Leadership in Energy and Environmental Design
Leadership in Energy and Environmental Design (LEED) consists of a suite of rating systems for the design, construction and operation of high performance green buildings, homes and neighborhoods.
Developed by the U.S. Green Building Council (USGBC), LEED is intended to provide building owners and operators a concise framework for identifying and implementing practical and measurable green building design, construction, operations and maintenance solutions.
Since its inception in 1993, the U.S. Green Building Council has grown to encompass more than 7,000 projects in the United States and 30 countries, covering over 1.501 billion square feet (140 km²) of development area. The hallmark of LEED is that it is an open and transparent process where the technical criteria proposed by USGBC members are publicly reviewed for approval by the almost 20,000 member organizations that currently constitute the USGBC.
The Green Building Certification Institute (GBCI) was established by USGBC to provide a series of exams to allow individuals to become accredited for their knowledge of the LEED rating system. This is recognized through either the LEED Accredited Professional (LEED AP) or LEED Green Associate (LEED Green Assoc.) designation. In 2011 GBCI named the organization's first class of LEED Fellows, the highest designation for LEED professionals. GBCI also provides third-party certification for projects pursuing LEED.
LEED has evolved since its original inception in 1998 to more accurately represent and incorporate emerging green building technologies. LEED NCv1.0 was a pilot version. These projects helped inform the USGBC of the requirements for such a rating system, and this knowledge was incorporated into LEED NCv2.0. LEED NCv2.2 was released in 2005, and v3 in 2009. Today, LEED consists of a suite of nine rating systems for the design, construction and operation of buildings, homes and neighborhoods. Five overarching categories correspond to the specialties available under the LEED Accredited Professional program. That suite currently consists of:
Green Building Design & Construction
- LEED for New Construction
- LEED for Core & Shell
- LEED for Schools
- LEED for Retail: New Construction and Major Renovations
- LEED for Healthcare
Green Interior Design & Construction
- LEED for Commercial Interiors
- LEED for Retail: Commercial Interiors
Green Building Operations & Maintenance
- LEED for Existing Buildings: Operations & Maintenance
Green Neighborhood Development
- LEED for Neighborhood Development
Green Home Design and Construction
- LEED for Homes
LEED also forms the basis for other sustainability rating systems such as the Environmental Protection Agency's Labs21.
After four years of development, aligning credits across all LEED rating systems and weighting credits based on environmental priority, USGBC launched LEED v3, which consists of a new continuous development process, a new version of LEED Online, a revised third-party certification program and a new suite of rating systems known as LEED 2009. In response to concerns that LEED's requirements are cumbersome and difficult to learn, in 2009 USGBC supported the development by BuildingGreen, LLC of LEEDuser, a third-party resource that contains tips and guidance, written by professionals in the field, on applying LEED credits and the LEED certification process.
In LEED 2009 there are 100 possible base points distributed across five major credit categories: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, plus an additional 6 points for Innovation in Design and an additional 4 points for Regional Priority. Buildings can qualify for four levels of certification:
- Certified: 40–49 points
- Silver: 50–59 points
- Gold: 60–79 points
- Platinum: 80 points and above
The LEED for Homes rating system is different from LEED v3, with different point categories and thresholds that reward efficient residential design. 
Prerequisites and credits
Goal of the credit system
The goal of the LEED 2009 performance credit system is to allocate points "based on the potential environmental impacts and human benefits of each credit." To weigh these impacts, the USGBC relies upon the environmental impact categories of the United States Environmental Protection Agency's Tools for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) as a basis for weighting each credit. LEED 2009 makes reference to the environmental-impact weighting scheme developed by the National Institute of Standards and Technology (NIST) in assigning credit weights. USGB stands for United States Green Building.
Points are distributed across major credit categories such as Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, and Indoor Environmental Quality.
Basic prerequisites for participating in LEED 2009 include compliance with all environmental laws and regulations, occupancy scenarios, building permanence and pre-rating completion, site boundaries and area-to-site ratios, and obligatory five-year sharing of whole building energy and water use data from the start of occupancy (for new construction) or date of certification (for existing buildings).
