According to my neighbor’s rain gauge, Asheville has had 16 inches of rain in the past 2 weeks. The 14-day forecast says that 10 days from now we might have a full day without rain. This is excessive even in our temperate rain forest. We expect 45-50 inches of rain in a typical year. In some locations the flooding and mud-slides are worse than they were during the hurricane rains in 2004. Welcome to climate change.
The language that we use to talk about climate change has evolved over time to encompass not just drought, but also more frequent devastating storms and flooding. Carbon emissions and energy use are the source of the problem, so they form the foundation of all the green building programs. Beyond that, most green building programs have (as they should) credits that address drought-resistance and reduced indoor water use. But the programs are much more varied and less responsive to climate-change issues like storms and flooding.
When we built our LEED-platinum, Green-built North Carolina platinum home two years ago, my husband and I wanted to earn a lot of “points” on the programs and achieve the bragging rights that come with platinum status. But we were also adamant that we wouldn’t chase points and that we would only do things that made sense for our specific home and site. We found the largest disconnect in the site and landscaping categories.
The LEED for Homes point system is heavily weighted to rewarding drought-resistant landscaping. When we did the LEED water-use calculation, it told us that we needed an absurd amount of water to maintain our planned landscape. We do have a rainwater cistern, but our ultimate expectation was that our landscaping would rarely, if ever, require watering after the first couple of years. Most people in Asheville have no problem growing the much maligned mowable turf without watering it.
On the other hand, we knew that our site had water management “issues” after heavy rains. We’re at the bottom of a mountain and we take a lot of runoff from homes and roads above us. The city didn’t do us any favors when they repaved our street last year and sloped it to dump all the water into our yard.
We’ve been taking a step-by-step approach to dealing with site water and landscaping. So far, we’ve installed two rock-lined channels to direct water around our home and into the flood plain that is our back yard. At various times of year, this area goes from being a dry creek to something that looks like the muddy Missouri river. We’ve also re-worked the grading uphill of our house and put some underground drainage in. So far, so good on the uphill side.
We haven’t done much to the back yard yet, and it may be that doing nothing is actually the best answer. We have a wide, low area that’s overgrown with vegetation that enjoys the flooding and silt that we get from the uphill neighborhood. I wish it had fewer invasive plants in it, but the engineer from the city who came to look at it commented that it appeared to be doing a valuable public service by filtering the water from the mountain before it hits the local streams. I’m not sure how much we’ll ultimately decide to intervene back there. But it’s pretty clear to me that removing what’s there and installing turf-free “drought resistant” landscaping (which could have earned us LEED points) would not be the right thing to do at all.
Some of the issues are so fundamental that they belong in the code and permitting process, rather than in green building programs. When Asheville’s steep slope ordinance passed several years ago, a lot of people were upset that the geotechnical testing requirements were increasing the cost of construction. Today, we have a condemned house on Black Oak Drive threatening to fall on homes located downhill. Suddenly, geotechnical testing starts to look like a very worthwhile expense.
The current position of LEED for Homes seems to be that all of these things fall in the “durability” category, and are things that builders should just do without being rewarded. In terms of basic serviceability, I see the point. But when we’re talking about enhanced resilience to unusual weather events caused by climate change, I tend to think that it should be rewarded the same as drought-resistance.
LEED does offer credits for planting trees and ground-cover, which help reduce wash-outs in heavy rains. However, not removing mature vegetation in the first place is a much more effective remedy. Here’s a photo of washed out areas near my home where someone removed mature trees and replaced them with new trees (of a different kind) about 5 years ago. You can see where the mature trees were left in place there’s no washout, and where stone has been added to stabilize the ground where the trees were removed and the ground washed out. It’s not particularly attractive, and doesn’t look like it will be as effective as the mature vegetation would have been.
LEED does offer a credit for minimizing the disturbed area of the site. However, the one point you can earn for doing this is probably less than you would obtain by disturbing the site and replacing it with something drought-resistant.
GreenBuilt North Carolina does a better job of rewarding builders for rain-resilient sites. They award credits for fencing existing trees (a great way to preserve those mature trees with large root networks), leaving sections of the site undeveloped, having a tree preservation plan, planning for stormwater control, and installing rain gardens, bio-retention bains or infiltration strips.
Greenbuilt North Carolina also rewards builders who go beyond the bare-minimum required erosion control measures during construction. I’ve seen quite a few sites in the past two weeks whose communities have benefitted greatly from builders liberal use of straw bales and mulch to enhance their erosion control.
Still, both programs could be doing more to reward sites with comprehensive plans that not only make homes more resilient but that are able to reduce the downstream impact of runoff by filtering and holding water after big storms. In some cases, water-friendly plants that can make use of the water and develop larger root systems could be more earth-friendly. Green building programs also have the opportunity to take a leadership role in educating builders and homeowners about how to make these decisions and develop plans that really serve the best interest of their particular sites.
Copyright 2013 Amy Musser.