NC-v2.2 SSc7.2: Heat Island Effect—Roof

  • NC_Schools_CS_SSc7-2_Type3_CoolRoof Diagram
  • Straightforward to achieve

    This credit is fairly straightforward and easy to achieve through prescriptive design measures such as using a light-colored roofing material or vegetation on a majority 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.

    The heat island effectHeat island effect refers to the absorption of heat by hardscapes, such as dark, nonreflective pavement and buildings, and its radiation to surrounding areas. Other sources may include vehicle exhaust, air-conditioners, and street equipment. Reduced airflow because of tall buildings and narrow streets exacerbate the effect. is more of a problem in urban environments with long stretches of hot weather. If your project is in such a location, this credit might be a higher priority from a comfort and energy perspective. Incorporating a reflective roof or green roof will help to reduce cooling loads, thereby lowing energy consumption and making for a more comfortable space.

    What’s “SRI”?

     “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 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. SRI can range from zero to over 100, with darker surfaces closer to zero and lighter surfaces approaching 100.

    Go green?

    Installing a vegetated, or “green” roof can be more expensive and complicated than installing conventional roofing. However, a green roof will be more effective in combating the urban heat island effect, can offer additional energy benefits to the building through insulation, and can offer stormwater and wildlife habitat benefits. 

    SRI diagramHigh-SRI roofing materials ensure that solar radiation is reflected back into space, rather than heating the building and the surrounding area. Image – BuildingGreen, LLCUsing a green roof to gain this credit helps contribute to many other LEED credits such as:

    FAQs for SSc7.2

    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?

    Yes, the credit allows for a weighted calculation approach. Many projects in this situation are able to comply. You will need to enter all the roof area that you hope to use to comply. See the calculator in LEEDuser's Documentation Toolkit.

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

    If it’s not possible to obtain values from the manufacturer, or a reliable industry source, then getting the material tested in a lab according to ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services standards is recommended.

    You can always simply exclude these materials and submit based on known materials.

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

    “Appurtenances” such as these are excluded from the credit. To quote from 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. #10235 made on 10/01/2012, “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.”

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

    You may exclude it. While pools are not specifically mentioned in LEED Interpretation #10235, GBCI has informed LEEDuse that it would probably count them as an appurtenance and exclude them. This is also supported by LEED Interpretation for SSc7.1, #1412 issued 2/7/2006, that excludes water features.

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

    Yes, if they protrude from the building and serve as a roof surface for conditioned spaces below.

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

    The square footage of a pitched roof (or a dome) should be determined by calculating the surface area of the roofing material itself, not the area as seen from above.

    What type of ongoing maintenance of the roof is required?

    Materials with high-reflexivity should be cleaned periodically to maintain their reflectance properties. An interval of every two years is usually sufficient. However, this is not a LEED credit requirement.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Pre-Design

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  • This credit is fairly straightforward and simple to achieve by using light-colored roofing, a vegetated roof, or both, on a large area of the roof. (See the credit language for exact thresholds—which are higher for light-colored roofing than for vegetated roofs.) 


  • Hold an integrated design meeting with the entire design team, including the architect, structural engineer, civil engineer, landscaper, owner, and others to help determine what kind of roof is most feasible and desirable for your project building. 


  • The following are a few of the many factors to consider:

    • Roof Pitch: If for climate or architectural reasons you need a sloped roof, a vegetated roof is less likely. Sloped roofs are also typically visible to passersby, so aesthetics are more of a consideration.   
    • Energy and comfort: The heat island effect is more of a problem in urban environments with long stretches of hot weather. If your project is in such a location, this credit might be a higher priority from a comfort and energy perspective. Light-colored and vegetated roofs reflect sunlight, thus lowering cooling bills. Green roofs also add insulation value to roofs, helping prevent both heat gain and heat loss. 
    • Climate and water: Does your site's climate support the use of a green roof? Will a vegetated roof require permanent irrigation? How does roof impact overall water balance of the site? Does your site need to control stormwater runoff?  Would a green roof help achieve stormwater runoff goals?
    • Structure: Does your project building have sufficient structural support for a green roof?  
    • Glare: Particularly for pitched roofs, consider impact of reflective or light-colored roofing on surrounding buildings and roadways. A glare study may be helpful in some cases.
    • Views: Often a green roof can enhance views compared with conventional roofing.
    • Maintenance: Light-colored roofs will benefit from periodic cleaning to maintain their reflectivity. Green roofs will need some level of landscape maintenance depending on the type of vegetation installed. 

Schematic Design

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  • Determine the total square footage of your building's roof surface, then subtract the space taken up by mechanical equipment, such as mechanical rooms for boilers and chillers, HVAC units, PV, skylights and other rooftop systems. The remaining area is the focus of calculations for this credit.


  • The square footage of a pitched roof should be determined by calculating the surface area of the roofing material itself, not the area as seen from above.


  • Treat terraces and balconies as roof square footage if they protrude from the building and serve as a roof surface for conditioned spaces below. The top layer over conditioned space counts as a roof. For example, in some high-rise applications a rooftop pool deck will need to factor into equations.  If an architectural covering or balcony does not have conditioned space below, it is counted as non-roof surface covering and is covered under SSc7.1: Heat Island Effect—Non-Roof.


