Metal buildings are an easy, cost- effective choice when going green, thanks to their efficient use of materials and labor and the steel’s high quantity of recycled content. However, documenting their savings and efficiency while keeping up with various sustainability codes and rating systems is an ever-changing and difficult task.
That’s why the Metal Building
Manufacturers Association (MBMA) engaged Walter P. Moore and Associates, an independent third party, to conduct a whole building life cycle assessment comparing the environmental impacts of metal building systems against other popular forms of construction.
The study was based on the results of the Athena Sustainable Materials Institute’s Impact Estimator report, which incorporates 30 building case studies from across the United States. It looked at six major environmental impacts that Athena’s software uses: the potential for global warming, ozone depletion, acidification, smog, non-renewable energy and eutrophication.
The study focused on primary and secondary structural framing, elements such as wall and roof materials, as well as insulation and foundations characteristics. It did not include items common to all case study buildings, such as finishes, sprinklers, doors and gutters, as those aspects likely would not affect the results related to environmental impact.
Three building types were used for the analysis: large industrial, medium-sized storage and small office buildings. Interestingly, the results highlighted the sensitivities in the Athena Impact Estimator software to individual material effects. Structural materials typically have the greatest potential impact for global warming, acidification, smog and ozone depletion, while insulation has more of a potential impact on eutrophication and non-renewable energy.
The study produced conclusive results for the larger building types, showing that metal buildings have lower environmental impacts in all six metrics. Comparisons were made to buildings with load-bearing masonry walls, as well as concrete, tilt-up and steel framed construction of the same footprint and functional equivalence. The metal buildings that are typically the most economical—medium and large sizes and multiple uses—are also the most environmentally friendly, according to the study.
While it’s clear that metal building systems can outperform other building types on the sustainability front, more information and documentation often is necessary to quantify results to meet the various codes and ratings standards that now proliferate the building industry. To validate the sustainability claims of metal buildings, MBMA partnered with both Athena Institute and UL Environment (ULE).
Athena Institute benchmarked the environmental impacts of the major parts of the building to derive the life cycle inventory data that is incorporated into the Athena databases. ULE then summarized the life cycle assessment study results into three environmental product declarations (EPDs) concerning the specific parts of a metal building: the primary framing, secondary framing and metal cladding.
ULE verified that the three cradle-to-gate EPDs are in compliance with ISO 14025 and ISO 21930 standards. They provide third-party documentation of the environmental impacts of each part of the metal building. Cradle-to-gate describes the environmental impacts of producing the metal building products, from raw material extraction through processing and up to the finished product when it leaves the production facility. The EPDs then can be used to demonstrate compliance with the building codes and standards, as well as earn credits for rating systems such as LEED. They give architects and designers the ability to earn EPD credits with LEED, as well as with similar provisions in the International Green Construction Code and ASHRAE 189.1 standards. The EPDs are available for anyone to access through ulenvironment.com.
While metal building systems already represent a significant portion of the commercial low-rise market, now owners, designers and builders have evidence that metal buildings are a sustainable choice.