NC-2009 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 credit form 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 2009 for New Construction and Major Renovations

    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 index2 (SRI)equal to or greater than the values in the table below for a minimum of 75% of the roof surface.

    Roofing materials having a lower SRI value than those listed below may be used if the weighted rooftop SRI average meets the following criteria:

    Area Roof Meeting Minimum SRI

    ————————————————

    Total Roof 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%



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

    [ Area of Roof A x SRI of Roof A

    ———————

    Required SRI


    ] + [ Area of Roof B x SRI of Roof B

    ———————

    Required SRI


    ] + ... Total Roof Area
    0.75



    Roof Type Slope SRI
    Low-sloped roof ≤ 2:12 78
    Steep-sloped roof > 2:12 29



    OR

    Option 2

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

    OR

    Option 3

    Install high-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 will be available in the LEED Reference Guide for Green Building Design and Construction, 2009 Edition. Product information is available from the Cool Roof Rating Council Web site at http://www.coolroofs.org and the ENERGY STAR® Web site at http://www.energystar.gov.

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. 

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.

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.

LEED Online Forms: NC-2009 SS

The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-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. USGBC has certain usage restrictions on these forms; for more information, visit LEED Online and click "Sample Forms Download."

Design Submittal

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

284 Comments

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Lauren Bellamy
Aug 27 2015
LEEDuser Member
34 Thumbs Up

Roof/Terrace

Project Location: United States

The project I am working on has a canopy over a terrace, and below the terrace is conditioned space. According to the roof definition "roofs(or canopy) over porches" are not included in my roof sq. footages, but will the terrace be included in 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.? Its purpose is to enclose conditioned space, but there will not be much sunlight hitting it.

Any thoughts on this?

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SOHA YAMANI
Aug 19 2015
Guest
510 Thumbs Up

SRI Value for concerete

Project Location: Egypt

Is there a standard SRI Value for concrete that i can use to comply with the credit requirements ? as a part of the roof i am using is concerete and the specs is not addressing this part

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ryan kremer
Jul 31 2015
Guest
14 Thumbs Up

Emissivity Values are Unknown

Project Location: United States

I apologize if this is a repeat comment. I tried posting it once before, but when I went back to the forum, I did not see my comment posted.

The manufacturers color charts for the roofing we are using do not include a valuefor EmissivityEmissivity is the ratio of the radiation emitted by a surface to the radiation emitted by a black body at the same temperature.. They do however include SRI and Reflectance values. The credit form requires a value for Emissivity. The Cool Roof Rating Council does not include this specific manufacturer.What am I supposed to do here?

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Kathryn West LEED AP BD+C, O+M, Green Globes Professional, Guiding Principles Compliance Professional, Energy Ace Jul 31 2015 Guest 5049 Thumbs Up

You can just enter the SRI.

The SRI is a product of the emissivityEmissivity is the ratio of the radiation emitted by a surface to the radiation emitted by a black body at the same temperature. and reflectance.

You need to fill in 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. to have the percent compliance show up.

No need to enter the reflectance and emittance if you've already entered the SRI.

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ryan kremer Jul 31 2015 Guest 14 Thumbs Up

Thanks for the speedy reply Kathryn. I really appreciate it.

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FABIO VIERO Head of Sustainability Manens-Tifs s.p.a.
Jul 10 2015
LEEDuser Member
931 Thumbs Up

Roof area exempt from the SSc7.2 calculation

Project Location: Italy

We have a project with a terrace that is about 50% of the building roof. The terrace is partly covered with green roof and the rest is covered by wood since this spaces will be used as lounge or some other event like a party, exhibition and so on.

Following 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. #10235 made on 10/01/2012, can we exempt from SSc7.2 the wood covered area as usable space, I think yes .

Is it True?

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Jiri Dobias
Feb 09 2015
LEEDuser Member
1480 Thumbs Up

SRI required testing amounts

Project Location: Czech Republic

Hello, could anybody tell me how we can state the number of SRI tests on a project? We intend to place gravel on the roof and provide a concrete parking log.
Is one test for the whole concrete or gravel delivery from the same supplier for one roof or parking lot suffiecient or must each delivery be tested?
A quarry has various colors of stones and gravel - how can we decide how many tests of SRI we have to provide for gravel which we intend to place on the roof?
Supposed it should be documented for each batch of gravel - how is a batch determined?
Thanks

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Annalise Reichert LEED Project Coordinator Environmental Building Strategies
Jan 20 2015
LEEDuser Member
137 Thumbs Up

Default Gravel SRI Values

I am also working on a project that has a large green roof with light colored gravel in some areas. The manufacturer has not performed testing to provide an SRI value for the gravel. However the Lawrence Berkeley National Laboratory (LBNL) has published a list of default SRI values for various types of roof membrane materials, including gravel. See the link below:
http://energy.lbl.gov/coolroof/membrane.htm#membrane

Has anyone successfully used a default SRI value for gravel? If not, does this mean i need to count all gravel-covered areas as non-compliant?