  • Consider whether high-SRI materials are appropriate for any given application. Partcularly for occupiable roof spaces and roofs adjacent to glazing, there is a danger that some roofing materials will be too reflective, and cause glare problems. Not all high-SRI materials are the same in this regard because the metric is determined by both reflectivity and emissivity, so examine your choices for materials that work well.


  • Determine the square footage of the roof needed to be light-colored roofing or  a green roof by following one of the options below.


  • Most projects choose to go with a light-colored roof because there is less maintenance and upfront costs. However, low-rise buildings in particular (in which the roof is relatively important in maintenance and cost considerations) should consider the life-cycle cost benefits of green roofs, due to improved insulation and better roof durability.  


  • Option 1: Light-Colored Roofing Material on 75% of the Roof Area


  • 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.


  • Sloped roofs have different minimum SRI requirements because of the different angles at which the sun’s rays will hit the roof. For example, flat roofs receive more of the sun’s rays at direct angles, thus the SRI requirement for flat roofs is higher (i.e., for lighter material) than for sloped roofs. (See chart, from the credit language.)


  • Why are sloped roofs treated differently? A surface absorbs more energy from the sun when it is parallel to the ground plane. In the summer months when the heat island effect is more of a problem, the sun is nearly overhead, and flat roofs are in a position to absorb more heat, so it’s more important for them to have a higher SRI value.


  • If your roof has multiple pitches and material types, you can use a “weighted- area SRI” value, using "Equation 1" as follows from the LEED Reference Guide. See the Roof Weighted Average Calculator in the Documentation Toolkit for more examples and to see if your roof complies.   

    SSc7.2 Equation 1


  • The Lawrence Berkley National Laboratory has a database of typical roofing materials and their SRI values. The LEED Reference Guide has reproduced these values, which can be used as a guide, but not as actual SRI values, which must be obtained from your product manufacturer.   


  • The use of a light-colored roofing material typically reduces cooling bills, especially for low-rise buildings. 


  • Generally, there is no cost differential between light-colored roofing material and darker roofing materials.


  • Some municipalities and utility companies offer rebate for projects that install “cool” roofs.


  • Option 2: Green Roof on 50% of Roof Area


  • There are many options for building a green roof. For a more comprehensive approach to designing green roofs, see LEEDuser’s green roofs strategy page


  • While modular, or tray, systems can count as a green roof, LEED does not consider potted plants on the roof as a green roof.


  • Installing a green roof can contribute to many other LEED credits:

    • SSc5.1: Site Development—Protect or Restore Habitat 
    • SSc5.2: Site Development—Maximize Open Space 
    • SSc6.1: Stormwater Design—Quantity Control 
    • SSc6.2: Stormwater Design—Quality Control 
    • WEc1: Water Efficient Landscaping
    • EAc1: Optimize Energy Performance.

  • Although green roofs cost more than conventional roofs, a green roof can have a favorable life-cycle cost by increasing the life of the roof system below via sun protection. Their energy savings can also contribute to long-term financial benefits. 


  • Some municipalities, like New York and Chicago, offer incentives in the form of tax credits, rebates, and density bonuses for building green roofs. Check with your municipality for incentive opportunities. 


  • Green roofs create habitat for birds and wildlife and, if accessible, add amenities and learning tools for building occupants.  


  • A green roof can be used as a space to grow local food.


  • Option 3: Combination Light-Colored and Green Roof 


  • When a combination of green and light-colored roofs, use the formula below (from the official credit language):

Design Development

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  • Select the materials for your roof, and revisit your roof surface area calculations to ensure that you are still meeting the requirements for a light-colored, green, or combination roof.  


  • There are several online databases that help consumers choose roofing materials. The Energy Star Roofing Product site, for example, lists compliant SRI products. (See Resources.)  


  • You'll need to find the SRI value of the roofing materials you use from the manufacturer of the material. The typical values listed in the LEED Reference Guide are reproduced here for reference—but don't rely on them!

    Typical SRI values - table


  • Create a roof plan for LEED submittal that clearly indicates the following:

    • Square footage of the roof surface, broken out to indicate the specific areas of different types of roofing materials, as well as mechanical and aperture areas. 
    • SRI values, green-roof areas, and slope for all areas.

  • It is best to show the credit math right on the plan: total applicable roof area versus compliant, heat island-reducing roof area.  This makes it easier for the LEED reviewers to confirm compliance with the credit.

Construction Documents

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  • Include all specific material properties and SRI criteria in your construction and landscaping specifications. Roofing materials are important, of course, but also remember other materials on the roof such as pavers, walking pads, and other roof accessories (mechanical equipment is excluded).


  • Fill out the LEED Online submittal template and upload your roof plan and material cut sheets with SRI values clearly indicated.

Construction

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  • Ensure that the correct materials and landscaping are used.

Operations & Maintenance

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  • Include regular cleaning practices of roofing materials, especially for light-colored surfaces, as they will lose their ability to reject heat as they get darker and dirtier.


  • Include regular cleaning, watering, and weeding for green roof areas.

  • USGBC

    Excerpted from LEED for New Construction and Major Renovations Version 2.2

    SS Credit 7.2: Heat island effect - roof

    1 Point

    Intent

    Reduce heat islands (thermal gradient differences between developed and undeveloped areas) to minimize impact on microclimate and human and wildlife habitat.

