Water likely will be the next big environmental crisis in the United States, probably first in the West/Southwest, then extending to rapidly growing metropolitan areas throughout the nation. The crisis likely will come as a result of drought and/or lack of funds for infrastructure upgrades to provide new supply sources. One result of America's growing water shortages likely will be an increased public-policy focus on water conservation, water-efficiency technologies, and on-site water treatment and reuse. This policy focus could offer unprecedented opportunities for mechanical contractors, technology suppliers, and engineering consultants.
A Yudelson Associates report for the Mechanical Contractors Association of America (MCAA) Education and Research Foundation titled “Water Efficiency Technologies for Mechanical Contractors: New Business Opportunities,” which can be found at http://bit.ly/6d1o7X, reviews opportunities for mechanical contractors, ranging from water-efficiency audits to rainwater harvesting, gray-water reuse, high-efficiency fixtures, and cooling-tower water conservation. The continued rapid growth of the Leadership in Energy and Environmental Design (LEED) green-buildings rating systems, especially LEED for Existing Buildings: Operations & Maintenance (EBOM), help put mechanical/plumbing contractors at the forefront of finding green solutions.
Rainwater harvesting and gray-water reuse are good technologies for new buildings and major renovations because both require dual-piping systems to collect and treat reuse water inside of a building, as well as space for treatment and storage systems.
Fixture renovations can be made at any time, using a new generation of low-water-using toilets, sinks, urinals, and other appliances. Concern has been raised that reduced water flows might cause drain-line problems because less water is available to flush solids and paper from lines. The plumbing industry is studying this issue.
Rainwater harvesting is gaining popularity in existing buildings because it is relatively easy to implement an on-site treatment and reuse system, whether for cooling-tower makeup water or landscape use. The report reviews opportunities in existing buildings for gray-water reuse, a technology that involves mechanical and landscape contractors. Most captured and treated gray water will be used for site landscaping.
Non-conventional technologies for on-site blackwater treatment and reuse slowly are gaining adherents, but probably will take another five years to gain any significant form of popularity. The use of these technologies presently is limited to new construction projects with educational objectives and those seeking high levels of LEED certification, such as Gold and Platinum.
Findings from the MCAA report include:
“Blue is the next green.” The relative importance of water conservation has increased as a topic among green-building professionals. As energy-efficiency measures become more widely adopted, the green industry has begun to shift its focus to water-conservation issues. Water was emphasized in the LEED 2009 Rating Systems: Available water-related points increased from about 5 percent to 14 percent of the LEED-EBOM system's total available points. A recent survey found that 85 percent of real-estate professionals believe water efficiency will be a very important aspect of green building in 2013, while 69 percent said it was important in 2008.1
Water and energy are inextricably intertwined. It takes energy to make water and water to make energy. For example, in California, nearly 20 percent of all electrical energy consumed is used for water transport and treatment and wastewater disposal. By contrast, most thermal-energy power plants (including coal, oil, gas, and nuclear) require water for cooling and, in the process, evaporate huge amounts of water.
Efficiency vs. Conservation
Water efficiency and water conservation are two very different things. Water efficiency refers to the use of water for a unit of activity, such as gallons per flush in a toilet or urinal. Water conservation is based on the actual water use of a fixture or appliance compared with a baseline. For example, if a sensor for a urinal or water closet is not working correctly, even an “ultralow-flush” fixture will consume a lot of water.
The new International Association of Plumbing and Mechanical Officials (IAPMO) Green Plumbing and Mechanical Code Supplement will open up new opportunities for using water of less-than-drinking-water quality inside of buildings for toilet and urinal flushing, cooling-tower makeup, and various process-water uses. Certain states, such as Oregon, already are showing enlightened leadership in rainwater and gray-water recycling and reuse by establishing an alternative pathway for code compliance.
U.S. urban water use can be reduced significantly without affecting quality of life through a focus on interior and exterior water use. In many of Australia's largest cities, which have been affected heavily by recent droughts, average water use is below 150 liters per day, whereas average water use in the United States is about 150 gal. Do the math: The United States could cut urban water use by nearly 75 percent and still only be at Australian levels.
Rainwater harvesting and gray-water reuse are ready for prime time. Many manufacturers are beginning to market packaged systems that can be combined to process almost any amount of input water for reuse. However, it is important that plumbing and mechanical engineers learn how to size systems and components appropriately for site-designed systems. A study conducted in Australia found that most rainwater-harvesting systems had pumps that were sized so large, they operated at less than 5 percent of capacity.
The U.S. Environmental Protection Agency's new WaterSense standards for fixtures and appliances ultimately will make it easier for designers to specify efficient components for new buildings and retrofit applications.
The key for designers is to manage an entire water cycle, starting with what is free (i.e., rainfall) and trying to get as many uses out of rainwater and gray water as possible. For example, if 80 percent of all of the water utilized in flushing toilets could be reused via on-site black-water treatment, the same water could be used five times. This would have a major impact on water use, especially in a low-rainfall climate.
Because rainfall in the United States varies from 8 to 12 in. per year in the desert regions to 36 in. in places such as Portland, Ore., and Chicago to nearly 50 in. in Orlando, Fla., it is important to look at each project's total water resources (and end-use demands) as a starting point for developing design strategies, especially in new construction.
Water pricing in urban areas favors examining full system costs, including meter-size charges and sewer/storm-sewer connection fees. Reclaiming all of the rainwater from a site, so that no storm-sewer connection is needed, can result in savings that exceed the cost of rainwater catchment and treatment. The same holds true for on-site sewage treatment, particularly if the treated wastewater can be used for toilet flushing, cooling-tower makeup water, and irrigation without ever leaving the project site. Why not take a more detailed and expansive look at the opportunities for 40 percent — or better — water conservation in your next project?
There are immediate revenue opportunities in water audits and water-efficient fixture and appliance retrofits that are cost-effective for building owners and facility managers. Longer term, more work in capturing rainwater and gray water and reusing it for cooling-tower makeup water and site irrigation is expected.
McGraw-Hill Construction. (2009). Water use in buildings: Achieving business performance benefits through efficiency. Retrieved from http://construction.ecnext.com/coms2/summary_0249-307522_ITM_analytics
Jerry Yudelson, PE, MBA, LEED AP, is principal of Yudelson Associates, a green-building and sustainability consultancy. He is the author of 13 books on green building, homes, and development, including the upcoming “Dry Run: Preventing the Next Urban Water Crisis.” He can be contacted through his Website, www.greenbuildconsult.com.
For previous Engineering Green Buildings columns, visit www.hpac.com.
FORESTALLING A CRISIS
Fresh-water shortages are an increasingly serious global problem. With water restrictions emerging in many developed countries, there is a growing need for innovative approaches to reduce our water footprint.
“Dry Run: Preventing the Next Urban Water Crisis” by Jerry Yudelson, PE, MBA, LEED AP, describes ways to manage scarce water resources and handle upcoming urban water crises. Featuring interviews with more than 25 water researchers and industry experts, the book explains water issues and proposes solutions for homes, buildings, facilities, and schools. Examining the links among water, energy use, urban development, and climate change, “Dry Run” demonstrates best practices for achieving net-zero water use in the built environment, including:
Water-conservation strategies for buildings, factories, cities, and homes.
Gray-water-reuse and water-reclamation systems.
On-site sewage treatment.
New water-reuse and supply technologies.