Precious Water: Sustainable Indoor Water Systems
Learning Objectives - After this course, you should be able to:
- Discuss water conservation, and describe trends and industry standards in water efficiency.
- List general criteria for evaluating water and plumbing-related design elements.
- Apply what you have learned in the contexts of both LEED and the EPA's WaterSense program.
Building designers and owners deserve a pat on the back for pushing the industry as far forward into green territory as possible, given the constraints within which they design, budget and manage projects. With sustainable energy use and a reduced global footprint in mind, we've created and implemented any number of innovations calculated to keep energy use, as well as embedded energy, low. Yet in the area of water conservation, there is room to expand.
The concept of "water efficiency" has recently taken on new urgency in the building design profession. Experts on global warming theory point to water as a rapidly dwindling resource-the result of rising temperatures and sea levels. Only 0.5 percent of the earth's water is potable and available for use, and of that amount up to half could ultimately become contaminated by seawater, according to a recent study from Ohio State University. With such challenges in mind, architects, engineers, contractors and facility managers are now implementing inventive retention, recycling and reuse strategies for water, as well as basic conservation strategies.
So then what's missing? In a word, "comprehensiveness." Too often, our approach to water systems has lacked holism and system-wide analysis. "Water is often subjugated in status to energy, but water is energy," says Gunnar I. Baldwin, LEED AP, Water Efficiency Specialist with TOTO USA, Inc. "Yet there's so much embedded energy, and that has not been well broadcast, although the EPA and some green-building professionals have recently been emphasizing this."
So what of the energy inextricably embedded in water? How much electricity, how much carbon output, goes into the treatment and delivery of usable water? A broad strategy for water conservation can't factor in energy and water separately.
The Energy in Water
About 8 percent of all electricity used in the United States is expended in the delivery and treatment of potable water, according to Benjamin Grumbles, Assistant Administrator for Water at the EPA. In California, the most populous state in the nation, 19 percent of the electricity is used for delivering water, and a staggering 32 percent of the state's natural gas consumption powers the treatment of water and wastewater.
In rough numbers, the American public water supply and its treatment facilities consume 50 billion kilowatt-hours annually-about as much electricity as is needed to power 4.5 million private homes each year. And this number is conservative; it only includes the energy used to bring potable water into the public consumer supply. Still more energy is used to deliver sewage and wastewater to treatment plants, and more still by rural homes using electric pumps for well water.
On the macro level the dilemma is obvious. Let's translate it for a moment to the micro level. How long do you run the hot water when you shower? Or wash dishes? Run a hot water faucet for just five minutes, and the user has consumed power equivalent to that used by a 60-watt light bulb after burning for 14 hours. The energy embedded in water, apparently, is massive; saving a little water saves a lot of energy.
Water efficiency, then, is a challenge for our nation as a whole, and as individuals. Where end-user behavior cannot be predicted or controlled, building design and operations professionals are uniquely placed to create and implement water-saving strategies and solutions. Vital to the effort is basic knowledge of sustainability issues and guidelines, cost-effectiveness strategies, building occupant and tenant desires, construction costs and limitations, as well as building codes, regulations and standards.