    Requirements

    Option 1

    Use roofing materials having 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 in the table below for a minimum of 75% of the roof surface.

    OR

    Option 2

    Install a vegetated roof for at least 50% 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..

    OR

    Option 3

    Install high albedoAlbedo is synonymous with solar reflectance. and vegetated roof surfaces that, in combination, meet the following criteria:

    (Area of SRI Roof / 0.75) + (Area of vegetated roof / 0.5) >= Total Roof Area

    [INSERT TABLE HERE]

    Potential Technologies & Strategies

    Consider installing high-albedoAlbedo is synonymous with solar reflectance. and vegetated roofs to reduce heat absorption. 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. Emit- tance is measured according to ASTM E 408 or ASTM C 1371. Default values will be available in the LEED for New Construction v2.2 Reference Guide. Product information is available from the Cool Roof Rating Council website, at www.coolroofs.org.

Web Tools

Cool Roof Rebate Database

This is a database for local utilities that offer rebates for cool roofs.


U.S. EPA, ENERGY STAR Roofing Products

This site provides 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 required to meet ENERGY STAR requirements for qualified roof products.


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. 


Cool Roof Rating Council

This website includes a page where you can plug in the roofing type, color, and SRI and emittance values you're looking for, and it will provide a variety of products and manufactures who meet your criteria.

Organizations

Green Roofs for Healthy Cities

This nonprofit industry association consists of individuals and public and private organizations committed to developing a market for green roof infrastructure products and services across North America. 


Penn State University, Center for Green Roof Research

The Center has the mission of demonstrating and promoting green roof research, education, and technology transfer in the Northeastern United States.

Technical Guides

Whole Building Design Guide, Extensive Green Roofs

This article by Charlie Miller, PE, details the features and benefits of constructing green roofs. 

Sample Plan – Cool Roof

Option 1

The project shown in this sample plan complies with the requirement to have greater than 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. light-colored.

Product Cut Sheets

Option 1

Look to product cut sheets like these examples to find high SRI values, indicating roofing materials that comply with the credit requirements.

Roof Weighted Average Calculator

As described in the LEED Reference Guide, a weighted average calculation may be performed for buildings with multiple roof surfaces to demonstrate that the 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. has an average SRI greater or equal to a baseline theoretical roof with 75% at an SRI of 78 and 25% at an SRI of 30. Use this spreadsheet (with sample calculation) to determine if your roof complies—and if not, what adjustments need to be made.

LEED Online Sample Template – SSc7.2

This template is the flattened, public version of the dynamic template for this credit that is used within LEED-Online v2 by registered project teams. This and other public versions of LEED credit templates come from the USGBC website, and are posted on LEEDuser with USGBC's permission. You'll need to fill out the live version of this template on LEED Online to document this credit.

USGBC

Official LEED Online Forms

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

72 Comments

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Thiago Bondini
May 16 2014
LEEDuser Member
293 Thumbs Up

Why could be considered as a roof?

My project has a garden above a parking area located underground. This garden can be considered as a green roof on credit SSc7.2, even the parking area is unoccupied and unconditioned area? (LEED v2009 for Healthcare).

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Alfred Servodidio Project Manager JMV Consulting Engineering
Nov 13 2013
LEEDuser Member
28 Thumbs Up

Roof covered by lattice

50% of the roof will have Mechanical Equipment on it. The Equipment will be covered by lattice. If the lattice is a reflective surface will this count toward this credit?

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Blake Jackson Sustainable Practice Leader, Tsoi/Kobus & Associates Nov 13 2013 LEEDuser Member 57 Thumbs Up

Mechanical equipment essentially shields a rooftop from solar radiation and is considered an "appurtenanceAn appurtenance is any built-in, nonstructural portion of a roof system, such as skylights, ventilators, mechanical equipment, partitions, and solar energy panels." by the LEED guide; thus, all area beneath MEP equipment should not be calculated towards contributing area for this credit (covered or not).

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Omar Mahfoudh Drees & Sommer
Aug 05 2013
Guest
6 Thumbs Up

concrete SRI values

hi all,
please can someone tell me ,if covered roofs with concrete do have standars solar emittance index or these must be an averaged value from ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services standards ?

thanks

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 04 2013 LEEDuser Moderator

Concrete is the one material for which you can use standard values, given in the LEED Reference Guide.

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radwa rostom Project engineer
Apr 04 2013
Guest
45 Thumbs Up

Installing solar panels on the roof

Dear all,
I have an inquiry concerning installing solar panels on the roof of a building, could it be counted in this credit?

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Heather Holdridge Sustainability Coordinator, Lake/Flato Architects Apr 10 2013 LEEDuser Member 1279 Thumbs Up

Yes

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Balaji kasiviswanathan Architect - Sustainability & LEED, Middle East Centre for Sustainable Development Apr 13 2013 Guest 312 Thumbs Up

Solar panels are not counted towards this credit. Check page no.100 of the LEED NCv2.2 Reference Guide Third Edition under Calculations Point No.1:

"Calculate the total roof surface area of the project. Deduct areas with equipment, solar energy panels and appurtenances."

