative water sources and smart scheduling. Water efficiencies are calculated using the EPA’s WaterSense Water Budget Tool.

BD+C WE Credit 2 (WEc2): Indoor Water Use Reduction

The title of this credit was also changed from LEED 2009 to LEED v4. The biggest change, however, is that projects can now earn up to 6 points by increasing percentages of indoor water-use reduction. Points are awarded according to Table 2.

Table 2. Points for reducing water use. h
Percentage reduction Points
25% 1
30% 2
35% 3
40% 4
45% 5
50% 6

Overall Reduction

Like previous versions of LEED, LEED v4 will encourage designers to use cutting-edge technologies for water-use reduction. These technologies may include modeling software, or high-efficiency fixtures, or a combination of both. Whichever the method, LEED v4 will ensure that buildings use less water than they did previously.