Could a rain garden on the lot of a private building help decrease crime in the neighborhood? Investments in green infrastructure such as vegetated roofs, rain gardens, and permeable paving not only illustrate a developer's commitment to healthier, sustainable communities, but they also can have a positive effect on the bottom line in the form of higher rents, increased sales, and reduced crime, according to a new report from the Natural Resources Defense Council (NRDC). Shutting down arguments that the investments don't pay off fast enouhg because first costs are greater than the economic benefits reaped by such investments, the report, "The Green Edge: How Commercial Property Investment in Green Infrastructure Creates Value," asserts that the cumulative benefits of these efforts can total in the millions of dollars over a 40-year period.

The report presents a compendium of data on the benefits of green infrastructure practices, which are identified as including "green roofs, rain gardens, bioswales, trees, parks, roadside plantings, rain barrels, permeable pavement ,and other mechanisms that mimic natural hydrologic functions or otherwise capture runoff on-site for productive use." Could it change the mind of many property owners going forward?

Communicating the value of such investments remains a challenge, which Alisa Valderrama, senior project finance attorney with NRDC’s Center for Market Innovation, sums up on her blog post on the study, writing that "it is very challenging to convince busy, cost-constrained commercial property owners to replace their driveways with porous pavement or to create rainwater catchment areas in their parking lots. Even if property owners did want to implement a green infrastructure retrofit, many would need financing for the project, all would require very quick project paybacks and all would want to avoid inconveniencing their tenants."

The data in the new report, however, may help change a few minds. According to the report, benefits of green infrastructure investments for private, commercial property owners include:

  • Increased rents and property values. According to past empirical studies, the use of landscaping, trees, or vegetation additions for single-family homes can increase property values 2 to 5 percent and as much as 7 percent, but how does this factor into commercial property values? NRDC asserts that landscaping could add 7 percent to the average office rental rate, which translates to an additional $72,150 each year in rent for a medium-sized office rental property in Philadelphia.
  • Increased retail sales. Research has shown that not only are shoppers willing to spend more on products, drive farther to shop, and visit more often to spaces with attractive landscaping or green streets, but a mature tree canopy could also potentially translate into a consumer's willingness to pay 8 to 12 percent more for goods.
  • Energy savings. I recently had a debate with some classmates in an energy modeling class regarding the insulating value of a green roof on a building. It turns out there's a growing base of empirical research proving such value. In Chicago, the green roof on city hall is yielding $3,600 in annual energy savings, while Minneapolis's Target Center Arenaweaetxdyvaydzcwq is keeping $300,000 in the owners' pockets due to decreased annual energy costs. Further research asserts that a green roof can reduce energy demand for cooling in a one-story Southern California building by more than 75 percent.
  • Stormwater fee credits and other financial incentives. This may be one of the more well-known benefits, but it's worth reiterating. Did you know that a mid-rise apartment building in Philadelphia with a 8,400-square-foot green roof could receive a one-time tax credit of over $50,000? Or that Milwaukee's Regional Green Roof Initiative provides up to $10 per square foot for green roof projects?
  • Reduced infrastructure costs. Assuming that a green roof has a typical lifespan of 40 years and a conventional roof is estimated at 20 years could mean saving hundreds of thousands of dollars in roof replacement costs over the lifespan of a building, the report's authors assert.
  • Reduced costs associated with flooding. Another potential no-brainer, reducing stormwater runoff via green infrastructure, which can absorb and/or slow potential flood waters. But did you know that if you decrease flood risk, you are also decreasing flood damage costs (since you don't need to replace what isn't flooded in the first place) and therefore increase property values by 2 to 8 percent?
  • Reduced water bills. Rain barrels and water cisterns = water captured and stored for reuse = reduced potable water use for irrigation = money in a building owner's pocket. by the way, for more on the various water-related benefits, check out Larry Levine's blog on the topic. He oversaw project development for NRDC on the report.
  • Increased mental health and worker productivity for office employees. 'Office workers have a clear preference for nature near the workplace, leading to improved health and job satisfaction, and reduced levels of stress," the report's authors write. And who knew: You don't need a full forest to reap these benefits, as vegetation among buildings and parking lots has been found to be effective in this regard.
  • Reduced crime. The theory of crime prevention through environmental design believes that "social monitoring of public spaces ... and quality landscape can encourage more public use of city spaces," and crime reduction is vegetation such as open space with grass and tall trees, according to the report's authors. While they admit that shrubs and bushes can abet those up to no good by providing hiding spaces, creating areas that promote and encourage gathering do the opposite, reducing crime. This one's a little more complicated. Click here to access the full report. The reasoning around the linkage between landscaping and other green infrastructure and crime reduction starts page 25. The flip back to page 1, read it all, and let us know via the comments section below: Does this sort of research change your perspective on green infrastructure? Does it help you build a business case for clients?