Each of the performance categories also have measures in each category which are mandatory and receive no points.
LEED 2009 Credit Weighting Process
A three-step weighting process has been defined for LEED 2009:
- A collection of reference buildings are used to estimate the environmental impacts of any building seeking LEED certification in a designated rating scheme.
- NIST weightings are used to judge the relative importance of these impacts in each category.
- Data regarding actual impacts on environmental and human health are used to assign points to individual categories and measures.
This system results in a weighted average for each rating scheme based both upon actual impacts and the relative importance of those impacts to human health and environmental quality. In addition, the LEED council appears to have assigned credit and measure weighting based upon the market implications of point allocation.
From 2010 buildings can use carbon offsets to achieve Green Power Credits for LEED-NC (New Construction Certification) :
In addition to the 100 points constituted by the five (5) main categories (Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, and Indoor Environmental Quality), an additional 6 bonus points can be obtained for credits in Innovation in Design and 4 bonus points are available for improvements in LEED-selected categories determined to impact Regional Priorities.
LEED for Homes
Additional performance categories in the LEED for Homes rating system are Locations and Linkages (recognizing the importance of transportation access, open space, and physical activity outdoors) and Awareness and Education (recognizing the need for buildings and settlements to educate occupants).
In 2003, the Canada Green Building Council received permission to create LEED Canada-NC v1.0, which was based upon LEED-NC 2.0. This version was updated and released on June 21, 2010 to LEED Canada NC 2009.
LEED certification is obtained after submitting an application documenting compliance with the requirements of the rating system as well as paying registration and certification fees. In order to establish a building's point awards in each credit category, buildings applying for certification are compared with a theoretical baseline building defined by a LEED methodology or the more stringent of either ASHRAE/ANSI/EISNA codes or local codes.
Certification is granted solely by the Green Building Certification Institute (GBCI), which is responsible for the third party verification of project compliance with LEED requirements.
The application review and certification process is handled in LEED Online, USGBC's web-based tool that employs a series of active PDF forms to automate filing documentation and communication between project teams and GBCI's reviewers.
The process of the LEED for Homes Rating System, available in both the USA and Canada, is significantly different than the LEED NC rating system. LEED for Homes projects are low rise residential and are required to work with either an American Provider Organization or a Canadian Provider Organization and a Green Rater. A Provider Organization helps the project through the process while overseeing the Green Raters. Green Raters are individuals that conduct the two mandatory LEED for Homes site inspections; the Thermal Bypass Inspection and the Final Inspection. Although LEED for Homes is typically viewed by the construction industry as a simpler rating system especially when compared to LEED NC, LEED NC does not require an on-site inspection. The Provider and the Green Rater do not certify the project, but rather assist in the certification process.
There are several means by which the effectiveness of the LEED system could be measured. At a basic level, the LEED standard itself aims for improvements in the environmental and human health through improving building performance in five key categories. The energy consumption of the building will be carefully checked by the MEP design engineers or Energy Modellers.The installation of mechanical, electrical and plumbing or any additional equipment or fixtures effect the sustainability features determining the efficiency of the building.
Energy efficiency effectiveness
In determining the weighting scheme of the new LEED 2009 standard the USGBC has placed a relatively greater emphasis on "the reduction of energy consumption and greenhouse gas emissions associated with building systems, transportation, the embodied energy of water, the embodied energy of materials and where applicable, solid waste." Evaluating the relative strength of the 2009 reforms is difficult, in part because the energy implications of LEED v.2.0 are not comprehensively evaluated. The LEED standard is still new and much of the energy-use implications of buildings design decisions only become apparent over the course of the building's operational lifetime.
Research regarding energy efficiency effectiveness
Several recent post-occupancy evaluations have used energy data from a number of LEED-certified buildings to assess post-construction performance of the LEED system. The focus of most of these studies, below, are on LEED New Construction (LEED-NC) projects. There are many LEED categories.