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Susan Walter Specifications Director, Populous Jan 20 2015 LEEDuser Expert 17662 Thumbs Up

Light colored gravel is going to count against you whether you use the LBNL data or not. Using the LBNL number and uploading a screen capture / download of it will at least give you a number to plug into the formula. It is worth a shot but I would be prepared to run it as a '0' in the formula. The online document makes this an easy calculation to run.

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Kathryn West LEED AP BD+C, O+M, Green Globes Professional, Guiding Principles Compliance Professional, Energy Ace Jan 20 2015 Guest 5049 Thumbs Up

I really don't think they will let you do that because that study says the values for the ballasted roof are "approximate."

Can you bump up the SRI of any other 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.? Using the weighted approach helps me on a lot of projects.

See LEED interpretations #2450 and #10113. #10113 says "to determine the SRI value for materials that do not have recognized standard values (e.g. new gray concrete) the materials must be individually tested."

LEED Interpretation #2450 says ballasted roofs need to meet the SRI requirements.

Anyone ever rented an emissometer? http://surfaceoptics.com/products/reflectometers-emissometers/et100-ther...

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Charles Nepps Apr 29 2015 LEEDuser Member 559 Thumbs Up

I know this thread is a few months old now, but I'm hoping there may be some new information out there, or others still interested in the topic. I understand that the LBNL test results on gravel are approximate, and there is the issue of how gravel, given it's irregular shape, can cast shadows on itself, but I'm not sure I understand the reasoning that, in lieu of approved test results on the gravel used on any particular project, you must consider the SRI value to be zero. If I took a random sampling of the GBCI reviewer's out to the desert at high noon and gave them the choice to walk barefoot across a patch of dark gravel or a patch of white gravel, would they say it doesn't matter to them because the test results are only approximate? Surely there should be some default number, a worst case average, that would be acceptable rather than zero.

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Noriko Yasuhara Woonerf Inc.
Nov 14 2014
LEEDuser Member
2286 Thumbs Up

Parking Roof

Are we supposed to include parking roofs on SSc7.2 heat island - roof's calculations? I assume that all roofs should be included. But parking roofs are part of SSc7.1, heat island - non roof's calculations.

Any ideas?

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Shenhao Li Atkins
Oct 15 2014
Guest
340 Thumbs Up

Some question about roof garden.

Project Location: China

I have a hotel project in china.
Our client will build a roof garden. Some areas of roof garden is vegetated roof, and other area will be construct as lane, tennis court or other things.
These areas are paved by wood, pebble,tiles instead of traditional roof material(paints, concrete etc.). Can we treat these parts as vegetated roof?
As reference guideline, occupants` use of roof gardens may be incompatible with high-reflectivity roofing materials. An area-weighted SRIAn area-weighted SRI is a weighted average calculation that may be performed for buildings with multiple roof surfaces to demonstrate that the total roof area has an average solar reflectance index equal to or greater than that of a theoretical roof 75% of whose surfaces have an SRI of 78 and 25% have an SRI of 30. equivalent may help allow for low-glare pavers where people congregate.
Is that means, an equivalent SRI for these parts by material color is more acceptable? If we equivalent SRI for this parts, is it acceptable i upload a test report or cut sheets of the equivalent material? (For example, if i have a pavement constructed by green tiles, and we know the SRI of green paints is 21, can we submit the SRI of green tiles as 21?)

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Heather Holdridge Sustainability Coordinator, Lake/Flato Architects Jan 02 2015 LEEDuser Member 1527 Thumbs Up

I think your question is answered in the FAQ above:
"What do I do about 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. covered by solar panels, skylights, space for occupants, helipads, etc.?"

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Marcio Alberto Casado Pereira
Oct 13 2014
Guest
4273 Thumbs Up

Stadium seating - need SRI? Is it an appurtenance/usable space?

