Volume 5, Issue 2 (February 2008)
Standards Versus Recommended Practice: Separating Process and Prescriptive Measures from Building Performance
Rating systems in North America are experiencing a fundamental shift in the way they approach sustainable design, away from a prescriptive methodology toward one that emphasizes quantifiable performance. They are maturing, placing more importance on issues such as life cycle assessment and how to strengthen the link between design forecasts and actual building performance over the long-term. But, they remain an inherent mix of objective and subjective elements—of process, prescriptive measures, and performance—which makes it difficult for them to evolve in their entirety into sustainable building standards. This paper will focus on fundamental issues related to the standardization of sustainable design principles in the context of assessment and rating systems, drawing on the experience of the Green Building Initiative (GBI) American National Standards Institute (ANSI) Technical Committee for Green Globes™. The GBI is the first national organization to take a green building rating system through the consensus-based ANSI process, and its technical committee will examine how process, prescriptive, and performance measures fit in a standard of this nature. For example, experience shows that an integrated design process tends to result in higher performance buildings. However, while it is recommended practice, can it be mandated as part of a standard if it isn’t a measure of the building’s actual worth? Indeed, can any process be dictated, or would this risk penalizing an exceptional building for something that has nothing to do with sustainability? Likewise, prescriptive measures such as favoring building materials with recycled content do not always deliver the benefits they are widely assumed to have. They are means to an end and should not be treated as objectives in their own right. It is tempting to include prescriptive measures in a standard because they are easy to verify. But do we not then risk perpetuating points of view that, while deeply entrenched, do not contribute positively to actual building performance?