LEED Green Building Rating System and Sustainable Sites By Steven Harrison, P.E., LEED AP and Jim Noll, P.E. November 2008
Professional Development Series LEED Green Building Rating System and Sustainable Sites By Steven Harrison, P.E., LEED AP and Jim Noll, P.E. Green building and construction increases the efficiency with which buildings and developments use resources while reducing impacts on human health and the environment. Many agencies and organizations recognize the importance of utilizing products and methods as green solutions to promote environmental, economic, health, and community benefits through better site selection and development, building design, construction, operation, maintenance, and pollutant removal. Various rating systems have been developed to certify green building and construction, including the U.S. Green Building Council s (USGBC) Leadership in Energy and Environmental Design (LEED) Green Building Rating System. LEED Green Building Rating System The USGBC created in 1993 recognized the need for a system to define and measure green buildings. In August 1998, the first LEED Pilot Project Program was launched. The pilot program, commonly referred to as LEED Version 1.0, was created by a USGBC committee comprised of architects, realtors, a building owner, a lawyer, environmentalists, and industry representatives. In 2000, a revised version was published, LEED Green Building Rating System Version 2.0. The current version is 2.2. LEED certification is a third-party validation of a building s performance and can lead to builders and developers receiving more lucrative projects, financial incentives/credits, and significant acknowledgments for their efforts. The LEED Green Building Rating System for New Construction and Major Renovation is organized into six different categories: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, and Innovation in Design. The LEED Rating System evaluates the overall performance of a green building project based on points. Within each of the six LEED credit categories, projects must satisfy particular prerequisites and earn points. The number of points earned determines the level of LEED certification the project receives (Certified, Silver, Gold, or Platinum). This article discusses several significant credits comprising the Sustainable Sites category. Sustainable site development A sustainable project starts with a sustainable site. Selecting the site and placing the building on the site are two of the most important steps in a green building project. Development on an inappropriate site can increase a building s water demands, transportation and energy impacts, ecosystem disturbances, and project costs. Where and how a building occupies a site has significant, long-term impacts on its efficiency and success. It is essential to analyze the building s relationship with its surrounding natural environment, including the sun, soil, wind, water, and trees, as well as the surrounding built environment, which includes other buildings, roads, and local transportation options. Continuing Education The Professional Development Series is a unique opportunity to earn continuing education credit by reading specially focused, sponsored articles in CE News. If you read the following article, display your understanding of the stated learning objectives, and follow the simple instructions, you can fulfill a portion of your continuing education requirements at no cost to you. This article also is available online at www.cenews.com/ pg.asp?id=20. Instructions First, review the learning objectives below, then read the Professional Development Series article. Next, complete the quiz and submit your answers to the Professional Development Series sponsor. Submittal instructions are provided on the Reporting Form on page PDH 6. Your quiz answers will be graded by the Professional Development Series sponsor. If you answer at least 80 percent of the questions correctly, you will receive a certificate of completion from the Professional Development Series sponsor within 90 days and will be awarded 1.0 professional development hour (equivalent to 0.1 continuing education unit in most states). Note: It is the responsibility of the licensee to determine if this method of continuing education meets his or her governing board(s) of registration s requirements. Learning Objectives After reading this article, you should understand the general benefits, prerequisites, and specific credits required to satisfy the Sustainable Sites category of the U.S. Green Building Council s Leadership in Energy and Environmental Design (LEED) for New Construction. Professional Development Series Sponsors David Evans and Associates, Inc. CONTECH Construction Products Inc. 2 PDH Professional Development Advertising Section CONTECH Construction Products Inc.
