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LEED v2009
Healthcare
Sustainable Sites
Heat island effect - roof

LEED CREDIT

Healthcare-v2009 SSc7.2: Heat island effect - roof 1 point

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© 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 »

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Addenda

8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the term, "Roof area is the area of the uppermost surface of the building which covers enclosed Gross Floor Area, as measured when projected onto a flat, horizontal surface (i.e. as seen in Roof Plan view). \'Roofs\', or portions of roofs, covering unenclosed areas (e.g. roofs over porches and open covered parking structures) are not included in the areas used to evaluate compliance with SSc7.2, though they may be applicable to SSc7.1."
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Rating System Correction
Description of change:
Below equation, add the text and equation:Alternatively, the following equation may be used to calculate compliance:(see image)
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Make the following text bold, "ASTM E408-71(1996)e1, Standard Test Methods for Total Normal Emittance of Surfaces Using Inspection-Meter Techniques".
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the term "An appurtenance is any built-in, nonstructural portion of a roof system, such as skylights, ventilators, mechanical equipment, partitions, and solar energy panels."
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Add "skylights" to the list of things deducted from the roof area so that the sentence reads, "Determine the area of the roof covered by mechanical equipment, solar energy panels, skylights, and other appurtenances, and deduct these areas from the total roof surface area."
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Below equation, add the text and equation:Alternatively, a weighted average approach may be used to calculate compliance for multiple materials:(see image)
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Rating System Correction
Description of change:
Below equation, add the text and equation:Alternatively, a weighted average approach may be used to calculate compliance for multiple materials:(see image)
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Below equation, add the text and equation:Alternatively, the following equation may be used to calculate compliance:(see image)
Campus Applicable
No
Internationally Applicable:
No
8/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the term "photovoltaic panels" with "solar energy panels" and add "other appurtenances" to the list of things deducted from the roof area so that the sentence reads "Projects may earn an Innovation in Design (ID) credit for exemplary performance by demonstrating that 100% of the project\'s roof area (excluding any mechanical equipment, solar energy panels, skylights, and other appurtenances) consists of a vegetated roof system."
Campus Applicable
No
Internationally Applicable:
No
8/1/2011
LEED Interpretation
Inquiry:

Many of the ASTM Standards we reference have been withdrawn, upgraded, or superseded. Provide guidance on which updated standards should be used.

Ruling:

The withdrawn ASTM Standards listed- ASTM E1980-01 and ASTM E903-96- are still the correct references for SSc1: Site Selection, SSc7.1: Heat Island Effect, Non-Roof, and SSc7.2: Heat Island Effect-Roof. These two standards were not withdrawn for technical reasons, but were withdrawn because they had not been updated within 8 years. Testing can still be performed for these as well as the superseded standards. The updated versions of the superseded standards can be used, but are not required:Old: ASTM E408-71(1996), Current: E408-71(2008)Old: ASTM C1371-04a, Current: C1371-04a(2010)Old: ASTM E1918-97, Current: E1918-06 Old: ASTM C1549-04, Current: 1549-09Note: This Interpretations is also applicable to Sustainable Sites Credit 7.1: Heat Island Effect- Non-Roof and Sustainable Sites Credit 1: Site Selection, see LEED Interpretations dated 8/1/2011 ID number 10092 and 10094 respectively. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012
LEED Interpretation
Inquiry:

Can sidewalks, roads, and other hardscape areas located above a project building\'s underground parking structure, which are required by the governing municipality to be constructed of non-compliant materials, be excluded from the SSc7.2 and SSc7.1 calculations?

Ruling:

Similar to LEED Interpretations #2293 and #3101, sidewalks, roads, and areas that cover un-conditioned spaces (such as parking garages) are considered hardscape or landscape nonroof surfaces. Thus, they should be included in the calculations for SSc7.1 Heat Island Effect- Nonroof. In situations where infrastructure, materials, or surfaces are owned, operated and maintained by the local governing body, project teams may exclude the area of the material from the calculations for SSc7.2 and SSc7.1. This exemption can be applied only if projects do not have any control over the materials used for the surfaces in question. If the materials are owned and operated by the project, but the local jurisdiction specifies that they must meet certain criteria, the materials may not be excluded from the calculations. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

There is a stainless steel tube veil that covers the complete building. The tubes are placed with a 1 mm spacing between each other, and the material interior cannot be seen. Therefore, we would like to conduct a test to verify if the SRI of the tubes will comply with the LEED requirements (equal or greater than 78). Due to the originality of the exterior facade, we would like to know what type of test should be conducted:
Option 1 - Test using a 4mx4m mock up of the roof assembly and test the reflectance per ASTM 1918,
Option 2 - A flat sample test of all the materials installed on the roof
Please advise if there are any other tests that would need to be conducted.

Ruling:

The Referenced LEED Standard of ASTM 1918-97 has been superseded by ASTM 1918-06. For a roof with a veil design, or similar non-homogenous materials, the project should perform a SRI test to ASTM E1175 - 87(2009) Standard Test Method for Determining Solar or Photopic Reflectance, Transmittance, and Absorptance of Materials Using a Large Diameter Integrating Sphere. When submitting for LEED Certification, please include a copy of this interpretation and a summary of any testing results that document the SRI rating for the installed veil surface.Projects may wish to test any mock-up to assess credit compliance before testing installed materials, but the testing for certification should be done for the installed roofing assembly. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012
LEED Interpretation
Inquiry:

Can helipads and other functional space areas be exempted from SSc7.2 Heat Island Effect- Roof calculations?

Ruling:

Roof area that consists of functional, usable spaces- such as helipads, recreation courts, and areas covered by equipment, solar panels, and appurtenances- can be exempted from the roof calculations for SSc7.2. Projects are not eligible for SSc7.2 if the exempted spaces encompass the entire roof area. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
See all forum discussions about this credit »

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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 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 LEEDuser forum discussions about this credit » Unsubscribe from discussions about Healthcare-v2009 SSc7.2