Diamond et al. in 2006 compared modeled and actual building energy performance of a sample of 21 LEED-certified new buildings (all certified under LEED-NC version 2.0/2.1). Results of this study indicate the effectiveness of the LEED energy model, which predicted average Energy Use Intensity to be 73% of baseline-building expected energy use. Actual energy use data from 18 buildings for which data was available was 72% of expected baseline demand, but with much higher variance (SD=46%). Despite accuracy of the mean, the authors also found wide variation in individual buildings' energy use compared with modeled predictions. The study also found no correlation between either the number of energy efficiency-specific LEED point totals and actual normalized building performance, or total LEED energy points and actual normalized building energy performance. The authors noted several limitations of the study, including the small sample size, bias resulting from sampling methodologies, uncertainties in actual floor area, and discrepancies between metered data.
Baylon and Storm in 2008 studied 24 LEED commercial buildings constructed in Washington and Oregon between 2002 and 2005, comparing them to non-LEED buildings built to relatively stringent state-level codes in the region. The study found that the randomly sampled LEED buildings only performed 12% better than randomly sampled baseline buildings in each building category in the study area, due in part to the more stringent state-level building codes in Oregon and Washington. However, the degree of improvement in energy performance in LEED buildings was highly varied by building type. The authors identified the limited size of the sample as the greatest limitation of the study.
Turner and Frankel in 2008 used a much larger data set to compare LEED certified buildings with baseline buildings. 121 LEED-NC (version 2.0) buildings were compared with their design-stage modeled energy use, as well as with average national energy use intensity (EUI) information from the Commercial Building Energy Consumption Survey (CBECS). LEED-certified buildings were found to perform 28% better than design-stage models; however, significant variation was found in individual buildings, with over 50% of projects deviating by more than 25% from design-stage energy use predictions, with 30% performing significantly better and 25% performing significantly worse. The median measured EUI for the 121 buildings was 24% lower (better than) the CBECS national average for all commercial building stock. However, it was found that relative EUI performance varied between different building types. The study also found that high energy type buildings whose energy use is more driven by process loads of occupants activities, were less accurately predicted by LEED modeling protocols. The authors noted that the study was limited by data availability, the collapsing of Platinum and Gold certified buildings into one category, the larger average size of the LEED buildings sampled compared with the CBECS database, and the over-representation of certain climate zones.
The data gathered by Turner and Frankel was reexamined in 2009 by Newsham et al., who attempted to improve on the methodology in several ways. Baseline building comparisons were better represented than the national averages used in Turner and Frankel by isolating within the CBECS database buildings that were as similar as possible to every building in the LEED sample, in terms of activity type, size, age, and climate zone. Furthermore, a variety of statistical tests were applied to ensure that the buildings used for benchmarking were not significantly different in a variety of ways from the LEED buildings to which they were compared. Results indicate that LEED buildings on average performed 18%–39% better than their CBECS best fit counterparts. However, 28% to 35% of LEED buildings used more energy-per-floor area than their individually matched CBECS counterparts. In addition, there was no significant correlation between LEED certification level and EIU, or percent energy saved over the baseline counterpart. Limitations of the study noted by the authors include the fact that most LEED buildings are newly constructed and may still be experiencing unexpected problems with systems operations, as well as other characteristics which commonly vary across individual buildings of the same type (plug loads, occupancy hours, construction differences, etc.).
Energy efficiency effectiveness summary
LEED's building energy modeling methodology is accurate to a high degree when energy performance results for many buildings are agglomerated. However, there is still a high degree of variation in how closely predicted energy savings match actual energy savings in individual buildings, with nearly one-third of buildings performing significantly differently from LEED v. 2.0 expectations. Variation between predicted and actual performance also appears to differ depending on building type, especially regarding high operational end-use buildings with diverse or rare use types and concordant less well researched plug load and behavior characteristics.
These studies are limited primarily by the relatively small number of buildings which could be represented in the sample — few buildings are able to provide a year's worth of energy use data because of a lack of individualized meters, concerns about privacy, ongoing building systems operations issues, and the newness of the LEED standard. In addition, LEED 2009's increased focus on energy and atmospheric credits and their resultant higher weighting may limit the generalizability of these initial findings towards future LEED products.