The first category of credits in LEED for New Construction focuses on Sustainable Sites, which addresses the building site s impact on the community, local infrastructure, and environment. It encourages best management practices for everything on the exterior of the building, including construction techniques that protect undeveloped land and open spaces, contaminated site remediation, traffic reduction, and stormwater minimization and treatment. Using sustainable building locations and features in the building design minimizes environmental impacts both locally and globally. LEED for New Construction Sustainable Sites The Sustainable Sites category consists of the following prerequisite and credits: Prerequisite Construction Activity Pollution Prevention. This prerequisite requires projects to implement an Erosion and Sedimentation Plan to reduce pollution from construction activities by controlling soil erosion, waterway sedimentation, and airborne dust generation. Credit 1: Site Selection. When selecting a site, identify sites that do not have sensitive site elements or restrictive land types. Select a building design and location with the least environmental impact. Credit 2: Development Density and Community Connectivity. When selecting a site, give preference to urban sites with dense development and pedestrian access to services such as banks, libraries, day care facilities, grocery stores, post offices, and restaurants. Credit 3: Brownfield Redevelopment. When selecting a site, give preference to brownfield sites and then identify an appropriate remediation strategy. Credit 4.1: Alternative Transportation Public Transportation Access. Reduce pollution and land development impacts from car use by situating the building near mass transit facilities. Credit 4.2: Alternative Transportation Bicycle Storage and Changing Rooms. Reduce pollution and land development impacts from car use by encouraging bike commuting and designing a building with bicycle storage and changing rooms. Credit 4.3: Alternative Transportation Low-Emitting and Fuel-Efficient Vehicles. Reduce pollution and land development impacts from car use by providing amenities such as alternative fuel refueling stations or preferred parking for low-emitting and fuelefficient vehicles. Credit 4.4: Alternative Transportation Parking Capacity. Reduce impacts from single occupancy vehicle use by providing preferred parking for carpool vehicles, sharing parking facilities with adjacent buildings, or minimizing parking lot space. Credit 5.1: Site Development Protect or Restore Habitat. Protect or restore habitat by conserving existing natural areas or restoring areas to provide habitat and encourage biodiversity. Credit 5.2: Site Development Maximize Open Space. Design the building with a minimal footprint and maximize open space on the site to encourage biodiversity. Credit 6.1: Stormwater Management Quantity Control. Reduce impervious surfaces, manage stormwater runoff, and increase on-site infiltration to maintain natural stormwater flows to avoid disturbing natural water hydrology. Credit 6.2: Stormwater Management Quality Control. Manage stormwater runoff in order to reduce disruption and pollution of natural water flow. Credit 7.1: Heat Island Effect Non-Roof. Reduce heat island effect through the use of shaded surfaces, vegetated surfaces, and open-grid paving or high-albedo materials. Credit 7.2: Heat Island Effect Roof. Reduce effect of heat island by installing high-albedo and vegetated roofs (which reduce heat absorption). Credit 8: Light Pollution Reduction. The site s internal and external light levels should be minimized to reduce impact on nocturnal environments, improve nighttime visibility (through glare reduction), and avoid night-sky pollution. Prior to selecting a site, potential environmental disturbances that may occur as a result of the project need to be evaluated. Sustainable Sites Credit 1 (SSc1), which focuses on site selection, identifies the following six criteria that should be avoided when choosing your location: 1) prime farmland as defined by the U.S. Department of Agriculture; 2) previously undeveloped land with an elevation lower than 5 feet above the elevation of the 100-year flood as defined by the Federal Emergency Management Agency; 3) land identified as habitat for any species on federal or state threatened or endangered list; 4) land within 100 feet of any wetlands; 5) previously undeveloped land within 50 feet of a body of water which supports or could support fish, recreation, or industrial use, consistent with the terminology of the Clean Water Act; and 6) land which was public parkland. The Sustainable Sites category also focuses on developing a site in urban areas with existing infrastructure. The site location will influence many things, including whether people drive or use alternative transportation to reach the site. Also, if fewer individual cars are traveling to your site, fewer parking spaces are needed. According to the Natural Resources Defense Council, automobiles are responsible for approximately 20 percent of greenhouse gas emissions in the United States each year. Professional Development Advertising Section CONTECH Construction Products Inc. PDH 3