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radwa rostom Project engineer Apr 14 2013 Guest 45 Thumbs Up

Thank you very much for you replies, but if we installed solar panels on the roof , such that it covered most of the area of the roof, then this will lead to achieving the credit, am I right or not?

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Balaji kasiviswanathan Architect - Sustainability & LEED, Middle East Centre for Sustainable Development Apr 14 2013 Guest 312 Thumbs Up

Refer to the LEED NC 2009 - 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. for SSc7.2 in the link below:

http://www.usgbc.org/node/1731100?view=interpretations

Interpretation No.: LI#10235

" Projects are not eligible for SSc7.2 if the exempted spaces encompass the entire 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.. Applicable Internationally."

Earlier the LEED Interpretaion Website Format included a tab called Applicability which provides you with information for which LEED NC versions the ruling is applicable. Unfortunately in the new format of the website i am not able to locate it...(might be I would have missed, please check again)

I hope your "most of the area" does not correspond to 100%

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BABAR MEHMOOD SAUD CONSULT
Mar 07 2013
Guest
366 Thumbs Up

Manufacturrer information

I am working on a clinic in City riyadh of KSA. I am having trouble to find the maufacturer/ suppliers who can have the materials for this credit compliance, since LEED is still not very common practice here in this region. If you have any information or can assist in finding the suppliers in KSA, it will be highly appreciated.

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Balaji kasiviswanathan Architect - Sustainability & LEED, Middle East Centre for Sustainable Development Mar 07 2013 Guest 312 Thumbs Up

Check the product search on www.thefuturebuild.com

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BABAR MEHMOOD SAUD CONSULT Mar 11 2013 Guest 366 Thumbs Up

Thanks for the great info, but still i am looking for tiles that can achieve SRI value of 78 which i couldnot found here, please if you can help me in finding the supplier in KSA or gulf region who deals in high albedoAlbedo is synonymous with solar reflectance. coating or tiles which can be applied to roof. Thanks

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 11 2013 LEEDuser Moderator

Babar, this website and forum are not typically places where people find products in such a specific region meeting such a particular specification. This forum is typically best for discussing LEED requirements and documentation issues. Sorry not to be of more help.

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Balaji kasiviswanathan Architect - Sustainability & LEED Middle East Centre for Sustainable Development
Nov 19 2012
Guest
312 Thumbs Up

Should we consider access doors for SRI Calculations?

We would like to know whether access doors on the top most roof, to access equipment on the floor below should be considered for SRI Calculations. These doors will not be opened quite frequently and its a flat roof, if that matters.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 19 2012 LEEDuser Moderator

I would consider an access door an appurtenanceAn appurtenance is any built-in, nonstructural portion of a roof system, such as skylights, ventilators, mechanical equipment, partitions, and solar energy panels., and not subject to the credit requirements. Doors are not specifically mentioned in the LEED definition for appurtenances, but they fit with the definition in other ways, in my opinion.

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Susann Geithner Global Sustainability Manager, Predictive Service Dec 06 2012 LEEDuser Member 11261 Thumbs Up

I second Tristan on that. I would excluded it too.

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kate dixon Feb 16 2013 Guest 98 Thumbs Up

Yet there are 'green' roof hatches that are double insulated and have high SRI surfaces that can be specified. So if you do have this and it complies, why not include it?

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T Ros Tros AICE
Jul 16 2012
Guest
121 Thumbs Up

convective coefficient for SRI

Hello, I would like to know which value of SRI should be considered according to the three convenctive coefficients considered in ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services E1980-11. Average of the three values of wind conditions? medium wind conditions?

Thanks,

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 30 2012 LEEDuser Moderator

T Ros, I don't know—I've never seen this question come up before. It seems like it would be safest to assume an average. I would suggest asking an manufacturer who reports these numbers what they do—and let us know.

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gita nandan principal architect thread collective
Apr 16 2012
LEEDuser Member
392 Thumbs Up

roof pavers

i am wondering how to incorporate or not incorporate roof pavers into the calculation. they have an SRI of greater than 29, and it is a flat surface. Do we include them as a roofing component or exclude them? all of the roof is white underneath the pavers and we have a green roof as well.

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Samantha Harrell LEED Project Reviewer certificate holder Apr 16 2012 Guest 2528 Thumbs Up

Gita, since 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. is the area of the uppermost surface of the building, the roof pavers should be included in the calculation.

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Mauricio Ramirez
Mar 23 2012
Guest
506 Thumbs Up

On-site poured White concrete SRI

I'm working on a unedrground museum project. So the roof is a green roof open to the public and one of the finishers materials is on-site poured white concrete. Tipycally white concrete, according to the LBNL complies with the credit as it has for tiles the following values: white concrete tile SRI 90. It's not easy to get 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 tests of this type of material. Is it valid to use the LBNV for white concrete tile instead of manufacturer data? Does anyone have got compliance documentation on this subject from a concrete manufacturer? Thanks.

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Susan Walter Sr Project Architect, Wilmot/Sanz Mar 28 2012 LEEDuser Expert 14056 Thumbs Up

I would say no, you can't apply the SRI for one product to a similar product although it can be a guide. This white concrete isn't too new and you should be able to find products and specify them.

But I'm confused, are you covering this white concrete with a vegetated roof system or do you have both? If you have plants over 50% of the SF then you can earn the credit. If you are covering the concrete, then why not use a standard product?

