Measuring Energy Efficiency in Buildings
LEED, or Leadership in Energy and Environmental Design, is an internationally-recognized green building certification and rating system. Developed by the U.S. Green Building Council (USGBC) in the late 1990s, LEED provides building owners and operators with a framework for identifying and implementing practical and measurable green building design, construction, operations and maintenance solutions. The Green Building Certification Institute administers LEED certification for all commercial and institutional projects registered under the LEED Rating System.
This system is one of the first rating systems designed to promote and measure sustainable and energy-efficient buildings. LEED promotes sustainable building and development practices through a rating system that recognizes strategies for better environmental and health performance. The LEED rating system is developed through an open, consensus-based process led by committees that are composed of diverse groups of professional volunteers representing a cross-section of the building and construction industry.
LEED points are awarded on a 100-point scale, and credits are weighted to reflect their potential environmental impacts. Additionally, 10 bonus credits are available, four of which address regionally specific environmental issues. LEED "Platinum" is the highest award level, followed by "Gold", "Silver" and "Certified".
A project must satisfy all prerequisites and earn a minimum number of points to be certified. The LEED rating system can apply to all building types, including commercial as well as residential. It works throughout the entire building lifecycle, from design and construction, operations and maintenance, tenant customization, and renovation. LEED also makes good business sense, benefiting commercial building owners as well as tenants by reducing operational and maintenance costs.
The LEEDS program issues a building score by measuring performance in the following key areas:
- Sustainable Sites: Site selection and development are important components of a building's sustainability. LEEDS discourages suburban sprawl by promoting development on previously undeveloped land, minimizes a building's impact on ecosystems and waterways, encourages regionally appropriate landscaping, rewards smart transportation choices, controls stormwater runoff; and promotes reduction of erosion, light pollution, heat island effect and construction-related pollution.
- Water Efficiency: Buildings are major users of our potable water supply, and the LEEDS program encourages smarter use of water. Water reduction is typically achieved through more efficient appliances, fixtures and fittings inside and water-conscious landscaping outside.
- Energy & Atmosphere: Buildings use significant amounts of electricity produced each year in the United States. The Energy & Atmosphere category encourages a wide variety of energy-conservation strategies such as energy use monitoring, efficient design and construction, the use of efficient appliances, systems and lighting; the use of renewable and clean sources of energy, generated on-site or off-site; and other innovative measures.
- Materials & Resources: During both the construction and operations phases, buildings generate significant amounts of waste and use large quantities of materials and resources. The Materials & Resources category encourages the selection of sustainably grown, harvested, produced and transported products and materials. Use of local products is encouraged. It promotes waste reduction as well as reuse and recycling, and it particularly rewards source reduction.
- Indoor Environmental Quality: The Indoor Environmental Quality category promotes strategies that improve indoor air as well as those that provide access to natural daylight and views and improve acoustics. Such practices result in a healthy living and working environment.
- Locations & Linkages: LEEDS recognizes that much of a building's impact on the environment comes from where it is located and how it fits into its community. This category encourages development on previously developed or infill sites and away from environmentally sensitive areas. Credits reward homes that are built near already-existing infrastructure, community resources and transit - in locations that promote access to open space for walking, physical activity and time outdoors.
- Awareness & Education: The Awareness & Education category encourages home builders and real estate professionals to provide homeowners, tenants and building managers with the education and tools that they need to understand what makes their home green and how to make the most of those features.
- Innovation in Design: This category provides bonus points for projects that use innovative technologies and strategies to improve a building's performance well beyond what is required by other LEED credits, or to account for green building considerations that are not specifically addressed elsewhere in LEED. This category also rewards projects for including a LEED Accredited Professional on the team to ensure a holistic, integrated approach to the design and construction process.
- Regional Priority: USGBC's regional councils, chapters and affiliates have identified the most important local environmental concerns, and six LEED credits addressing these local priorities have been selected for each region of the country. A project that earns a regional priority credit will earn one bonus point in addition to any points awarded for that credit. Up to four extra points can be earned in this way.
How can we use LEED?
Besides the savings in energy that can be achieved, LEED buildings can help to discourage suburban sprawl by building in appropriate areas, reduce the burden on stormwater systems and promote development at sustainable densities. A building's LEED status is commonly promoted to tenants as a type of status symbol. Local design professionals also gain important certification as specialists in LEED design methodology. Some municipalities offer density bonuses for buildings that are designed with the goals of achieving LEED certification.