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Water Use and Green Building
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Written by Jerry Yudelson
09/17/2010 09:11

Among green building professionals, the relative importance of water conservation has increased as a topic of concern during the past two years. As energy-efficiency measures have become more widely adopted in new construction, the green building industry has shifted more of its focus to water conservation. In the LEED 2009 rating system, for example, certification requires that buildings reduce water use by at least 20 percent from a baseline or"code" building. A 2008 survey found that 85 percent of real estate professionals believed that water efficiency would be a very important aspect of green building in 2013, compared to 69 percent who said that it was in 2008.

The same survey found that early adopters of new water-conservation technologies are building owners/occupiers, with 42 percent of owners reporting in the same survey that more than three-quarters of their projects have water-efficient practices incorporated in the design. This compares with only 28 percent of architecture and design firms and 20 percent of contractors who reported that they used water-efficient technologies in their projects. One possible explanation is that owner/occupiers have likely inflated their own adoption figures owing to the utility cost saving they have already decided to pursue.

Water Use Patterns in Commercial Buildings in the US

California shows important demand sources: landscaping, process water,restrooms and cooling towers.

Figure 1. shows water use patterns in commercial, institutional and industrial (CII) buildings in California. One-third of water use goes to landscaping (a fraction found also to residential use), about one-sixth each to process water (non-fixture, non-cooling) uses, restrooms and cooling towers, with the balance for kitchen, laundry and miscellaneous uses. Consider the variety of water uses in different commercial buildings such as hotels, schools, restaurants, hospitals and offices, as well as industrial applications such as food processing included in CII water use, and you'll understand why there is such a large demand for process water.

In terms of the purpose of the water use, some 38 percent of the total CII water use went to landscaping in 2000 (representing about 10 percent of total urban water use, not even counting household water use for landscaping)! Clearly, the CII sector can reduce water use substantially over time just by focusing on landscaping, cooling towers and bathroom fixtures.

One important study of the CII sector in California estimated that widespread adoption of best practices could result in annual savings of about 39 percent or 1,200 million cubic meters (975,000 acre-feet) of water use in the year 2000. Half the savings would come from landscaping water use, while restroom and laundry use would also be cut by 50 percent.

Water Efficiency Technologies

What are some new water efficiency technologies that might be of interest for green buildings in the non-residential sector? There are many responses to the water supply crisis engulfing many regions of the US in 2009, particularly in California; some involve creating new water supplies from desalting saline or brackish water; others derive from buying “saved water” from investing in irrigation water efficiencies, and still others rely on reusing fully treated municipal wastewater. What methods show he most immediate promise, in both new and commercial buildings, as shown in Table 1 and Figure 2. Some are well known, such as low-flow fixtures and sub-metering, and their use is beginning to accelerate, while others are just coming into general distribution, such as rainwater harvesting and graywater reuse.

Table 1- New Technologies and Systems for Buildings

Figure 2. Commercial buildings have many opportunities to reduce water use, as well as to recycle and reuse currently wasted water.

Driving Forces to Use Water-efficient Products and Methods

What are the driving forces that make water efficiency an increasing concern for the built environment?

Table 2 shows some of them, roughly in descending order of importance.

Table 2- Driving Forces for Water Efficiency

According to the survey report cited earlier, for some users concern over future climate changes and the possibility of further governmental regulations will drive adoption of new water technologies. Many building owners and facility managers are aware that the built environment, both residential and non-residential, is a significant contributor to climate change, with buildings contributing 38 percent of US carbon dioxide emissions each year.8 Increasing water scarcity, an indirect effect of climate change in some regions, is leading engineers and architects to design new buildings with significantly reduced water demands.

A larger concern among building owners is risk management and risk mitigation, especially prevalent with concern over energy use in buildings. In the survey cited earlier in this article, 87 percent said that energy-use reduction was a motivator for water conservation (even though the financial correlation between the two is not that direct, except for service hot water and cooling towers), 84 percent cited operating cost reduction, while 79 percent cited directly the motivation to reduce water use. Higher costs for water and energy were the primary trigger for water conservation, especially in response to conservation pricing structures (increasing prices with increasing levels of water use) increasingly adopted by municipal water providers.

Water Efficiency vs. Water Conservation

Many water experts distinguish between water-efficiency devices and systems, which lower the water use per activity (such as a flush), and water conservation, which includes issues such as behavior and economics and can also reduce water consumption, from whatever source. In some cases, a low-flow or high-efficiency toilet could end up using more water if people feel they have to flush twice to get the bowl clean. Hence, the result is “efficiency but not “conservation!” John Koeller, an engineer and water expert, speaks to this point:

“Efficiency versus conservation is an important distinction because people incorrectly use the terms interchangeably. In LEED, for example, the term that’s used is “water efficiency” not “water conservation,” because it’s about designing green buildings, and among other things, efficiency is what you design into those buildings. You cannot design conservation into the building; perhaps you design that into the building managers through education and other means.”

Koeller also questions the value of some efficiency devices in achieving actual conservation, even if they are “working” correctly.

