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LEED v2009
Schools
Sustainable Sites
Heat Island Effect—Roof

LEED CREDIT

Schools-2009 SSc7.2: Heat island effect - roof 1 point

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LEEDuser expert

Summer Minchew

Ecoimpact Consulting
LEED AP ID+C, O+M

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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 desk, 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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Frequently asked questions

We don't have enough SRI-compliant roofing to earn the credit, but we have a lot of relatively high-SRI roofing (SRI 70). Is there any way to earn the credit?

The answer to this question is available to LEEDuser premium members. Start a free trial »

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We don't know the SRI value of some roofing materials we are using. What should we do?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

What do I do about roof area covered by solar panels, skylights, space for occupants, helipads, etc.?

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Speaking of appurtenances, there is a rooftop pool. Should that be included? Do I need to figure out the SRI value of water?

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Do balconies and terraces need to be counted towards the roof square footage?

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How does one calculate the square footage of a pitched roof?

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What type of ongoing maintenance of the roof is required?

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Credit achievement rate

XX%

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LEEDuser expert

Summer Minchew

Ecoimpact Consulting
LEED AP ID+C, O+M

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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 desk, 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.

XX%

Upgrade to LEEDuser Premium to see how many projects achieved this credit. Try it free »

Got the gist of SSc7.2 but not sure how to actually achieve it? LEEDuser gives step-by-step help. Premium members get:

  • Checklists covering all the key action steps you'll need to earn the credit.
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  • Ideas for going beyond LEED with best practices.
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In the end, LEED is all about documentation. LEEDuser’s Documentation Toolkit, for premium members only, saves you time and helps you avoid mistakes with:

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  • Tracking spreadsheets for materials purchases.
  • Spreadsheets and forms to give to subs and other team members.
  • Guidance documents on arcane LEED issues.
  • Sample templates to help guide your narratives and LEED Online submissions.
  • Examples of actual submissions from certified LEED projects.

We don't have enough SRI-compliant roofing to earn the credit, but we have a lot of relatively high-SRI roofing (SRI 70). Is there any way to earn the credit?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

We don't know the SRI value of some roofing materials we are using. What should we do?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

What do I do about roof area covered by solar panels, skylights, space for occupants, helipads, etc.?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

Speaking of appurtenances, there is a rooftop pool. Should that be included? Do I need to figure out the SRI value of water?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

Do balconies and terraces need to be counted towards the roof square footage?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

How does one calculate the square footage of a pitched roof?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

What type of ongoing maintenance of the roof is required?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

LEEDuser expert

Summer Minchew

Ecoimpact Consulting
LEED AP ID+C, O+M

See all LEEDuser forum discussions about this credit » Subscribe to new discussions about Schools-2009 SSc7.2