Taxonomy Term en 18853 How Much Water to Turn on a Light Bulb?
Cooling towers at a nuclear power plant in Byron, Illinois.
Photo Credit: Scott Olson, Getty Images

Nearly all of our methods for generating electricity involve water consumption—some a lot, some not as much. Producing electricity with hydropower is the most water-intensive method, owing to evaporation from reservoirs. Nationwide, electricity from hydropower plants consumes about 9 gallons of water per kilowatt-hour (kWh) of electricity produced.

In some parts of the world, this evaporation is a big problem because of the relative scarcity of water and its use for drinking water. In the arid Southwestern U.S. this evaporation is a huge issue, especially from reservoirs like Lake Mead.

Water use for thermoelectric power plants

Most electricity in the U.S. (about 89%) is produced using thermoelectric power plants. These use a heat source (most commonly coal, natural gas, or nuclear fission) to boil water, creating superheated, high-pressure steam. This steam spins a turbine to generate electricity. Cooling water is then used to condense the steam back to water.

Depending on the type and age of the power plant, the cooling water is once-through (pulled from a river, for example and then returned to the river at a higher temperature), provided by a cooling pond, or recirculating. The once-through systems use tremendous quantities of water, but the vast majority returns to the water source from whence it was drawn—albeit at a higher temperature (thermal pollution can be a major problem). Some evaporates, however, and is not returned to the river; this is the consumptive use.  

Recirculating cooling systems in power plants use far less water and they don’t add thermal pollution to the body of water from which the water was originally drawn, but they still evaporate considerable water—in fact, typically more than once-through cooling systems—so the consumptive water is very significant.

Comparing coal, natural gas and nuclear relative to water use

Of the three primary fuels used in thermoelectric power plants, natural gas power plants have the lowest water intensity. According to Burning Our Rivers: The Water Footprint of Electricity, by the River Network in Portland, Oregon, coal power plants consume 0.69 gallons of water per kWh of electricity produced, natural gas power plants consume 0.17 gallons/kWh, and nuclear plants 0.57 gallons/kWh.

With coal, according to the report, 73% (0.506 gal/kWh) of the water consumption is from evaporation, as described above, while 27% (0.186 gal/kWh) is from upstream sources (mostly mining, and transportation). Once-through cooling of coal plants results in consumptive water use (evaporation) of about 0.3 gal/kWh, while recirculating systems evaporate about 0.7 gal/kWh.

Water consumption from nuclear plants is similar to that of coal though the spread between once-through and recirculating systems is even greater: 0.27 gal/kWh for once-through cooling versus 0.76 for recirculating systems.

While the water intensity of natural gas power generation is a lot lower than for coal and nuclear, there are significant differences depending on the type of power plant. Combined-cycle plants are nearly two-and-a-half times as water-efficient as single-cycle power plants.

Burning Our Rivers shows very low upstream water consumption for natural gas power plants, but the report did not consider hydraulic fracturing (fraking), which results in far greater water use (typically 4-5 million gallons per well) and heavily contaminates that water. An October 2013 report on the water intensity of natural gas extraction from Marcellus Shale in Pennsylvania and West Virginia (PDF download) by researchers at Downstream Strategies and San José University sheds some light on this issue.

The massive, 377 MW Ivanpah solar-thermal power plant in California's Mojave Desert.
Photo Credit: BrightSource Energy

Solar and wind power generation

There are two primary ways electricity is generated from solar: utility-scale solar-thermal power plants and either utility-scale or building-scale photovoltaic power generation. Surprisingly, most utility-scale solar thermal is more water-intensive than coal or nuclear power plants.

From Burning Our Rivers, parabolic trough systems are shown to consume about 0.80 gal/kWh, while linear Fresnel systems consume about 1.0 gal/kWh, solar power tower systems consume 0.63 gal/kWh, and dish Stirling Engine systems, which are far less common but do not use the heat to generate steam, consume only 0.020 gal/kWh.

Adding to the challenge with large-scale solar-thermal is that these systems want to be located where there is a lot of sunlight, such as the American Southwest, and those places tend to be much drier.

Photovoltaic systems use almost no water in their operation—only 0.002 gal/kWh—with most of that upstream water use for manufacturing.

Finally, wind systems consume less than 0.001 gal/kWh—the lowest of any electricity source—with most of that also upstream.

An array of dual-axis-tracking, 25-kW SunCatcher collectors using Stirling engine technology, which does not require water.
Photo Credit: Stirling Energy Systems

Low global warming and low water use

It is worth pointing out that the renewable energy technologies for power generation that are growing the quickest in implementation (photovoltaics and wind) are the least water-intensive.

The only measures that do even better from a water-use standpoint are efficiency measures. Using less electricity is the place to start if the goal is to conserve water resources—see Saving Energy by Conserving Water, and Saving Water by Conserving Energy.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.

2014-04-16 n/a 9118 A Foot-control faucet for convenience and savings
Tapmaster Model 1751 includes both a kick-plate and button activated by the cabinet door to turn the tap on and off. Photo: Tapmaster. Click on image to enlarge.

For the past eight years we've been able to turn our kitchen faucet on and off using a knee- and foot-control valve from the Canadian company Tapmaster. This may seem like a convenience-only product designed for lazy people. I can't argue with all of that--and admit that I probably wouldn't have installed one if I hadn't received it for testing from the manufacturer after we had reviewed a competing product in Environmental Building News. But I gotta say, I love it, and I'm convinced that it does result in significant water and energy savings.

Foot and knee controls for faucets have been used for decades in hospitals, where doctors and nurses don't want to risk re-contaminating their hands by touching the faucet handle after washing. Now these controls are making their way into high-end homes as a convenience feature (as are sensor-activated controls), and our company has recommended this type of product since our first review of a foot-control faucet in 1999 (log-in required to read full article). With foot- and knee-controls for faucets, you set the desired temperature and flow rate using the standard hot and cold levers. Then you turn the tap on and off by pushing an under-sink cabinet door with your knee, by stepping on a foot valve, or by depressing a "kick-plate" beneath the cabinet. Our particular model allows us to use either a knee against the cabinet door or the tip of a foot pushing against a kick-plate. To adjust the rate of flow or the temperature, one simply adjusts the levers like normal--but you turn the flow off by releasing pressure on the cabinet door or foot pad.

