LEED v2009
Retail – New construction
Sustainable Sites
Heat island effect - roof

Retail-NC-v2009 SSc7.2: Heat island effect - roof

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Credit language

USGBC logo

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

Intent

To reduce heat islands1 to minimize impacts on microclimates and human and wildlife habitats.

Requirements

Option 1
Use roofing materials with a solar reflectance index2 (SRI)equal to or greater than the values in the table below for a minimum of 75% of the roof surface. Roofing materials having a lower SRI value than those listed below may be used if the weighted rooftop SRI average meets the following criteria:

Area Roof Meeting Minimum SRI

————————————————

Total Roof Area

x

SRI of Installed Roof

——————————

Required SRI

≥

75%
Alternatively, the following equation may be used to calculate compliance:

[

Area of Roof A

x

SRI of Roof A

———————

Required SRI

]

+

[

Area of Roof B

x

SRI of Roof B

———————

Required SRI

]

+

...

Total Roof Area

0.75

Roof Type

Slope

SRI

Low-sloped roof

≤ 2:12

78

Steep-sloped roof

> 2:12

29

OR

Option 2
Install a vegetated roof that covers at least 50% of the roof area.

OR

Option 3
Install high-albedo and vegetated roof surfaces that, in combination, meet the following criteria:

Area Roof Meeting Minimum SRI

————————————————

0.75

+

Area of Vegetated Roof

——————————

0.5

≥

Total Roof Area

Roof Type

Slope

SRI

Low-sloped roof

≤ 2:12

78

Steep-sloped roof

> 2:12

29
Alternatively, a weighted approach may be used to calculate compliance for multiple materials:
1 Heat islands are defined as thermal gradient differences between developed and underdeveloped areas. 2 The solar reflectance index (SRI) is a measure of the constructed surface's ability to reflect solar heat, as shown by a small temperature rise. It is defined so that a standardblack surface (reflectance 0.05, emittance 0.90) is 0 and a standard white surface (reflectance 0.80, emittance 0.90) is 100. to calculate the SRI for a given material, obtain the reflectance value and emittance value for the material. SRI is calculated according to ASTM E 1980. Reflectance is measured according to ASTM E 903, ASTM E 1918, or ASTM C 1549. Emittance is measured according to ASTM E408 or ASTM C 1371. 3 For the purposes of this credit, under cover parking is defined as parking underground, under deck, under roof, or under a building.
SITES-LEED Equivalency
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.
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LEEDuser overview

Frank advice from LEED experts

LEED is changing all the time, and every project is unique. Even seasoned professionals can miss a critical detail and lose a credit or even a prerequisite at the last minute. Our expert advice guides our LEEDuser Premium members and saves you valuable time.

For full access, sign up now for LEEDuser Premium

Already a premium member? Log in now

Credit language

USGBC logo

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

Intent

To reduce heat islands1 to minimize impacts on microclimates and human and wildlife habitats.

Requirements

Option 1
Use roofing materials with a solar reflectance index2 (SRI)equal to or greater than the values in the table below for a minimum of 75% of the roof surface. Roofing materials having a lower SRI value than those listed below may be used if the weighted rooftop SRI average meets the following criteria:

Area Roof Meeting Minimum SRI

————————————————

Total Roof Area

x

SRI of Installed Roof

——————————

Required SRI

≥

75%
Alternatively, the following equation may be used to calculate compliance:

[

Area of Roof A

x

SRI of Roof A

———————

Required SRI

]

+

[

Area of Roof B

x

SRI of Roof B

———————

Required SRI

]

+

...

Total Roof Area

0.75

Roof Type

Slope

SRI

Low-sloped roof

≤ 2:12

78

Steep-sloped roof

> 2:12

29

OR

Option 2
Install a vegetated roof that covers at least 50% of the roof area.

OR

Option 3
Install high-albedo and vegetated roof surfaces that, in combination, meet the following criteria:

Area Roof Meeting Minimum SRI

————————————————

0.75

+

Area of Vegetated Roof

——————————

0.5

≥

Total Roof Area

Roof Type

Slope

SRI

Low-sloped roof

≤ 2:12

78

Steep-sloped roof

> 2:12

29
Alternatively, a weighted approach may be used to calculate compliance for multiple materials:
1 Heat islands are defined as thermal gradient differences between developed and underdeveloped areas. 2 The solar reflectance index (SRI) is a measure of the constructed surface's ability to reflect solar heat, as shown by a small temperature rise. It is defined so that a standardblack surface (reflectance 0.05, emittance 0.90) is 0 and a standard white surface (reflectance 0.80, emittance 0.90) is 100. to calculate the SRI for a given material, obtain the reflectance value and emittance value for the material. SRI is calculated according to ASTM E 1980. Reflectance is measured according to ASTM E 903, ASTM E 1918, or ASTM C 1549. Emittance is measured according to ASTM E408 or ASTM C 1371. 3 For the purposes of this credit, under cover parking is defined as parking underground, under deck, under roof, or under a building.
SITES-LEED Equivalency
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.
See all forum discussions about this credit »
See all forum discussions about this credit »