LEED is the leading green building rating system in the US for commercial, institutional, and mid-rise to high-rise residential buildings. It is developed, trademarked and owned by the US Green Building Council. At the end of 2006, nearly 5,000 buildings had registered their intention to use the LEED rating system for new buildings, renovations, tenant remodels and existing buildings, a 50% increase over 2005 year-end totals. Almost 650 million square feet of buildings were involved in LEED-regis-tered projects, representing close to $78 billion worth of construction. By the end of 2006, according to the US Green Building Council, more than 650 projects had already been certified, an increase of 66% over the 2005 year-end totals. In an industry that grows typically by 5% per year, this increase in green building projects is astounding. The stated goal of LEED is to transform the building industry by introducing rating systems that reflect scientific knowledge, leading-edge architectural and engineering design approaches and best practices in construction and development. LEED is divided into six rating systems:
• LEED for New Construction (and major renovations).
• LEED for Commercial Interiors (remodels).
• LEED for Core and Shell (typically office buildings and other speculative projects).
• LEED for Existing Buildings (the effects of continuing building operations).
• LEED for Homes (custom homes and production homes, including low-rise apartments).
• LEED for Neighborhood Development (campuses and urban districts, new subdivisions).
The dominant rating system at this time is LEED for New Construction (LEED-NC), comprising 77% of certified projects and 79% of all project registrations. (Registering a project is like getting engaged, declaring your intention to certify when a building is completed and ready for occupancy.) In my opinion and experience, LEED-NC is a very carefully constructed rating system. It was introduced in March 2000 after a two-year beta test or pilot program and has seen widespread use and popularity.
LEED for New Construction (LEED-NC)
The basic and most frequently used LEED rating system contains 32 categories of environmental design and energy concern, with 64 core points and 5 extra credit points, for a total of 69. A basic LEED-NC certified project must score at least 26 points in the categories of site, water, energy, materials and indoor environment. There are also Silver (33 points), Gold (39 points) and Platinum (52 points) certification levels. Less than 20 LEED-NC projects had been certified Platinum by the end of 2006.
Each project requires rigorous documentation that is evaluated by independent auditors. A finished LEED-NC certified project is well within the top 10% of all buildings constructed each year, in terms of its green attributes. LEED-NC certified projects also tend to be 30% or more energy efficient than their conventional counterparts, use 30% less water and have healthier indoor air, more daylighting and views to the outdoors.
LEED for Core and Shell (LEED-CS)
The LEED-NC standard relies on evaluating a completed and fully furnished building. Many commercial buildings are built as "core-and-shell" projects, meaning that 50% or more of the project is empty (a "see-through" building) when construction is completed, and the office spaces are left for tenants to build out. A core-and-shell building typically has a lobby, an elevator core, a finished external and interior structure, major HVAC, plumbing and electrical systems, parking garage and little else. These projects are evaluated using the LEED for Core and Shell standard that makes allowances for items that developers do not finish, such as lighting, carpeting, paints and similar items. The original idea was to link the LEED-CS rating with a LEED for Commercial Interiors rating, so that the entire building would ultimately be certified similar to a LEED-NC
project. In practice, this does not always work out, since even committed green developers are reluctant to impose green tenant improvement standards.
LEED for Commercial Interiors (LEED-CI)
This rating system covers the environmental design and energy issues that a tenant improvement project can address, including lighting energy use and quality, HVAC energy use and controls, access to public transportation, energy use by office equipment, office furniture, other building materials choices, cabinetry, carpets, paints, furnishings and a host of issues related to the constraints of working within an existing building. Introduced late in 2004, the LEED-CI standard has registered nearly 500 projects and certified nearly 100. There are 57 potential points in a LEED-CI project; a certified project must achieve 21 points, 27 for Silver, 32 for Gold and 42 for Platinum.
LEED for Existing Buildings (LEED-EB)
This rating system attempts to deal with the continuing environmental footprint of a building or development after it is occupied. According to
the US Green Building Council, LEED-EB "is a set of voluntary performance standards for the sustainable upgrades and operations of buildings. It provides sustainable guidelines for building operations, periodic upgrades of building systems, minor space use changes and building processes."90
Most of us would think of the energy and water use in evaluating building operations, but LEED-EB broadens this perspective to include recycling rates, chemical use in landscaping and pest management, environmentally preferable purchasing policies, green cleaning and maintenance and a number of other building management issues. The long-term effect of a building on the environment is the sum of a lot of little choices that building owners and operators make throughout its lifetime. LEED-EB is the first comprehensive system to assess these effects and to suggest how to mitigate them.
Introduced late in 2004, LEED-EB registered almost 250 projects and certified about 40 by the end of 2006. LEED-EB has 32 credit categories and 85 possible points; 32 points are required for certification, 40 for Silver; 48 for Gold; and 64 for Platinum.
LEED for Neighborhood Development (LEED-ND)
LEED-ND was unveiled early in 2007 as a pilot project (beta test) rating system for assessment of up to 240 projects. Developed in a close partnership with the Natural Resources Defense Council and the Congress for the New Urbanism, LEED-ND seeks to provide a national set of standards for neighborhood location and design based on the combined principles of smart growth, new urbanism and green building. LEED-ND will certify exemplary development projects, based on evaluating location efficiency; environmental preservation; compact, complete and connected neighborhoods; and resource efficiency.91 We expect the finished version of LEED-ND to be rolled out in the fall of 2008, after the USGBC assesses the results of the pilot program.
LEED for Homes (LEED-H)
The pilot phase evaluation of LEED-H, 2005 to 2007, will culminate in the release of version 2.0 in 2007. The pilot phase certification system contains the five basic LEED categories (sustainable sites, water efficiency, energy efficiency, materials and resources use, and indoor environmental quality) plus two categories unique to the residential situation: location and linkages (land development practices, infrastructure, community resources and compact development); and homeowners awareness and education about green buildings. The pilot phase had 108 total points; the version 2.0 system is likely to have fewer. There is also an issue of cost and verification;
because most homebuilders will not spend more than $250 to $400 per home for certification and inspection, LEED-H has had to come up with a sampling protocol for housing tracts, unlike the other rating systems for larger projects.
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