LEED (Leadership in Energy and Environmental Design) standards are parameters for sustainable building that were developed in America and applied in 40 countries in the World.
Processed by USGBC in collaboration with companies and researchers of American and Canadian universities, LEED standards indicate the requisites for constructing eco-compatible buildings capable of functioning in a sustainable and self-sufficient way as far as energy is concerned. In synthesis, it is a rating system (Green Building Rating System) for the development of “green” buildings. The organization that defines and promotes the LEED standards is the U.S. Green Building Council, a non-profit association born in 1993 that today has 11,000 members. Apart from a technical role, the USGBC has also the task of informing, making aware and orientating the community towards eco-sustainable building. LEED is a flexible and articulated system that foresees differentiated formulations for new constructions (NC, New Construction and major renovations), existing buildings (EB, Existing Buildings), schools (LEED for Schools), and small houses (LEED Homes), although maintaining a basic setting that is coherent amongst the various environments. The system is based upon the attribution of credits for each of the requisites characterizing the sustainability of the building. The level of certification derives from the total sum of credits.
The criteria are grouped into six categories that foresee compulsory prescribed prerequisites and a number of environmental performances that together define the final score of the building:
- Sustainable sites (1 prerequisite = 14 points): LEED certified buildings must be constructed on the basis of a demolition system that reduces the production of waste and uses materials recycled or produced locally.
- Efficient water management (5 points): The presence of systems for the recovery of rainwater or with flow regulator taps must guarantee the maximum efficiency in the consumption of water.
- Energy and atmosphere (3 prerequisites, 17 points): By utilizing energy as efficiently as possible from renewable and local sources, it is possible to significantly reduce the energy bill of buildings. In America, each year LEED constructions issue 350 metric tons of carbon dioxide less into the atmosphere than other buildings, thereby guaranteeing a saving of electricity of approximately 32%.
- Materials and resources (1 prerequisite, 13 points): Buildings constructed with natural, renewable and local materials such as wood obtain a greater score in the LEED evaluation system.
- Quality of the internal environment (2 prerequisites, 15 points): Internal spaces of the building must be planned in such a way as to permit a substantial parity of the energy scale and favour the maximum home comfort for the end user.
- Planning and innovation (5 points): The use of improved construction technology in respect of best practices is an added value element to the LEED certification.
By totalling the credits achieved within each of the six categories, a specific certification level is obtained that attests the performance achieved by the building in terms of environmental sustainability. The LEED certification is subdivided as follows:
- Basic certification (Certified / 26–32 points)
- Silver certification (Silver / 33-38 points)
- Gold certification (Gold / 39-51 points)
- Platinum certification (Platinum / 52-69 points)
Addressing the whole process (from the planning to the actual construction) and every part of the building, LEED opts for a global vision of sustainability, taking advantage of all possibilities to reduce various types of environmental impact and harmful emissions of buildings under construction. The best practices can therefore be identified and delineated for engineers, architects, professionals and the whole community of the building sector and these best practices can then become the guidelines in the certification of third parties. The competitive advantages for the companies and professionals who adopt LEED standards are identifiable above all by the certification by a third party authority, considered fundamental for obtaining a positive reaction in the marketplace. In fact, LEED certification supplies the market with a shared definition, a common objective and a measurable standard. It is a voluntary standard adopted by the market through a creation process of agreement. It can therefore be confirmed that LEED certification of buildings corresponds to the informative labelling on all food packets indicating the ingredients, calories, fats, etc. The aim is to have the same detailed information also for buildings, the value of which is normally estimated in hundreds of thousands of Euros. In the case of LEED certified buildings, the same evaluation method permits providing detailed information: the aggregation of LEED key-area criteria (refer to the indicated areas in the table to one side) permits identifying high-performance buildings.
