Get more bang for your buck: Valuing green infrastructure’s multiple benefits

If you were buying a house, you’d want to know something about the place. How many bedrooms does it have? Is there a yard? What’s the neighborhood like? You’d want to know what you’re going to get out of such a big investment. What kind of return are you getting on your hard earned dollar?

The same idea applies to most things we spend money on. Or at least it should. One area where we throw this logic out the window though is with water infrastructure. Not all types of infrastructure are created equal. When it comes to controlling stormwater – one of the largest sources of water pollution in the country – there are the big pipes and deep tunnels that we’ve used for decades. They have their place, but in many cases, green infrastructure such as green roofs, rain gardens, trees, etc offer a much more attractive alternative.

From a cost perspective alone, green infrastructure is often justified. In many cases, it’s cheaper than the big pipe alternative. But on the question of “what am I getting out of this?” we’ve been flying blind for some time. Green infrastructure has a ton of benefits in addition to the basic goal of stopping polluted runoff from fouling our rivers, lakes, and coastal waters. But for the most part, planners don’t factor in these additional benefits if they consider green infrastructure at all. Air quality improvements? Zero. Reduced energy consumption? Nada. That’s what we’re assuming despite all the evidence to the contrary. By ignoring these extra benefits, we’re making massive investments in infrastructure without thinking about what we’ll get out of them.

There are a few reasons for this. Many of the benefits vary significantly from place to place, and translating existing research to another community is difficult. In order to measure and value these benefits, the only option has been to conduct a detailed and expensive analysis for each community. In addition, research on green infrastructure’s benefits has been fairly limited, and most studies have focused on one specific benefit like how much CO¬2 a tree takes up. No one has really looked at how the benefits all fit together. Until now.

Today, American Rivers and the Center for Neighborhood Technology released a guidebook that pulls together the existing research on green infrastructure benefits and creates a framework for measuring and valuing them. It’s a first of its kind effort to create a user friendly method that planners can use to create a bottom line dollar figure of what green infrastructure would do for their community. The guide walks through calculations for valuing the air quality, energy use, carbon capture, and other benefits green infrastructure provides. All of these benefits are in addition to the basic stormwater control benefits, which are assumed to be equal to a similar investment in green infrastructure.

Some important things to keep in mind: This guide is a first stab at valuing some of the benefit values that we have ignored for a long time, but much more research is needed. We’re not able to put a value on the reduced urban heat island effect, for example, because we don’t yet know how much certain green infrastructure practices contribute. We’re still not putting a dollar figure on all of the benefit categories, and we’re likely underestimating the value of others. In short, the calculations here understate green infrastructure’s true value, but it’s a first step in the right direction.

The water category in the guide is a great example. First off, as I mentioned above, we’re not valuing the main benefit, which is control of stormwater. We’re assuming that the gray infrastructure system would do that equally well. We’re trying to look at the additional water-related benefits of green infrastructure. We provide a calculation for estimating reduced treatment costs (since green infrastructure prevents stormwater from entering the sewer and needing treatment before being discharged). In the demonstration toward the back of the guide, that comes out to a fairly small number, but that’s all we’re able to value right now. We’re not really able to provide guidelines on valuing other water-related benefits like reduced flooding, decreased wear on other infrastructure, or improved groundwater recharge. It doesn’t mean those benefits don’t exist.

Despite the remaining gaps in our knowledge, this guide lets us start comparing what you get for investments in different types of infrastructure. The picture that starts to emerge is that we’re settling for a studio apartment when we could be getting a spacious, LEED certified three bedroom house for the same or less money. Both of them take care of our basic need for shelter, but one of them comes with a lot more perks and is a much better investment in the long term.