Project Location: Brazil

We just got a review from a stadium Project we are working on in Brazil and the review team asked us to double check 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. considered, stating that part of our seating area covers enclosed areas below, which it actually does. However, we read in one post in this section, that "functional, usable spaces" are considered appurtenances and as such may be excluded from the calculations. I think is obvious that the seating area is an usable space, therefore it should not count. Nevertheless, I assume that the review team is aware of this definition, and if so, I'm confused why they asked us to include then...

I even found a LI#10235 that refers to that definitions and was excited to read that one of the related addendas within this tab mentioned LI#1091551 stadium seating! However, as I clicked in the link it saids no matches were found....that would solve our problems here. http://www.usgbc.org/leed-interpretations?keys=10235&=Search

What do you think? Could the seating area be considered appurtenance functional/usable space? The material below the seats is concrete, which has SRI of 35, which would comply for SRI 7.1 but not for SSc7.2 since it's a flat surface therefore requiring SRI 78.

Thanks for all the insights!

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Marcio Alberto Casado Pereira Oct 27 2014 Guest 4273 Thumbs Up

Hey folks, any insights on the matter above? Would be great to hear your opinion!

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Kathryn West LEED AP BD+C, O+M, Green Globes Professional, Guiding Principles Compliance Professional, Energy Ace Oct 27 2014 Guest 5049 Thumbs Up

All I can tell you is that they made me count it on my project and considered it "low slope."

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Amanda Johnson Penicaud Green Building
Oct 10 2014
LEEDuser Member
346 Thumbs Up

Solar Panels

Project Location: France

Hello,
We have a project with Thermal solar panels for hotwater, and I just want to double-check that they can be deducted from the roof-surface for this credit since most of the documents (and posts) that I find refer to solar energy / PV ...?

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Heather Holdridge Sustainability Coordinator, Lake/Flato Architects Dec 30 2014 LEEDuser Member 1527 Thumbs Up

These should be considered appurtenances.

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E&Z LEED Consulting Director of Sustainability Edwards & Zuck
Oct 09 2014
LEEDuser Member
12 Thumbs Up

Occupied Roof Areas

Can the areas on the roof that are being used for recreations purposes: restaurant, poolside, lounge, etc. be exempt from the roof square footage calculation?

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Heather Holdridge Sustainability Coordinator, Lake/Flato Architects Dec 30 2014 LEEDuser Member 1527 Thumbs Up

Your question is addressed in the FAQs. This would be considered "space for occupants."

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Susan Di Giulio Project Manager Zinner Consultants
Aug 20 2014
LEEDuser Member
1390 Thumbs Up

Another "is it a roof or is it hardscape" inquiry

We are working on a mixed use project in a dense urban environment. It will contain one tower with hotel, other hospitality and entertainment functions topped by many floors of condos, two all-condo towers, a big chunk of retail and lots of (100% covered)parking. Some open space will be on street level but most will be the vast podium plaza about 7 stories up, containing over 25% greenspace and covering half the site.

The raised plaza covers 5 stories of above-ground parking, over 2 floors of retail, over another 2 floors of underground parking.

There are also two pool/roofdeck areas on higher floors that are over mechanical floors/spaces, over regularly occupied space. In other words, none of this open space is directly over conditioned space, but there is conditioned space somewhere below.

If the roof is defined as "the area of the uppermost surface of the building which covers enclosed Gross Floor AreaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.)", for the purposes of deciding whether these spaces should be applied towards SSc7.1 or 7.2 requirements, are these roof or non-roof open spaces?

We are hoping we can use this towards SSc7.1. Covering the unshaded portions of the hardscapeHardscape consists of the inanimate elements of the building landscaping. Examples include pavement, roadways, stone walls, concrete paths and sidewalks, and concrete, brick, and tile patios. with a material with SRI of over 29 will be hard but over 78 would be blinding.

Thanks!

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esra ozkonuksever architect iltay mimarlık
Aug 02 2014
Guest
12 Thumbs Up

Attached roofs to the new constucted building

hi everyone,
i m working on project where there is a security check point seperate from the original building and a single floor entrance attached to the 3 floor building. now , while calculating the heat island -roof for this project; are these two diffrent roofs going to be included in 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.?
thanks!

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Jon Clifford LEED-AP BD+C, GREENSQUARE Aug 05 2014 LEEDuser Member 2451 Thumbs Up

Merhaba!
If the project boundary includes two roofs, the calculation should include both.
Bir şey değil. İyi şanslar!