LEED Green Building Rating System and Sustainable Sites Consider the proposed uses of the building and what services are located nearby. Locating the development near other common destinations and dense residential areas allows access through alternative modes of transportation such as walking, bicycling, or public transit, and the location can improve quality of life as commuters spend less time in their automobiles. Sustainable Sites Credit 2 (SSc2): Development Density and Community Connectivity focuses on reducing urban sprawl. There are two ways to earn this credit. A dense development is defined by LEED as property with an average density greater than or equal to 60,000 square feet per acre (sq.ft./acre), including the area of the project. Development density is calculated by dividing the total square footage of the building by the total project site area in acres (see Equation 1). The total project site area must remain consistent throughout LEED documentation. Development Density (sq.ft./acre) = Gross Building Square Footage (sq.ft.) Project Site Area (acres) (Equation 1) Once the development density is determined, convert the total site area from acres to square feet, then calculate the square root of this number and multiply the result by three to determine the density radius (see Equation 2). Density Radius (feet) = 3* (Property Area [acres]*43,560 [sq.ft./acre]) (Equation 2) To determine the density boundary, overlay the density radius on a map that includes the project site and center the circle over the project site. For all properties inside the boundary (or intersecting the boundary circle) determine the building square footage, the site area, and add the total for each. Divide the total building square footage by the total site area (not including public roads and right-of-way areas) in acres to find the average density (see Equation 3). Average Density (sq.ft./acre) = (Sq.ft. of buildings within density radius) (Total site area in acres) (Equation 3) Community connectivity can be achieved by locating a project within 1/2 mile of a residential zone with an average density of 10 units per net acre and at least 10 basic services with pedestrian access. LEED identifies a list of basic services that many people use on a regular basis and that meet the community connectivity criteria for SSc2. These services include banks, places of worship, convenience or grocery stores, pharmacies, post offices, senior care facilities, laundry facilities, day cares, fire stations, restaurants, fitness centers, libraries, schools, salons, hardware stores, medical/dental offices, public parks, theaters, and community centers. To document this credit, define a 1/2-mile radius circle centered around the site on a map. Then identify on the map each of at least 10 basic community services and the area with a residential zone having at least 10 units per net acre. Only one of each service, except restaurants which can count for two, can be used to attain 10 total. In addition to basic services, LEED prefers sites that are located near mass transit. Sustainable Sites Credit 4.1 (SSc4.1) requires the building to be within 1/2 mile (via pedestrian route) of an existing or planned and funded commuter rail, or within 1/4 mile of one or more stops for two or more public or campus bus lines usable by building occupants. To document achievement of this credit, submit an area map that indicates the project site location and the location of either a commuter rail stop or two bus stops. The map must also include a scale bar and a north arrow indicator. Stormwater management The intent of USGBC credits for stormwater management is to minimize the site development impact to the natural hydrology of the project site. SSc6.1 Stormwater Design: Quantity Control The intent of this credit is to avoid potential downstream flooding and excessive stream bank erosion by minimizing the rate and quantity of stormwater runoff. By promoting stormwater infiltration, this credit also attempts to keep the natural hydrology of the pre-developed site. The criteria for this credit are separated in two existing condition scenarios: Case 1 Existing imperviousness is less than or equal to 50 percent; and Case 2 Existing imperviousness is greater than 50 percent. When the project site existing surface conditions are equal to or less than 50 percent impervious, the design team must implement a plan that prevents the post-developed peak stormwater runoff rate and quantity from exceeding the pre-developed (existing condition) rate and quantity. If the stormwater design does not result in limiting the runoff rate and quantity to pre-developed conditions and the project is located near a stream or creek, the design team can implement a plan that protects the receiving channel from excessive erosion. A narrative must be written describing the strategies that have been implemented to reduce stormwater runoff and protect the stream bank from excessive erosion. If the project site existing conditions reflect Case 2 Existing imperviousness is greater than 50 percent, the design team must implement a stormwater management plan that reduces the post-developed stormwater runoff rate and quantity by 25 percent from the pre-developed condition. Documentation for this credit can be in the form of the Letter Template associated to this credit. A Letter Template is a standard LEED form provided by USGBC that outlines 4 PDH Professional Development Advertising Section CONTECH Construction Products Inc.