We usually have only the cold water lever turned on (to quickly fill a water glass or rinse a spoon off during the day). When we're going to wash dishes, we simply turn off the cold lever and turn on the hot (because we keep our water heater set to about 120°F, we usually don't have to mix cold with hot for washing dishes).

Shown here is a Tapmaster kick-plate for Model 1750 or 1751; Kick-plates are available in black, white, and stainless steel. Photo: Tapmaster. Click on image to enlarge.

It's certainly a convenience to turn the water on and off without using your hands. But it also saves water. This morning, when I was filling the water bowl for our golden retriever, for example, I was able to hold the bowl with both hands and not waste water by turning on the faucet and then lifting the bowl under the tap. When washing pots and pans, with the hot-water tap turned on, I control the flow very simply using my knee, while many people leave the water running.

While you save water whether it's hot or cold water that's being controlled, there's a whole lot more money to be saved by reducing use of hot water, because it's water that doesn't have to be heated.

The biggest problem we have is when guests are over and can't figure out how to turn on the water. For this reason, we often lock the control in the "on" position (a simple process using the kick-plate) so that the flow is controlled with the faucet levers--like normal. Our younger daughter used to enjoy tricking her friends, though, by snapping her fingers as she surreptitiously pushed in the cabinet door or foot pad. Her friends would try to turn on the tap by snapping their fingers....

Tapmaster's foot- and knee-control systems start at about $300 (not including installation), with some systems costing over $500. Would I recommend this as starting-point investment in water and energy savings? Certainly not. But, I have to say that after using one of these for eight years (with absolutely no problem), if I were building a new house today I would figure out a way to work this feature into the budget.

In addition to this Energy Solutions blog, Alex contributes to the weekly blog BuildingGreen's Product of the Week, which profiles an interesting new green building product each week. You can sign up to receive notices of these blogs by e-mail--enter your e-mail address in the upper right corner of any blog page.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. To keep up with his latest articles and musings, you can sign up for his Twitter feed.

2010-12-07 n/a 9129 10 Questions with 2010 Hanley Award winner Alex Wilson

Alex Wilson, the founder of our company and our current executive editor (i.e., my boss), is being named the 2010 Hanley Award winner in a special event here at Greenbuild 2010 tomorrow. In recognition of this achievement, and to better understand how this innovative, always-curious visionary looks at the world, I recently asked him 10 questions. Here's the conversation.

Congratulations on being the 2010 winner of the Hanley Award. How would you sum up your feelings on this honor?

Thanks Tristan. It's a tremendous honor--and an honor for all of us at BuildingGreen. EBN, GreenSpec, LEEDuser and our other products are all group efforts from the whole company. I'm truly humbled to receive this award.

What are your thoughts on following Ed Mazria, FAIA in winning the Hanley Award?

That makes it even better. I have tremendous respect for Ed and what he's done to engage the design community as well as governments in the goal of reducing our carbon footprint. I knew Ed, though not well, when I lived in Santa Fe in the late '70s, and I have a well-worn copy of his Passive Solar Energy Book in my home library. He is a pioneer in the true sense of the word, and I'm deeply honored to be following Ed in receiving the Hanley Award.

You've built your reputation in part on taking stands on issues like dangers of treated wood, brominated flame retardants, and the global warming impact of some insulation products, while drawing attention to cool new ideas like passive survivability. What's a stand that you've taken that you wish had caught on more?
A couple come to mind. I was really hoping that the concept of "transportation energy intensity" would catch on as a metric of building performance. My analysis, which we published in EBN in 2007, showed that, on average, in an office building in this country we expend 30% more energy getting people to and from the building than the building itself uses--assuming national-average commuting distances, mode of transportation for commuting, square footage per person, etc. For an office building built to the ASHRAE 90.1-2004 energy code, transportation energy use is 2.3 times greater than the building energy use! Yet, we rarely think about this in the green building movement. For me that article was a real wake-up call; I think it was the most important article we've ever run in EBN... so far!

I 'm also disappointed that "passive survivability" hasn't caught on more. In retrospect, it may have been a mistake to chose such a negative term. "Resilient design" might be better from the standpoint of a term that would gain traction. The issue, no matter what the term, is really important, and I think it will eventually come back into the conversation much more actively. For that to happen, though, I'm afraid, that it will take a tragedy of some sort (such as a major heat wave coinciding with a prolonged drought that causes widespread, extended power outages in southern cities during the summer). I'm sure I'll be returning to this topic in the future. The design criterion of passive survivability makes a lot of sense.

EBN is well-known for not running advertising on its pages. What was the moment when you made that decision?

Nadav [Nadav Malin, current president of BuildingGreen] and I decided not to carry advertising before we launched EBN. For me there were two reasons: first, we wanted to be free to say what we wanted to say about products and emerging technologies without having to worry about push-back from advertisers; and second, I knew that I didn't want to spend my time selling ads. I had seen other people start publications and end up not being able to spend time on the content. I didn't want to go that route.

This is such a hackneyed question, but, what the heck: If you could have a conversation with anyone, alive or dead, that you're not currently in touch with, who would it be?

Samuel Clemens (Mark Twain) would be right near the top of the list; I'd like to sit on a porch with him and listen to his satire in person. It would be great to go for a long hike with John Muir and learn about his motivations in launching the environmental movement. And I'd like to stand in the corner of a dimly lit pub in 1775 and listen to Thomas Jefferson debate with his cohorts how to create a nation from scratch.

What are you reading right now?

I'm reading Ecotopia, a classic novel from 1975 that describes a utopian nation created when Washington, Oregon, and Northern California split off from the U.S. I'm reading it because I'm thinking a lot about how you can inspire change in a society. In the same vein, I just finished reading a new novel, Solar, by Ian McEwan (Doubleday, 2010). A copy was sent to me by the publisher (perhaps because one of the subplots is about how dumb building-integrated wind energy is?). It's mostly about this has-been, womanizing scientist who is still coasting from a long-ago Nobel prize in physics, but he happens into a synthetic photosynthesis technology that may be the holy grail that everyone has been looking for to save the world. I should note that it's rare for me to read novels in such a short timespan; I'm usually reading a few nonfiction books about water resources, climate change, and the like--you know, the doom-and-gloom stuff.

