Finding the Green Lining: Surviving and Thriving in an Economic Downturn

Feature

Finding the Green Lining: Surviving and Thriving in an Economic Downturn

The iconic American investor Warren Buffet once mused that it’s only when the tide goes out that you learn who’s been swimming naked. Headlines are full of companies who have been found without swimsuits, and their lack of caution is affecting all of us. With the incredible slowdown in much of the design and construction industry, will green building and its practitioners feel repercussions?

Green building was one of the darlings of the recently collapsed construction boom and has now been cast as the knight in shining armor for an otherwise gloomy industry. The evidence for that was on display at the November 2008 Greenbuild conference in Boston, which again saw an impressive increase in attendance, closing in on 28,000 people, along with another big jump in the number of trade show vendors, at a time when other construction trade shows are stagnant or losing business. We’ve taken to calling the hope around green building the “green lining” in the economic storm cloud.

The iconic American investor Warren Buffet once mused that it’s only when the tide goes out that you learn who’s been swimming naked. Headlines are full of companies who have been found without swimsuits, and their lack of caution is affecting all of us. With the incredible slowdown in much of the design and construction industry, will green building and its practitioners feel repercussions?

Green building was one of the darlings of the recently collapsed construction boom and has now been cast as the knight in shining armor for an otherwise gloomy industry. The evidence for that was on display at the November 2008 Greenbuild conference in Boston, which again saw an impressive increase in attendance, closing in on 28,000 people, along with another big jump in the number of trade show vendors, at a time when other construction trade shows are stagnant or losing business. We’ve taken to calling the hope around green building the “green lining” in the economic storm cloud.

In this article, we’ll examine the evidence for a green lining. We’ll look at what opportunities such a lining may present for architecture, engineering, and construction firms to succeed financially while maintaining or increasing the environmental benefits of their work.

Published January 2, 2009

(2009, January 2). Finding the Green Lining: Surviving and Thriving in an Economic Downturn. Retrieved from https://www.buildinggreen.com/departments/feature

Energy Dashboards: Using Real-Time Feedback to Influence Behavior

Integrated Project Delivery: A Platform for Efficient Construction

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Integrated Project Delivery: A Platform for Efficient Construction

Integrated project delivery--IPD--aligns the interests of the owner, designers, and contractors with the overall success of the project, and reduces risk for everyone involved.

Published October 29, 2008

Bringing Nature Indoors: The Myths and Realities of Plants in Buildings

Feature

Bringing Nature Indoors: The Myths and Realities of Plants in Buildings

Some proponents of indoor plants promise that they will clean the air and promote occupant health and productivity. But will they? Scientific backing for these claims is still being developed, but some of the results are promising.

Published September 25, 2008

Water Policies: Encouraging Conservation

Feature

Water Policies: Encouraging Conservation

In a state facing widespread water woes, Cambria, California, is unique. The coastal town of 6,200 people, located halfway between San Francisco and Los Angeles, gets all of its water from the groundwater basins of two relatively small creeks that are recharged annually by rainfall. Even with water conservation measures, there simply isn’t enough water to provide adequately for fire protection and other town needs.

Responding to this acute water shortage, in 2001 Cambria instituted a moratorium on water permits, blocking almost all new construction. For the few homes that are built each year, with water service that is grandfathered in or transferred from a house being razed, the developers have to offset the projected water use from those houses by as much as ten-to-one. Based on the lot size and the number of bedrooms of the planned house, a certain number of points must be earned by retrofitting existing buildings in Cambria with water conservation measures. These measures range from replacing toilets, faucets, and clothes washers to adding cisterns for rainwater catchment. Developers may choose to carry out these offsets themselves or pay a hefty fee to the town. Cambria has more severe problems than the rest of the state, but the situation is bad enough that Governor Arnold Schwarzenegger announced a statewide drought emergency in June 2008.

Droughts and water shortages are not unique to California. According to scientists, climate change will likely increase precipitation in some places while reducing it in others, particularly the West, where populations are growing fastest. Las Vegas receives just four inches (100 mm) of rain in a typical year, while the population has doubled just since 1990—with irrigated Kentucky bluegrass lawns sprawling farther and farther into the desert each year. In some areas, the annual rainfall may not drop with climate change, but storm events may become more intense, with a single storm dumping a half-year’s worth of rain, followed by prolonged drought. The combination of changing precipitation patterns and population growth could turn short-term droughts into a long-term water resource crisis.

The Southeast has been facing its share of water shortages, and the reserve capacity of water in the East is generally a lot lower than in the West because the reservoirs are shallower. In the fall of 2007, Atlanta came within a month or so of running out of water—with no real contingency plans in place. The governor of Georgia led residents in prayer for rain. The Southeast, like the West, has to face up to the reality of continuing water shortages.

We can address both short-term and long-term water shortages only by implementing wise policies. The challenges will be huge, but leading municipalities and water authorities coast to coast are using a panoply of incentives, regulations, and other policies to ensure a more sustainable supply of water.

