WE: Outdoor Water Use Reduction (Prerequisite + Credit)
Use less water first. Then use smarter water.
๐ฏ Why This Topic Matters
Outdoor water use is one of the largest sources of potable water consumption in buildings.
๐ LEED focuses on:
Reducing irrigation demand first โ then using smarter water sources
๐งฉ Prerequisite vs Credit (Key Distinction)
๐ Quick Comparison Table (HIGH VALUE FOR USERS)
| Requirement | Prerequisite | Credit |
| Mandatory? | โ Yes | โ No |
| Points | 0 | Up to 2 points |
| Intent | Reduce outdoor water use | Further reduce outdoor water use |
| Option 1 | No irrigation | Same |
| Option 2 Reduction | โฅ30% | โฅ50% (1 pt), 100% (2 pts) |
| Use of alternative water | โ Not allowed for first 30% | โ Allowed beyond 30% |
๐ฏ Key Insight
Prerequisite = baseline efficiency
Credit = deeper performance
๐ฟ WE Prerequisite: Outdoor Water Use Reduction
Intent
๐ Reduce outdoor potable water consumption
Compliance Options
โ Option 1: No Irrigation Required
- No permanent irrigation system
- Allowed only for:
- โค2-year establishment period
๐ Requires:
- narrative explaining:
- rainfall adequacy
- plant suitability
โ Option 2: Reduced Irrigation
๐ Must achieve:
๐ โฅ30% reduction
(from baseline landscape water requirement)
โ๏ธ How is this calculated?
Using:
๐ EPA WaterSense Water Budget Tool
๐งฎ WaterSense Tool โ Key Steps
๐น Step 1: Climate Data
- input project location (ZIP code)
- tool generates:
- precipitation
- evapotranspiration
๐น Step 2: Landscape Inputs
- enter:
- plant types
- landscape areas
โ ๏ธ Important Rule:
๐ Include:
- vegetated areas
๐ Exclude:
- hardscape
- non-irrigated surfaces
- mulched pathways
๐น Step 3: Results
- baseline water use
- design water use
- % reduction
๐ฑ WE Credit: Outdoor Water Use Reduction
Intent
๐ Same as prerequisiteโbut with higher performance
Compliance Options
โ Option 1: No Irrigation Required
Same as prerequisite
๐ Eligible for maximum performance
โ Option 2: Reduced Irrigation
๐ Thresholds
- 50% reduction โ 1 point
- 100% reduction โ 2 points
โ ๏ธ Critical Rule (VERY TESTABLE)
๐ First 30% reduction MUST come from:
- plant selection
- irrigation efficiency
๐ Beyond 30%, you can use:
- alternative water (rainwater, graywater)
- smart controls
- advanced systems
๐ฏ Exam Insight
LEED = Efficiency First โ Then Alternative Water
๐ฟ Strategies to Achieve This Credit
๐ฑ 1. Native / Adaptive Plants
- require less water
- suited to local climate
๐ง 2. Efficient Irrigation Systems
Example:
๐ Drip Irrigation
- low-pressure system
- delivers water directly to roots
- minimizes evaporation
๐ต 3. Xeriscaping
๐ Landscaping that:
- requires little to no irrigation
โป๏ธ 4. Alternative Water Sources
- rainwater harvesting
- graywater reuse
- reclaimed water
๐ 5. Smart Irrigation Controls
- weather-based controllers
- soil moisture sensors
๐ 6. Submetering
- track irrigation use
- identify inefficiencies
๐ง Where People Get Confused
โ Misconception 1:
โAlternative water helps meet prerequisiteโ
๐ No
๐ First 30% must be from:
- efficiency + plant selection
โ Misconception 2:
โCredit and prerequisite are the sameโ
๐ No
- 30% โ prerequisite
- 50โ100% โ credit
โ Misconception 3:
โAll landscaped areas are included in calculationsโ
๐ No
๐ Only:
- vegetated areas count
Official FAQs
What is the minimum reduction required for the prerequisite?
What tool is used for calculations?
A project achieves 40% reduction using only efficient irrigation. Does it meet the prerequisite?
A project uses rainwater to achieve the first 30% reduction. Does it comply?
Must use:
โข efficiency + plant selection
Why does LEED require efficiency before alternative water?
โข reduces overall demand
โข ensures long-term sustainability
โข avoids over-reliance on systems
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