EBOM-2009 SSc7.2: Heat Island Reduction—Roof

  • EBOM_SSc7-2_Type3_CoolRoof Diagram
  • Cool roof basics

    This credit provides a variety of options for using your project’s roof to reduce your contribution to the urban heat islandA densely populated area in which pavement and buildings absorb, store, and release solar energy, making the vicinity warmer than it would be if the pavement and buildings were not present. effect, while also potentially reducing your building’s cooling load.

    • Option 1: A light-colored roof with a high solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 index (SRI) on at least 75% of the roof areaRoof 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.
    • Option 2: A green roof on at least 50% of the roof area. 
    • Option 3: A combination of Options 1 and 2.

    Most projects will choose Option 1, since many buildings already have reflective roofs that comply with the high-SRI requirement. For these projects, this option is a no-cost way to achieve the credit, but teams should be aware that roofs will need to be cleaned and maintained on a biennial basis in order to preserve their reflective properties.

    You might also pursue Option 1 if your roof is nearing the end of its life and you need to replace it. You can fairly easily find light-colored roofing materials that are cost-competitive with conventional materials.

    If you have a newer roof that is not reflective, there are high-reflectance coatings on the market that can bring your roof up to the required SRI, but these can be expensive per square foot and are a less common strategy for achieving the credit.

    SRI diagramThe most common approach to this credit is Option 1, the use of roofing materials with a high SRI, meaning that more heat is reflected. Most projects pursue Option 1 when a compliant roof is already in place. Illustration – BuildingGreen.com

    What’s “SRI”?

    The “solar reflectance index” or SRI is the measure of a surface’s ability to reflect solar heat. Higher reflectivity is desirable, because it helps combat the urban heat island effect. SRI can range from zero to over 100, with darker surfaces closer to zero and lighter surfaces approaching 100.

    Slope matters

    When dealing with the high-SRI option for this credit, the SRI requirements vary according to the slope of the roof. A steep-sloped roof must have an SRI greater than 29 in order to be eligible for the credit, while a low-sloped roof must have an SRI greater than 78.

    A little wiggle room

    If your roofing material doesn’t quite have a high-enough SRI value but it covers more than the required 75% of the surface area, you can still comply with this credit through a calculation done automatically in the LEED Online credit form. For example, if a building has a flat, 10,000-square-foot roof, and 7,500 square feet has an SRI of 78, the project meets the minimum qualification for the credit. An otherwise identical building with a roof-SRI-value of 59 for the entire roof surface area would also meet the requirement.

    Chicago City Hall green roofA green roof is a less common way to earn this credit, but if you have one, like Chicago City Hall, the credit should be a piece of cake. Photo – RoofScapes, Inc.

    Green roofs are somewhat less common

    Vegetated or “green” roofs are a less common strategy for achieving this credit. The presence of a green roof will effectively contribute to increased energy savings, improved wildlife habitat, and better stormwater management (see LEEDuser’s green roofs strategy page); however, implementation may be limited by variations in roof structural capacity, local climate, and cost.

    Vegetated roofs generally have higher first costs compared with more traditional roof systems, although they may have a more favorable life-cycle costEconomic cost of a product or building over its expected life, including first cost, operating cost, and, when appropriate, cost of disposal or demolition.

    Consider these questions when approaching this credit

    • Is the existing roofing membrane credit-compliant? Can you track down the SRI value from the manufacturer?
    • Has regular cleaning (at least every two years) been conducted to maintain the SRI value? Can cleaning be arranged in the future? 
    • If the roof is not compliant, when is it due for replacement? Could the roof be replaced with credit-compliant roofing before or during the performance period?
    • If the roof is not compliant, can a coating be applied to raise the SRI value to a compliant level?
    • Is a vegetated roof a viable alternative? Can a green roof be supported structurally? Is the climate conducive to supporting native plant life without permanent irrigation? Have other buildings in this locale successfully used green roofs? Is a green roof cost effective over the long term?

    FAQs for LEED-EBOM SSc7.2

    We’re working on an international project and having a hard time finding a coating with a published value for Solar Reflectance Index. If the coating is white, can we assume that it qualifies?

    It is not possible to assume that a light-colored roof or coating has a compliant or high SRI value. The SRI for different products vary even if they have a similar looking color. The SRI value of any coating has to been verified through manufacturer data or independent testing.