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esra ozkonuksever architect , iltay mimarlık Aug 05 2014 Guest 12 Thumbs Up

thanks a lot !' teşekkür ederim

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John Covello LEED AP BD+C, EBOM, LEED and Sustainability Manager Development Management Group
Jul 31 2014
LEEDuser Member
544 Thumbs Up

Green Roof Plant overhang

Hello,

We have larger planters set upon our project's roofs. The rest 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. will be covered in gravel. Much of the plant growth will droop and overhang onto the gravel. If we can calculate this area of plant overhang does it count towards the vegetated roof area coverage? Or is it strictly the areas where there are planters with soil in them?

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S S
Jul 14 2014
Guest
166 Thumbs Up

Temperature rise due to Urban Heat Island Effect

We would like to know the temperature rise due to 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 in the following cases;

1. Total Plot Area of : 150 Acres.
Total Building FootprintBuilding footprint is the area on a project site used by the building structure, defined by the perimeter of the building plan. Parking lots, parking garages, landscapes, and other nonbuilding facilities are not included in the building footprint. : 95% of Plot Area
Landscape : 5% of Plot Area
Roof SRI : 40%

2. Total Plot Area of : 150 Acres.
Total Building Footprint : 90% of Plot Area
Landscape : 10% of Plot Area
Roof SRI : 80%

Looking forward your support.

Whether it is possible through Ecotect software or any other software.

Please help us.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jul 26 2014 LEEDuser Moderator

S S, I don't know of a reliable way to model this. I don't think there is enough field data to support robust modeling of this situation. There are a lot of unknowns that you don't give, such as temperature, windspeed, etc.

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Erin D.
May 29 2014
Guest
14 Thumbs Up

When your manufacturer doesnt have SRI values

In regards to this credit the LEED REFERENCE GUIDE FOR BUILDING DESIGN & CONSTRUCTION WITH GLOBAL ALTERNATIVE COMPLIANCE PATHS for LEED 2009 says that "Projects outside the U.S. may meet the material 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) testing requirements by consulting the Cool Roof Rating Council’s (CRRC) Rated Products Directory at http://coolroofs.org/products/results and ANSI/CRRC Standard 1, for a list of materials and associated SRI values. If the project’s specific material is listed, provide the SRI rating from this
website as documentation in the credit form to fulfill the testing requirements.

Color values do not have direct correlation to emissivityEmissivity is the ratio of the radiation emitted by a surface to the radiation emitted by a black body at the same temperature. and solar reflectance values which are the basis for the SRI calculation. The project can meet the testing requirement in one of three ways: by conducting in-place testing, finding a local lab for sample testing, or by using previous project data to determine the SRI."

Does that mean that ONLY projects outside the U.S. can do in-place testing or local lab testing when the material they want to use doesnt have manufacturer SRI values?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jul 26 2014 LEEDuser Moderator

Erin, I think that's how it's written, but it seems reasonable to me to be able to apply this domestically. I would contact GBCI to confirm.

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Erin D.
May 26 2014
Guest
14 Thumbs Up

SRI Testing Labs, Do They Need to be Certified in some way?

For users who are not using a roofing material with a known SRI, or for manufacturers who want to add SRI data to their product data sheets, does the lab they send their samples to need to be certified in some way by the cool roof rating council or some other third party? Does the project manager need to provide any specific documentation from the lab to prove they are providing SRI data that was collected following the correct ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services methods? If not, what if any, is the benefit of a manufacturer working with a CRRC accredited testing lab to get the SRI data?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jul 26 2014 LEEDuser Moderator

No. They can self-attest to following the correct ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services methods.

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E H Sustainability Architect
May 12 2014
Guest
3642 Thumbs Up

Courtyard over underground garage

I have a project with underground parking under the entire footprint of the site. About 70% of the parking is covered by the building, and 30% is covered by a ground-level courtyard accessible from the public sidewalk. Is the courtyard considered roof or hardscapeHardscape consists of the inanimate elements of the building landscaping. Examples include pavement, roadways, stone walls, concrete paths and sidewalks, and concrete, brick, and tile patios.? Would one count it towards this credit and SSc7.2? Or one or the other? If I count it as roof in SSc7.2 only, the project would essentially have no hardscape to include towards SSc7.1. Thanks, in advance, for your input!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jul 26 2014 LEEDuser Moderator

E H, I would definitely include it in only one or the other. As to choosing one, I would tend to count is as 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., per that LEED definition.

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E H Sustainability Architect
May 05 2014
Guest
3642 Thumbs Up

what defines a roof for this credit?

