LCA versus Prescriptive Standards

People make environmental decisions all the time…paper towels over cloth…plastic bags over paper. Many are intuitive decisions. So it is with the building industry in looking for guidance to achieve green standards. However, many green standards in use - bamboo floors, bike racks, steel framing vs. wood framing, for example - are just as intuitively based, without regard for their total energy implications or greenhouse gas emission. Because it is a protocol-based scientific methodology that measures energy, raw material and other manufacturing inputs as well as wastes, emissions, use and disposal, the LCA is a more comprehensive approach to indicating a product's green quotient.

Western redcedar is carbon neutral. Photo: Western Red Cedar Lumber Association

In a 2008 report entitled "Green Building Programs in the United States: A Review of Recent Changes Related to Designation of Environmentally Preferable Materials," Dr. Jim Bowyer and Alison Lindburg of Dovetail Partners, Inc., concluded that "critical issues related to designation of environmentally preferable construction materials remain unaddressed in most green building programs." The authors went on to say that "variability in the standards is causing confusion, and proliferation of scientifically unsubstantiated prescriptive standards is occurring as new programs are developed and existing programs are revised. Despite the strong adoption rate for green building programs, there is much room for improvement and work needs to be done to reach the goal of ensuring that programs truly result in improved environmental performance. To this end, expanded adoption of life cycle assessment for identification of environmentally preferable materials is essential."

Wayne Trusty, President of the Athena Institute, a non-profit organization that seeks to improve the sustainability of the built environment through better information and tools, adds: "Prescriptive standards are attribute oriented. To assume that something like rapid renewables are green just because they grow quickly, without considering factors like water, energy or fertilizer usage is misleading. It's presumptuous to think that rapid renewables are automatically better or to make them part of an environmental code. The LCA, as opposed to prescriptive standards, gets at the full range of a product's implications, and that is important information."

LCA Concerns

LCAs are recognized around the world as one of the most effective analytic tools for estimating the sustainability profile of a product or service. But not all LCAs are created equal. There are several areas that architects will want to pay particular attention to in determining the credibility of an LCA.

Data. An LCA is heavily data dependent and in the end will be only as valid as its input. Obviously, data should be as accurate and up to date as possible. While this can be particularly challenging as new processes, manufacturing methods and materials are being introduced constantly, using old data will invalidate the quantitative analysis and inaccurately reflect the product's environmental profile. In some instances data will be hard to obtain, particularly pproprietary or commercially-sensitive raw data or information indicating that a company's product is in any way inferior to a competitor's product.

Interpretation. Challenges increase in this second stage, life cycle assessment, as it involves interpretation of the data, and that requires value judgments to be made. Difficult decisions are routine here - is heavy energy demand less burdensome than heavy water use, for instance, or how utilizing non-renewable mineral resources like oil or gas stand up to the production of softwoods for paper. Skeptics also voice the concern that while an LCA may be able to characterize the effect of a product on global warming, it is less clear when it comes to what the effect will be on human health or the integrity of ecosystems.

Comparisons. In comparing the life cycle analyses of two different products if the same level of data, both quantity and quality, are not available for both products, the findings will be flawed. Comparisons are rarely easy because of the different assumptions that are required - even evaluating two same-size items that were identically distributed and recycled, though seemingly simple, will require a number of assumptions. For example, something as apparently straightforward as assessing the impacts of truck transportation to deliver a product will necessitate judgments about the truck's size, condition, route, and speed, any of which might have significant bearing on the outcome of the analysis. When it comes to making life cycle comparisons of different products, considerably more and greater judgments and assumptions will be called into play.

Yet when reliable, high-quality data is available, the boundary of the study has been clearly defined and the methodology rigorously applied, the LCA can yield valuable results that increase environmental transparency. Experts maintain that the most rigorous approach is an LCA conducted according to the International Organization for Standardization (ISO) 14000 series, a family of standards that addresses environmental management, and the actions of the organization in question to minimize harmful effects on the environment caused by its activities, and to achieve continual improvement of its environmental performance. According to Athena's Trusty, ISO 14044 is the main standard for LCAs, with ISO 21930 standards providing a more detailed specification for building materials and, on the horizon, ISO 21931 that will form the basis of an LCA at the level of the whole building-an amalgam of its constituent parts.

"There is noise in the system, especially from industries that LCA is perceived to affect negatively, with consequent arguments that it is not quite ready for prime time," says Trusty. "But it's an evolving process, and currently there are many things being done on a national and international level to create databases that will reduce uncertainties in the LCA process."