You often say that green products don't make a green building, but you also have an incredible curiosity and excitement about about cool green products. Why?

It's really fun to see what new products are coming along--and figure out how they can be part of the solution in creating a low-energy, low-carbon future that shifts us towards sustainability. I've had a lot of fun this year writing the "cool product of the week" blog. I wish I could spend even more time researching new products. I've also enjoyed helping choose and then presenting BuildingGreen's "Top-10 Green Products" each year--this will be our ninth year; I'll be announcing this year's picks at the Greenbuild conference.

With Katrina, with the BP oil spill, I've heard lots of prognosticators say, "Maybe this is the disaster that will really wake us up to our environmental problems," but so far none of them seem to be right. Do you think we'll ever turn things around? What will it take?

For 40 years I've been called an alarmist or Chicken Little, warning that the sky is falling. I keep thinking that new evidence will wake up the general public to the problems we're facing, but I keep being proven wrong. This is frustrating.

Even the BP oil spill, which galvanized interest in environmental protection for a while, will likely be quickly forgotten or--even worse--be presented as evidence of how quickly nature can rebound, with the conclusion that we don't need to worry so much about safeguards. I'm afraid that the only things that will really galvanize attention on what we need to do are things that affect the general public directly: dramatically higher energy prices, actual shortages of fuel or prolonged power outages, or dramatic heat waves and changing weather patterns. I read in The New York Times that with the heat waves and fires in Russia this summer, everybody is talking about global warming. To date, Russia hasn't engaged much in the discussions about reducing greenhouse gas emissions; perhaps now they will. If Washington, D.C. bakes at 110°F for a few weeks perhaps our politicians will take notice.

The Hanley Award recognizes a long and distinguished career--with a lot yet to come, we hope. What's your advice to students or those earlier in their careers in design and construction on how to help meet our environmental challenges?

What I almost always recommend to students--in any field--is to include in your studies some science. (I've been only marginally successful in this with my own two daughters!) Whether going into architecture, construction management, journalism, or foreign policy, learning how to investigate a problem scientifically and objectively evaluate courses of action will usually result in better solutions. I believe that if more politicians had a background in science they would be creating better legislation and policies. Relative to building design, some training in science will come in handy in understanding everything from the offgassing of VOCs in adhesives to the moisture dynamics in walls--and help you design better, healthier, more durable buildings.

You've been with the green building movement since the 1970s. Today we have global warming deniers, "green fatigue," and a green movement that's big enough to have factions divided over issues from nuclear power to the LEED rating system. What do you see as the green movement's biggest challenge (and hopefully, opportunity) in the twenty-teens?

I wish I had a good answer to this question. It's key to our future. Last night I watched a screening of the film "Carbon Nation." It's a great documentary and speaks very effectively to those who already get it--but it needs to be repackaged to reach the audiences that it really needs to reach. It turns out that I know the producer, and I plan to contact him and discuss some ideas for doing that. For Fox News fans and the Glenn Beck, Rush Limbaugh crowd, I think it's going to be pretty hard to change minds without something dramatic happening. But if we go through a year in the United States like Russia is going through this year (where temperatures are as much as 20°F higher than normal), perhaps that would begin to convince even them.

And if that crowd comes around to the reality of climate change and the importance of doing something about it, can you imagine the influence they would have? If Beck and Limbaugh were to issue a joint statement urging action on greenhouse gas emissions, I think even the dozen or so newly elected global-warming-deniers in the Senate would have to pay attention. Unlikely, yes, but stranger things have happened.

Illustration by Stacey Curtis, BuildingGreen (Awesome)

2010-11-16 n/a 9148 Revised Air Conditioner Condensate Calculator Available on
This online calculator allows you to calculate how much condensate can be captured from an air conditioning system. Click on image to enlarge.

Back in 2008 when I wrote a series of articles for Environmental Building News on water (all three can be accessed with this link), one of those articles, Alternative Water Sources: Supply-Side Solutions for Green Buildings, examined various ways of harvesting water and included an in-depth look at collecting air conditioner condensate.

Here's an excerpt from that article on how that condensate is generated:

Cooling systems rely on evaporator coils through which refrigerant fluid changes from liquid to vapor, cooling the coils in the process. Air blowing past the coils cools off as it goes by, and moisture from the air condenses on the coils. Condensate drains carry away the water, usually into the sewer. Instead of wasting it, more and more buildings, especially in parts of the country with hot, humid summers, are capturing that condensate for reuse. The city of San Antonio, Texas, has actively pursued this practice. It makes so much sense there because of the large cooling load and high humidity. The downtown Rivercenter Mall in San Antonio collects about 250 gallons of condensate per day, which is used to replenish the cooling tower losses, and the San Antonio Public Library collects about 1,400 gallons on condensate per day, which is used for irrigation. A six-month payback was calculated on the condensate-recovery system at the Rivercenter Mall.

When we ran that EBN article, we also provided an online calculator to assist designers or building owners estimate how much air-conditioner condensate could be recovered. Eddie Wilcut and Elliot Fry, of the San Antonio Water System (SAWS), developed the spreadsheet, and then Kelly Lucas on our staff "webified" it.

Users brought to our attention some problems with the condensate calculator, however, so we took it off our site.

I'm pleased to report that the BuildingGreen Condensate Calculator is back up, following some refinements by the SAWS team and Kelly's work to incorporate those changes into the online version.

Have a look, and take it for a test drive. Feedback will be very welcome; use the comments field.

Alex also writes the weekly blogs on Alex's Cool Product of the Week, which profiles an interesting new green building product each week, and Energy Solutions. You can sign up to receive notices of these blogs by e-mail--enter your e-mail address in the upper right corner of any blog page.

Alex is founder of BuildingGreen, LLC and executive editor of Environmental Building News. To keep up with his latest articles and musings, you can sign up for his Twitter feed.

