For a long time we’ve known that preservation helps create quality communities that are character-rich, vibrant, and dynamic places in which to live, work and play. And there’s also been lots of good news over the years about the economic value that preservation brings – especially in tough economic times. But today, with the Preservation Green Lab’s release of The Greenest Building: Quantifying the Environmental Value of Building Reuse, we have the most comprehensive research to date showing preservation is good for the environment too. The findings from this study offer additional compelling evidence that preservation makes sense for communities.
Each year, approximately 1 billion square feet of buildings are demolished. The Greenest Building explores the environmental impacts associated with the decision to demolish and replace existing buildings – and especially the carbon dioxide savings that might be offered by reusing and retrofitting these places instead of demolishing them. With generous funding from The Summit Foundation, this effort brought together a team of leading thinkers with unparalleled expertise in building and life cycle science. The study team included Cascadia Green Building Council, Green Building Services, Quantis, and Skanska.
Using life cycle assessment, an internationally recognized approach to evaluating the potential environmental and human health impacts associated with products and services throughout their respective life cycles, this study compares the reuse of existing buildings to demolition and new construction. Six different building types are examined: single family; multifamily; commercial office; mixed-use (main street style); elementary school, and warehouses converted to multifamily and commercial buildings.
Notable study findings include:
- Building reuse typically yields fewer environmental impacts than new construction when comparing buildings of similar size, functionality and energy efficiency. This result was found to be true irrespective of climate – though differences in climate can affect the extent of savings
- The absolute carbon-related impact reductions can be substantial when these results are scaled across the building stock of a city. Consider this example: In Portland, Oregon retrofitting just one percent of the city’s office buildings and single family homes that would otherwise be demolished and rebuilt over the next ten years would help to meet 15 percent of the entire county’s total CO2 reduction targets.
- The study also explores how the reuse of an average performing existing building would stack up against a new, efficient building; it’s often assumed that a new, green building will rapidly compensate for any climate change impacts that occur during the construction process. The Greenest Building analysis finds that it can take 10 to 80 years for a new energy efficient building to compensate, through efficient operations, for the climate change impacts created by its construction. The study finds that the majority of building types in different climates will take between 20-30 years to overcome the initial carbon impacts from construction.
- The design of buildings matters. Those buildings that tend to use the fewest materials will have the most significant environmental savings – and in fact renovation projects that require many new materials can reduce or even negate the benefits of reuse. It’s important to make sure buildings (whether new or existing) are designed to minimize material inputs -- and to make sure designers have the tools needed to select materials with the best environmental profile.
The bottom line: As preservationists, the work we do to save buildings makes sense for our communities, our pocket books and our environment! For more information on The Greenest Building, download the full report or see our report webpage.