    Are solar panels always excluded from the roof area for the purposes of the credit calculations?

    Yes, solar panels, including building integrated solar panels are treated the same as mechanical equipment and other roof appurtenances and are excluded from the credit applicable roof area. For example, if you have a 10,000 ft2 roof and 5,000 ft2 is covered by solar panels, only the remaining 5,000 ft2 of uncovered roof area is considered in the credit calculations.

    Why does the form calculate my high-albedo roof area, as a value greater than 100% of total roof area?

    The form is calculating a weighted high-albedoAlso known as solar reflectance: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 area based on the solar reflectance index of the roofing material. So, a low-sloped roof with an SRI value of 100 has a higher weighted area than a roof with an SRI value of 85. Because the required SRI value is 78 for at least 75% of the roof area, if you have SRI value greater than 78 or if you have more than 75% of the roof covered with high-albedo materials, your weighted average can easily be more 100%.

    What needs to be included in the roof maintenance program?

    The program needs to confirm that maintenance activities are conducted at least every two years in order to retain the roofing material’s SRI characteristics. Generally, the program should involve cleaning the roof according to the manufacturer recommended protocol.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Before the Performance Period

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  • Assess the building’s current roof for compliance. Compliance can be demonstrated through:

    • Option 1: A light-colored roof with a high “solar reflectance index” (SRI) on at least 75% of the roof area. 
    • Option 2: A green roof on at least 50% of the roof area. 
    • Option 3: A combination of both Options 1 and 2.

  • Projects usually approach this credit through Option 1 materials, particularly if reflective roofing is already in place. High-SRI roofs are typically white or light-colored.


  • If your project already has a credit-compliant roof in place, this is a no-cost credit.


  • If your roof is light-colored and appears to be compliant, track down the manufacturer’s documentation confirming the roof’s SRI value. Product cut sheets typically include this information. Manufacturers might report an SRI value, or they may provide values for reflectance and emittance (both are numbers between 0 and 1) from which SRI can be calculated using the LEED Online credit form.  


  • If you can’t find published SRI numbers for your existing roof, you can send a piece of the roofing material to a lab for testing to confirm its SRI value. However, this is not commonly done because most buildings do not want to take out a piece of the roof. The Cool Roof Rating Council website provides a list of available Accredited Independent Testing Laboratories across the country (see Resources). Testing fees will vary, but are typically a few hundred dollars; check with each lab on its testing fee.


  • The LEED Reference Guide provides a table of typical SRI values for common roofing materials. These values are for reference only and cannot be substituted for the actual product SRI value in your LEED documentation.


  • If the SRI value is high enough, confirm that the compliant area covers at least 75% of your building’s roof.


  • Different SRI values are required for low-sloped roofs (SRI >78) and steep-sloped roofs (SRI >29). 


  • Quantify areas covered by any mechanical equipment or other appurtenances such as plumbing stacks, air vents, skylights, and solar panels. These areas will be deducted from the total roof area when calculating compliance in the LEED Online credit form. 


  • SRI value not high enough? Check the weighted-average value, which is calculated automatically through the LEED Online credit form. This situation applies to flat roof with SRI value less than 78, but covering greater than 75% of the roof area, or steep roofs with SRI less than 29 covering more than 75%. For example, for a flat 10,000 ft2 roof, if 7,500 ft2 (75%) is covered in a material with an SRI of 78 the project qualifies for the credit. An identical building with an SRI-roof-value of 59 for the entire 10,000 ft2 would also comply.


  • If your building has an existing vegetated roof, confirm that it covers at least 50% of the roof area.


  • If your roof does not meet credit criteria, investigate options for retrofitting the roof in order to become compliant.


  • In cases in which the roof may be ready for replacement, compliant roofing materials can easily be selected.


  • Most buildings in this circumstance will already have money allocated for roof replacement, and compliant roofing materials are consistently cost-neutral or cost-competitive compared with more conventional options.


  • If roof replacement is not necessary, project teams can investigate coatings that are applied to a roof retroactively to increase the SRI value.


  • High-SRI coatings tend to work best on low-sloped roofs, and non-metallic coatings provide the best reduction in roof heat gain.


