Over the past 15 years, the United States Green Building Council’s (USGBC) LEED® rating system has been the principal rating system used to guide teams seeking to create more sustainable buildings. As sustainable design continues to evolve, the standards have become more comprehensive and a host of new rating systems have been released, such as SITES (Sustainable Sites Initiative), Greenroads®, Envision (prescribed by the Institute for Sustainable Infrastructure), and Parksmart — formerly Green Garage Certification — the world’s only rating system designed to advance sustainable mobility through smarter parking structure design and operation.
USGBC's newest version of LEED — LEED v4 — is now mandatory for all new project registrations. LEED v4 contains significant changes in all areas of the rating system. The combination of the previous stormwater quality and quantity credits represents a more holistic approach that permits additional pathways to achieve the credit intent of improving water quality by replicating the natural hydrology and water balance of the site. LEED v4 also explicitly includes envelope commissioning as a component of the “Enhanced Commissioning” credit, rewarding third-party review of enclosure documents.
The most significant changes to the rating system are in the Materials and Resources section. This section is now based on material disclosure and optimization instead of assessing material attributes. The inclusion of Whole Building Lifecycle Assessment (WBLCA) into LEED v4 allows design teams to compare structure and enclosure design options based on quantified reductions in environmental impacts instead of attribute-based comparisons.
The WBLCA model is often described as analogous to an energy model for material impacts. The model must be created early in the design and is used to inform design choices to minimize the material impacts. WBLCA represents a significant opportunity for the project’s structural engineer to become more engaged in the early stages of the LEED process and to make a meaningful impact to both the project’s environmental goals and certification pursuit.
These evolutions to LEED represent the market’s acknowledgement of emerging areas of importance in sustainable design.