It turns out that “building reuse almost always offers environmental savings over demolition and new construction,” according to a new study published by the Preservation Green Lab of the National Trust for Historic Preservation.  The Green Lab published its findings after a life cycle analysis of environmental impacts of various buildings located in four cities around the country.

Green LAB compared building reuse and renovation with new construction in four environmental areas (climate change, human health, ecosystem quality, and resource depletion), six building types (single-family, multifamily, commercial office, urban village mixed-use building, elementary school, and warehouse conversion), and four cities (Portland, Phoenix, Chicago, and Atlanta).

The Green Lab found it takes anywhere from 10-80 years for a new building that is 30% more efficient than an average-performing existing building to overcome — through efficient operations — the negative climate impact of construction.  The majority of buildings will take between 20-30 years to compensate for the climate impact of construction.

That being the case, a renovation that requires many new materials may reduce OR NEGATE the environmental benefits of building reuse such as in a situation where the footprint and use of the renovation remains the same.  In other words, an elementary school addition or warehouse conversion to office or residential use will not provide significant environmental advantages.

The study, you may note, doesn’t compare some of the greener buildings you’re used to seeing on this site.  The authors note that “further research is needed to clarify how impacts are altered if a new or existing building can be brought to a net-zero level using various technologies, including renewable energy.“  Keep in mind the standard — 30% more efficient than an average-performing existing building — isn’t all that high.

Download and read the report and then come back to share your thoughts …

[PDF] Download the full report by the Preservation Green Lab.

Credit: National Trust for Historic Preservation.