Some experts say that water may be an even more challenging problem than energy in the coming decades, and in

EBN we’ve tackled the issue with a three-part look at water use. In “Water: Doing More With Less” (EBN

Vol. 17, No. 2), we examined demand-side solutions—water conservation. In “Alternative Water Sources: Supply-Side Solutions for Green Buildings” (EBN

Vol. 17, No. 5), we explored unconventional water sources that can be harvested in and around buildings or recovered from wastewater. This article describes policies and programs for changing our water consumption habits.

Product Standards

Arguably, the best way to reduce water consumption is to mandate that only water-efficient fixtures can be sold. The Energy Policy Act (EPAct) of 1992 generated dramatic water savings after taking effect in January 1994 by establishing maximum water use for toilets, urinals, showerheads, and faucets. Manufacturers complained that there wasn’t enough time to modify products to function well with less water, and customers complained about misting showerheads and toilets that needed double-flushing to do the job, but those problems were eventually solved, and today’s plumbing products generally perform well.

In 2007, California adopted legislation that will lower the allowable flush volume for toilets and urinals to the high-efficiency toilet (HET) and high-efficiency urinal (HEU) standards that many water utilities have been promoting (see

EBN

Vol. 16, No. 1). These new standards—which reduce the flush-volume limit from the EPAct-mandated 1.6 gallons (6.1 l) to 1.28 gallons (4.8 l) for toilets and from 1.0 gallons (3.8 l) to 0.5 gallons (1.9 l) for urinals—will be phased in starting in 2010, with full implementation by 2014. The Plumbing Manufacturers Institute (PMI), the leading plumbing industry organization in the U.S., supported this measure in California and is advancing the idea of a parallel federal standard.

Federal regulations are steadily reducing the water consumption of other products. The federal Energy Policy Act of 2005 established a limit of 1.6 gallons per minute (gpm; 6 lpm) for pre-rinse spray valves, which are used to remove food scraps from dishes in commercial kitchens. EPAct 2005 also established, for the first time, a maximum

water factor (gallons per wash cycle per cubic foot of capacity) for commercial dishwashers (setting that maximum at 9.5). No federal regulations limit the water use of residential dishwashers or clothes washers; the primary way to meet the energy requirements, however, is to reduce hot water use, so the energy standards effectively address water as well.

There are opportunities to mandate limits on water use for other products, including irrigation equipment, where advanced, reduced-evaporation spray nozzles could be required. There is also a need to

enforce the existing standards more effectively. According to Thomas Pape, an Illinois-based advisor to the nonprofit Alliance for Water Efficiency, many showerheads on the market have been independently tested and shown to exceed the federal 2.5-gpm (9.5-lpm) limit. Pape told

EBN that the U.S. Department of Energy (DOE), which oversees EPAct compliance, “has done nothing to enforce EPAct, despite water-conservation advocates providing DOE with test reports to prove the law is being violated.”

Plumbing Codes

While certain laws, principally EPAct, regulate what can be

sold, building codes and plumbing codes regulate how products must be

installed. Herein lies an opportunity to fix a loophole that has allowed a major trend in water waste with showers. While the federal limit for showerheads is 2.5 gpm (9.5 lpm), some custom bath builders and a number of manufacturers get around that limit by installing multiple showerheads in a single shower stall or selling towers that incorporate multiple showerheads and body-spray nozzles. Kohler’s WaterHaven custom shower tower, for example, can deliver more than 10 gpm (38 lpm).

“The solution is in the code,” says Pape, who has been lobbying for a modification to the Uniform Plumbing Code (UPC). He has proposed a twofold strategy: first, limit the flow of shower stalls to 2.5 gpm (9.5 lpm) per 2,500 square inches (17.4 ft2, or 1.6 m2) of stall area; and, second, for larger shower stalls require a separate control valve for every showerhead, with those valves separated by at least three feet (1 m). Pape is hoping to get this change incorporated into the 2009 revision to the UPC, published by the International Association of Plumbing and Mechanical Officials (IAPMO), but he told EBN that he faces an uphill battle. The measure was initially recommended for approval by the UPC Technical Committee in May 2008, but a month later the Plumbing Manufacturers Institute successfully lobbied a few committee members to change their votes, nullifying the original recommendation. The Alliance for Water Efficiency plans to reintroduce the proposed amendment to the IAPMO General Assembly in October.

In the meantime, however, a number of municipalities have enacted local code modifications based on Pape’s proposal that will take effect in 2009. “When the model codes do not address the needs of jurisdictions,” Pape told

EBN, “the jurisdictions are compelled to write their own codes, and the plumbing industry is not likely to be pleased with the results.” California recently adopted voluntary green building standards that (though not based on Pape’s proposal) prohibit multiple showerheads in a single stall (see

EBN

Vol. 17, No. 9).

Codes can also affect water conservation in other ways. They can allow (or prohibit) waterless urinals. They address water-supply piping; currently codes establish only

minimum, not maximum, diameters, and larger-diameter pipes increase waste as users wait for hot water. They also have a major impact on the ability to use graywater (usually defined as wastewater from showers, bathtubs, bathroom faucets, and clothes washers). Most graywater codes require expensive and burdensome subsurface delivery of collected graywater, notes Pape, while other options, such as allowing delivery through shallow trenches covered with mulch, would be both less expensive and more effective.