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Susann Geithner Global Sustainability Manager, Predictive Service Apr 04 2012 LEEDuser Member 11261 Thumbs Up

You will need the SRI for your specific procuct and manufacturer. This can be tricky if you aren't located in the US, but you can send them for testing to the US. I also know an institute in Germany that does those test.

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Mauricio Ramirez Apr 16 2012 Guest 506 Thumbs Up

Thanks for your comments. Answering: 1. I don't have 50% of green roof, so It's a mix between green roof and the hardscapes spaces will be in white concrete, ina balanca that let me earn the credit.
Susan, I'll appreciate if you can share the contact information on companies or labs that could make the test of our actual material.

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Susann Geithner Global Sustainability Manager, Predictive Service Apr 16 2012 LEEDuser Member 11261 Thumbs Up

The "Fraunhofer Institut" in Stuttgart, Germany does SRI testing. They need a product sample to do that. They will also translate it into English for an extra fee. http://bit.ly/pHZG5Z

I' didn't had to get it tested yet in the US, but I sure other user, would be happy to refer you to an institute. Post the question under LEED NC 2009. That is more frequented.

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Brian Lutey VP of Green Building, Ozinga RMC Inc May 21 2012 LEEDuser Member 145 Thumbs Up

CTL Group in Skokie Illinois, USA can do ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services C 1549 SRI testing on concrete samples. THey need three specimens each with a min surface area of 3 inches or greater.
CTL Group phone: 847-972-3180

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T Ros Tros, AICE Jul 16 2012 Guest 121 Thumbs Up

ITC (Tecnological Institute of Ceramics) in Spain, can test SRI in all building materials. Visit www.itc.uji.es or email: tros@itc.uji.es

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Sunayana Jain Energy Engineering Specialist FTC&H
Feb 13 2012
Guest
142 Thumbs Up

Roof Area Calculations

I have a steep sloped roof for my project. I am wondering if 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. will be total flat projection on a horizontal surface or will it be actual surface area of roof. Please clarify.
Thanks!

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Susann Geithner Global Sustainability Manager, Predictive Service Feb 13 2012 LEEDuser Member 11261 Thumbs Up

Please see the definition of 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's the projection, not the actual surface.

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Udana Ratnayake
Dec 28 2011
Guest
981 Thumbs Up

Solar Panels on Roof

What if the roof is fully covered by Solar Panels? will we be still eligible to meet credit requirements?

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Susann Geithner Global Sustainability Manager, Predictive Service Jan 03 2012 LEEDuser Member 11261 Thumbs Up

I would say yes. You should check the 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. rulings, if this has happened before. Otherwise I would submit as special circumstances since your roof doesn't create a heat island effectHeat island effect refers to the absorption of heat by hardscapes, such as dark, nonreflective pavement and buildings, and its radiation to surrounding areas. Other sources may include vehicle exhaust, air-conditioners, and street equipment. Reduced airflow because of tall buildings and narrow streets exacerbate the effect.. So you do achieve the intent of the credit.
However be careful to just say it's all covered by solar panels. You will need to show that in drawings and be precise. If you have areas not covered by them for maintenance access or else, these than have to comply with the credit requirements.

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Alberto Miranda Mar 12 2013 Guest 6 Thumbs Up

Hello Udana, I have the same situation as you do for a project in Mexico. Could you let me know if you find out how to obtain the credit of the heat island by using the solar panels?
thanks.

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Pal Ahuja President Millennium Engineering Inc.
Sep 04 2011
LEEDuser Member
278 Thumbs Up

Sourcing Roof Shingles with SRI 70 or more

For our project, we are trying to source Roof Shingles (for sloped roof) which have SRI 70 or more. Any feed back will be appreciated.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 13 2011 LEEDuser Moderator

Pal, I think this will be hard to find, in part because higher-SRI roofing may cause glare, which can be a problem on sloped roofs. Let us know if you come up with anything.

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Lauren Ford Project Architect Cooper Carry
Aug 19 2011
LEEDuser Member
670 Thumbs Up

Reflective Roof Ballast

Has anyone found a ballast stone that meets the low-slope SRI requirement of 78 and has been accepted by GBCI? Alternatively, if an approved Energy Star coating were used, is it acceptable to apply to the surface of the ballast after installation, or must each ballast stone be coated on every surface?

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Mike Barker Principal : Energy / Electrical Engineer, BuildingPhysics South Africa Aug 22 2011 LEEDuser Member 1413 Thumbs Up

SRI is dependant on the suface's ability to reflect Solar Spectrum IR in particular. Covering a hight SRI surface with other material does not make sense, unless you are expecting that material to radiate in the near-IR range ?

You may wish to read the research papers from the American Concrete Pavement Association on the effect of the colour of aggregates on the SRI of pavements.

You have asked an interesting question, and i think you will find a light coloured ballast stone could help. How to prove this without coslty Lab measurements is another thing ...

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Alicja Bieszyńska Skanska Jan 09 2012 LEEDuser Member 1007 Thumbs Up

I was going to ask similar question to Lauren - does anyone know a light-colored gravel supplier that would fulfill SRI requirement for a low-sloped roof? I'm looking for one i Europe, but shipping such material from the USA is also an option.