the specific requirements of the credit and provides direction as to how to explain or justify how the proposed strategies achieve the credit. Calculations must be submitted that show the preand post-development stormwater runoff rate and quantity for the two-year, 24-hour storm event. The Letter Template also provides space for a written narrative. Strategies for stormwater quantity control include green roofs, infiltration trenches or ponds, detention/retention facilities, or stormwaterharvesting facilities. Green roofs provide stormwater detention in the growing medium of the green roof and also provide evapotranspiration. Design considerations include additional structural load on the roof, and irrigation to allow the green roof plant material to establish. Infiltration and detention/retention facilities have several design factors, including the size of contributing areas draining to the facility, surface runoff characteristics, and soil infiltration rates. Stormwaterharvesting facility design factors also include the size of contributing areas draining to the site and surface runoff characteristics, but also consider average annual rainfall and necessary water demand for irrigation and toilet flushing. These facilities are typically supplemented with a domestic water supply during potentially dry summer months. The difficult part of this credit is meeting the stormwater runoff quantity criteria. The stormwater rate can be managed through the use of detention facilities and orifices that are designed to release at a specific rate. But, the quantity of stormwater runoff leaving the site is much more difficult to manage. The most effective and efficient way This flow-through planter, located at Clackamas Community College in Oregon City, Ore., provides stormwater quality control for the roof area and is an example of a water quality strategy. This water quality swale is another example of a water quality strategy. It provides stormwater quality treatment for all impervious areas on the project. This swale is located at the Nike Vivian Stringer Child Development Center in Beaverton, Ore. On this tight site in Baltimore, a manufactured stormwater filtration BMP is installed in combination with a swale to allow both stormwater management regulations and low impact development goals to be met. to achieve this is by using infiltration facilities. However, if the existing soils on the project site are not conducive to infiltration, the quantity of stormwater runoff must be managed by a retention or harvesting facilities. Retention facilities will allow gradual infiltration and evapotransporatation of stormwater. The stormwater harvesting facilities will utilize the stormwater for other uses such as landscape irrigation or toilet flushing within the building. Integrating the stormwater management facilities into the overall site plan can be challenging. Stormwater facilities may impact site grading, building plumbing, pedestrian and vehicular traffic, and landscape planting. Coordinated design teams can achieve multiple credits using one strategy. For example, a stormwater-harvesting facility utilizing stormwater to irrigate landscaping and flush toilets within the building can also assist in achieving Water Efficiency credits WEc1.1 and WEc1.2 for water-efficient landscaping, and credits WEc3.1 and WEc3.2 for potable water use reduction. Another example is to utilize a pervious pavement material to infiltrate stormwater, which may also have material characteristics to achieve Sustainable Sites credit SSc7.1 for reducing the heat island effect for non-roof areas. SSc6.2 Stormwater Design: Quality Control The criteria for this credit include implementation of a stormwater management plan that captures and treats 90 percent of the average annual rainfall. The treatment must remove 80 percent of the average annual post-development total suspended solids (TSS). Professional Development Advertising Section CONTECH Construction Products Inc. PDH 5
LEED Green Building Rating System and Sustainable Sites The criteria 90 percent of the average annual rainfall are defined for three different watersheds: humid, semi-arid, and arid. Humid watersheds are defined as those that receive at least 40 inches of rainfall in a year. Semi-arid watersheds are those that receive between 20 and 40 inches of rainfall in a year and arid watersheds receive less than 20 inches of rainfall in a year. For humid, semi-arid, and arid watersheds, 90 percent of the average annual rainfall is 1-inch, 3/4-inch, and 1/2-inch of rainfall, respectively. Documentation for this credit can also be in the form of the Letter Template associated to this credit. The Letter Template separates natural or non-structural best management practices (BMP) from black box or structural treatment facilities. The template also allows for multiple treatment facilities and calculates their total rainfall treatment volume by percentages automatically. The Letter Template also provides space for a written narrative. Natural treatment systems include green roof, biofiltration or grassy swales, infiltration basins or trenches, sand filters, filtration basins, or extended wet detention ponds. These treatment facilities will require a certain amount of property area on the site. The size of the area is dependent on the proposed facility and the amount of stormwater being treated. These facilities can also add an aesthetically pleasing component to the site by using appropriate landscape planting. There are also products on the market that can provide effective treatment of the stormwater without taking up potentially expensive real estate. These black box facilities are compact, located at specific points, and are typically below grade. Both the natural and black box treatment facilities require at least annual maintenance to ensure they are operating effectively. These types of treatment facilities are acceptable solutions to meeting the water quality credit if in-field performance exists for monitoring data demonstrating compliance with the listed criteria. Resources and the future of green building Although this article focuses primarily on several significant credits within the Sustainable Sites category, additional detailed information about all of the credits within the LEED Green Building Rating System can be found on USGBC s website (www.usgbc.org). The site also contains information about registering a project and the fees and certifications involved. Professional Development Series Sponsor: 9025 Centre Pointe Dr., Suite 400, West Chester, OH 45069 Phone: 800-338-1122 Fax: 513-645-7993 Email: info@contech-cpi.com Web: www.contech-cpi.com CE News Professional Development Series Reporting Form Article Title: LEED Green Building Rating System and Sustainable Sites Publication Date: November 2008 Sponsor: CONTECH Construction Products Inc. Valid for credit until: November 2010 Instructions: Select one answer for each quiz question and clearly circle the appropriate letter. Provide all of the requested contact information. Fax this Reporting Form to 513-645-7993. (You do not need to send the Quiz; only this Reporting Form is necessary to be submitted.) 1) a b c d 6) a b c d 2) a b c d 7) a b c d 3) a b c d 8) a b c d 4) a b c d 9) a b c d 5) a b c d 10) a b c d Required contact information Last Name: First Name: Middle Initial: Title: Firm Name: Address: City: State: Zip: Telephone: Fax: E-mail: Certification of ethical completion: I certify that I read the article, understood the learning objectives, and completed the quiz questions to the best of my ability. Additionally, the contact information provided above is true and accurate. Signature: Date: 6 PDH Professional Development Advertising Section CONTECH Construction Products Inc.