Labeling Programs

The U.S. Environmental Protection Agency (EPA) launched its Water-Sense program in 2006 to do for water what Energy Star has done for energy (see

EBN

Vol. 15, No. 7). To date, toilets, lavatory faucets, irrigation controls, landscape irrigation services, and entire new homes can carry WaterSense labels, and additional product categories, including showerheads and urinals, will be added in the future.

The U.S. Green Building Council's LEED Rating System includes provisions for water savings, and the LEED 2009 revisions will raise its bar for water savings. The current draft of LEED 2009 includes a prerequisite of reducing projected water use by 20% compared with that of a building with standard plumbing fixtures, plus two points for achieving 30% savings and another two points for achieving 40% savings. The proposed LEED 2009 also awards two points for a 50% reduction in irrigation and another two points for eliminating potable water use for irrigation. Overall, 10 out of the 100 points (10%) in the proposed LEED 2009 relate to water, while only 5 out of a possible 69 points (7%) relate to water in LEED version 2.2; a project may earn additional points for addressing regional priorities, such as water conservation, and others for innovation.

Financial Incentives

The pocketbook has a powerful influence on decisions—including those related to water use.

Tiered or volumetric pricing

One of the most effective strategies for encouraging water conservation is to implement tiered or volumetric pricing structures—charging a low rate for the first several thousand gallons of monthly water use, then significantly increasing the price for higher-usage increments. Many cities and water utilities have adopted such programs. Residential water rates for Austin, Texas, for example, vary more than eightfold between the lowest and highest rates. Austin’s wastewater fees are also tiered, jumping more than twofold between the lower and higher rates.

While progressive municipalities are implementing this sort of tiered pricing structure, many still use pricing policies with the opposite effect—charging more for lower water use and less for greater use. Eliminating this type of pricing is a high priority.

Some municipalities establish a

water budget for each home or business and use that as the base rate to establish different usage categories. The approach is a form of tiered pricing, described above, but the tiers are based on usage levels that can vary from customer to customer. The water budget is set based on such factors as number of bedrooms, irrigable area, and historical water use. A downside of such an approach is that it essentially penalizes customers who have already been practicing water-efficient lifestyles and rewards those who have been more wasteful.

Boulder, Colorado, has five tiers of water use—referred to as Blocks 1 through 5—that are all based on the water budget or base rate (see table). As in Austin, the tiered pricing in Boulder is incremental. By offering a block below the base rate, the city offers a discounted rate to customers who use very little water.

Customers are more responsive if water consumption is reported and billed in gallons rather than cubic feet, as most people relate better to gallons than they do to cubic feet. We are also more likely to save water if we are billed monthly, as opposed to quarterly or annually, so we can see and respond more immediately to variations in water use.

Cash for grass

Some jurisdictions encourage customers to save water by giving away replacement fixtures, or providing rebates on replacement fixtures that reduce water use. The Southern Nevada Water Authority (SNWA), which serves Las Vegas and the surrounding region, has probably gone the furthest with direct payments. SNWA’s Water Smart Landscapes program pays customers to replace turf with xeriscaping. The current payment is $1.50 per ft2 ($16.15/m2), with no cap on the area—meaning that some homeowners can earn tens of thousands of dollars through such conversions.

According to Doug Bennett, who manages the water conservation programs at SNWA, each square foot of lawn conversion saves 56 gallons per year (2,300 l/m2/year). Since the program began in 1999, SNWA has spent over $110 million on more than 30,000 conversion projects, paying for the removal of nearly four square miles (1,000 ha) of irrigated turf. The water authority can afford to spend so much money on water conservation because the cost of ensuring supply to support the growth that the Las Vegas region is experiencing is even greater.

Product giveaways

Some municipalities save water by giving away water-efficient toilets, showerheads, and other products. San Antonio, Texas, currently provides up to two free high-efficiency toilets (HETs) per household as long as the house was built prior to 1992 and the toilet or toilets being replaced use more than 1.6 gpf (6 lpf).

Rebates

More common than giveaways are

rebates or

coupons for the purchase of water-conserving products. In many areas facing water shortages, municipalities and water utilities offer generous programs to provide a range of products. In the mid-1990s, New York City provided cash rebates for 1.3 million toilets, reducing water consumption in the city by 80–90 million gallons (300–340 million l) per day, or about 20%.

The Metropolitan Water District of Southern California, a consortium of 26 cities and water districts that provide water to 18 million people, currently offers residential rebates on HETs, clothes washers with a water factor of 5.0 or lower, timers and water-efficient nozzles for irrigation systems, and artificial turf. For commercial customers, 15 different products qualify for rebates, according to Bill McDonnell, a senior resource specialist with the agency; these products include various plumbing fixtures, cooling-tower conductivity controllers, pre-rinse spray valves and other commercial kitchen products, recirculating x-ray film processing systems, artificial turf, and irrigation equipment.

