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Lewis: The Environmental and Safety Benefits of Building with Concrete Over Wood

Having spent 20 years focusing on sustainable architecture, creating green homes and buildings, and studying the effects buildings have on our environment, I was surprised to read Phil Bernstein’s recent article regarding mass timber and the supposed environmental benefits of its use. I studied at Yale under Professor Bernstein, and I have long admired his enthusiasm for and dedication to important issues related to the practice of architecture. So it is with all respect and appreciation for his work that I am compelled to offer an alternate viewpoint on mass timber.

Simply stated, cross laminated timber is not an effective carbon sink. Deforestation is estimated to contribute 20% of all greenhouse gas emissions, and up to a third of carbon dioxide emissions. And should a timber-based structure burn — which, due to wood’s combustibility, they are dangerously prone to do — the atmospheric carbon issue grows drastically. One need look no further than the massive blaze that occurred last year in England that devastated the University of Nottigham’s new, cross laminated timber chemistry building to see the problem. Because trees function essentially as Earth’s natural filtering system, widespread deforestation is indeed detrimental to the global environment. What should be equally troubling to all of us is that when carbon sequestration is calculated, industrial deforestation does not account for logging emissions, irreparable damage to local ecosystems, and soil and water pollution.

Professor Bernstein argues that “a ‘net zero’ building means nothing if the systems that delivered it generates huge amounts of unaccounted carbon.” While I concur, it is clear that wood procurement through deforestation contributes such unaccounted carbon en masse. Furthermore, when accounting for a structure’s environmental impact — and the environmental impact of the industry involved — one must also consider the structure’s energy efficiency and sustainability. Wood structures, notoriously porous and thermally unstable, require mass amounts of energy to maintain, and have comparatively short lifecycles. Conversely, non-wood based structures, such as concrete, have been shown to contribute 3–5% less greenhouse gasses when compared to wood-framed construction.

What is not mentioned in Professor Bernstein’s article is the matter of safety. It is inarguable that wood-based structures can, and do burn at a faster clip and lower temperature than those composed of alternate materials. Resultantly, multi-alarm fires have become all-too frequent across the globe, and they must be prevented at all costs. I firmly believe that this responsibility falls first and foremost upon our world’s architects: from design, to planning, to construction, the architect must always prioritize the wellbeing of those who live, work, and learn within their completed projects. Fortunately, improvements in construction materials and building efficiency — as with the abovementioned example of concrete — can allow for this.

Professor Bernstein notes that “architects must change the scale of their influence…by understanding, incorporating, and (dare I say it) controlling the flows of capital, energy, materials, and production.” Again, I agree: as in any trade, the creator must wisely consider his or her process and material choices. But just as Professor Bernstein calls for a readjustment of perspective regarding the architect’s role, we must at once reexamine the role of building methods and materials according to 21st century needs.

Surely, as long as our species continues to erect buildings, no construction method will be viewed as perfect. Until then, however, it will remain the architect’s obligation to prioritize both environmental responsibility as well as a steadfast commitment to safety and structural security. As long as we consider all pertinent factors, there is no reason we can’t have both.

Gregg Lewis, AIA, LEED AP, is vice president of building innovations for the National Ready Mixed Concrete Association


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