What defines a roof for this credit? Is it slope, construction, or function? I have a project with a mansard roof. It has a 65% slope, very steep. I would count it as a roof, as it's construction is like a roof and is not vertical. But, one could argue that a mansard roof (the steep part anyway) functions programmatically more like a wall. Any thoughts? When does a wall become a roof (for LEED)?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jul 26 2014 LEEDuser Moderator

I would reference the defiition 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.. I would rely on the plan view to decide if something is a roof or a wall. If it shows up in the plan, it's probably a roof.

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Davis Kantor LEED AP BD+C
Apr 28 2014
Guest
69 Thumbs Up

intensive vs. extensive green roofs

My recent research shows that installing a green roof system on a project aimed at LEED certification has the potential to contribute to the following LEED credits:
SS 5.1 Site Development - Protect or Restore Natural Habitat (1 point) - extensive green roof only
SS 5.2 Site Development - Maximize Open Space (1 point)
SS 6.1 Storm water design quantity control (1 point)
SS 6.2 Storm water design quality control (1 point)
SS 7.2 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 (1 point)
WE 1 Water Efficient Landscaping (2-4 points)
EA 1 Optimize Energy Performance (up to 19 points)
MR 3 Materials Reuse (1-2 points) and Recycled Content (1-2 points)
MR 5.2 Regional Material (1-2 points).

Thus, installing a green roofing systems of 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. guarantees 2 LEED points and can contribute to 33 possible points which is 82.5% of the points required to be LEED certified.

That being said, why does LEED not differentiate between extensive and intensive green roof? SS5.1 is only eligible with an extensive green roof which is composed of native plants. An intensive green roof on the other hand, which has deeper substrate, foreign plants and requires watering (which creates evapotranspiration) would contribute higher to SS6.1, SS6.1, SS7.2 and EA1. Why does LEED assume any green roof will have the same affects? Shouldn’t different types of green roof systems contribute to different scores in particular categories?

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E H Sustainability Architect Apr 28 2014 Guest 3642 Thumbs Up

If your project is eligible, a green roof can contribute to SSc5.1 if it is intensive (not extensive). LEED does not assume any green roof will have the same affects. It depends on the credit, and what the credit it focusing on. For SSc5.1, the credit focuses on biodiversity, an intensive system allows for more plant variety. For SSc6.1 & 6.2, and intenive system may also help reduce stormwater impacts because it can hold more water, but your civil engineer will have to do the calcs to determine what system would be most appropriate if you are just looking at just stormwater management. Not all credits have multiple threshold levels for varying points. But, you can 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. for this credit with an entirely green roof.

Not sure how to answer your question, but obviously you have done a lot of research, and know the properties of a green roof can contribute to many credits. That is the advantage of a green roof, over other roof systems.

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Davis Kantor LEED AP BD+C Apr 29 2014 Guest 69 Thumbs Up

The problem is an intensive green roof is typically composed of foreign plants. yes, it can host a wide variety. but the optimal roof for habitat restoration is really a seeded green roof of native plants as SS5.1 suggests. Only plant species that grow naturally in the region are going to promote biodiversity. these roofs are generally a few centimeters unlike intensive green roofs with much thicker substrate which requires more maintenance and LCC.

Shouldn't a green roof that better promotes biodiversity and requires little to no maintenance be awarded more points in the LEED rating system? I ask because I am researching green roofs in Switzerland where there are many city wide mandates requiring unoccupied, new or renovated flat roofs to be extensive green roofs. I'm currently preparing a plan for a Masters thesis on this topic and i want to promote a change in the LEED system which awards more points to an extensive green roof because ultimately it has a better affect on the environment. I'm just not exactly sure how to go about it.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 28 2014 LEEDuser Moderator

Davis, a couple comments. One, I would be looking at LEED v4 (see LEED-NC v4 SSc5), because that is where LEED has developed to today. Not that it is much different with respect to the heat island credit, but you might see some changes with rainwater management that might have an impact.

Two, I agree with the earlier comment to this thread, in that LEED does reward intensive green roofs for their better stormwater management potential.

Three, your previous comment on this thread leaves me confused. At the end of your comment you say you want to award "more points to an intensive green roof because ultimately it has a better affect on the environment," but in the rest of your comment you seem to suggest that an extensive (i.e. thinner) green roof better supports biodiversity.

Which roof do you think is better? If you're saying that extensive roofs  are better, I'm confused, because it seems to me that a deeper substrate simply allows more opportunity for biodiversity and more choice of plant species, as well as potential for a more three-dimensional habitat space that supports more species. Look at the intensive green roofs  in Chicago, for example, that support entire botanical gardens and prairie landscapes.

