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LEED v4
Homes
Sustainable Sites
Rainwater management

LEED CREDIT

Homes-v4 SSc2: Rainwater management 1-3 points

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SPECIAL REPORT

SPECIAL REPORT

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USGBC logo

© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Projects that must comply with local requirements of the National Pollutant Discharge Elimination System (NPDES) must follow Case 2.

Case 1. Low impact development
Use low-impact development (LID) techniques to minimize the amount of stormwater that leaves the site. Examples of acceptable techniques include the following:
  • planting areas with native or adapted plant material (e.g. trees shrubs);
  • installing a vegetated roof;
  • using permeable paving, consisting of porous above-ground materials (e.g., open pavers, engineered products), a base layer designed to drain water away from the home, and (often) a 6-inch-deep (150 millimeters) subbase; and
  • installing permanent infiltration or collection features (e.g., vegetated swale, rain garden, rainwater cistern) that can handle 100% of the runoff from a two-year, 24-hour storm.
Single-family home projects may use Table 1 or Table 2 to determine points; multifamily projects must use Table 1. To determine compliance for single-family and multifamily homes, calculate the percentage of the lot area, including the area under roof, that is permeable or can direct water to an on-site catchment or infiltration feature.
Table 1. Points for permeable area, as percentage of total lot area
Percentage Points
50–64% 1
65–79% 2
≥80% 3
As an alternative approach to determining compliance for single-family homes only, credit is given for reducing the total impermeable area compared to the ENERGY STAR reference home, as listed in Table 2.
Table 2. Conditioned floor area of reference home, by number of bedrooms

 

1

2

3

4

5

6

7

8 or more

Floor area (square feet)

1,000

1,600

2,200

2,800

3,400

4,000

4,600

+ 600 ft2 per additional bedroom

Floor area (square meters)

93

148

204

260

315

371

426

+ 55.6 square meters per additional bedrooms
Thresholds for total impermeable area are then calculated according to the values in Table 3, column 1.
Table 3. Points for reducing total impermeable area
Impermeable area (square feet) Points
Reference home size * 1 1
Reference home size * 0.66 2
Reference home size * 0.33 3
Case 2. National Pollutant Discharge Elimination System (NPDES) projects
Using low-impact development and green infrastructure to replicate natural site hydrology, manage on-site the runoff from the developed site for the percentile regional or local rainfall events listed in Table 4. Use daily rainfall data and the methodology in the U.S. Environmental Protection Agency’s Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects, under Section 438 of the Energy Independence and Security Act, to determine the percentile amount.
Table 4. Points for on-site management of water from rainfall events
Percentile rainfall event Points
95th 2
98th 3
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Cost estimates for this credit

On each BD+C v4 credit, LEEDuser offers the wisdom of a team of architects, engineers, cost estimators, and LEED experts with hundreds of LEED projects between then. They analyzed the sustainable design strategies associated with each LEED credit, but also to assign actual costs to those strategies.

Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.

This information is also available in a full PDF download in The Cost of LEED v4 report.

Learn more about The Cost of LEED v4 »

Addenda

10/5/2018 – Updated: 10/5/2018
Reference Guide Correction
Description of change:
Remove the following sentence:

“Where this is not possible or practical, retaining, treating, and then gradually releasing rainwater are acceptable.”
Campus Applicable
No
Internationally Applicable:
No
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Documentation toolkit

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USGBC logo

© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Projects that must comply with local requirements of the National Pollutant Discharge Elimination System (NPDES) must follow Case 2.

Case 1. Low impact development
Use low-impact development (LID) techniques to minimize the amount of stormwater that leaves the site. Examples of acceptable techniques include the following:
  • planting areas with native or adapted plant material (e.g. trees shrubs);
  • installing a vegetated roof;
  • using permeable paving, consisting of porous above-ground materials (e.g., open pavers, engineered products), a base layer designed to drain water away from the home, and (often) a 6-inch-deep (150 millimeters) subbase; and
  • installing permanent infiltration or collection features (e.g., vegetated swale, rain garden, rainwater cistern) that can handle 100% of the runoff from a two-year, 24-hour storm.
Single-family home projects may use Table 1 or Table 2 to determine points; multifamily projects must use Table 1. To determine compliance for single-family and multifamily homes, calculate the percentage of the lot area, including the area under roof, that is permeable or can direct water to an on-site catchment or infiltration feature.
Table 1. Points for permeable area, as percentage of total lot area
Percentage Points
50–64% 1
65–79% 2
≥80% 3
As an alternative approach to determining compliance for single-family homes only, credit is given for reducing the total impermeable area compared to the ENERGY STAR reference home, as listed in Table 2.
Table 2. Conditioned floor area of reference home, by number of bedrooms

 

1

2

3

4

5

6

7

8 or more

Floor area (square feet)

1,000

1,600

2,200

2,800

3,400

4,000

4,600

+ 600 ft2 per additional bedroom

Floor area (square meters)

93

148

204

260

315

371

426

+ 55.6 square meters per additional bedrooms
Thresholds for total impermeable area are then calculated according to the values in Table 3, column 1.
Table 3. Points for reducing total impermeable area
Impermeable area (square feet) Points
Reference home size * 1 1
Reference home size * 0.66 2
Reference home size * 0.33 3
Case 2. National Pollutant Discharge Elimination System (NPDES) projects
Using low-impact development and green infrastructure to replicate natural site hydrology, manage on-site the runoff from the developed site for the percentile regional or local rainfall events listed in Table 4. Use daily rainfall data and the methodology in the U.S. Environmental Protection Agency’s Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects, under Section 438 of the Energy Independence and Security Act, to determine the percentile amount.
Table 4. Points for on-site management of water from rainfall events
Percentile rainfall event Points
95th 2
98th 3
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