2010-09-25 n/a 9155 Saving Water by Conserving Energy
Lake Mead, the nation's largest reservoir, which supplies 90% of Las Vegas's water and millions of other residents, shown at about half capacity in 2007. Ken Dewey photo. Click on image to enlarge.

Last week we examined the amount of energy it takes to transport and treat water--and how we can conserve energy by using less water. This week, we'll look at the inverse of that: how much water it takes to produce energy and how our energy conservation efforts reduce water use. The water intensity of energy Whenever water shortages loom anywhere, we hear about how much "embodied water" there is in various products. According to the Water Footprint Network, producing a slice of bread requires 11 gallons of water and producing a pound of beef takes 1,800 gallons. The same sort of analysis can be done with our energy sources. As with foods, different types of energy have different water intensities. Electricity: Electricity generation is highly variable in its water-intensity. Roughly 89% of U.S. electricity is produced in "thermoelectric" power plants. These are plants that use heat from burning coal or natural gas or from controlled nuclear fission to generate steam, which then spins turbines. Water is used to create the steam, and then more water is used to cool that steam, condensing it back into water. Most thermoelectric power plants built before 1970 have "open-loop" or once-through cooling systems that result in relatively little evaporation--though significantly warmer water is returned to the river or other source from which it was taken (which has its own environmental costs). Most newer plants use "closed-loop" recirculation cooling; far less water is required, but most of that evaporates (consumptive use). Averaged nationwide, 0.47 gallons of water is consumed (evaporated) for each kilowatt-hour (kWh) of electricity produced by thermoelectric plants, according to a 2003 paper by researchers at the National Renewable Energy Laboratory (NREL), Consumptive Water Use for U.S. Power Production. Most of our electricity not produced by thermoelectric power plants is generated by hydroelectric plants. This accounts for about 9% of the U.S. total. Hydroelectric plants don't heat water to create steam, so water isn't needed for cooling, but they use a lot of water nonetheless. Most hydropower is generated by damming rivers to create reservoirs. These reservoirs have significantly larger surface areas than the free-flowing rivers prior to damming, and evaporation from these reservoirs can be significant. Hydrologists produce "free water surface evaporation" maps to model this evaporation, which varies greatly by climate. For the NREL study mentioned above, researchers calculated evaporation from the 120 largest power-generation reservoirs in the U.S. (representing 65% of total hydropower generation) and used that data to extrapolate evaporation from all of the nation's 2,300 power-generation reservoirs: 9.05 billion gallons per day. Here's how the water consumption from hydroelectric power generation in a few states compares: 18 gallons/kWh in Colorado, 21 gal/kWh in California, 65 gal/kWh in Arizona, and 137 gal/kWh in Oklahoma. Nationally, the average is 18 gal/kWh. By weighting thermoelectric and hydroelectric power generation sources, the NREL report calculated an average water-intensity of electricity in the U.S. to be 2.0 gal/kWh. So if you use 500 kWh per month, that's requiring, on average, 1,000 gallons of water. Oil and gas: Electricity isn't the only form of energy that requires a lot of water to produce. According to a 2006 U.S. Department of Energy report to Congress, Energy Demands on Water Resources, conventional onshore oil extraction consumes relatively little water: 0.12 to 0.31 gallons of water per gallon of oil (0.8 – 2.2 gal/million Btu). But "enhanced" oil recovery practices, which are becoming increasingly common, are much more water-intensive. These practices range from 1.9 gal water/gal oil (14 gal/million Btu) to over 300 gal water/gal oil (2,500 gal/million Btu). Extracting oil from tar sands in Alberta takes 20-50 gallons/million Btu. Another 1.0 to 2.5 gallons of water are required to process and transport each gallon of oil (7-18 gal/million Btu). With natural gas, conventional onshore extraction requires negligible water use, but processing and transport averages 3 gal water/million Btu. New "hydraulic fracturing" techniques (sometimes referred to as "frac'ing"), as are being used to recover natural gas from the Marcellus Shale formation, use a great deal of water (and contaminate that water in the process). Renewables: On the renewable energy front, some biofuels, especially ethanol produced from corn, are very water-intensive. A 2008 paper in the journal Environmental Science & Technology reported that a light-duty vehicle driven on an E85 fuel (85% ethanol) "consumes" a remarkable 28 gallons of water per mile! Utility-scale solar-thermal power plants that focus sunlight to super-heat an oil heat-transfer fluid, which in turn generates steam, require a lot of water, and that's an issue in the desert environment where these are being built. (Some other solar-thermal technologies rely on Stirling engine technology, instead of steam turbines, so use almost no water.) Bottom line: Save Energy to Conserve Water! The bottom-line conclusion from all this--you saw this coming!--is that by conserving energy we save a lot of water. Replacing incandescent light bulbs with CFLs, upgrading to Energy Star appliances, insulating your house--virtually any energy improvement you make--will also save water. Some experts say this is really important; in the coming decades fresh water could become a more limited resource than energy.

In addition to this Energy Solutions blog, Alex writes the weekly blog on Alex's Cool Product of the Week, which profiles an interesting new green building product each week. You can sign up to receive notices of these blogs by e-mail--enter your e-mail address in the upper right corner of any BuildingGreen blog page. Alex is founder of BuildingGreen, LLC and executive editor of Environmental Building News. To keep up with his latest articles and musings, you can sign up for his Twitter feed.

2010-08-31 n/a 9157 Saving Energy by Conserving Water
Niagara uses innovative "vacuum-assist" hydraulics to provide an effective, yet super-quiet flush in the Stealth toilet, requiring just 0.8 gallons. By using less water, this toilet saves energy. Photo: Niagara Conservation. Click on image to enlarge

It takes a lot of energy to transport and treat water in this country, and it takes a lot of water to produce the energy we use. To put this a different way: when we save water we save energy, and when we save energy we save water. Most people don't think about this tight-knit relationship between energy and water, but public officials in a growing number of regions around the country are becoming quite aware of it.