I would say that opposite is true—only sedums and some grasses grow on extensive roofs, and those plants might very likely not be native to the area.

Regarding maintenance, every installation will be different. No green roof will be maintenance  free, just as no landscape is maintenance free.

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Davis Kantor LEED AP BD+C Apr 29 2014 Guest 69 Thumbs Up

Hi Tristan-
Excuse me, I meant to say 'I want to promote EXTENSIVE green roofs because ultimately they has a better affect on the environment.' Thanks for catching that! I edited my previous comment to say what I intended.

So, actually extensive green roofs provide great habitat restoration because they are generally composed of native plants. Again, only native plants naturally growing in the region are going to improve biodiversity. This is why Switzerland has mandated such roofs in all major cities, and you can really notice the difference! Please read my experience of the top 5 green roofs in Switzerland. http://land8.com/profiles/blogs/top-five-green-roofs-from-switzerland-tour

I'll tell you that these roofs are naturally seeded and the only maintenance required is bi-annual mowing. I'm not kidding, these roofs are practically maintenance free because the plants grow naturally in the region! They don't ever water their roofs here, that is also important to consider when you talk about maintenance requirements.

True, intensive green roofs, with a deeper substrate, provide better storm water retention. More plant diversity will provide better biodiversity ONLY if they are native plants. However, intensive green roofs are generally composed of foreign plants. I say this because I have been a PM on the LEED project at USF. http://land8.com/profiles/blogs/under-construction-center-for-science-an...

You only need an intensive roof for native plants if say, you have trees and large shrubs growing. Does this make sense?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 29 2014 LEEDuser Moderator

Davis, I am still getting tripped up by definitions. In the U.S. "extensive roofs typically are defined as roughly 4" (10 cm) of soil, and no more than 20 cm.

Some of the projects you highlighted in your blog post have about that much, but some have a lot more soil.

I think you are oversimplifying. Deeper green roofs, like any landscape, can have native vegetationPlants indigenous to a locality (native) and adapted to the local climate; they require limited irrigation following planting, do not require active maintenance such as mowing, and provide habitat value. if designed and planted with it. Shallow green roofs may have native grasses, but in the U.S. they often have sedums which are not native. These may effectively provide habitat, or might not. It's not a simple matter. I think the lack of simple prescriptions here may be a factor in LEED not preferring one specific type of green roof. Here is one study that indicates the variation that can occur.

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Davis Kantor LEED AP BD+C May 03 2014 Guest 69 Thumbs Up

Tristan-

Yes, in America storm water retention is the biggest motive for future public policies to incentivize green roofs. And the deeper the substrate, the more rain water which gets retained. This is clear.

All of those examples in my blog post are shallow, extensive green roofs. So, you are wrong in saying that the examples in my blog post 'have a lot more' than 20cm. The point is that a native plant palette does not need a thick substrate.

However, deeper substrate can potentially host native plants which would promote biodiversity and retain more rain water. According to LEED v2009 it seems that this would be the best strategy for a green roof design seeking LEED certification. Is this a strategy projects can use to earn SS 5.1 Protect or Restore Habitat, SS6.1 Storm water Design- Quantity Control and SS6.2 Storm water Design- Quality Control?

I'm curious as to what strategy a project team would take to maximize points/benefits from a green roof. If you know of any projects that attained ID points in conjunction with green roofs I would be very interested to know what they did. Thanks!

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Gahl Sorkin Spanier
Apr 22 2014
LEEDuser Member
226 Thumbs Up

Solar panels effect on heat island

Does anyone know of any research relating to the effect of solar panels , or thermosolar collectors on 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.. Intuitively their effect should be positive as they absorb heat. But, I learned to be cautious with my intuitions.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 22 2014 LEEDuser Moderator

Gahl, typically dark surfaces contribute to 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., because they absorb light and then release the heat to the local environment. I don't have any data on this, but I would assume that PV panels would contribute to the heat island effect, while solar thermal might be more neutral, because it is capturing and using the heat.

To go further than what you were asking, I think generally people don't worry too much about the heat island contribution of solar panels because they generally are a small proportion of a 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., they are ventilated, or provide shading of pavement in some cases, and they are also generating renewable energy and thus providing a benefit.

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Alexander Benning Project Manager ES EnviroSustain GmbH
Apr 22 2014
LEEDuser Member
311 Thumbs Up

SRI equal to Light Reflectance Value (LRV) ?