Other effectiveness research
A 2003 analysis of the savings from green building found from a review of 60 LEED buildings that the buildings were on average 25-30% more energy efficient, but it also attributed substantial benefits to the increased productivity from the better ventilation, temperature control, lighting control, and reduced indoor air pollution.
As of 2008, LEED (and similar Energy Star) buildings had mostly been evaluated by case studies. From a purely financial perspective, in 2008 several studies found that LEED for-rent office spaces generally charged higher rent and had higher occupancy rates. CoStar collects data on properties. The extra cost for the minimum benefit has been estimated at 3%, with an additional 2.5% for silver. More recent studies have confirmed these earlier findings in that certified buildings achieve significantly higher rents, sale prices and occupancy rates as well as lower capitalization rates potentially reflecting lower investment risk.
LEED focuses on the design of the building and not on its actual energy consumption, and therefore it has suggested that LEED buildings should be tracked to discover whether the potential energy savings from the design are being used in practice.
Directory of LEED-certified projects
The Canada Green Building Council provides an online directory of LEED Canada-certified projects.
The Green Building Certification Institute describes Professional Accreditation as follows: "LEED Professional Credentials demonstrate current knowledge of green building technologies, best practices, and the rapidly evolving LEED Rating Systems. They show differentiation in a growing and competitive industry, and they allow for varied levels of specialization. A LEED Professional Credential provides employers, policymakers, and other stakeholders with assurances of an individual's level of competence and is the mark of the most qualified, educated, and influential green building professionals in the marketplace." Credentials include the LEED Green Associate (GA) and the various types of specialized LEED Accredited Professionals (AP).
Benefits and disadvantages
LEED certified buildings are intended to use resources more efficiently when compared to conventional buildings simply built to code. LEED certified buildings often provide healthier work and living environments, which contributes to higher productivity and improved employee health and comfort. The USGBC has compiled a long list of benefits of implementing a LEED strategy, which ranges from improving air and water quality to reducing solid waste, benefiting owners, occupiers, and society as a whole.
Often, when a LEED rating is pursued, the cost of initial design and construction rises. There may be a lack of abundant availability of manufactured building components that meet LEED specifications. Pursuing LEED certification for a project is an added cost in itself as well. This added cost comes in the form of USGBC correspondence, LEED design-aide consultants, and the hiring of the required Commissioning Authority (CxA)—all of which would not necessarily be included in an environmentally responsible project, unless it also sought a LEED rating.
However, these higher initial costs can be effectively mitigated by the savings incurred over time due to the lower-than-industry-standard operational costs typical of a LEED certified building. This Life cycle costing is a method for assessing the total cost of ownership, taking into account all costs of acquiring, owning and operating, and the eventual disposal of a building. Additional economic payback may come in the form of employee productivity gains incurred as a result of working in a healthier environment. Studies have suggested that an initial up-front investment of 2% extra will yield over ten times the initial investment over the life cycle of the building.
In the progression of sustainable design from simply meeting local buildings codes to USGBC LEED (Certified, Silver, Gold and Platinum) to the Architecture 2030 Challenge, the Living Building Challenge is currently the most stringent sustainable design protocol. The LBC sets 20 imperatives which compel building owners, designers, operators and tenants beyond current USGBC LEED rating levels.
LEED is a design tool and not a performance measurement tool. It is also not yet climate-specific, although the newest version hopes to address this weakness partially. Because of this, designers may make materials or design choices that garner a LEED point, even though they may not be the most site- or climate-appropriate choice available. On top of this, LEED is also not energy-specific. Since it only measures the overal performances, builders are free to choose how to achieve points under various categories. A USA TODAY review showed that 7100 certified commercial building projects targeted easy and cheap green points, such as creating healthy spaces and providing educational displays in the building. Few builders would really adopt renewable energy because the generators for those energy resources, such as solar photovoltaic, are costly. Builders game the rating system and use certain performances to compensate for the others, making energy conservation the weakest part in the overall evaluation.
