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What Is the Carbon Footprint of Interior Renovations?

March 24, 2022
LMN Office

It’s often noted that the built environment contributes 40% of carbon emissions worldwide. Architects and facilities professionals have responded to this number by attacking carbon emissions on two fronts; architects have worked to reduce the embodied carbon in common materials like concrete and steel, while facilities teams have focused on reducing energy use and implementing renewable energy as a way to reduce dependence on fossil fuels, which release emissions as they’re burned.  

But this conversation has so far left out the impact of building interiors—and according to new research by LMN Architects, the carbon footprint of interior design may be bigger than anyone realized. 

“Everybody thought [the impact] was zero because they didn’t measure,” explained Kjell Anderson, principal and director of sustainable design for LMN Architects. “You need to draw the circle a bit bigger to know what your impacts are.” 

[Related: Better Climate Challenge Aims to Cut Carbon in Half by 2030]

How Interiors Affect Carbon Emissions 

Anderson and colleague Jenn Chen, a principal interior designer for LMN, used the firm’s own Seattle office to test their theory that interior design—and specifically, cyclical renovations that repeatedly replace interior products—were responsible for considerable carbon emissions. Chen and Anderson decided to analyze several past renovations of the office space using a tool by the Carbon Leadership Forum to estimate the relative carbon impacts of different interior products used in the renovations. The firm moved into Seattle’s Norton Building in 1984 and has done a major renovation about every nine years, making it the perfect case study for Chen and Anderson’s investigation. 

The Carbon Leadership Forum tool uses product data from Environmental Product Declarations (EPDs), which were of course not available for the earliest renovations. Chen and Anderson substituted comparable materials that did have EPDs available, which means that their estimate of the carbon impact of interiors is a conservative one—it’s likely that older products have a larger carbon footprint than modern products that have EPDs. 

[Related: How to Specify: Climate-Positive Materials]

Embodied carbon impacts
Major elements in the LMN Architects office have different carbon impacts, according to available Environmental Product Declaration (EPD) data. Courtesy of LMN Architects.

Even so, the results are stark. In spaces that undergo cyclical renovations, the cumulative carbon impact of interiors can actually surpass the emissions generated by building the structure and envelope. The structure and envelope are only built once unless you’re constructing an addition, but interiors change relatively frequently. 

“When you think about the building when it’s first built, the embodied carbon of the envelope and structure seems really high compared to the interiors, and that’s why it wasn’t part of the conversation for a long time,” Chen said. “But when you take into consideration the cyclical nature of interiors and how often things get remodeled, the embodied carbon of the interiors really adds up.” 

Three scenarios
The chairs, carpet and workstations comprise over 75% of the total embodied carbon of LMN Architects’ 2014-2015 remodels, shown as the baseline in the middle column. The left column imagines the impact of adding acoustic ceilings throughout the space instead of leaving the ceilings open. The right column shows the carbon reduction that would be possible by aggressively pursuing embodied carbon reductions with products that were on the market as of 2021. Courtesy of LMN Architects.

What to Do About Interior Embodied Carbon 

All is not lost when it comes to the embodied carbon of interiors. All spaces will need a renovation eventually, but there are ways to lower the renovation’s carbon impact. Try these strategies for lowering the carbon footprint of your interiors. 

1. Think about what you can reuse. You don’t have to gut spaces to renovate them. You may be able to reuse or repurpose materials you already have, which will save both carbon and money. 

2. Save what you can. If you can’t use a material again in your renovation, chances are someone else can. Many cities have architectural salvage programs to which you can donate materials and furnishings. “What can I salvage and reuse on this project or what can be reused by somebody else?” Anderson asked. “Salvage walkthrough sometimes doesn’t happen, but it really should happen on projects because there’s value there.” 

3. Specify products salvaged from somewhere else. There are several handy tools out there that can help you find furniture and other products that have been salvaged from previous owners. Doors Unhinged is a pioneer in the space that has diverted scores of doors from the waste stream. Heirloom Design, a digital platform for refinishing and reselling commercial-grade furniture, is another. 

4. Opt for lower-carbon alternatives. Manufacturers are starting to address the carbon impacts of their products with strategies like incorporating recycled materials and improving manufacturing efficiency. One such manufacturer, Interface, has reduced the embodied carbon of its carpet tile by 76% since 1996 by changing how it makes its products.  

“What you do is make the best decisions and really think about the impact of everything you’re putting into your design,” Chen advised. “Just slow down, examine how the practice has been and whether that serves our environment the best, and what we can change now to do it. Just examine one material to start and you can start building that habit and muscle memory to make a bigger impact.” 

Carbon timeline
Chen and Anderson separated the results of their study into structure, envelope and interiors, arranged in five-year segments. This scenario assumes that an additional remodel happened halfway between 1960 and 1995 and was equal to the 1995 remodel in embodied carbon. It also accounts for the 30% reduction in the embodied carbon of concrete available today. The results estimate that the embodied carbon of the interior remodels is higher than the combined impact of the structure and envelope over 60 years. Courtesy of LMN Architects.

Read next: Take Action Now to Reduce Building Carbon Emissions

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About the author
Janelle Penny | Editor-in-Chief BUILDINGS

Janelle Penny has more than a decade of experience in journalism, with a special emphasis on covering facilities management. She aims to deliver practical, actionable content for facilities professionals.