  • Though coatings are available to increase the SRI value of a non-compliant roof, this strategy is not often pursued. This may be due in part to the cost of cool-roof coatings, which can run from $0.75–$1.50 per square foot. Teams should consider the payback from reduced cooling costs when considering this option.


  • Vegetated roofs are less often pursued due to a number of factors, including the structural capacity of the roof, the local climate, and cost. However, green roofs can also have a number of other environmental benefits beyond heat-island mitigation. These include stormwater management (SSc6), wildlife habitat (SSc5), and increased roof life, which can lead to capital costs savings in the long term. See LEEDuser’s green roof strategy page for more information.


  • Vegetated roofs consist of layers that are generally installed as a layered system or all at once as a set of interlocking trays: 

    • waterproofing membrane, 
    • root barrier, 
    • drainage layer, 
    • lightweight soil or engineered growing medium, 
    • and vegetation.

  • Determine the load-bearing capacity of the building before investigating different vegetated roofing types. Consider these issues: 

    • the weight of the system, 
    • maintenance issues and access, 
    • upfront and long-term costs, 
    • and irrigation needs.

     

During the Performance Period

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  • For SRI-compliant roofs, implement a maintenance program to ensure that the roof is cleaned at least every two years to maintain its reflective properties.


  • Many buildings don’t have an official procedure for roof cleaning, so this will need to be established. If you are attempting SSc2: Building Exterior and Hardscape Management Plan, you can add this task as part of that plan.


  • Accessing the roof, and safety while cleaning, can be issues for some buildings. If necessary, contract with a roof-cleaning service to conduct regular roof maintenance and cleaning. Your project team can also consult with the roofing manufacturer for advice on cleaning your building’s roof.

  • USGBC

    Excerpted from LEED 2009 for Existing Buildings: Operations & Maintenance

    SS Credit 7.2: Heat island effect - roof

    1 Point

    Intent

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

    Requirements

    Option 1

    Use roofing materials with a solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 index (SRI)2 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 SIR value than those listed below ay be used if the weighted rooftop SRI average meets the following:

    Area Roof Meeting Minimum SRI

    ————————————————

    Total Roof AreaRoof 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.


    x SRI of Installed Roof

    ——————————

    Required SRI


    75%


    Implement a maintenance program that ensures all SRI surfaces are cleaned at least every 2 years to maintain good reflectance.

    OR

    Option 2

    Install and maintain a vegetated roof that covers at least 50% of the roof area.

    OR

    Option 3

    Install high-albedoAlbedo is synonymous with solar reflectance. 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 ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services 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.


    Potential Technologies & Strategies

    Consider installing high-albedoAlbedo is synonymous with solar reflectance. and vegetated roofs to reduce heat absorption.. Default values are available in the LEED Reference Guide for Green Building Operations & Maintenance, 2009 Edition. Product information is available from the Cool Roof Rating Council Web site at www.coolroofs.org. Also visit the ENERGY STAR® Web site, at www.energystar.gov.

Organizations

Cool Roof Rating Council

This nonprofit organization is dedicated to implementing and communicating fair, accurate, and credible radiative energy performance rating systems for roof surfaces; supporting research into energy-related radiative properties of roofing surfaces, including durability; and providing education and objective support to parties interested in understanding and comparing roofing options. 

Web Tools

Lawrence Berkeley National Laboratory, Heat Island Group—Cool Roofs

This site offers a wealth of information about cool roof research and technology, including links to a cool roofing materials database. 

 

Publications

Energy Star Roofing Products

This site indicates the solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 levels necessary to meet Energy Star requirements for qualified roof products. 


EPA Heat Island Effect

Provides some background and cost/benefit analysis of cool roofs.

LEED Online Forms: EBOM-2009 SS

The following links take you to the public, informational versions of the dynamic LEED Online forms for each EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems.-2009 SS credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.

Version 4 forms (newest):

Version 3 forms:

These links are posted by LEEDuser with USGBC's permission. For more information, visit LEED Online and click "Sample Forms Download."

LEED Online Form

This sample LEED Online form with annotations demonstrates how to document SSc7.2.

58 Comments

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Mary Ann Santos
Feb 12 2013
LEEDuser Member
1217 Thumbs Up

Weighted approach / SRI below 78

Our project has a low-slopped roof deck that proposes to comply to this credit via Option 3 - combination of high-SRI material and vegetated roof.