The amount of energy needed to deliver clean water and treat that water once we've used it varies tremendously by region. If you live in southern California, your drinking water is pumped either from the Colorado River and its assorted reservoirs (including the nation's largest, Lake Mead, which is now half empty) or from northern California. In either case, that water flows through hundreds-of-miles-long open aqueducts and, via pipelines, up and over mountain ranges.

Averaged statewide, roughly 5% of California's electricity is used for moving and treating water and wastewater. (The oft-quoted figure of 19% includes water heating and other things we do with water in homes, businesses, and farms.) But these figures vary widely in different parts of the state. A 2005 report from the California Energy Commission found supply and conveyance of water to range in intensity from 0 to 16,000 kilowatt-hours per million gallons (kWh/MG), while filtration and treatment varied from 100 to 1,500 kWh/MG, distribution varied from 700 to 1,200 kWh/MG, and wastewater collection and treatment varied from 1,100 to 5,000 kWh/MG. Not surprisingly, average totals are far higher in southern California (12,700 kWh/MG) than in northern California (3,950 kWh/MG).

This issue isn't limited to California. Nationwide, roughly 4% of total power generation is dedicated to pumping and treatment of water. For many cities and towns around the country, this is the largest single user of electricity. Water filtration plants and sewage treatment plants are very energy intensive. In places where desalination is needed, the energy-intensity of drinking water rises dramatically.

On a per-capita basis, this energy use for water varies from about 350 kWh/year in the South Atlantic states to over 750 kWh/year in the Mountain states, according to a 2006 report by the U.S. Department of Energy. (Here in New England, each of us uses just under 400 kWh/year, on average.) This means, for a lot of us, our domestic water accounts for about as much electricity as our refrigerator. For most homeowners, the energy-intensity of water use is hidden in water and sewer utility bills, while those of us in rural areas who have our own water systems and onsite wastewater systems pay those energy costs directly.

If you have a really deep well, water pumping costs can be one of your largest electricity demands. And while gravity-flow wastewater disposal systems (in-ground septic tanks and leach fields) use little if any energy, some of the newer "aerobic" treatment systems that work in places without suitable soils for standard in-ground systems have pumps that operate 24/7, consuming as much electricity, annually, as four or five refrigerators.

The bottom line is that because there's a lot of energy "embodied" in the water we use, we should conserve water in order to save energy. In fact, in some places, such as California, energy conservation programs provide rebates on water-conserving appliances and plumbing fixtures such as toilets and irrigation-control systems, even if those products do not use energy directly. Any conservation measure that reduces hot water use, such as low-flow showerheads, front-loading clothes washers, and efficient dishwashers, will directly save energy by reducing the amount of water we have to heat.

A good starting point in saving energy by reducing water use is to look for WaterSense-listed products whenever shopping for a product covered by the EPA WaterSense program.

2010-08-24 n/a 9159 Is America Ready for a Home Urinal?
The Waterless Company's new residential Baja urinal begins shipping this week. Photo: Waterless Company. Click on image to enlarge.

There are some significant advantages to urinals when it comes to bathroom maintenance (I won't go into the messy details of splashing that happens when males stand and urinate into a toilet). With ultra-efficient urinals (often called one-pint urinals) and waterless urinals, there are also very significant water savings that are achieved.

The Waterless Company, which invented the non-water-using urinal in the early 1990s (see our February 1998 EBN product review of their first product--log-in required), has now introduced a waterless urinal designed specifically for the residential market. The Waterless Company's Baja urinal, which should start shipping this week, according to company president Klaus Reichardt, is somewhat smaller than a commercial urinal, and available in vitreous china for easy cleaning. The Baja urinal works on the same principle as other Waterless-brand urinals--using the company's EcoTrap system (see schematic). The EcoTrap uses a lighter-than-urine, plant-based oil (EcoBlue) that serves as the sanitary trap. The EcoBlue fluid is topped off as needed, and the entire trap is replaced about once per year, assuming typical usage. Because the urinal dries out between uses, waterless urinals are actually more sanitary than conventional urinals, according to the Waterless Company and other manufacturers.

In commercial buildings, with typical usage patterns, a waterless urinal saves about 40,000 gallons per year. For residential applications, the savings will be significantly lower. Reichardt estimates that if there are two males in a home, each using the urinal three uses per day, times 340 days at home, the Baja urinal will replace about 2,040 toilet flushes per year, providing annual water savings of about 3,250 gallons (assuming 1.6 gpf toilets). The savings go up with more males (family members or friends).

Reichardt told me that they're getting a lot of calls from diabetics who have to urinate frequently and who hate to waste all the water. While these water savings should not be dismissed, I suspect that the primary motivation for purchases--if it succeeds--will be more about sanitation and reduced cleaning needs than it is about water savings.

The EcoTrap and a lighter-than-urine plant-based oil provides the sanitary trap in the Baja urinal. Photo: Waterless Company. Click on image to enlarge.

I should note that waterless urinals are not without problems. We've been using one at our office for 12 years or so, and salt build-up on the drain line forced us to remove and clean out those lines once, and it's showing signs of needing that servicing again. Some argue that it's important to periodically flush a urinal to prevent the build-up of deposits, or that ultra-efficient urinals make more sense than waterless models. Clearly, regular maintenance is required to ensure good performance.

The suggested retail price of the Waterless Baja urinal is $248. The product is distributed through plumbing wholesalers and the company's sales reps.

For more information:

Waterless Co.
Vista, California

Alex Wilson is the executive editor of Environmental Building News and founder of BuildingGreen, LLC. In addition to this product-of-the week blog, he writes the weekly Energy Solutions blog. To keep up with his latest articles and musings, you can sign up for his Twitter feeds. Products covered in his product-of-the-week column are--or soon will be--listed in BuildingGreen's GreenSpec database.

See more on this product in the GreenSpec Guide

2010-08-19 n/a 9172 The DOE Showerhead Rule: Someone is all wet

You would think that establishing a definition for “showerhead” would be simple. But, as the Department of Energy (DOE) is discovering after issuing a draft interpretive rule on the matter, nothing is simple when it comes to getting people wet.