With architects, real estate professionals, facility managers, engineers, interior designers, landscape architects, construction managers, lenders, and government officials all taking a vast interest in helping to transform the built environment toward a more sustainable environment, the green design field grows and develops constantly. With the bar of sustainable living ever increasing and new technologies and products surfacing on the marketplace every day, there is infinite opportunity to effect change in the way buildings are designed, built, operated, and maintained. Steven Harrison, P.E., LEED AP, is a project manager for David Evans and Associates, Inc. He can be contacted at sdh@deainc.com. Jim Noll, P.E., is director of Engineering Services for CONTECH Construction Products Inc. He can be contacted at jnoll@ contech-cpi.com. Professional Development Series Quiz 1. The acronym LEED stands for: a) Lighting and Energy Efficiency Design b) Land, Environment, and Energy Demands c) Leadership in Energy and Environmental Design d) Leaders in Energy Efficient Design 2. All of the following credits pertain to the Sustainable Sites category of the LEED Green Building Rating System with the exception of: a) Development Density and Community Connectivity b) Alternative Transportation c) Stormwater Management d) Construction Waste Management 3. Identifying potential environmental impact due to construction of a new building is a key focus of the Sustainable Sites Credit. Criteria to be concerned with include: a) Land classified as habitat for any species included on the federal or state endangered species list b) Land set aside as a public park c) Any lands within 100 feet of a classified wetland d) Both (a) and (b) e) All of the above 4. The Community Connectivity Credit (SSc2) identifies key basic services needs for the local community that must be located within the following distance of the planned construction site being evaluated: a) 10 miles c) 1/2 mile b) 1 mile d) 2 miles 5. SSc2 criteria for identifying basic service needs of a community include all of the following businesses with the exception of: a) Restaurants d) Banks b) Fire stations e) Sports bars c) Laundromats 6. LEED Credit SSc6.1 Stormwater Design: Quantity Control permits the designer to exceed the pre-developed site runoff rate as long as the design includes: a) A plan to prevent excessive erosion of the banks of the stream channel receiving the site runoff. b) A pretreatment system for the site runoff. c) Sufficient green space on the site to maximize open space. d) A plan to provide habitat and encourage biodiversity. 7. The most efficient method of controlling the quantity of stormwater runoff from the building site is to: a) Collect and treat the water first. b) Incorporate detention ponds into the site design. c) Use infiltration or retention facilities. d) Use stormwater for irrigation. 8. Identify which of the following statements is most applicable to the Letter Template associated with SSc6.2: a) Enables the designer to incorporate multiple treatment facilities b) Incorporates stormwater harvesting facilities to control site runoff c) Separates natural best management practices from structural treatment facilities d) Both (a) and (c) e) None of the above 9. An important aspect of black box treatment facilities is: a) They must be located offsite. b) They can not be located within 100 feet of wetlands. c) They require annual maintenance to ensure operational effectiveness. d) They must incorporate both detention and infiltration capabilities. 10. Pertaining to LEED Sustainable Site Development, development of the wrong site can: a) Increase the cost of construction b) Result in excessive construction material waste c) Require longer lead times for design review and approval d) Increase the building s water demands and environmental impacts e) Both (a) and (d) Professional Development Advertising Section CONTECH Construction Products Inc. PDH 7
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