The Southern Nevada Water Authority provides rebates on pool covers (because they reduce evaporation), and San Antonio offers rebates on on-demand hot-water circulators (see

EBN

Vol. 12, No. 5) and air-cooled ice makers.

Regulations and Permits

Regulations, ordinances, and permitting policies can significantly reduce water use.

Restrictions on development

A law passed in California in 2001 requires water utilities to evaluate any proposed project for water demand. A second law requires developers of large subdivisions (over 500 residences) to demonstrate that there is a 20-year supply of water before water authorities grant approvals. To demonstrate sustainable supply, developers must look at historical water availability in dry years as well as projected demand for their projects. According to Dave Todd, land and water use program manager for the state of California, the measure has slowed development in some cases. “I think that development has gone forward, but there have been a number of cases where projects were halted for a period of time pending the water supply assessment,” he said.

In Columbia, South Carolina, water authorities have limited new water service connections due to the tight water supply. Mayor Bob Coble announced in June 2008 that new water taps would be capped at 1,700 during the subsequent 12-month period.

More commonly, utilities or local governments assess impact fees on new developments based on the cost of providing the new buildings with services, including water and sewer connections. Such fees are usually calculated based on the cost of infrastructure, not the cost of supplying or treating water. According to Tim Fisher, assistant director of water utilities in Denton, Texas, “There’s a more or less complete disconnect between impact fees and water conservation.”

Douglas Frost, principal planner with the Phoenix Water Services Department, notes that while infrastructure costs are more or less fixed, the cost of water can balloon when easily accessible sources are exhausted. To address this problem, developments in the Phoenix area incur water resource acquisition fees on top of impact fees; these acquisition fees run from $1,200 to $1,300 per unit, but Frost believes they could rise as high as $5,000 per unit. However, developers can receive credits against the fees for incorporating conservation measures.

Product bans

Amy Vickers, president of Amy Vickers & Associates, a Massachusetts-based consulting firm specializing in water conservation, suggests that we will not only have to alter our landscaping practices to use more climate-appropriate native plants but also ban certain outdoor water features, such as fountains. “It’s something we’re going to have to start regulating,” she told

EBN. Some argue that conventional, water-intensive lawns should be banned in areas receiving less than 10–15 inches (250–380 mm) of rain per year, or that irrigating those lawns with potable water should be prohibited.

Pape puts our water use for landscaping into a broader perspective. “Water professionals from all over the world are aghast to learn we still waste our treated drinking water to irrigate our landscapes,” he told

EBN.

Some experts also argue for bans on certain commercial kitchen appliances and industrial equipment, such as once-through steamers that use cold running water to cool the condensate, water-cooled ice-makers, and water-cooled vacuum pumps.

Water-demand offsets

One of the more creative strategies to reduce water use is to require

water-demand offsets with new development. As a condition of permitting a new house or subdivision, the permitting agency may require that the developer offset the project’s expected water use (or more) as a condition of the permit. About a dozen communities, mostly in California, currently require demand offsets as a condition of permitting. Some of these offsets target agricultural water savings—often the lowest-hanging fruit; others focus on savings in and around urban and suburban buildings.

One of those communities is the East Bay Municipal Utility District (East Bay MUD) in Oakland, California, and the surrounding area. East Bay MUD has required either a one-to-one or a two-to-one offset from the largest residential developments during the last several years; these are negotiated on a project-by-project basis. To permit the recent 1,400-unit Alamo Creek subdivision in Danville, the developer Shapell Homes not only had to implement onsite water conservation measures but also had to pay $6,000 per unit to offset twice the expected water demand, according to Richard Harris, the manager of water conservation programs at East Bay MUD. The funds will be used to pay for urban retrofit projects—such as plumbing fixture replacements, submetering, installation of graywater systems, and creating water budgets—in the East Bay MUD territory. As noted earlier, Cambria, California, has an even more aggressive demand-offset program.

While demand-offset programs are rare, and most are in California, they are not limited to the Golden State. Weymouth, Massachusetts, for example, requires any new water-use applicants to offset water use in existing buildings at a two-to-one ratio.

Retrofit-on-resale ordinances

Another important—yet controversial—tool for conserving water is the

retrofit-on-resale ordinance. Under this provision, which has been strongly opposed by real-estate organizations wherever it has been proposed, either the seller or the buyer of a building is required to replace inefficient plumbing fixtures—usually toilets, urinals, showerheads, and faucets—with efficient models at the time of resale. Such ordinances have been in place in a handful of California communities as far back as 1992, when San Luis Obispo implemented its program. At least seven other California cities and water districts—including San Diego, Los Angeles, and San Francisco—have retrofit-on-resale ordinances. Most of them require only that replacement fixtures comply with current federal water-efficiency standards, though the North Marin Water District requires that retrofit showerheads and lavatory faucets exceed the federal standards—mandating 2.0 and 1.5 gpm (7.6 and 5.7 l), respectively.