If we apply a paint that has an SRI value below 78, say 68 (gray color), will we be able to claim the credit? Can we use the weighted average formula? Thanks.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Feb 12 2013 LEEDuser Moderator

Mary Ann, this seems to go along with how Option 3 should work. Do you have any concerns about the approach?

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Mary Ann Santos Feb 13 2013 LEEDuser Member 1217 Thumbs Up

Thanks, Tristan. Also found an answer to my inquiry in the "A little wiggle room" section above.

I just thought that it is a must that the roofing materials have a solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 index (SRI) equal to or greater than the values for low-slopped roof, i.e. SRI of 78.

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David Tetro Principal & LEED-AP David A. Tetro - Architect P.C.
Apr 10 2012
LEEDuser Member
23 Thumbs Up

Documentation of Roof - In General

Hi all - just a question as I am new to this...
I am looking to get certification for an existing building (EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems.) and I have all the drawings in CAD - however, under normal circumstances, there are a series of drawings for the project. In LEED Certification, do you create a drawing(s) for each credit you are going for separately or do you just have all the darwings for all the credits and upload that. I am thinking you make a 'package' with all relevant documentation and calculations and data for each point separately. Am I correct to assume this? I am just asking all of you that have more experience than me...I thank you in advance for your assistance.

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Ben Stanley Sustainability Manager, YRG sustainability Apr 10 2012 LEEDuser Expert 3037 Thumbs Up

You're on the right track and I would customize the plans and supporting documentation for individual credits based on the documentation requested on the credit form for each credit on LEED Online.

Don't upload a single package. The reviewer will just want to see the specific information requested on the credit form.

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Kelly Wieczorek Bay Design Associates Architects
Feb 16 2012
Guest
161 Thumbs Up

Can the existing roof count?

If our existing roof meets the requirements can we achieve the credit, or does there have to be a change/upgrade from the existing to comply?

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Emily Catacchio Sustainability Specialist, Wight and Company Feb 17 2012 LEEDuser Moderator

As long as you can document that the existing roof complies, you do not need to change it.

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David Tompos President NTA, Inc.
Jan 30 2012
Guest
60 Thumbs Up

Roof Area definition

The definition for roof areaRoof 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. indicates that only the roof area directly above the Gross Square FootageSum of the floor areas of the spaces within the building including basements, mezzanine and intermediate-floored tiers, and penthouses with headroom height of 7.5 ft or greater. It is measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but excluding covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features. should be used for the Option 1 - 75% calculation. However, on our project site, there is a maintenance/stoarge building. It is not connected to the project building, has no occupants, no plumbing or HVAC units. It is enclosed (walls, doors etc). Do we need to consider this other building's roof area (above its Gross Square footage) in the Option 1 compliance path? It appears that it should not be included in the Option 1 copmliance path calculation, but can anyone confirm that it doesn't apply?

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Ben Stanley Sustainability Manager, YRG sustainability Feb 21 2012 LEEDuser Expert 3037 Thumbs Up

I'm not 100% sure whether your required to include that roof areaRoof 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. or if it should be excluded. But, given that the intent of the credit extends beyond cooling loads and electricity consumption in the building, it seems like a good idea to include.

If the project is compliant either way, I would include the area and then add a narrative explaining that you've included both roof areas. This is important also to explain any inconsistencies this might cause with values reported in the PI forms.

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Mauricio Ramirez
Jul 06 2011
LEEDuser Member
285 Thumbs Up

Floated tile paving and Heat Island Effect

I have a building that has in the most part of their roof, a floating tile paving, that creates an air-chamber between the slab of the roof and the tilies of the paving. Is it considered a cool roof strategy valid for LEED in this Credit?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Sep 02 2011 LEEDuser Moderator

Mauricio, this strategy is not a "preapproved" strategy for this credit, which is not to say that it wouldn't work. I would encourage you to submit documentation showing how effective it will be, but I would not count on earning the credit in this way.

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Andy Rhoades Partner Leading Edge Consulting
Apr 29 2011
LEEDuser Member
317 Thumbs Up

Helipad

Would a helipad be considered as an exclusion in the square footage count, similar to the mechanical equipment or solar panel?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. May 24 2011 LEEDuser Moderator

I wouldn't see a helipad meeting this standard. Seems like it could easily have a reflective coating, anyway?