Some showerhead background
Back in early 1994, under the Energy Policy and Conservation Act (EPCA) of 1975, all showerheads manufactured in the U.S. could have a maximum flow no greater than 2.5 gallons per minute (gpm) at 80 psi. The intent, of course, was to save water, particularly hot water and its associated energy use.

Over the years, plumbing manufacturers have gotten pretty creative about how people can get wet in their showers or baths. In recent years, the trend has been toward “multi-spray” systems, which have up to six “showerheads” (each of which complies with the 2.5 gpm flow maximum) and “waterfalls,” which aren’t really “showerheads” and therefore aren’t subject to the requirement (see photo: this Kohler shower system has 8 separate showerheads, each one complying with the 2.5 gpm maximum). These systems can use up to 20 gallons of water per minute, just for one person. And even though the actual installation number for these DOE-dodging plumbing fixtures is relatively low, they represent an important, high-end product for plumbing manufacturers. Manufacturers erupt over new ruling
When DOE quietly issued a draft interpretive ruling earlier this year that essentially made these systems illegal, the water world erupted. The ruling said:

  1.  “…a showerhead is any [emphasis added] plumbing fitting that is designed to direct water onto a bather.”
  2. “…the Department will find a showerhead to be noncompliant with EPCA’s maximum water use standard if the showerhead’s standard components, operating in their maximum design flow configuration, taken together, use in excess of 2.5 gpm when flowing at 80 psi, even if each component individually does not exceed 2.5 gpm.”

Bye-bye “multi-spray” and “waterfall” direct-water-to-bather devices.

Water conservation community not happy either
It’s not just the plumbing manufacturers but also the water conservation community and water conservation experts who are upset with the DOE showerhead rule. It all stems from the key word “interpretive”—both camps agree that DOE should have invited them to comment on this “interpretation,” which they say actually represents a rule change.

Here is what DOE says about its action in the draft rule itself:

“This draft interpretative rule represents the Department’s interpretation of its existing regulations and is exempt from the notice and comment requirements of the Administrative Procedure Act. See 5 U.S.C. § 553(b)(A).“

In other words, DOE did not need to treat this rule as a “substantive” rule change, an approach with exacting and lengthy requirements for input from the outside. So plumbing manufacturers and trade industry groups are upset because they consider this change to be more than a little bit substantive and one in which they should have a say (see the trade industry letter to DOE Secretary Chu opposing the interpretive rule affecting multiple showerhead systems).

Water conservationists are upset for the same reason, but from a different side of the issue—they’re quite certain that manufacturers will manage to find loopholes. “This is a substantive change and working out all the definitions and conditions to make sure the language is watertight will take a lot of effort from a lot of folks,” says water expert John Koeller, P.E. “And frankly, lots of hard work has been done on this topic within ASHRAE 189.1 (a code-ready green building standard) and the IAPMO Green Building Supplement, work that is not reflected in the DOE interpretive rule.”

One source within the plumbing industry who asked not to be named said, “I know that DOE is way behind on its rulemaking and is even under a consent decree including this particular rule, but this is not the way to get caught up.”

Rule will harm the elderly? NAHB goes too far
Of course, every rule change brings along a few fear mongerers. I was flabbergasted to get a press release from the National Association of Home Builders (NAHB) entitled, “DOE Showerhead Rule Limits Choices for Elderly and Disabled, Says NAHB.” The release included this quote from current NAHB President Bob Jones:

“This is going to make it much more difficult for older Americans to live independently. Under the new definition, replacing a traditional, single showerhead with one that includes a flexible hose to take a shower while seated will result in half the water pressure for each—which would be too weak for either one.”

This sort of overstatement undermines NAHB’s credibility and the legitimate concerns the building industry has with the nature of the rule change. I contacted Marsha Mazz, the Technical Assistance Coordinator for the U.S. Access Board, the agency that handles accessibility issues for the federal government. “We don’t see it as a disability issue at all,” stated Mazz. “People with     disabilities will not use both showerheads simultaneously and all the combination hand-held/mounted showerheads of which we are aware have a diverter that directs all of the flow to one head or the other.”

NAHB’s e-release (and the NAHB letter to DOE regarding the rule, supplied by NAHB to BuildingGreen) goes on to express the same legitimate concerns expressed in the trade letter above. NAHB should have stuck to that line; the unfortunate title and quote lands them squarely under a compliant showerhead, fully dressed.

A bit of good news on WaterSense

Meanwhile, the U.S. Environmental Protection Agency’s (EPA’s) WaterSense® program is merrily proceeding on its way to market its WaterSense labeled product and new homes, using its specification for water-efficient showerheads and shower compartments—a specification achieved by consensus. And it is not luck but hard and intelligent work that resulted in specification language that holds water and aligns well with the DOE draft rule, ASHRAE 189.1, and the IAPMO Green Building Supplement.

2010-07-07 n/a 9177 Pressure Reducing Valves Save Water and Prevent Problems

Pressure-reducing valves, an element of EPA’s WaterSense® new homes specification, are green: they can save water, increase the service life of plumbing system components, and reduce risks of water leaks.

What is a Pressure Reducing Valve (PRV)?
PRVs have spring-loaded diaphragms that resist the incoming pressure of the water supply to a home. They are typically installed just after the water meter on the system side (see top photo: This basement photo, starting from the bottom, shows the insulated incoming water main, the single-throw main shut-off (red handle), the water meter, and the pressure reducing valve (set screw stem sticking out to the right). PRVs usually come set at 45 pounds per square inch (PSI) but have a set-screw adjustment so that the PRV’s range of operation is from approximately 30 to 80 psi. PRVs cost around $80; installation costs may double the total cost, depending on installation circumstances (new or existing home, location of incoming line, ease of shutting off water service to the home, etc.). Why are PRVs included in the WaterSense new homes specification?
The 2009 WaterSense Single-Family New Home Specification requirement ( is for static water pressure no greater than 60 psi. For homes with wells, a pressure tank must be installed as part of the domestic water system. For homes on municipal water distribution systems, you need either a PRV or a determination the home complies with the static pressure maximum (see the Inspection and Verification Guidance for WaterSense®  Labeled New Homes - .