In February 2008, DeKalb County, Georgia, which includes a portion of Atlanta, became one of the first places outside California to adopt such a program—in this case a

retrofit-on-reconnect ordinance. The law applies only to unincorporated parts of the county. The ordinance applies to houses and commercial buildings built before 1993. Bowing to pressure from the real-estate community, DeKalb placed the responsibility for replacing fixtures on purchasers, not sellers. Certain exemptions apply, including buildings that will be demolished and historic buildings.

Emergency ordinances

Special ordinances and regulations that restrict certain water uses during drought emergencies are becoming more common as populations grow and droughts increase in frequency and severity. The most common restrictions apply to watering lawns, washing cars, power washing driveways, and filling pools and outdoor water features, such as fountains. Other measures have included prohibiting restaurants from serving drinking water and hotels from replacing towels and linens unless requested. In Cambria, California, as well as most of the above restrictions, leaks in plumbing must be repaired within eight hours of their discovery.

Metering and Submetering

Requiring metering for water use—and submetering for multifamily and institutional buildings—is another important regulatory approach to reduce water use. As with energy, it’s hard to conserve what we aren’t measuring. The Alliance for Water Efficiency recommends metering all new connections, retrofitting meters onto existing unmetered connections, and submetering all new multifamily and institutional buildings. Separate meters for irrigation use are also recommended, at least for commercial buildings. Not only do meters provide direct feedback to customers about their water use, but they can identify unusual spikes in water use, which are often due to leaks.

In the early 1980s, New York City was one of the few large municipalities that did not meter the water use of most residential buildings. Water fees were levied based on the street frontage of buildings, so there was no incentive to conserve. Metering began in earnest in 1985 and, although data about the effect on water use is scarce, a 15%–17% drop in consumption was observed in some parts of the city. In 2008, the city embarked on a $68-million program to install wireless transmitters on the city’s 875,000 water meters, which serve 8 million residents. This technology, known as advanced metering infrastructure (AMI) or automatic meter reading (AMR), will result in more accurate billing, allow customers to track their water use online, and even notify customers by email of possible leaks. Both Philadelphia and Washington, D.C., already have such technology in place.

A New Era

More and more experts believe that parts of the U.S., like many other regions of the world, will face water crises in the coming decades. “We no longer live in an era of cheap and plentiful water,” says Pape. These shortages will force us to use far less water than we currently do, and achieving those savings will require a wide range of regulations, codes, pricing mechanisms, and incentives. Some of these programs won’t be popular, but they will be necessary. Existing programs in places like San Antonio, Austin, Las Vegas, San Luis Obispo, and Seattle will serve as models for towns and cities across the country.

For more information:

Alliance for Water Efficiency

www.allianceforwaterefficiency.org

EPA WaterSense Program

www.epa.gov/watersense/

Published August 28, 2008

Ductless Mini-Splits and Their Kin: The Revolution in Variable-Refrigerant-Flow Air Conditioning

Counting Carbon: Understanding Carbon Footprints of Buildings

Feature

Counting Carbon: Understanding Carbon Footprints of Buildings

Everyone seems to be talking about measuring carbon footprints and designing carbon-neutral buildings, but these terms mean different things to different people. Some focus just on operating energy, while others also look at transportation, materials, and other building-related emissions. As with so many things, the results depend on what you count and how you count it.

Published June 27, 2008

Making Air Barriers that Work: Why and How to Tighten Up Buildings

Alternative Water Sources: Supply-Side Solutions for Green Buildings

Feature

Alternative Water Sources: Supply-Side Solutions for Green Buildings

Water efficiency should be a top priority for our buildings. At the same time, finding alternative sources of water is also important for sustainability and passive survivability. Several sources of water can be harvested at the building level as well as through municipal-scale wastewater treatment and desalination.

The severe 2007 drought throughout the southeast U.S. was a wake-up call. This drought taught us that even areas of the country we have long assumed to have plenty of water are not immune from water shortages, and it showed us how woefully inadequately prepared we were—and still are— to respond to severe drought.

Changing precipitation patterns, including increased drought in some parts of the country, are predicted with global climate change. Yet even without the wild card of climate change, unsustainable groundwater extractions for burgeoning populations in the western U.S. and throughout the world have become front-page news.

While using water more efficiently should remain the top priority, we also need to take a look at alternative sources of water, including those we can harvest at the building level. Providing alternative water supplies in buildings can also help achieve resilience—maintaining livable conditions when electricity, heating fuel, or municipal water are lost for extended periods of time. This article examines the spectrum of unconventional water sources that can be used in and around buildings.

Potable versus Nonpotable Uses

In identifying alternative sources of water, the first consideration is what those sources will be used for. Potable water, which we can use for drinking, cooking, and bathing, among other uses, must meet a high level of purity and safety. Nonpotable water is less pure but, when handled properly, it can be fine for landscape irrigation, makeup water for cooling towers, and toilet flushing. Many alternative water sources are best suited to nonpotable uses, though some can be made potable with additional treatment.