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Andy Rhoades Partner, Leading Edge Consulting Aug 24 2011 LEEDuser Member 317 Thumbs Up

It has a Sherman Williams white coating, but the paint is not tested, and the company is not about to go test it either. Do you think the white coating would pass regardless? It's been there for years now.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Sep 02 2011 LEEDuser Moderator

Andy, I doubt it. You would be expected to get the paint tested by sending a sample to the lab. That is the standard approach for this credit, even if it can be a pain.

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Andy Rhoades Partner, Leading Edge Consulting Nov 10 2011 LEEDuser Member 317 Thumbs Up

We should get at least 1 point without excluding the helipad, but could get 2 if they were to exclude it (as a backup IO pt.) We'll keep you posted on the outcome.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Feb 12 2013 LEEDuser Moderator

Andy, I was surprised to learn recently that there is a LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. that counts helipads as appurtenances and thus excluded from the credit. At least, I know this Interpretation applies to LEED-NC. If the project is still active you could check on its applicability to EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems..

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Jaida Anderson-Lozano Enivronmental Engineer, Skanska Sverige AB Feb 13 2013 LEEDuser Member 294 Thumbs Up

We submitted a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide to exclude the helipad sqft from the roof areaRoof 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. and it was approved. The arguement was the helipads are confined to standards set by the Swedish Air Aviation Regulator and material must comply with those requirements. In addition our project was a hospital project and the helipad area is considered an emergency area which was supported by the CIR reviewer, "because the helipads are for public health, safety, and welfare and their standards are set for the local governing body, they may be excluded from SSc7.2 calculations"

Not sure what your building type is but this could be a strategy.

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Matthew Perna Architect CMA
Dec 30 2010
Guest
243 Thumbs Up

Roof with solar panels

Does anyone know why a roof covered with solar panels wouldn't apply to credit 7.2: Heat Island Reduction--Roof? The USGBC allows it to be used toward credit 7.1 where a roof with solar panels is used to shade a parking area, but not toward 7.2.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 30 2010 LEEDuser Moderator

Solar panels do help you with SSc7.2, in the sense that they are considered appurtenances and are not counted as part of your roof areaRoof 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.. So use of solar panels effectively reduces the area that you need to consider for other measures.

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Kendall E Design Partners Inc. Jan 10 2011 LEEDuser Member 267 Thumbs Up

does anyone know if the same applies to a green roof application as well?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jan 10 2011 LEEDuser Moderator

Denise, green roofs are a key way to earn SSc7.2. I'm not sure if that's your question, though -- can you clarify?

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Kendall E Design Partners Inc. Jan 10 2011 LEEDuser Member 267 Thumbs Up

sorry, i meant for option 1 of ssc7.2. If I go the reflective materials route, am i able to not count green roof and photovoltaic panels as part of my total roof areaRoof 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.?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jan 10 2011 LEEDuser Moderator

Denise, Option 3 is a combination of Options 1 or 2. So it's not either/or.

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John Kinch Mar 23 2011 Guest 172 Thumbs Up

To clarify,

We have existing solar roof shingles which cover approximately 50% of our roof. Are solar shingles still considered appurtenances? Because of the slope and the weight load we cannot do the green roof option, though we are considering the white roof option for the other portion of it.

Thanks!

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David Posada Sustainability Manager, GBD Architects Mar 24 2011 LEEDuser Expert 11303 Thumbs Up

That should work - your solar shingles in this case would be considered mechanical equipment, which you subtract from your total roof areaRoof 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., and use white/ high SRI roof for 75% of the remainder.

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Ben Hollon Mechanical Engineer Antella Consulting Engineers
Dec 17 2010
Guest
421 Thumbs Up

Roof Plan Submittal

I have a roof plan that was created by the original architect. I can add a few things in Photoshop and have a pretty nice looking submittal but I was wondering if this would be frowned upon. It feels like I am "stealing" the architects work. My team has debated erasing the existing title block and adding our own, or adding a blurb about how the drawings are being used w/ permission from the client solely for LEED purposes. What is normally done in the submission process with this issue? Do we even need to change anything with the existing title block?

Thanks.

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David Posada Sustainability Manager, GBD Architects Dec 20 2010 LEEDuser Expert 11303 Thumbs Up

It may be acceptable to mark up or alter the drawings, as long as you a) have permission from the architect as well as the client for the specific use or changes, and b) make it clear which information is yours.