Whe have problems to get SRI-values for parking deck coatings.
Sto says on their website that the Light Reflactance Value (LRV) can be used to calculat the SRI-value.

Has anyone documented the SRI-value based on the LRV and was that accepted by the reviewers?

From http://www.stocorp.com
"Sto's Color charts list the % Light Reflectance Value (LRV) of each color. This value (divided by 100) may be used to calculate the SRI for a given color."

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 28 2014 LEEDuser Moderator

My understanding is that LRV is used for measuring visible light (and is relevant for interior design), and SRI is used for measuring solar heat, including non-visible wavelengths. Converting one to another simply by division is not possible. I would ask Sto Corp to verify how they convert one to another.

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PAWAN DAHIWAL
Apr 11 2014
Guest
423 Thumbs Up

Just Want to Know

It may be a silly question.
If both both low sloped and steep sloped roof material is same, why steep sloped roof requires lower SRI paint?

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Heather Holdridge Sustainability Coordinator, Lake/Flato Architects Apr 14 2014 LEEDuser Member 1527 Thumbs Up

The material for steep-sloped and low-sloped roofs on a single project do not have to be the same, but if they are, they need to meet the more stringent requirements of the low-sloped roof. Low-sloped roofs are subject to more stringent requirements because for buildings with a large 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. relative to building height, the roof surface area is the main source of heat gain to the building. It is much more critical in these applications to use a "cool roof."

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Amber Richane Associate Principal Callison
Mar 10 2014
LEEDuser Member
238 Thumbs Up

Question on Option 3

How is a team supposed to achieve Option 3 for this credit? It requires a minimum of 75% be an appropriate SRI and minimum 50% be vegetated. that's 125% 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....how is that possible? or, what is intended there?

thanks!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 10 2014 LEEDuser Moderator

Amber, it's a weighted average. You can have a value greater than 100, because it's just a number, not a percentile.

If you do the math, it'll make sense. Using our calculator in the Doc Toolkit tab above will also illustrate different scenarios.

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Alexia Anastassiadis
Feb 26 2014
Guest
419 Thumbs Up

Gravel as a part of green roofs

Hi! We are working on a project that has a large green roof. Some parts of it are covered with gravel (crushed stone) as a surface to walk on. The gravel is on top of the same green roof system as the vegetation, only the top layer is the stone instead of vegetation. Do we count this as part of the green roof? Thanks for any advice you can give!

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Susan Walter Specifications Director, Populous Feb 27 2014 LEEDuser Expert 17662 Thumbs Up

Yes, you do count the gravel. No, I don't know what the SRI of gravel is but my working assumption is that it will not meet the SRI requirements. (As i recall it has to do with the shadows the gravel casts.) We've been specifying compliant pavers instead.

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CT G
Jan 16 2014
LEEDuser Member
362 Thumbs Up

Maintenance Paths at Green Roof

Dear all,
We are working on a project looking to incorporate a green roof for 100% 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., excluding areas covered by mechanical equipment. However, the green roof will be made of modular trays that cannot be walked on and, therefore, maintenance paths for access to the mechanical equipment need to be provided. The project wants to earn the 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. point for achieving 100% green roof. The question is whether the paths for maintenance can be excluded from the calculation in the same way the mechanical equipment is, mainly because access cannot be granted through the vegetated roof surface because of its nature? Thanks in advance for any insight.

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Mara Baum Healthcare Sustainable Design Leader, LEED Fellow, HOK Jan 16 2014 LEEDuser Expert 8909 Thumbs Up

Unfortunately you can't exclude the maintenance pads. (IMHO this is a problem with the credit and the EP threshold should be 95%, as with things like construction waste management, but it is what it is.)

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Michael D. DeVuono Senior Staff Engineer, T&M Associates Jan 16 2014 LEEDuser Expert 3673 Thumbs Up

Has this been tested, Mara? No green roof is ever 100% green. I would submit this and make them tell you no.

Can you do some form of elevated walkway to get where you need to go?

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Susan Walter Specifications Director, Populous Jan 16 2014 LEEDuser Expert 17662 Thumbs Up

If your maintenance pads are SRI compliant, I would submit it for EP also. Review your layout and minimize the paths. Do everything you can to minimize the paths. The only thing they can say is no and you may be able to get a better reading on the topic from a reviewer.

We did a project that used 14,000 s.f. of vegetated tray system. The rep at the time said that the trays could handle some traffic but to keep it to foot traffic for plant maintenance only. Mechanical equipment can require more than that and you would need pavers of some sort.

But Mara is often right about these things...