The thing is that I'm not sure gravel has high reflectance... the stones are not flat and usually have polygonal shapes, so if we take the principle "angle of incidence equals the angle of reflection", the rays can be reflected towards the deeper layer of the roof, not to the atmosphere. Please, correct me if I'm wrong...

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Michael E. Edmonds-Bauer Edmonds International Nov 13 2012 LEEDuser Member 1573 Thumbs Up

I have the same situation, we are using white marble pebbles in some greenroofs in Mexico City and we did some research. I emailed The Marble Institue of America regarding SRI values for marble and the answer I got yesterday morning was this:

"There are no generic SRI data for stone. Values are stone and finish specific. There are very few producers that have measured SRI for any stone.

Per the LEED for New Construction Reference Guide version 2.2, the standard method for calculating the SRI is ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services E1980, Standard Practice for Calculating Solar Reflective Index of Horizontal and Low-Sloped Opaque Surfaces. If you review this standard, you will find references to other standards that describe the actual measurement protocols used to obtain the necessary data to perform the calculation."

I kind of have the idea that testing is the only option which will be bad for projects in places like latin america where no extra cost is well welcome specially if the application of marble (or pebble or gravel) is quite small.

By the way there is a case study about SRI for natural stone that can be found at this website through the Marble Institue of America:

http://www.marble-institute.com/pdfs/CaseStudy4_SolarReflectanceOfStone.pdf

Hope this can help, I will keep on researching about SRI values for natural stone, if I learn something new I will post it.

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Charline Seytier CEO, Co-owner. LEED AP BD+C, ThemaVerde, France Apr 17 2013 LEEDuser Member 505 Thumbs Up

Hi everyone,
Just checking if any of you did find a Lab in Europe to run the SRI tests on a gravel/ballast sample?

Any suggestions on materials that got tested available in Europe would be much appreciated!
(We are actually using ballast on site, SRI required of at least 29.)
Thanks,

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T Ros Tros, AICE Apr 25 2013 Guest 121 Thumbs Up

Hi Charline,
the Technological Institute of Ceramics (ITC), Spain, can run SRI test.

Instituto de Tecnología Cerámica
Campus Universitario Riu Sec | Av. Vicent Sos Baynat s/n | 12006 Castellón (Spain)
T. +34 964 34 24 24 | F. +34 964 34 24 25 | www.itc.uji.es
itc@itc.uji.es

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Heather Holdridge Sustainability Coordinator Lake/Flato Architects
May 26 2011
LEEDuser Member
1279 Thumbs Up

2:12

What if your slope is exactly 2:12? I assume we should follow v3 credit language and call it low slope. Would 2.1:12 make it steep slope or would we need to step it all the way up to 3:12?

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Simon S. SL+A International, Taipei Jun 03 2011 LEEDuser Member 4607 Thumbs Up

I will take it as low slope as the reference show ≤2:12 (equal or lower). if 2.1:12, it will be a steep sloped roof, as the pitch is 0.1 steeper.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jun 28 2011 LEEDuser Moderator

I agree with Jason. Rounding is generally not a part of LEED—so once you're over 2, you're steep.

If this wasn't working for the project in some way, it's possible GBCI would allow a different view—I just wouldn't bank on it.

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Carrie Bradley
May 04 2011
Guest
374 Thumbs Up

Weighted SRI calc

Has anyone used the LEED 2009 sample credit form and uploaded a copy to document compliance for a v2.2 project? It's very straightforward for weighted average SRI calcs. The roof in question is 20,000 sf (low-slope) where 100% is SRI 77. Using the LEED 2009 form, it shows the weighted SRI is well over the minimum.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. May 19 2011 LEEDuser Moderator

Carrie, does the v2.2 form not do this calc for you? I would avoid uploading the 2009 form unless it was absolutely necessary.

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Adam Barker
Mar 02 2011
Guest
121 Thumbs Up

Effectvie Reflective Roof Area

This has been driving me crazy today - how does the LEED letter template calculate the effective reflective 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. if you have an SRI lower than 78 for a low sloped roof?

Example - we have a total effective area of 1853.2 sq.m, and we have 634.5 sq.m with an SRI of 74. The LLT assumes this as an 'effective reflective roof area' of 582 sq.m (derating because the SRI is less than 78). WHAT, is the calculation the LLT uses to get this number?? I have tried every calculation in every reference guide and 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 I can find on this - none of them reach this number. What am I missing - or is there a glitch in my file?

Any help is greatly appreciated!!

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

Adam, it's a weighted average. We have a spreadsheet in our Documentation Toolkit (above) that you might find is a useful tool for exploring this. That should also make the calcs transparent.

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Blake Jackson Sustainable Practice Leader Tsoi/Kobus & Associates
Feb 23 2011
LEEDuser Member
57 Thumbs Up

SRI Value Green Roof System

I am working on a project which is specifying a Xero Flor XF301 Sedum Mat for part of the roof. We are approaching SS7c2 from Option 3. In the online template ("roofing materials table") they ask for "reflectance", but I cannot find any value for this or any other green roofing material. I called the rep, and they had not advice to offer. Is there a value we can place in here as default for all green roof products or do I leave it blank and leave a note in the optional narrative?

