Leadership in Energy and Environmental Design (LEED) credits are a series of qualifications that were devised to rate the effectiveness of green building. The voluntary certification program was developed by the U.S. Green Building Council (USGBC) in order to provide guidelines for environmentally friendly building to property and building owners. There are LEED credits for new construction, cores and shells, commercial interiors, schools, and the operations and maintenance of existing buildings. Each entity is evaluated in the categories of building efficiency, energy savings, environmental impact, emissions, and sensitivity to the surrounding environment.
The categories for LEED credits are organized into six sub-categories, including: sustainable sites, water efficiency, energy and atmosphere, materials and resources, innovation and design process, and indoor environmental quality. Entities are evaluated by representatives of the independent Green Building Certification Institute. According to adherence to the guidelines in each category and the underlying sub-categories, LEED credits are assigned for each item under review. These credits are then combined to arrive at a number score for the entity.
The criteria for sustainable sites includes evaluation of the design of the building, including storm water runoff, the temporary and long term effect of construction on the environment, and how many services are available for tenants seeking to use alternative transportation. Water efficiency criteria include landscaping, whether or not the project allows for water conservation of at least 20%, and how wastewater is managed. The energy and atmosphere category also includes evaluation of energy savings in addition to the overall efficiency of the project and the use of green power when possible.
Materials and resources are evaluated for the use of rapidly renewable and regional materials, certified wood, and recycled content. There are also criteria for the project’s capacity to recycle waste from both the construction and long-term operations. Indoor environmental quality is also evaluated, from ventilation, lighting, and thermal comfort to low-emitting materials and fixtures.
The LEED credits are given according to a 100 point scale. There are also additional bonus points available in increments of 10, primarily for special regional considerations. For the entity to receive certification, it must receive at least 26 points.
There are several levels of certification, the attainment of which depends on the number of LEED credits given. The basic certification level is from 26 to 32 points. In order to achieve the middle levels — silver and gold — the entity must receive 33 to 38 and 39 to 51 points respectively. The top level is platinum which requires a minimum of 52 points.