If we can provide separate plumbing in and around buildings for potable and nonpotable water, it opens up significant new options for water supply. Installing separate supply piping for landscape irrigation and cooling-tower makeup water is fairly easy, while installing separate nonpotable supply plumbing for toilet flushing, which requires dual piping throughout a building, is more difficult.

Scale of Delivery

Described in this article and summarized in the table are the most prevalent alternative water sources for use in and around buildings. Scale of delivery can dictate what solutions to focus on. Graywater, for example, is typically dealt with only on an individual-building scale. With rainwater collection or air-conditioner condensate, it may be possible to aggregate water from several roofs in a university or office campus and use common storage, improving the economic viability of such systems. Using reclaimed water (treated wastewater) and desalination water is usually viable only when a municipality supplies that water.

Graywater Collection and Reuse

As the term is most commonly used, graywater refers to wastewater from clothes washers, showers, bathtubs, and lavatory faucets—and not water from toilets, kitchen sinks, and dishwashers. Graywater is collected with separate drain lines (requiring a building to be dual-plumbed for graywater and other wastewater drainage), filtered to remove large particles, and stored until use for landscape irrigation—usually below ground.

Because graywater generally contains organic matter (such as hair, textile fibers, and skin cells), it should not be stored for long. Bacteria in the water quickly break down this organic matter, using up dissolved oxygen in the process (chemists refer to organic matter in water as biochemical oxygen demand or BOD). Once the oxygen is depleted, different bacteria take over and the decomposition becomes anaerobic, which can produce smelly methane and hydrogen sulfide gas. For this reason, most graywater systems quickly deliver water to irrigation piping. If a system stores graywater, it is usually to allow just enough to build up that it can be discharged in larger doses that fill the irrigation pipes and provide even distribution.

Water conservation expert John Koeller, P.E., predicts that graywater will be “the next major breakthrough” in the field of water savings. He expects to see significant developments of both whole-building systems and units that are tied directly to lavatory sinks or clothes washers.

Several whole-building graywater systems are available. These systems necessitate reconfiguring drainage piping, so are less expensive when installed in new construction than when retrofit for existing buildings.

In addition to these whole-house or whole-building graywater systems, there are products that capture wastewater from an individual lavatory sink or clothes washer. Some can store it in an under-counter tank to flush an adjacent toilet.

The biggest challenges facing graywater today are regulatory. Most states do not permit separate collection and use of graywater, though severe droughts have helped to ease those restrictions in some regions. California, Arizona, New Mexico, Nevada, Utah, Texas, and Montana all have statewide regulations permitting graywater use, though in some cases local regulations can supersede statewide rules. These regulations primarily address use of graywater for landscape irrigation, and they have important differences. California permits only subsurface irrigation, for example, and vegetable crops are specifically excluded in most states that allow the use of graywater. Arizona’s law is tiered, with different standards and levels of review required depending on the daily flow. Some localities have adopted regulation that allows graywater to be used, but only for toilet flushing—and only after it has been filtered, disinfected, and dyed blue or green to distinguish it from potable water. Key aspects of a sampling of the country’s graywater regulations are described in the table above.

Rainwater Harvesting

A few places in North America rely almost totally on harvested rainwater. In the town of Volcano, Hawaii, near Hilo, the rock is so porous that wells would have to be thousands of feet deep to reach freshwater. It’s far less expensive to simply capture and store the abundant rainfall. The vast majority of homes and businesses there rely on harvested rainwater for all of their water needs—potable and nonpotable—storing the collected water in large, covered, above-ground cisterns (usually swimming pools adapted for this purpose).

Rainwater harvesting is also common as a sole residential water source on the island of St. John in the Caribbean, and it is fairly widely used in parts of Texas, Kentucky, Ohio, and the Pacific Northwest—especially in locations where the groundwater is brackish, very hard, or in limited supply. “There are pockets around the country,” says Hari Krishna, Ph.D., of the Texas Water Development Board in Austin and founder of the American Rainwater Catchment Systems Association. Less sophisticated rain-barrel systems for irrigating gardens and lawns are common in the Pacific Northwest and seen occasionally in the rest of the country. Krishna estimates that there are about 10,000 rainwater-harvesting systems in Texas, including about 1,000 that serve as the sole water source for a home.

Rain barrels are very simple—most often a covered container connected to the downspout beneath the eaves of a house, with an overflow and a spigot attached to a hose. Whole-house and commercial rainwater-harvesting systems are significantly more involved (see EBN Vol. 6, No. 5).

Components include:

  • a smooth roof surface that neither leaches chemicals into the water nor traps organic matter that could contaminate harvested water;
  • a first-flush system to divert the first rain that falls during a storm, carrying off accumulated particulate matter;
  • a coarse filter to keep out leaves and other detritus;
  • a cistern large enough to serve expected water needs (almost always the most expensive component); and
  • for potable water systems, a treatment system to purify at least the water used for drinking and cooking.