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

Blake, you're being asked for that since you're using the Option 3 path that combines green roof and high-SRI areas. I think the LEED  Online template is just not smart enough to recognize when you're entering green 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 when you're entering SRI area, for which reflectance would be relevant. I would look for a way to "trick" the form to not requiring this information, and explain in the narrative what you did.

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Maura Adams Environmental Stewardship Manager
Feb 10 2011
Guest
2272 Thumbs Up

No SRI available

We have a zinc-coated copper roof and the manufacturer won't give us the SRI as they say it's variable. This seems odd! I can't find an industry standard for zinc-coated copper... any ideas about what to do next?

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

Maura, here's an article from RealLifeLEED that is a useful starting place in understanding SRI values on copper roofs. I think you'll find two things that don't work in your favor, a) the SRI value will be very low, and b) you'll need to test it to verify a value for your LEED documentation.

http://www.reallifeleed.com/2009/08/sri-values-for-copper-roofing-old-vs...

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Maura Adams Environmental Stewardship Manager Feb 10 2011 Guest 2272 Thumbs Up

Thanks! We thought the zinc coating would raise the SRI...

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

It might... you never know. But you won't know, or be able to document the credit, without some data.  Too bad the manufacturer is holding back. Sounds like they just don't have the data themselves.

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RUMI ENGINEER
Jan 09 2011
LEEDuser Member
131 Thumbs Up

Podium at 3rd level will be a calculated under roof or non roof

We have a podium at the 3rd level, which is partially covered by landscape.
Will this podium be considered under 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 non-roof area for SS cr 7 calculation.
All Level beneath are used for parking.

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Susann Geithner Global Sustainability Manager, Predictive Service Jan 10 2011 LEEDuser Member 11261 Thumbs Up

That depends, is the space underneath the roof heated or cooled? If so, the roof is to be considered under Heat Island EffectHeat island effect refers to the absorption of heat by hardscapes, such as dark, nonreflective pavement and buildings, and its radiation to surrounding areas. Other sources may include vehicle exhaust, air-conditioners, and street equipment. Reduced airflow because of tall buildings and narrow streets exacerbate the effect. - Roof. That would also be the case if the space is underground.
If the spaces underneath the roof are not conditioned, it will be parking under cover under credit:"Heat Island Effect - Non-Roof". So to make it count, it needs to have a minimum of SRI 29 or vegetated green roof.

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James Keohane, PE LEED BD+C CxA CPMP Sustainability and Commissioning Consultant Sustainable Engineering Concepts, LLC
Dec 30 2010
LEEDuser Member
643 Thumbs Up

Exemplary Performance for SS7.2

Reference Guide say a that you earn Exemplary PerformanceIn LEED, certain credits have established thresholds beyond basic credit achievement. Meeting these thresholds can earn additional points through Innovation in Design (ID) or Innovation in Operations (IO) points. As a general rule of thumb, ID credits for exemplary performance are awarded for doubling the credit requirements and/or achieving the next incremental percentage threshold. However, this rule varies on a case by case basis, so check the credit requirements. credit if 100% of projects 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. is comprised of a green roofing system.

Question: Does a roof using Option 1 ( roofing materials with a compliant SRI for a min. of 75% of roof surface) with a 100% of roof surface having a compliant SRI meet the requirements for Exemplary Performance??

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

I would interpret the Reference Guide has being specific about green roofs being the sole EP path here. I think if the intention was to allow an SRI path, it would have been stated that the EP path is simply a "100%" version of the regular credit.

Has anyone found anything different on their projects?

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James Keohane, PE LEED BD+C CxA CPMP Sustainability and Commissioning Consultant, Sustainable Engineering Concepts, LLC Jan 06 2011 LEEDuser Member 643 Thumbs Up

The definition of a green roof has been a moving target with GBCI reviewers and depends on the version of the reference guide you use. First Edition NC2.2 Reference Guide is not clear on this point. The Third Edition apparently clarifies the definition of a green roof. The 2009 Reference Guide specifically refers to a "vegetated roof system" for SS7.2EP. From a LEED Review Team we recently received the following clarification:

The project team is correct to assume the credit was denied because 100% of the roofing material was only high-albedoAlbedo is synonymous with solar reflectance. and not vegetative. The LEED NCv2.2 Reference Guide, Third Edition defines green roofs as vegetated surfaces that reduce heat island effectHeat island effect refers to the absorption of heat by hardscapes, such as dark, nonreflective pavement and buildings, and its radiation to surrounding areas. Other sources may include vehicle exhaust, air-conditioners, and street equipment. Reduced airflow because of tall buildings and narrow streets exacerbate the effect. by replacing heat-absorbing surfaces with plants, shrubs, and small trees that cool the air through evapotranspiration (or evaporation of water from leaves). As submitted, the project has not demonstrated exemplary performanceIn LEED, certain credits have established thresholds beyond basic credit achievement. Meeting these thresholds can earn additional points through Innovation in Design (ID) or Innovation in Operations (IO) points. As a general rule of thumb, ID credits for exemplary performance are awarded for doubling the credit requirements and/or achieving the next incremental percentage threshold. However, this rule varies on a case by case basis, so check the credit requirements. for SSc7.2: Heat Island Effect, Roof.

