Yes. New standards should include life-cycle assessments.
Robert Zabcik is director of R&D at NCI Building Systems, a metal components producer.
We anticipate a divergent evolution, where the rating system involves more complicated and holistic scientific models with sophisticated rubrics to determine a building’s performance.
This would be a kind of “rating system on steroids,” in which a computer does most of the calculation. Much of the simpler criteria that are currently in existing green building rating systems would appear as requirements in high-performance building standards (aka “green codes”), and some might even find their way into traditional building codes.
We are seeing hints of this evolution in commercial construction. LEED v4 is a traditional rating system, but will have credits that evaluate environmental performance using a Life Cycle Assessment (LCA) model. Meanwhile, many of the original LEED and Energy Star requirements can be found, in a tweaked form, within documents like ASHRAE 189.1 (high-performance design standard) and the International Green Construction Code, or IgCC.
A residential rating system might see ICC-700 evolve into a base code, with performance-based criteria for buildings that strive to achieve net-zero energy and carbon as an addendum.
By adopting this approach, NAHB, USGBC, and other standards-setting groups would be free to push the envelope with increased sophistication and LCA playing a critical part.
Much as an energy model simulates building energy systems, LCA tools simulate material and energy flows, which help determine the environmental impacts of the entire building life cycle. In LEED v4, this is limited to building creation, but it could naturally grow to include use-phase effects, including energy, deconstruction, and disposal/reclamation. With additional development, an LCA model has the potential to encompass the scope of LEED and ICC-700 as they exist today.
The variety in housing stock, construction specifications, and climatic conditions across the United States makes it challenging for one rating system to meet the needs of all homes.
Southface has seen and tried them all, having run a successful regional program for 14 years and been active with national green building programs. On paper, there are no flaws in any of these programs that I would call out. But similar to cereal options at the grocery store, there isn’t a single brand that fits all needs.
Over the past four years, programs have placed more emphasis on expanding requirements leading to integrative design. For many builders this has been a breath of fresh air as they have more flexibility in how projects meet specific performance thresholds. Other builders, though, have found this approach overwhelming and continue to prefer programs that provide plain language and prescriptive checklists that are easy to understand and delegate for implementation.
Regardless of the rating system being used or its stringency on paper, the real measure of a program’s effectiveness is how well the builder and project team understand and implement the criteria for their projects.
Good green building programs help builders set clear green performance goals, and provide training and technical assistance for all trade partners. Our recommendation, then, for any rating system is to ensure thorough upfront training of builders, trades, and technical assistance providers (often called raters), and to follow that up with back-end checks through in-field quality assurance monitoring at all levels of the process.
Great green ratings programs also recognize that homeowners play a critical part in achieving the benefits of green building by providing feedback on performance.