We've had LEED reviewers who suggested we hide or turn off unnecessary information in the drawings or make it very obvious where the relevant LEED info was. Their priority is more for efficient review and are less concerned with format formalities. Anecdotally, I'd say that LEED submissions need to "clear, complete, and credible," (to coin a phrase) but there are no legal or policy guidelines for format, title blocks, or attribution.

Many architects will remove their stamp from the title block of drawings submitted for LEED and provide a disclaimer "For LEED Documentation - Not Intended for Construction" to make it clear that these are not Construction Documents, which become part of a legal contract between the general contractor and owner.

You might consider adding a key note with date and LEED purpose to the title block or notes area and then use revision clouds, color circles, or highlighting, etc to make the LEED specific information on the drawings more obvious. With permission, you could also use the original drawings as "backgrounds" for your own photoshoped sheet, and make your markup and highlighting clearly your own.

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Jorge Lopez de Obeso Principal Energia y Arquitectura
Dec 08 2010
Guest
47 Thumbs Up

Example Roof Maintenance Program.

Do any of you guys have a complete roof maintenance program that can be shared? I'm not sure if the document needs to be as simple as it sounds or would need to have a number of specifications. My roof isn't sloped at all and it has an area of approx. 1800sq ft. Thanks in advance!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 28 2010 LEEDuser Moderator

Jorge, we don't have a sample. I think it can be pretty simple, though.

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Marc Mondor Principal evolve LLC
Oct 08 2010
LEEDuser Member
527 Thumbs Up

Glass SRI

Has anyone had any experience with glass roofs? We are working on a greenhouse and need some advice on calculating the area covered in glass. I assume that this cannot be considered one large skylight.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Oct 08 2010 LEEDuser Moderator

I think you would have to test the glass, if there isn't a manufacturer you can get specs from. There is so much variation in the performance of glass.

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Jutta Berns-Mumbi principal ecocentric cc
Aug 31 2010
LEEDuser Member
1042 Thumbs Up

material specification

where we are located, SRI is not a common terminology and we are currently in the process of specifying an SRI compliant roof coating for a roof which is currently undergoing repainting/repair.

the product we are looking at gives us the following data:
heat reflectance: >99%
emittance: 0.88

if i assume that heat reflectance equates to solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892, we can achieve an SRI of over 126. Are my assumptions correct? or is heat reflectance not the same as solar reflectance?

all the other information contained in the data spec for this particular product indicate that this is a cool roof product - but since it is not a US product, the terminology is a bit confusing to us.

many thanks!

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Jacob Arlein Director of Energy Services, Environmental Building Strategies Aug 31 2010 Guest 550 Thumbs Up

Jutta,
I am not exactly sure what you mean by heat reflectance, do you mean thermal reflectance? Either way, heat reflectance is not the same as solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 or albedoAlbedo is synonymous with solar reflectance.. AlbedoAlso known as solar reflectance: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892 is the ratio of total-reflected to incident electromagnetic radiation from the sun. This is a measure over all wavelengths of light.

It is likely that this product is still a cool roof product with such a high thermal emmitance level, but you will have to determine the solar reflectance of the material to be able to accurately calculate SRI.

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Jutta Berns-Mumbi principal , ecocentric cc Aug 31 2010 LEEDuser Member 1042 Thumbs Up

many thanks for the response and i understand the point you make.

unfortunately the data sheet simply states "heat reflectance" and "emittance" - as above - and also has a value for thermal conductivity (0.09 W/m°K).

are there any other resources we could consult to help us calculate the SRI correctly with the information that we have available?

indeed all products that we have been able to source so far (we are located in South Africa) only provide, if at all, values for heat reflectance and emittance.

we are being pushed to make a decision on the coating and really do not want to lose the point on documentation, if it seems that we may be quite close!

many thanks!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 31 2010 LEEDuser Moderator

Can you ask the manufacturer to clarify, or offer better data?

