It’s All Water
Green Building Practitioners are noticing three trends that, while not new concerns, truly speak of the momentum gathering within the sustainable design movement. One is the issue of water scarcity, second is the issue of environmental chemicals emitted by and residing in our built environment and third is the interest in adding the component of social justice to our battery of integrated building design strategies. I see these three paths as critical components of a broadening new way of practice.
At GreenBuild last month, I attended several sessions given by lawyers, educators, builders, planners, engineers and architects on the issues of water efficiency and maximization. Some common themes surfaced throughout the presentations. Most salient were:
The relationship of water and energy. Known as “watergy” or “embedded water,” it is interesting to note that treating and conveying water is not only the most expensive component of the cost of water, but also the most energy intensive. We must start to connect our water use policy with our energy policy and to find more energy efficient ways to deliver water to and within buildings.
The end of landscaping.Solutions to current water scarcity involve incorporating at least 50% of appropriate, climate adaptive plant species as part of the landscape and providing alternative means of irrigation through captured rainwater and stormwater and building-issued greywater. Municipal water should be thought of as a supplementary, rather than primary, source. The era of the fantasy landscape is over.
We must stop using drinking water to flush waste. Other sources water are on site greywater, rainwater, municipal reclaimed water, mechanical water (from blow-down or condensate) and blackwater.
Centralized wastewater treatment is wasteful and inefficient. Wastewater treatment plants need to be localized, even to the neighborhood scale. They should be thought of as a source of renewable resources, as they offer opportunities to harvest nutrients such as ammonia, nitrogen and phosphorous rather than expend dollars on their removal and disposal. Our infrastructure needs to be re-vamped from a combined sewer system to a split wastewater/stormwater management system. Because wastewater is electron-rich, it is also time to start thinking of wastewater treatment plants as sources of energy.
What does this mean to green designers? It means that landscape designers need to concentrate on species selection and water infiltration. An example of this “spread and infiltrate” strategy is to divert runoff to a series of tree planting basins or rain gardens. For architects and builders, this means a new way of assessing how we convey water to, in and around buildings. Is the building a treatment facility? Has a water budget (catchment area multiplied the amount of rainfall) and water footprint been calculated? How do we design to make conservation easier for the user?
Barriers:Several barriers compound the challenging issue of maximizing water efficiency. Water prices are artificially low, thus stymying innovative technologies. Another barrier is the apprehension about using greywater indoors due to insufficient treatment of potential contaminants. Last, current rating systems do not consider water issues as a whole. LEED splits water credits into two categories of credits, sustainable site and water efficiency. Rating systems should focus on more than just fixture selection, irrigation controls and stormwater diversion. It’s time to think of water design on the community level, as holistic, land-based management, as a watershed, that will steer building design, community design and infrastructure planning to a greener, more water-abundant future.
, Assoc. AIA, LEEP AP is the author of Fundamentals of Integrated Design for Sustainable Buildings, Wiley, 2009.