Towards Net Zero Enclosures
Designing a Framework for Carbon Accountability in Building Envelopes
Presented on October 12, 2022 at Facade Tectonics 2022 World Congress
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Overview
Abstract
As architects and designers we understand the urgency of addressing the building sector’s role in the ongoing environmental crisis. Architecture2030 tells us that the embodied carbon in new construction will account for almost half of greenhouse gas emissions in the next thirty years – pointing to the importance of reducing these numbers drastically, and quickly.
Over the past few decades, building envelope designers have focused on high performance as an additive approach to reducing building operational energy. Triple pane glass, exterior sun shades, PV devices, double wall systems and other strategies - all effective at increasing thermal performance or reducing mechanical loads - come with a cost of embodied carbon. Beyond the direct carbon cost of those assemblies, there is cost in building structure to support heavier, more complex wall systems, as well as the energy expended in the shipping of these components.
How then can designers make intelligent decisions about the expense of embodied carbon in walls and how can they be stewards in the race to get to carbon neutral?
This paper will survey existing research on embodied carbon in exterior wall assemblies and the availability of product declarations for relevant materials. Frameworks for evaluating embodied carbon in building structure will be reviewed as examples for understanding the complexities of the highly varied and often highly customized world of high performance exterior walls.
Authors
Jessica Santonastaso, AIA
Architect, Associate
Gensler
jessica_santonastaso@gensler.com
Alan Estabrook, AIA
Architect, Associate
Gensler
alan_estabrook@gensler.com
Keywords
Designing a Framework for Carbon Accountability in Building Envelopes
Over the past several years the AEC industry has seen a significant and necessary rise in attention to the role of embodied carbon in the sustainability landscape. Concrete, steel and aluminum together make up almost a quarter of global emissions. 1 Using standard BIM technology, it can be relatively easy for designers and engineers to estimate tonnages of concrete and steel in building structures. Other building components and materials, however, can be much harder to track.
This paper will focus on embodied carbon in envelopes- one portion of the 40% of greenhouse gas emissions introduced into the environment due to construction. While envelopes are far from the only component of buildings that have high cost in embodied carbon, they are among the more difficult to quantify and measure. Site work, structural systems, mechanical systems and interior fit ups all represent embodied carbon in the same ways that cladding and insulation do. However, where EPDs for manufactured interior materials and tonnage calculations for steel make quantification more simple, envelopes are often composed of custom and complex assemblies where little standardized documentation is available and few modeling tools for quantifying those systems exist.
Framework
Discussions about embodied carbon use several terms which themselves can be used in varying ways. In this paper, embodied carbon is intended to refer to the carbon dioxide and carbon
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Why is Embodied Carbon Critical Right Now?
Over the typical life cycle of a building the embodied carbon of its materials and the carbon emissions produced by the building’s operation can be expected to equal out. In
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Moving the Needle on Embodied Carbon in Building Envelopes Will Take the Best Efforts from All Parties in the AEC Community
Many groups in the AEC industry are already working to tackle these difficult questions. The Carbon Leadership Forum is a network of industry professionals working to consolidate resources and create
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Better Understand Our Carbon Footprint - Tools to Quantify and Analyze
Ideally, architects would have a tool that could quickly and easily report the embodied carbon footprint of all aspects of a building directly from a BIM model so that the
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Don’t Add Unless You Can Subtract
Designers can’t wait for the perfect tool to begin to design enclosures with embodied carbon reduction in mind- and for many practitioners it will require a shift in mentality. In
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Build Only What You Need
A corollary to form follows function in this case is to build only what needs to be built. Sensitive and responsible design requires that architects and designers become able to
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Don’t Waste Carbon Investment
As mentioned previously, the time period of greatest concern when considering the importance of embodied carbon is the next 5-10 years. It might therefore be tempting to argue that life
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Consider the Carbon Expense of Construction and How it Can Be Quantified and Minimized
To this point, this paper has considered research and development that can be done primarily by architects, designers and their consultants. However, it is imperative that designers and architects engage
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Don’t Forget that the Design Process Can Be Carbon Intensive
Designers and architects must also engage in a self-reckoning. The whole team should consider the carbon footprint of the design process itself- and envelope design can be especially costly. Envelope
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Footnotes
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Architecture 2030, Embodied Carbon Actions – Architecture 2030, accessed 3/8/22
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Acknowledgements
Thanks to Daniel Nauman, Zach Trattner and Melissa Kelly at Gensler.
Thanks to Melanie Silver and Becca Sturgeon at Payette.
Thanks to Walter Hartnett, Courtney Cochran, Melissa Wong, Gunnar Hubbard and Emma Reif at Thornton Tomasetti.
Thanks to Jennifer Sze and Adrian Tuluca at Vidaris