LEED is a measurement tool for green building in the United States and it is developed and continuously modified by workers in the green building industry, especially in the ten largest metro areas in the U.S.; however, LEED certified buildings have been slower to penetrate small and mid-major markets. Also, some criticism suggests that the LEED rating system is not sensitive and does not vary enough with regard to local environmental conditions. For instance, a building in Maine would receive the same credit as a building in Arizona for water conservation, though the principle is more important in the latter case. Another complaint is that its certification costs require money that could be used to make the building in question even more sustainable. Many critics have noted that compliance and certification costs have grown faster than staff support from the USGBC.
For existing buildings LEED has developed LEED-EB. Research has demonstrated that buildings that can achieve LEED-EB equivalencies can generate a tremendous ROI. In a 2008 white paper by the Leonardo Academy comparing LEED-EB buildings vs. data from BOMA's Experience Exchange Report 2007 demonstrated LEED-EB certified buildings achieved superior operating cost savings in 63% of the buildings surveyed ranging from $4.94 to $15.59 per square foot of floor space, with an average valuation of $6.68 and a median valuation of $6.07.
In addition the overall cost of LEED-EB implementation and certification ranged from $0.00 to $6.46 per square foot of floor space, with an average of $2.43 per square foot demonstrating that implementation is not expensive, especially in comparison to cost savings. These costs should be significantly reduced if automation and technology are integrated into the implementation.
Many federal, state, and local governments and school districts have adopted various types of LEED initiatives and incentives. A full listing of government and school LEED initiatives can be found online and is updated regularly.
Some areas have implemented or are considering incentives for LEED-certified buildings.
The city of Cincinnati, Ohio adopted a measure providing an automatic 100% real property tax exemption of the assessed property value for newly constructed or rehabilitated commercial or residential properties that earn a minimum of LEED Certified.
In the state of Nevada construction materials for a qualifying LEED building are exempt from local taxes. Pieces of construction that are deemed "inseparable" parts, such as concrete or drywall, qualify.
The state of Maryland passed its High Performance Buildings Act in 2008, requiring all new public construction and renovation of buildings greater than 7,500 square feet to meet at least the LEED Silver standard, or two Green Globes. Between 2009 and 2014, the state is required to fund half of the required additional cost for public school construction or renovation to attain that standard.
Many local governments have adopted LEED incentive programs. Program incentives include tax credits, tax breaks, density bonuses, reduced fees, priority or expedited permitting, free or reduced-cost technical assistance, grants and low-interest loans.
Notable LEED buildings
The Philip Merrill Environmental Center is recognized as one of the "greenest" buildings ever constructed in the United States. Sustainability issues ranging from energy use to material selection were given serious consideration throughout design and construction of this facility. It was the first building to receive a Platinum rating through the U.S. Green Building Council's LEED Rating System, version 1.0. When it opened in 2003, Pittsburgh's 1,500,000-square-foot (140,000 m2) David L. Lawrence Convention Center was the first Gold LEED-certified convention center and largest "green" building in the world. The convention center subsequently became the first convention center to earn Platinum certification in 2012. In May 2012, Soldier Field in Chicago became the first National Football League stadium to be certified LEED. In Pittsburgh, Phipps Conservatory & Botanical Gardens visitors center has received a Silver certification, its Center for Sustainable Landscapes has received a Platinum certification along with fulfilling the Living Building Challenge for net-zero energy, and its greenhouse production facility has received Platinum certification, the first and only greenhouse to be so certified.
The Empire State Building is currently undergoing a $550 million renovation, with $120 million spent in an effort to transform the building into a more energy efficient and eco-friendly structure. Receiving a gold LEED rating in September 2011, the Empire State Building is the tallest LEED-certified building in the United States.
The Cashman Equipment building is the first construction equipment dealership to receive LEED certification. It is the largest LEED industrial complex in Nevada. Caterpillar corporate has rewritten their development guidelines for new facilities based on this building.
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