According to Krishna, ultraviolet (UV) light is the most common treatment for potable rainwater systems. With proper first-flush systems, filtration, and UV treatment, Krishna says chemical treatment should be unnecessary, especially since rainwater starts out so clean (assuming there are no severe local sources of air pollution). “Rainwater is one of the purest sources of water that exists in the world,” he says, noting that rainwater’s low mineral content makes water softening unnecessary (see EBN Vol. 15, No. 4, for more on water treatment).

Most rainwater harvesting systems are made up of components that were intended for other purposes, but that may be changing. Several Australian companies, including BlueScope Water, are entering the North American market. BlueScope and its companion company, Pioneer Tanks, offer rectangular storage tanks that fit into walls or under the floor. With harvested rainwater proving increasingly attractive for cooling-tower makeup water in commercial buildings and for landscape irrigation, we can expect to see specialized components designed for commercial buildings as well. “The market is growing,” Krishna told EBN. While some experts suggest that a minimum of 20"–24" (500–600 mm) of rainfall is required annually for harvested rainwater to serve whole-house needs, Krishna says that in areas in Texas receiving as little as 15" (380 mm) of rainfall per year, there are homes that have relied on 100% rainwater for years.

Landscape-Scale Stormwater Harvesting

Stormwater is nearly always managed in the landscape surrounding a building, and it is commonly channeled into retention ponds. Occasionally, such retention ponds are designed so that water from them can be pumped out for nonpotable uses in and around a building. At the Heifer International headquarters building in Little Rock, Arkansas, completed in 2006, stormwater from parking areas is captured in a large retention pond, from which water is drawn off for landscape irrigation and an innovative cooling system for parts of the 94,000-ft2 (8,700-m2), five-story building.

Air-Conditioner Condensate

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.

 

In large commercial buildings, condensate recovery often produces enough water to supply all of the landscape irrigation needs or a significant portion of makeup water for cooling towers. In San Antonio, Texas, with its high temperatures and high humidity, condensate recovery is an easy choice. “When you take the humidity out of the air, that condensate water is a huge volume in a large building,” says Karen Guz, director of the Conservation Department for the San Antonio Water System. In the ASHRAE Journal, Guz reported that the San Antonio Public Library is producing a gallon of condensate per minute, or over 1,400 gallons (5,300 l) per day, which is used for irrigation. The downtown Rivercenter Mall produces 250 gallons (950 l) of condensate per day, which is used to replenish cooling-tower losses—this condensate recovery system paid for itself in less than six months, according to Guz.

If condensate is being used only for cooling-tower makeup, the condensate can often be fed directly into the cooling tower without storage—because condensate produced in a building will never exceed the evaporative losses from the cooling tower. This can reduce costs significantly, according to Guz. Using condensate as a source of irrigation water is more expensive, as it requires storage and a system to pressurize the water.

In San Antonio, it is becoming more common to combine rainwater harvesting and condensate recovery for use in irrigation—the city refers to this as rainwater plus. “The combination is great,” Guz told BuildingGreen. “Our rainfall patterns are so erratic that a rainwater system by itself must have an enormous, expensive tank in order to go through the long periods we can go without rain.” Because the production of condensate is fairly steady, and increases as the weather gets hotter, smaller storage tanks are sufficient.

Air-conditioning condensate recovery is most practical in climates with high cooling-season humidity. Along with the obvious places like Houston, San Antonio, Atlanta, and Miami, it also makes sense in cities like Philadelphia, Chicago, and New York, which experience high humidity that coincides with the greatest cooling loads. Condensate recovery is especially attractive in facilities like shopping centers, where there is a high degree of air exchange.

The quantity of condensate water produced depends on the temperature and humidity conditions (both outdoors and indoors) and the amount of cooling being provided. Guz has developed a rule of thumb for large buildings in the summer months of 0.1 to 0.3 gallons (0.4–1.1 l) of condensate per ton of air conditioning for every hour that the cooling system operates. In the San Antonio climate during peak summertime months, this translates into roughly 0.5–0.6 gallons per hour for every 1,000 ft2 of cooled area (20–24 l/hr per 1,000 m2).

While air-conditioner condensate is inherently pure—it is essentially distilled water—there is potential for contamination, especially if it sits in a warm environment. For this reason, chlorine is usually used to treat condensate. San Antonio hasn’t experienced problems with the moderate chlorine concentrations in its irrigation water, according to Guz, but chlorine could harm some plants.

Cooling-Tower Blowdown

A lot of water is lost from cooling towers through evaporation and drift losses. Water is also intentionally drawn off—a process referred to as blow- down—because minerals and other contaminants become more concentrated as a result of evaporation. Typically, the blowdown water is drained into sewer lines, but it can be collected and reused for applications where the salinity or mineral content is acceptable.

Water conservation expert Bill Hoffman, P.E., of Austin, Texas, suggests that if blowdown water is being reused, the “cycles of concentration” (a measure of how concentrated the minerals become due to evaporation) shouldn’t exceed two or three. The building housing the San Antonio Water System, however, has been using blowdown water for eight years, according to Guz, and “during the past two years the cooling-tower operations have been documented at no less than four cycles of concentration with no ill effects on the plants (though there may be additional dilution from groundwater that is also captured in French drains).”