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Nick _ Architect, LEED AP
Nov 29 2010
Guest
548 Thumbs Up

Helipad

Our project (a hospital addition) has a large portion of its roof covered by a helipad. We are proposing that this surface be excluded from the SS 7.2 calculations for the following reasons:

Per U.S. Department of Transportation / Federal Aviation Administration guidelines, helipad surfaces are to be portland cement w/ broom finish for saftey purposes. A highly relective surface may result in glare in the eyes of pilots using the helipad, impair visibility in the vicinity, or otherwise create a hazard or endanger the landing, takeoff or maneuvering of helicopters intending to use the helipad.

This would leave us with a relatively small porion of a lower roof which would apply to the credit. Thoughts?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 29 2010 LEEDuser Moderator

LEED allows you to exclude mechanical systems and other appurtenances from this credit, so if it is more like a mechanical system or a similar appurtenance (solar array) then you could say there is some precedent for excluding it. It's not clear-cut, however.

A couple thoughts. One, if you want to exclude it and only include the small portion of the remaining roof for this credit, are you down a path of following the letter of the requirements, but not the intent? Perhaps this isn't the most appropriate credit for the project.

Two, would it be more appropriate to consider it as a "non-roof" surface and see if the SRI requirements and technologies for parking would be more appropriate?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 09 2010 LEEDuser Moderator

Nicholas, have you gone any further with this situation? A similar question just came up on our v2009 forum... that made me curious to hear more on your situation.

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Joseph Celentano
Aug 03 2010
LEEDuser Member
166 Thumbs Up

Covered roof

Our project has a flat roof that is completely shaded under a separate building, it is tucked under an existing building and at no time is the roof subject to sunlight. Would this be considered an alternative compliance path? Any suggestions on how to document this credit from this approach?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 03 2010 LEEDuser Moderator

If the buiding were adjacent to your project and shading it, this would not be allowed. It's very possible that the same rule would apply here, strange as it may seem.

LEED is certifying your building only, and there is no guarantee that the other building will always be there to provide the shade.

I'm curious what your LEED boundary looks like? Might be kind of tough to exclude the other building. Have you discussed this with GBCI?

Anyone else have thoughts?

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Kimberly Frith Sustainability Consultant Alto Sustainability, LLC
May 17 2010
LEEDuser Expert
3590 Thumbs Up

SRI of Earth-Covered Roof?

Our project has a flat roof and is using a concrete structure covered with earth for the roof (for blast requirements). The roof will not be vegetated - just dirt. Any suggestions of how to find an SRI value for dirt? This would not be considered a green roof since it's not vegetated - the building is basically underground.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. May 20 2010 LEEDuser Moderator

Do you really mean loam, and not some kind of gravel surface? Seems odd, since loam will tend to grow weeds in no time. Just checking, since this obviously affects SRI.

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Ben Koenig Gensler
May 13 2010
Guest
549 Thumbs Up

Several questions

1. Does one submit the actual Construction Documents with highlighting the various areas of roof/non-roof, green roof etc or can one submit a composite drawing that makes it easier to read for the reviewer? The Construction Documents are difficult to read for this purpose because of different levels and types of roofing materials.
2. Does a roof overhang count as roof (the overhang is not over conditioned space). If not, must it be counted towards the non-roof?
3. What is the SRI of water?
4. In the "Checklists' section, it suggests that unconditioned space below a roof surface does not count. Is that correct?
5. What is the SRI of shade? (roof has a tree, the tree shade is larger than the foot print of the soil below)

A suggestion for this credit section would be two lists, one that lists SRI's of materials or how to deal with water/shade or other unusual roof situations. The other list should list what counts as roof and what doesn't (like overhangs) maybe some sample illustrations that have different scenarios.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. May 13 2010 LEEDuser Moderator

Let's see... here are some answers.

1) You have discretion here. LEED Online says: "Upload the project roof plan(s) or drawing(s) depicting project 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 highlighting the location and quantity of specific roofing materials areas and/or vegetated roofing systems as applicable.

2) I would say that you have the discretion to count overhangs as non-roof (if over the ground), or perhaps not include them at all if over other roof surfaces. If treating overhangs differently in your calculations or specifications has no effect, I might not bother to do this, though.

3) I don't know. I think this would vary based on the depth and the surface underwater. Anyone? This wikipedia page was a start, but not that helpful. Try LBNL and let us know if you find out.

4) Yes.

5) That would really vary among vegetation types and seasons and I'm not sure counting it as an SRI surface is the right method. Either it qualifies as a green roof, or you probably need to count the pavers under the tree. Mara's comment on SSc7.2 for v2009 gives some nuance on this.

Your suggestion is great—we'll work to incorporate it in the future.

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Ben Koenig Gensler May 13 2010 Guest 549 Thumbs Up

1) Thanks, I might try a composite as the project is also split in phases and this way it's easier for everyone to see the full picture.
2) thanks
3) that's a tricky one, but since the water is over uncondtioned space anyway, I don't have to count it. However in the 'Get it done section' it talks about a swimmingpool but doesn't address how to deal with it. Aside from the reflectivity of water, it does absorb the heat, thus it could be considered as beneficial towards the intent of the credit. If it's a waterfeature that moves the water constantly, it would even be better.
4) thanks
5) thanks

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