“In my presentations, I highlight a few things that people think are true that are actually false. My favorite one is sensor valves in restrooms on sinks, toilets and urinals in commercial buildings. People cannot believe [it when I say] that. They think that if you put an infrared motion sensor on a fixture, that it is automatically, by definition or design, a water-saver. Quite the opposite is true: the water waste when a sensor-activated valve is substituted for a manual valve is very significant. For example, in flush valves for toilets and urinals, we talk about “phantom flushes,” the unnecessary flushes due to untimely activation of the sensor.We have all experienced phantom flushes, and our experiences tell us that these things don’t save water.”

I can relate totally to phantom flushes. How many times have you sat in a stall at an airport or some other location with motion sensors? Every time you lean forward, for whatever reason, there’s a flush. Beyond the inconvenience, the water waste can be disconcerting, if you’re trying to “do the right thing.”

Public Programs for Water Conservation in the US

Politics may wind up as the major driver of water conservation, rather than the marketplace, particularly in drought-stricken areas and in jurisdictions with strong environmental constituencies. In the survey cited earlier, building industry respondents ranked government regulations on wastewater runoff (69%) and mandates and incentives for water efficiency (67%) as key drivers over the next five years for their efforts aimed at saving water in buildings.

Ike Casey of the Plumbing Heating Cooling Contractors (US) national association agrees that politics is likely to be the driver and that the plumbing industry needs to be aware of potential problems, lest the plumbing contractor be left holding the bag for future problems. He says,

“I think low-flow toilets are going to be the big driver. The water efficiencies in toilets and urinals are going to be a big issue in our industry coming down the road because some states are already requiring it. At this time, California and Texas have passed legislation to phase out the sales of anything but HETs.10 The State of Washington made it a requirement [in April 2009]. Texas has a bill that’s pending [in early 2009] to require high-efficiency toilets (HETs). This is a political issue for us because HETs don’t work all the time. When your toilet doesn’t work, you don’t look on the label and call the manufacturer. You call the plumber [who installed it]. The plumber is the one that’s left in the middle.”

Increasing Importance of Controlling Water Losses

In Sydney, Australia, I found a study that indicated up to 30% of delivered water is lost inside the building to leaks. This is probably a worldwide phenomenon, so it’s vitally important for public water agencies to consider such leaks as a “free” water resource that can easily and cheaply extend the capacity of their systems. In addition, there is “unbilled water” that is lost in transit from the water treatment plant to the building. Water agencies need to redouble their efforts, especially in older systems, to reduce the amount of water lost into the ground from broken or leaking pipes. This loss is analogous to the problem faced in sewage treatment by infiltration of groundwater into sewer pipes, thereby adding to the burden of treatment plants. Fixing water losses is not glamorous stuff, for sure, but controlling water loss is essential to extending our water supplies to meet future demands.

Further attesting to the importance of strong controls over public water supply systems, in Germany low water losses within the public drinking-water network are considered an important indicator of the quality of pipelines and security of supply.During the past few years, for example, water losses in the German water -supply network have been decreasing. With lessthan seven percent revenue loss from unbilled water, German water suppliers have by far the lowest water loss in Europe.24 However, in Asian countries, this “non-revenue water” averages about 30 percent of all water produced, indicating a considerable potential for handling growth just through finding and fixing leaks in the existing systems.

From a public policy and public investment perspective, finding and fixing leaks is probably the most cost-effective investment a water utility can make and should be a central element of future water supply planning.

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Endnotes

McGraw-Hill Construction, 2009, Water Use in Buildings: Achieving Business Performance Benefits through Efficiency, construction.ecnext.com/ coms2/summary_0249-307522_ITM_analytics, accessed August 18, 2009. Personal communication, Amin Delagah, Food Technology Research Center, Pleasanton, CA, December 2009. Peter H. Gleick and Nicholas L. Cain, The World’s Water, 2004–2005: The Biennial Report on Freshwater Resources, Washington, DC: Island Press, p. 39. Ibid. Table 6.1, Dry Run: Preventing the Next Urban Water Crisis, p. 133. Ibid. p. 142. 18. Based on a presentation by Dr. Daniel Yeh, “Tools for Recovery of Embedded Renewable Energy, Water and Nutrients from Wastewater,” U.S. Green Building Council, Greenbuild Conference, Phoenix, 2009. Source: the author. US Department of Energy, Emissions of Greenhouse Gases in the United States 2002, October 2003, eia.doe.gov/oiaf/1605/archive/gg03rpt/index.html, accessed December 15, 2009. Interview with John Koeller, PE, May 2009. Koeller is technical advisor to both the Alliance for Water Efficiency and the California Urban Water Conservation Council. This information is current as of the end of 2009, but keep checking, as the legislation in this field is constantly changing. Interview with Ike Casey, PHCC, April 2009. Andrea Stahl, 2008, “Germany: Water Supply and Wastewater Disposal,” US Commercial Service, Report 14264596, p. 5. www.adb.org/water/topics/non-revenue/default.asp, accessed January 17, 2010. This article is adapted from Chapter 5 of Dry Run: Preventing the Next Urban Water Crisis (New Society, 2010), Jerry Yudelson’s latest book on green building and green development issues. Jerry Yudelson, PE, MBA, LEED AP, is the founder and principal of Yudelson Associates, a green building, water conservation and sustainable business consultancy, based in Tucson, Arizona. Jerry is a frequent keynote speaker at conferences worldwide. His next books deal with financing the green revolution and with improving building performance globally.