This may simply be a language issue, where what they are calling "heat reflectance" is in fact "solar reflectanceAlso known as albedo: the fraction of solar energy that is reflected by a surface on a scale of 0 to 1. Black paint has a solar reflectance of 0; white paint (titanium dioxide) has a solar reflectance of 1. The standard technique for its determination uses spectrophotometric measurements, with an integrating sphere to determine the reflectance at each wavelength. The average reflectance is then determined by an averaging process, using a standard solar spectrum, as documented by ASTM Standards E903 and E892."

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Jutta Berns-Mumbi principal , ecocentric cc Sep 01 2010 LEEDuser Member 1042 Thumbs Up

Many thanks! have done so and it was indeed simply a language issue and the test reports have now confirmed the values. Such is the excitement of working on projects outside the US!

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Yun Day Firm Administrator Shlemmer+Algaze+Associates
Aug 30 2010
LEEDuser Member
361 Thumbs Up

75% COMPLIANCE area

Our roof is 100% covered with White EPDM material. On top of that material are the HVAC units. There are also a couple of vents and a hatch opening for roof access. All these things add up to 56.5% of the roof areaRoof 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.. Does this forfiet me from getting credit SS c 7.2? Since I do not have 75% of the roof clear of obstructions? Thanks.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 30 2010 LEEDuser Moderator

Appurtenances such as HVAC equipment, etc., can be excluded from the calculations. Good news for your project.

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Paul C Sep 10 2010 Guest 1842 Thumbs Up

Does this mean if the building 100' x 100' for example = 10,000 sq/ft total roof surface, you will use 10,000 sq/ft as your total roof sq/ft. even though your roof may only be really covered by 50% SRI membrane and the other 50% HVAC appurtenances, etc...??

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Sep 10 2010 LEEDuser Moderator

When you're documenting this credit in LEED Online, the form asks you to provide total roof areaRoof 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. "excluding mechanical equipment, photovoltaic panels, and skylights)." So, you're not entering total roof area, you're entering total roof area that is eligible for consideration under the credit. You're also uploading a roof plan and other documentation. Make sense?

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Yun Day Firm Administrator, Shlemmer+Algaze+Associates Sep 13 2010 LEEDuser Member 361 Thumbs Up

That makes perfect sense Tristan. What doesn't make sense is that when LEED asks for the SF (from LEED;Note that in the table below, 'Square footage' refers to the actual area of roof covered by the SRI surface) and then asks for "Total roof areaRoof 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. (excluding mechanical equipment, photovoltaic panels, and skylights) (sf):"
and then I calculate I get a number of 243.55%. Because my the overall SF is 5932 sf and the number excluding the appurtenances is
2591.75 I come out with that strange number.

LEED's response was this;
Response: The information provided above indicates that the area of White EPDM (5932 sf) exceeds the total roof area (2591 sf). This information would indicate that the reported square footages may be incorrect and would indeed result in > 100%. Perhaps the numbers are switched? Also, please note that the calculation for the SRI compliant area is weighted based on the SRI value. Therefore, when using high SRI materials, it is possible that this calculation will demonstrate > 100% compliant roof area.

I guess what they are saying is that it is okay to have a 200+% number. Does that make any sense to you? If it does I have completed this credit.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Sep 15 2010 LEEDuser Moderator

You didn't mention your SRI values, but if they're higher than the minimum requirements, it's not surprising that the weighted value would generate a weird-looking percentage number.

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Andrea Marzullo LEED Specialist, OSC/CFEEA Oct 03 2011 Guest 203 Thumbs Up

Just to be sure....table SSc7.2-1 asks for the total square footage of the reflective material. And THEN it asks for the total square footage of the roof MINUS the solar panels, skylights and mechanical equipment. I have entered in the relective material square footage which is a larger number than the square footage minus the appurtenances. And this will be okay? Shall I upload a spreadsheet with all the square footage numbers in it (total roof, roof minus LEED-allowed appurtenances, roof minus terrace and other "non-roof" surfaces, etc)?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 14 2011 LEEDuser Moderator

Andrea, I don't see how the SF of your reflective material could be larger than the SF of the applicable roof areaRoof 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.. It implies that some of the area you are counting as appurtenances actually has relfective roofing on it. Or am I misunderstanding something?

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Andrea Marzullo LEED Specialist, OSC/CFEEA Nov 15 2011 Guest 203 Thumbs Up

Exactly, Tristan. Our RTU-1 rooftop unit (5794 square feet) actually has the reflective roofing on it. I should be okay, right? I uploaded a very clearly labeled Google Earth map.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 15 2011 LEEDuser Moderator

Yes, that sounds okay. Hopefully everything is clear to the reviewer and you don't have any difficulties.

