The National Trust for Historic Preservation recently published a comprehensive study, “The Greenest Building: Quantifying the Environmental Value of Building Reuse,” which analyzed the environmental impacts of demolishing existing buildings and replacing them with new construction, as compared to reusing and retrofitting existing buildings.
The study examined several different types of rehabilitations such as mixed use/urban villages, single family residential, commercial office space, as well as conversions (e.g., warehouse to office), in Chicago, Atlanta, Phoenix and Portland. The study concluded that it can take anywhere from 10 to 80 years for a new building that is 30% more efficient than an average performing existing building to “overcome, through efficient operations, the negative climate change impacts related to the construction project.” Of these rehabilitations, mixed use/urban villages took the longest time to overcome the climate change impacts of new construction, and thus, these building types make the most sense to rehabilitate, instead of build new. The majority of the building types, even though utilizing more efficient and environmentally friendly materials, take between 20 to 30 years to compensate for the initial environmental impacts of the construction project.
The study further revealed that, even though rehabilitation has less of an impact on the environment, both the quantity and types of materials used in the rehabilitation can reduce or even eliminate the advantage of converting an existing building. For example, converting warehouses to multifamily residential, which requires extensive modifications and new materials, can completely negate the benefits of rehabilitation. “In the case of the warehouse-to-multifamily conversion scenario, the newly constructed building actually demonstrated fewer environmental impacts in the categories of ecosystem quality and human health.”
The report ultimately concludes that for those concerned with climate change and environmental impacts, “reusing an existing building and upgrading it to be as efficient as possible is almost always the best choice regardless of the building type and climate. However, careful material selection and efficient design strategies for reuse are critical and can play a major role in minimizing the impacts associated with building renovation and retrofit projects.”
With green construction at the forefront of today’s building world, it is certainly worth considering from an environmental standpoint, as well as a business standpoint, the findings of the study and the potential benefits of rehabilitation.
Reference: National Trust for Historic Preservation.