News Brief

Raze or Retrofit? CARE Tool Has the Answer

Should it stay or should it go? From a carbon perspective, conventional wisdom says most buildings should stay. The CARE Tool backs that up with data.

outputs of free CARE tool carbon modeling for building projects

The tool compares three scenarios—Do Nothing, Reuse, and New Building—and shows various outputs, including embodied and operational carbon over time.

Images: CARE Tool (Architecture 2030)
Is the greenest building the one that’s already built?

Yes! Usually? Sometimes …

Taking carbon into account, it may seem like a no-brainer to retrofit existing buildings rather than build new ones, but to make a good climate case for reuse, you need good data. That’s where the free online Carbon Avoided: Retrofit Estimator, or CARE Tool, can help.

“In most cases, the greenest building is the one that already exists, but that wisdom has not been proven with comprehensive data,” says the tool website. “This means that the carbon benefits of reusing existing buildings are rarely incorporated in climate action plans, carbon tracking, or design decision-making, a critical missed opportunity … to quantify their impact potential and make the strongest case for building reuse.”

Recently released by Architecture 2030, the tool compares project-scale greenhouse gas emission scenarios for retrofitting vs. building new, taking both operational carbon (emissions from energy use in the building) and embodied carbon (emissions associated with building materials) into account. Development of the software was led by design experts: Larry Strain, FAIA, of Siegel and Strain Architects; and Erin McDade, Assoc. AIA, of Architecture 2030; and Lori Ferriss, AIA, P.E., director of sustainability and climate action at Goody Clancy.

Users enter data in four categories:

  • General information, such as location and building typology
  • Proposed renovation parameters and operational targets
  • Proposed new construction parameters and operational targets
  • Information about special conditions, such as seismic considerations

The graphical outputs, which update in real time during data entry, compare three scenarios: leaving the existing building as is, retrofitting and optionally adding to the existing building, and replacing the existing building with new construction. Built-in grid assumptions based on location mean that building electrification measures are considered.

Future development will include creation of a CARE Portfolios tool, incorporation of regional grid decarbonization projections, the ability to compare more scenarios at a time, and improved international support, according to the tool website.

Update 12/6/22: This article now includes a third lead developer of the software, Lori Ferriss.

Update 12/19/22: Some language was changed to remove the implication that the CARE Tool is designed to find exceptions to climate arguments for reuse. That is not the intent.

More on existing building decarbonization

We Must Decarbonize Existing Buildings by 2050—but How?

Existing Buildings Are Architecture’s Future

Mind the Gaps: Making Existing Buildings More Airtight

For more information:


Originally published December 5, 2022 Reviewed December 6, 2022

Melton, P. (2022, December 6). Raze or Retrofit? CARE Tool Has the Answer. Retrieved from

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