Imagine a world in which we consciously care for and improve the buildings we already have as a lever for climate action. Architecture 2030’s CARE Tool, which allows stakeholders to estimate the embodied, operating, and avoided carbon impacts of reusing and upgrading existing buildings compared to replacing them with new construction, aims to realize that world. While currently designed to analyze single building projects, the CARE Tool can also support research into the potential impact of strategic reuse at a building portfolio, campus, or entire jurisdiction level.
A recent study by CARE co-founder Lori Ferriss, AIA, with Agnes Scott College’s Center for Sustainability in Decatur, Ga., and the Boston firm Goody Clancy, indicates that when and how we reuse existing buildings can dramatically increase total carbon savings. Using the CARE Tool, Ferriss analyzed the college’s historical campus to evaluate how a reuse-first approach was contributing to its goal of achieving net zero by 2037. She modeled three scenarios: replace buildings with high-performance new construction at end of life, renovate buildings to a high level of performance at end of life, and, the college’s current approach, renovate buildings at end of life while also making continuous improvements to energy performance across its entire portfolio, including strategies like retro-commissioning, upgrading to LED lights, and improving occupant behavior.
Architecture 2030
The annual carbon emissions of the Agnes Scott College campus for three decarbonization scenarios.
Of the three scenarios, the approach that emphasized continuous care of the existing building stock resulted in a 41% reduction in total emissions compared to a do-nothing baseline, avoiding roughly 115,000 metric tons of CO2 emissions. In contrast, reusing buildings at end of life yielded a 10% reduction, and replacing buildings at end of life yielded only a 3% reduction compared to taking no action at all.
The opportunity to reduce total carbon emissions through building reuse at scale is massive, and a nuanced approach to continuous improvement yields the most impactful results. The University of Washington’s Carbon Leadership Forum recently published an Embodied Carbon Policy Reduction Calculator, a toolkit that used CARE to model the potential benefits of increasing adaptive reuse at the city scale through embodied carbon policy. The Carbon Leadership Forum’s accompanying report found that reuse can significantly reduce emissions, demonstrating a savings of roughly 4 million metric tons in Portland, Ore., one of three case-study cities.
Results confirm the high impact potential of city-wide reuse, but we must develop the data, tools, and policy mechanisms stakeholders need to realize the full climate benefits of building reuse. To help fill this gap, the CARE team is exploring the development of CARE for Portfolios, an initiative that aims to offer an accessible platform and data that can inform reuse policy at the campus or city scale. Feeling the urgency to attain a zero-emissions built environment, the CARE team is also exploring the expansion of data for single-family residential projects and for regions beyond the United States. Even with unprecedented federal support and jurisdictions nationwide increasingly adopting policies that promote zero operating energy and emissions, we must keep our focus on the embodied emissions we expend along the way.
This article first appeared in the November/December 2023 issue of ARCHITECT.
Read more on building a greener world: Putting Decarbonization Back on the Global Stage | Now Is the Time for Radical Collaboration | Can We Halve Carbon in the Built Environment? | The Race to Decarbonize Buildings Is On. | Building on the Best of COP27