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Mara Baum Healthcare Sustainable Design Leader, LEED Fellow, HOK Jan 16 2014 LEEDuser Expert 8909 Thumbs Up

There's certainly nothing wrong with trying - it would be a design phase ID credit, and you can always submit a new one in construction.

I previously have been required to include walking pads as part of the calculation - they not an exclusion such as an appurtenanceAn appurtenance is any built-in, nonstructural portion of a roof system, such as skylights, ventilators, mechanical equipment, partitions, and solar energy panels. - but that may have been a reviewer judgement call.

I totally agree that green roofs aren't 100% green, hence my comment about the innappropriate threshold. However, many green roof designs still allow for walkable surfaces within the same system, which this one does not.

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Mara Baum Healthcare Sustainable Design Leader, LEED Fellow, HOK Jan 16 2014 LEEDuser Expert 8909 Thumbs Up

Susan and I posted simultaneously just now. I totally agree that if you try an EP, you definitely want SRI compliant pads. You should definitely give it a shot.

Also, if it's a very small green roof then the pads may be a high percentage, in which case it wouldn't look as good.

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Michael D. DeVuono Senior Staff Engineer, T&M Associates Jan 16 2014 LEEDuser Expert 3673 Thumbs Up

Carlos, if you attempt this, be sure to check back, and let us know how it goes.

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Ghaith Moufarege
Jan 09 2014
LEEDuser Member
9006 Thumbs Up

Alternative Compliance Path for SRI compliant products

Dear All,

I received an email from LEEDUser called "LEED Updates: New Interpretations & Addenda"

One interesting point was the following:

"USGBC introduces multiple new options for non-U.S. projects that have had limited access to heat-island compliant products for SSc7.1 and SSc7.2."

The link doesn't direct to the proper page. Anyone has further guidance on what can be done?

Thanks!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jan 09 2014 LEEDuser Moderator

Omar, the article that I sent out in the email is here. That contains a link with the detailed USGBC guidance.

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Ghaith Moufarege Jan 09 2014 LEEDuser Member 9006 Thumbs Up

Thanks Tristan.

I don't really understand what's "new" here - couldn't we previously use the SRIs of a material listed in the the Cool Roof Council website? The SRI is a property and if it is available on this website this means that the product manufacturer knows the SRI.

The issue with international projects is that many suppliers have not even heard of the SRI term.

Have I misunderstood something?

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Fabien Challeat Deputy Project Manager Archetype Group
Jan 08 2014
LEEDuser Member
18 Thumbs Up

Calculation

Hi,

Our project has several buildings going for LEED certification.
We are using 2 different roofing materials with SRI of 106 and 84 for low slope roofs.

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. for all 7 buildings is 99,491 sf.
Two buildings will be covered with a SRI 84 material with roof area of 63,033 sf.
One building will have roof material with SRI of 106, roof area of 6,975 sf
All other buildings will have concrete roof.

Question: Do we use the weighted rooftop SRI average equation to see if we meet this credit requirement?

Thanks.

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Heather Holdridge Sustainability Coordinator, Lake/Flato Architects Dec 23 2014 LEEDuser Member 1527 Thumbs Up

Have you tried entering this into the LEED Online template?

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MM K
Jan 06 2014
Guest
1856 Thumbs Up

Fire exits

Are fire exits/emergency stairs considered part of the roof or can these be excluded?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jan 06 2014 LEEDuser Moderator

MM, per the guidance above, appurtenances such as mechanical equipment, skylights, pools, helipads, and more are excluded. The terminology used is "functional, usable spaces." I haven't seen stairs mentioned on a list of exclusions but it seems like they fit the mold.

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MM K Jan 06 2014 Guest 1856 Thumbs Up

Thanks Tristan!
On another note, when part of the roof is covered by louvres that do not fully shade the roof (i.e., lets in strips of sunlight in), which part has to be documented, the roof or the louvres?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jan 06 2014 LEEDuser Moderator

What are the louvres covering? Just roof? That's a bit of an odd case, and I could see an argument for going one of three ways.

If the louvres are over a skylight, which makes more sense to me funtionally, it would be an appurtenanceAn appurtenance is any built-in, nonstructural portion of a roof system, such as skylights, ventilators, mechanical equipment, partitions, and solar energy panels..

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Susan Walter Specifications Director, Populous Jan 06 2014 LEEDuser Expert 17662 Thumbs Up

Be careful on the stairs, if you have covered, conditioned stairs leading up to the roof that stair roof IS part of the calculation. Ask me how I know.

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