Retail-EBOM-v4 WEc1: Outdoor water use reduction

  • How will you demonstrate compliance?

    The big question for this credit is how your team will demonstrate compliance. Though this credit is similar to the LEED 2009 credit that addresses landscape irrigation use, the v4 iteration stipulates different compliance paths depending on the conditions of your building’s systems. 

    Find out what’s behind options 1, 2, and 3

    The first and easiest path is when landscaping does not require irrigation. If not, the credit is yours via Option 1.

    If your landscaping does require irrigation there are two separate paths to compliance, depending on whether or not you have irrigation metering installed. (Teams should also know that projects with no landscape areaThe landscape area is the total site area less the building footprint, paved surfaces, water bodies, and patios. automatically meet Option 1 and earn the credit.)

    For Option 2, if your site doesn’t have an irrigation meter, you need to calculate the expected landscape irrigation reduction using the EPA WaterSense Water Budget Tool. Most landscapes that use basic water conservation strategies such as low water vegetation, drip irrigationDrip irrigation delivers water at low pressure through buried mains and submains. From the submains, water is distributed to the soil through a network of perforated tubes or emitters. Drip irrigation is a high-efficiency type of microirrigation., and WaterSense controllers are likely to meet the 40% reduction threshold. The catch is that the project must also install an irrigation meter before the performance period ends in order to earn the credit. 

    If your site already has an irrigation meter you must pursue Option 3, and it will likely be much harder to demonstrate compliance with the credit threshold. In this case your performance is calculated based on a straight reduction from your historic metered water usage. If your team has made efficiency improvements to the irrigation system recently, this credit may be good to pursue.

    What’s New in LEED v4

    • The U.S. EPA WaterSense Water Budget Tool is now a referenced calculation tool.
    • The performance thresholds and points available have changed compared to the WEc3: Water Efficient Landscaping credit from LEED 2009.

    Readiness Review Questions

    • Can plantings thrive without a permanent irrigation system (Option 1)?
    • If your project doesn’t currently have irrigation metering in place, it is feasible to install (Option 2)?
    • If irrigation systems are already submetered, are records of potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. use from previous years available (Option 3)?
    • Do you have landscaping plans that show species composition and areas?
    • What opportunities exist to incorporate native or adaptive landscaping onto the project site? 

    • What opportunities exist to optimize or upgrade the irrigation system? 

    • Are there local, regional, or state programs that assess irrigation performance in your area?
    • Could graywaterUntreated household waste water which has not come into contact with toilet waste. Graywater includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washers and laundry tubs. It must not include waste water from kitchen sinks or dishwashers (Uniform Plumbing Code, Appendix G, Gray Water Systems for Single-Family Dwellings); waste water discharged from lavatories, bathtubs, showers, clothes washers and laundry sinks (International Plumbing Code, Appendix C, Gray Water Recycling Systems). Some states and local authorities allow kitchen sink wastewater to be included in graywater. Other differences can likely be found in state and local codes. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. or captured rainwater be used to meet irrigation needs in whole or in part?


    Do the 30% and 40% reductions need to be achieved prior to the application of alternative water sources in order to earn the credit?

    The required savings can be achieved via any of the available water reduction strategies listed in the LEED Reference Guide, including alternative water sources.

    When pursuing Option 2 do I have to use the EPA WasterSense Water Budget Tool or USGBC’s Outdoor Water Use Reduction Calculator?

    Teams can choose to use the EPA or USGBC tool to complete the calculations for Option 2. This is confirmed on the v02 form for this credit posted on USGBC’s website.

    Does the project site need to have a minimum amount of vegetation in order to pursue the credit?

    No, there is no minimum amount of vegetation identified in the Rating System or Reference Guide. In fact, the Reference Guide states that projects that have no landscape area automatically meet the requirements.

  • WE Credit 1: Outdoor water use reduction


    To reduce outdoor water consumption.


    Reduce outdoor water use through one of the following options. Nonvegetated surfaces, such as permeable or impermeable pavement, should be excluded from landscape areaThe landscape area is the total site area less the building footprint, paved surfaces, water bodies, and patios. calculations. Athletic fields and playgrounds (if vegetated) and food gardens may be included or excluded at the project team’s discretion.

    If landscape irrigation is not submetered, use Option 2.


    Option 1. No irrigation required (2 points except Healthcare, 1 point Healthcare)

    Show that the landscape does not require a permanent irrigation system beyond a maximum two-year establishment period.

    Option 2. No irrigation meter installed: calculated water budget (1–2 points)

    Use the existing landscape to calculate the landscape water requirement using the EPA WaterSense Water Budget Tool.

    Install an irrigation meter.

    Option 3. Irrigation meter installed (1–2 points)

    The baseline is established using the annual average of at least 3 years of consecutive data out of the last 5 years.


    Option 1. No irrigation required (2 points)


    Option 2. No irrigation meter: calculated water budget (1–2 points)

    Points are earned according to Table 1.

    Option 3. Irrigation meter installed (1–2 points)

    Demonstrate a reduction in outdoor water use over the most recent 12 months compared with the established baseline. Points are earned according to Table 1.

    Table 1. Points for reducing irrigation water
    Percentage reduction from baseline Points
    30% 1
    40% 2

The WaterSense Water Budget Tool

Project teams can use The WaterSense Water Budget Tool to comply with section 4.1.1 of Version 1.2 of the WaterSense New Home Specification, or to ensure a measure of efficiency and regional suitability for the amount of water applied to a landscape based on local climate data.

LEED v4 Outdoor Water Use Reduction Calculator

This calculator is recommended for use by teams for projects outside of the U.S.


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Aug 22 2017
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