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wayne hendrickson
Aug 05 2010
Guest
83 Thumbs Up

Shaded roof

If the shaded roof areaRoof 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. exceeds the 75% does that meet the requirement of this credit. I have a building that has an architectural crown of white glass that shades over 75% of the roof surface at any given time.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 05 2010 LEEDuser Moderator

Wayne, there's no shading option for this credit. The white glass must meet the SRI requirements of Option 1. (See above for more.)

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Michael Williams
Jun 01 2010
Guest
81 Thumbs Up

What if the roof doesn't requiring replacing?

Our project's roof does not meet the credit requirements. The owner is willing to spec a compliant roofing system; however, the roof is in good conditions and still has 7 years left on its warranty. Is a commitment to purchase a compliant roofing system once the roof requires replacement a valid compliance path? I'm guessing based on Kim's experience above that this is not likely a possibility. It seems a bit 'counter-green' to replace a roofing system that is still in good working order.

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Natalie Bodenhamer Associate, Altura Associates, Inc. Jun 01 2010 LEEDuser Expert 676 Thumbs Up

A commitment to purchase a compliant roof system does not meet the credit requirements of SSc7.2. This is a great opportunity to integrate the roof replacement into the LEED EB Recertification plan/strategy. The replacement may impact energy efficiency (EAc1), in addition to SSc7.2.

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Cara Weber
May 21 2010
Guest
136 Thumbs Up

Ballasted Roofs SRI?

Has anyone had luck getting a good SRI rating out of existing ballasted roofs? Apart from sending this to a lab, are there any charts or other information to use? Has anyone successfully gotten this credit when their building has a majority of light-colored ballasted roofs?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. May 28 2010 LEEDuser Moderator

Cara, I don't have definite answers to any of your very good questions, but I did find some interesting resources. A fairly recent note in the Cool Roofs Rating Council newsletter that makes it sound like ballasted roofs are gaining acceptance as "cool" roofs. Also, a study from ORNL that may be behind some of this recognition.

I'm not sure where this leaves you, except perhaps with some encouragement that you're on a reasonable path.

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BKSK Architect BKSK Architects Jun 01 2010 LEEDuser Member 467 Thumbs Up

Just to clarify a bit further, while white ballasted roofs are showing evidence of performing as well as other "cool roof" systems, the USGBC does not recognize any flat roof material under a 78 SRI for the SScr7.2 LEED credit. This is because the intention of the credit for micro-climate development is not met by materials that do not meet this threshold.

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Jonathan Weiss Aug 16 2010 LEEDuser Member 1623 Thumbs Up

Just to echo what is stated above - we submitted a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide about a ballasted roof referencing the ORNL study and the CRRC information, and the response to the CIR confirmed that although the ballasted roof performs as well or better than a white roof for energy purposes, it does not meet LEED's requirements, because of the micro-climate issues listed above. It still may be better to use a ballasted roof in some situations, and forgo this particular LEED point.

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RASHID HAMEEN
Mar 25 2010
Guest
460 Thumbs Up

SRI compliant paints

What if we apply a paint, for instance lets say we apply White color paint which is not a specific reflective coating on our roof. Will we able to claim the credit?
If not, do we specifically need to make the roof by a compliant SRI material or by a specific reflective coating to meet the credit needs?
Please forward your ideas....Thanks

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 25 2010 LEEDuser Moderator

Rashid, you will need documentation showing that the paint or whatever else you apply is actually high SRI. You can't simply claim the credit by using a white color, since SRI values vary so much even with materials that may appear to be simlar colors. Also, keep in mind that SRI factors in emissivityEmissivity is the ratio of the radiation emitted by a surface to the radiation emitted by a black body at the same temperature. which is different than reflectivity. Polished aluminum, for example, is highly reflective but very poorly emissive.

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RASHID HAMEEN Mar 26 2010 Guest 460 Thumbs Up

Thanks tristan for your comments. In case if we couldn't find a coating which has data sheets to show compliance of that having a suitable SRI will it be sufficient if we check a sample with lab and show the compliance or does our test has to be done to a sample of the roof material which is after applying the paint..please post your comments.

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