PRVs save water by reducing flow rates. The greater the water pressure, the greater the rate of flow for many plumbing fixtures. Reducing the system pressure by as little as 10 to 20 psi can save thousands of gallons a year in a typical home. Reflecting this benefit, it is not uncommon for PRV installations to be supported by water utilities. The City of Austin’s water utility gives a $100 rebate for PRV installations in homes with greater than 80 psi water pressure (

But PRVs in homes with high water pressure are green and smart for other reasons. Many residential plumbing fixtures are engineered for pressures no greater than 75–80 psi; some manufacturers void their warranties if pressures are above this range. Fixtures such as storage-type water heaters, dishwashers, refrigerator icemakers, and pressure-assisted toilets can be particularly prone to reduced service life or leaks at pressures above 75–80 psi.

Is high water pressure really that common?

Municipal water systems vary tremendously in water-delivery pressure, depending on distance from water plant, elevation, and other factors. Pressures in excess of 100 psi are not unusual. In my own home, we measured water pressures ranging up to 110 psi routinely over a week-long period.

It’s easy to test your water pressure—you can screw a pressure gauge right on to a hose bib (see bottom photo). If pressures exceed 200 psi, two PRVs can be installed in series to manage the load. But leave the installation of the PRV to a plumbing professional, hopefully a green one (

2010-06-24 n/a 9184 WaterSense Labeled New Homes Make Sense

EPA's new specification for water-efficient homes works well for all sorts of builders and even remodelers Although EPA's criteria for WaterSense labeled new homes were only recently released, custom and production builders from Georgia to Arizona, from Montana to Hawaii, are signing up. With typical overall water savings of more than 20 percent compared to other homes, WaterSense homes are just that--sensible.A custom builder (and remodeler) perspective "Water is the next big issue," says Bill Christopher, Secretary/Treasurer of ILM Design and Build, Inc in Wilmington, North Carolina. "While the energy issue is sucking the air out of the room--and there is nothing really wrong with that--we should be paying just as much attention to water." Bill and his business partner, Matt Hosner, took a look at the specification for WaterSense labeled new homes and decided to do a field test of the specs on a LEED® for Homes Platinum gut rehab project, 3404 Talon Court, which they recently completed. They learned three things:

  1. They were already including most elements of the WaterSense new homes specification.
  2. The WaterSense criteria they were not already implementing were good ideas without a huge price tag. "A lot of this has to do with our commitment to USGBC's LEED for Homes," says Bill. "There is a pretty good fit between the two."
  3. According to EPA, gut rehabs can qualify as WaterSense-labeled homes.

Bill also likes how WaterSense content and marketing approaches are a lot like the Department of Energy and EPA's ENERGY STAR® for New Homes. "WaterSense has the same flavor as ENERGY STAR. I hope that it develops the same kind of muscle; it sure deserves it." ILM Design and Build's first WaterSense labeled new home will be the Ferguson residence, a 2700 square foot home on a half acre lot at Lauralis Bluff, scheduled to break ground sometime in June. [NOTE: we will be spending more time on ILM's approach to WaterSense--from toilet selection to their rainwater harvesting--in future blogs; stay tuned.] A production homebuilder perspective The first national production builder in the country to sign on to EPA's WaterSense program in a commitment to build WaterSense labeled new homes is KB Home based out of Los Angeles, California. Craig LeMessurier, Director of Corporate Communications for KB Home, explains why KB Home made this move. "There are really two reasons we moved quickly to join WaterSense. First, our customer surveys show buyers want to reduce their carbon footprint AND their operating expenses. Second, our biggest competition is resale of existing homes; WaterSense is a huge differentiator for our company in the marketplace. It builds nicely on our 2009 commitment to build all of our homes to ENERGY STAR." KB Home has spent the last several months prepping for WaterSense. "We have already set up several mock inspections and our WaterSense service providers gave valuable feedback that will help us align our homes to the WaterSense for New Homes program; but they all went smoothly." LeMessurier feels that KB Home's Built to Order? approach and My Home. My Earth.? Program make the move to WaterSense easier for his company and his customers. LeMessurier went on to say that finding a single provider for one-point coordination of quality assurance across several programs in all of their markets may be an issue. When I asked LeMessurier how KB Home will get started on WaterSense, he replied, "KB Home plans to pilot this program in several markets with some WaterSense communities opening mid to late summer." We will be checking back with KB Home during the course of the summer. In the meantime, it seems as though WaterSense labeled new homes are a wave that any builder ought to catch.

2010-06-01 n/a 9186 Pearl's Premium: An Environmentally Friendly Lawn Seed We dump a huge amount of water, chemicals, and money on lawns in America, and we spew lots of pollution into the air mowing them. There are some better options. One is to eliminate lawns. The other is to plant a lawn seed mix that doesn't need to be kept on life-support. Pearl's Premium lawn seed, developed by environmental activist Jackson Madnick with help of soil scientists, offers northern-climate landowners a much greener (!) option.

Pearl's Premium, named after Madnick's mother and his daughter, is available in two different mixes: a shady-site version, which is appropriate for lawns fully in the shade to 50% sun; and a sunny mix for sites with 50% sun to full sun. The shady mix consists of five different fescues (fescue is a type of grass), three of which are native and two "adaptive," to use Madnick's term. The sunny mix contains three of the fescues in the shady mix, plus a special deep-rooted adaptive bluegrass and an adaptive ryegrass.

There are four important benefits of Pearl's Premium turf compared with conventional Kentucky bluegrass turf:

1. Drought tolerant

Pearl's Premium is highly drought tolerant. The grasses establish much deeper roots than conventional turfgrass. While the roots of Kentucky bluegrass and the other grasses used in conventional turf mixes rarely extend more than two or three inches deep, the fescues and other grasses in Madnick's mixes extend down about 12 inches, where they can usually find enough moisture to eliminate the need for watering.

