Gaining certification

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Dr Afshin Afshari. (Valeriano Handumon/ITP)

Although several environmental rating systems have been developed, the US Green Building Council's Leadership in Energy and Environmental Design (LEED) is the first to gain significant momentum. Increasing numbers of developers are applying for a LEED label for their building despite the perceived high cost of certification and the cost premium associated with green design. Despite this heightened interest, the rating system's inner workings remain mysterious to many.

Most designers are generally aware of the negative impact that buildings can have on the environment and are willing to reduce this impact. The ability to assess a building's green credentials in a rigorous and verifiable manner is an essential factor in the success of sustainable design among designers and end-users alike. Without the ability to quantify, it is not possible to compare. And without knowing how green a design is, it is difficult to sell the idea to clients or the public.

In 1998, the US Green Building Council (US GBC) introduced the LEED Green Building Rating System. This sets minimal benchmarks, awarding points to buildings if it is demonstrated that they perform better than these levels. The minimal performance requirements are termed prerequisites, while above-benchmark performance is prescribed according to credits. The achievement of the prerequisites is mandatory under the rating system, but does not provide any points; achieving compliance with all prerequisites and a certain number of credits determines the certification level of a building.

In addition to creating a working definition of green buildings, the LEED rating system and its highly detailed reference guide is seen as a guideline to promoting integrated whole building design practices. The goal of LEED is to provide a standard of measurement for quantifying and comparing designs. It can also be used to raise end-user awareness through the establishment of a recognisable brand, indeed branding buildings with the LEED label can be a powerful marketing tool.

There are several LEED products being actively commercialised by the US GBC at present, with several others in pilot stage. Already available are LEED for New Constructions and Major Renovations (LEED-NC); plus versions for commercial interiors; core and shell development; existing buildings; homes; and schools.

LEED-NC version 2.2 was released in September 2006. Using this system, up to 69 points can be awarded to a design according to six different categories. Depending on the number of points awarded, buildings will be ranked in one of four classes: certified, silver, gold or platinum. While the lowest class is relatively accessible, obtaining a platinum classification can be a difficult task that requires an above average proficiency in most categories.

The seven prerequisites of LEED-NC are: erosion and sedimentation control; fundamental building systems commissioning; minimum energy performance in accordance with ASHRAE 90.1; the reduction of cfcs; storage and collection of recyclables; minimum indoor air quality; and the elimination of tobacco smoke.

The six categories of LEED-NC

• Sustainable sites: This category deals primarily with the issues of site selection, access and design. The prerequisite concerns erosion and sedimentation control on site. There are eight credits available, offering a maximum of 14 points covering the topics of alternative transportation (four points), site disturbance (two points), stormwater management (two points), heat islands (two points), and light pollution (one point). Items covered in this category include brownfield remediation, sediment traps and basins, bicycle racks, sharing facilities with neighbours and green roofs.

• Water efficiency: This is the smallest section of LEED-NC, comprising no prerequisites and only three credits. The credits cover landscaping (two points), water use reduction (two points) and wastewater treatment (one point). Items such as waterless urinals, composting toilets and greywater/stormwater recycling can be rewarded with points in this category.

• Energy and atmosphere: This section includes three prerequisites: fundamental building systems commissioning, minimum energy performance and the reduction of cfcs in hvac equipment. These are followed by six credits for energy optimisation (10 points), renewable energy (three points), advanced building commissioning (one point), measurement and verification (one point), ozone depletion (one point) and green power (one point).

• Materials and resources: This section has only one prerequisite - the storage and collection of recyclables - and seven credits. The credits focus on building reuse (three points); construction waste management (two points), reused, recycled or local/regional materials (two points each), certified wood (one point), and rapidly renewable materials (one point). Items covered in this category include the salvage of large timbers for re-use and flyash concrete.

• Indoor environmental quality: This category places a high emphasis on occupant comfort and well-being. It has two prerequisites - minimum indoor air quality (IAQ) performance and environmental tobacco smoke control - followed by eight credits that generate a maximum of 15 points. The credits cover the topics of low-emitting materials (four points), construction IAQ (two points), the controllability of systems (two points), thermal comfort (two points), optimimisation of daylight and views (two points), outdoor air delivery (one point), increased ventilation (one point), plus chemical and pollutant control (one point).

• Innovation and design process: This category allows up to four design innovation points to be gained, plus an additional point for the use of a LEED Accredited Professional in the design process. The points may be awarded for tasks such as lifecycle analysis, community development or the education of occupants. Substantially exceeding one of the earlier credits may also merit an innovation point.

Making the application

While it is possible to apply for certification after a building design is complete, the US GBC encourages applicants to establish their LEED goal early in the process. Indeed, some credits are impossible to obtain unless they have been targeted from the start, for example those relating to advanced commissioning and energy optimisation.

The main LEED submittal item is termed the Letter Template. This may be a simple declaration by the responsible party or may include calculations. A specific template exists for each prerequisite/credit and additional submittals, such as plans or drawings, may be required for some prerequisites/credits. Furthermore, the applicant must keep all relevant documentation in case the prerequisite/credit is selected for audit. Six prerequisites/credits are systematically audited during the evaluation procedure, including the energy optimisation credit. If any of the audited prerequisites/credits is denied, there may be a second review with a new set of audits; the applicant is also able to appeal the decision of the Review Team.

Undertaking the LEED process represents a learning curve for the designer, contractor and suppliers on a project. For instance, in order to obtain kitchen cabinetry satisfying LEED's criteria, a product with low-emitting adhesives must be used, which may mean that the supplier must change their standard practice. It is this kind of issue that creates the incremental cost of LEED certification. However, while the first few pioneering projects are usually the most expensive ones, with cost premiums occasionally reaching 6-8% for a platinum-rated project, the second or third project of the same kind will carry a cost premium of perhaps 3-5%.

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