2. No need for chemicals

Consting of native and adaptive grasses, Pearl's Premium does not require fertilizers and other chemicals. In fact, one of Madnick's primary purposes in developing these mixes was to help detoxify our back yards. Runoff from American lawns has become a witches brew: nutrients that cause algae blooms in surface waters; herbicides that are used to kill weeds; and pesticides to kill grubs, insects, and other assorted organisms attempting to eek out a living in our lawns. Some health advocates suggest that these lawn chemicals are responsible for such problems as the surge in cancers being found in pets. It is concerns like these that have led the province of Quebec and Westchester County, New York to ban most lawn chemicals.

3. Infrequent mowing

Pearl's Premium is very slow-growing and, according to Madnick, only needs mowing once a month--instead of once a week for most lawns. By mowing less, you'll not only use less gasoline and generate less air pollution (and many lawnmowers spew out far more pollution than cars with modern pollution-control equipment), but you'll also save a lot of time. You can put that time to better use--maintaining a vegetable garden, going for walks in the woods, reading, or whatever.

4. It grows where other lawn mixes don't

While it admittedly takes some effort to get Pearl's Premium established, it has proved successful in locations where all other efforts to establish lawn have failed--beneath trees, for example. Madnick's website is full of testimonials about this, and the reviews he makes available on his website are quite positive. I'll be testing this myself and will report back!

Madnick spent years perfecting the two mixes he offers, growing hundreds of plots. He told me that sales are tripling annually and that the seed has now been used for over 4,000 lawns. More than 100 professional landscapers or landscape architects have also used it--either for their own lawns or for lawns of clients.

Madnick is quick to caution that Pearl's Premium isn't a miracle turf, and it's not perfect for every application. First of all, it's not going to grow well in the deep south; the soil  can't be too warm, or germination will be poor. He recommends it for about the northern half of the U.S. and into Canada--from about North Carolina or central California north). The seed is most commonly used in the Northeast.

Lawns produced from Pearl's Premium are also going to have a different look and feel than the bluegrass lawns most of us are used to. The grass is softer and not as robust and thick. If you want the "Chem-lawn" look, you'll probably want to stick with Kentucky bluegrass.

Pearl's Premium can be established on freshly graded soil around a new house or by mowing an existing lawn as low as possible--right down to the ground almost--and scratching up the surface with an iron rake before seeding. Ideally, the soil temperature should be in the range of 50-70 degrees Fahrenheit. The key to successful lawn establishment in the spring is to water regularly (as often as daily) for the first month as the lawn is being established. If planting in the fall, it's often possible to get by with less watering.

Pearl's Premium is fairly expensive: list price of $35.95 for a 5-pound bag of either mix, and $145.95 for a 25-pound bag. But once established, maintenance costs are low, so you should save in the long run. You can buy direct from the company's website or, in certain states, find the seed at Whole Foods stores.

Follow instructions on the company's website for how to plant and establish the seed. Given the cooler-temperature requirements for seed germination, it's getting pretty late this spring to establish a lawn (though I'm going to try!); you might want to wait until fall.

For more information:

Pearl's Premium, Inc.
Wayland, Massachusetts

I invite you to share comments on this blog. Has anyone tried out one of these mixes or another low-water, low-chemical turfgrass?

Alex Wilson is the executive editor of Environmental Building News and founder of BuildingGreen, LLC. To keep up with his latest articles and musings, you can sign up for his Twitter feeds.

Photos and graphics: Pearl's Premium, Inc.

See more on this product in the GreenSpec Guide
2010-05-28 n/a 11982 Water: The Back Seat Driver

Welcome to our new blog dedicated to the issues of water, water efficiency, and water policy.

When we talk about the environment and environmentally responsible building, it’s almost always energy that takes the spotlight, with water pretty far down the list. But it’s not hard to see just how much of a back seat driver water can be:

  • Water and sewer infrastructure costs: We don’t have any substitutes for clean water and we use a ton of it every day. Actually, more like a ton and a half; the typical U.S. household uses 400 gallons of water a day and that’s about 3,200 pounds! (Source: EPA WaterSense)
  • Impact fees: Even in areas of the country with long histories of more than 40 inches of precipitation a year, we can be just a few short years away from not enough water to support our needs. Atlanta averages more than 50 inches of rain a year but it was just a few short years ago that Atlanta was experiencing a severe prolonged drought. (Source: US Drought Monitor)
  • Water rates: In many areas of our country, the connections between water and energy are deep—in the state of California, more than one-sixth of all energy consumed is related to meeting water demands. Nationwide, about 80% of municipal water processing costs are for electricity. (Source: Center for Sustainable Systems)

And water is essential to more than just environmental quality; it is increasingly becoming a driver economically as well:

  • EPA reports that updating our water and sewer infrastructure could cost nearly $500 billion over the next 20 years. (Source: EPA)
  • In 2009, the impact fees for a water hook-up alone (not including sewer) averaged $3,582 in Florida; $5,792 in Virginia; $6,879 in Colorado. And forget about beautiful Oro Valley in Arizona—hook-up fees for new homes there are a whopping $27,381 per lot. (Source: National Impact Fee Survey: 2009)
  • In general, we have pretty low water rates, but that’s not true across-the-board. Typical monthly water bills for both Seattle and Atlanta are well over $70, and in Santa Fe are over $120. (Source: The Price of Water: A Comparison of Water Rates, Usage in 30 US Cities)

In this column, Alex and I will be covering everything from products to practice to policy. That means key information on the most advanced water-conserving toilets, how to avoid water waste with hot-water distribution, better ways to manage stormwater, and that complicated issue of water rights, particularly in the West.

Alex is the executive editor of Environmental Buildings News (EBN) and the founder of BuildingGreen. You can keep up with his various musings and articles by following him on Twitter. In 2008 for the first time ever, EBN had a special year-long focus on a particular—we addressed water. You can access his three feature articles on reducing water demand, alternative water supplies, and water conservation policies at

I’m Peter Yost—director of our residential program at BuildingGreen. Along with many years of work in the building science field, I’ve been very involved with residential water efficiency issues. And even in the fairly damp state of Vermont, I’m one of those people who takes “military showers” (turning off the flow when soaping up to save water)!

Alex and I promise to do our best to keep our reporting anything but “dry,” covering water from both the front and the back seat!

2010-05-07 n/a