It is also possible to treat the water in cooling towers to remove minerals—for example by chemical precipitation or by using reverse osmosis (see discussion of desalination below)—but this is costly and rarely practiced.

While air-conditioner condensate is inherently pure (at least when first produced), that is not the case with blowdown water. Along with concentrating minerals, cooling towers also concentrate bacteria and other contaminants, including Legionnella (a bacteria that causes potentially fatal Legionnaires’ disease). If blowdown water is used for irrigation, treatment is essential.

Building-Scale Treated Wastewater

While it is relativley uncommon, an increasing number of large buildings are treating their wastewater onsite and producing nonpotable water for landscape irrigation and toilet flushing. The Solaire in New York City was one of the first examples of this approach. An advanced, multistep, biological treatment and micro-filtration process treats 100% of the wastewater produced in the 28-story, 293-unit, LEED Gold apartment building. The treated wastewater is used for all the toilets in the building, the building’s cooling tower, and all landscape irrigation requirements, including 5,000 gallons per day (19,000 l/d) for an adjacent part. Potable water use in the Solaire was reduced by 50%.

Similarly, the Audubon Center at Debs Park in Los Angeles treats 100% of its wastewater onsite—and, in fact, has no connection to the municipal sewer. This treatment system consists of a hybrid anaerobic/aerobic treatment and filtration process and a peracetic acid and UV advanced oxidation disinfection process. This treated wastewater will be used for toilet flushing. Overall, this building has achieved a 70% reduction in potable water use.

Ecological wastewater treatment provides another option for more comprehensive onsite treatment of both graywater and blackwater.

Municipal-Scale Treated Wastewater

The first U.S. municipality to distribute treated wastewater through separate piping was Grand Canyon Village, Arizona, beginning in 1926. Freshwater had to be trucked in, so wastewater was too valuable to discard. The town’s small system reclaimed and treated wastewater for use in landscape irrigation and toilet flushing. Similarly, in 1942, Sparrows Point, Maryland (near Baltimore), built a 4.5-mile (7.2-km) pipeline to supply treated wastewater to the Bethlehem Steel factory for process use and cooling.

The first large-scale, municipal reclaimed water system began operation in 1977 in St. Petersburg, Florida. By 2008, the city was delivering 21 million gallons (80 million l) per day to 4 cemeteries, 7 golf courses, 64 schools, 92 parks and recreation facilities, 339 businesses, 135 multifamily housing projects, and 10,200 single-family homes. This reclaimed water, supplied by 299 miles (481 km) of pipe, is used primarily for landscape irrigation, though some commercial customers use the water for industrial processes and cooling towers. The city uses about two-thirds of all available treated effluent each year, according to Patricia Anderson, the water resources director for the City of St. Petersburg.

Irrigation remains the largest use of reclaimed water in the U.S., according to James Crook, Ph.D., P.E., a water reuse expert in Boston. The earliest systems provided mostly agricultural water, but urban irrigation for parks, playgrounds, and lawns has been growing rapidly. Cooling is the next major use—for power plants, industrial processes, and makeup water for cooling towers. Use for toilet and urinal flushing in commercial buildings is less common but quickly gaining popularity, especially in the green building community. In many places where reclaimed water is used, its piping is painted purple to distinguish it as nonpotable.

Some regions of California now mandate that commercial buildings be dual-plumbed so that they can use reclaimed water (referred to as “recycled water” in California) for toilet and urinal flushing. In the Irvine Ranch Water District south of Los Angeles, for example, all buildings seven stories or taller are required to include dual plumbing for reclaimed water use.

With reclaimed water use, the question often comes up as to whether this water can be deemed suitable for potable uses—so-called “direct potable water reuse” or pipe-to-pipe reuse. Some experts think that cities in the U.S. will eventually accept direct potable water reuse, though public resistance is strong. Denver and San Diego have studied the idea, according to Crook, but an effort to permit potable reuse in San Diego was defeated several years ago. Crook believes that we won’t get direct potable water reuse until water-quality monitoring improves to the point that safety problems can be identified almost immediately.

But some suggest that direct potable water reuse isn’t that different from what we’re doing today. “Proponents say, ‘Hey, we’re doing it now,’” says Crook. Many of our rivers are dotted with cities and towns, each with drinking water intakes and sewage treatment plant outlets along the river. The Colorado River, which provides drinking water for San Diego, Los Angeles, Phoenix, Las Vegas, and many other municipalities, has more than 450 wastewater discharge permits along its course. The U.S. Environmental Protection Agency (EPA) refers to this as “surface water augmentation for indirect potable reuse.”

Indirect potable water reuse can also occur through aquifer storage. A large indirect potable water reuse system is used in Orange County, California. Each day 70 million gallons (260 million l) of highly treated wastewater are injected into an underground aquifer, from which drinking water is withdrawn for 2.3 million Californians in 20 cities. In EPA parlance, this is “groundwater recharge for indirect potable reuse,” and, because there is dilution as well as physical separation of wastewater delivery and drinking-water withdraw, it is more acceptable to the public than direct potable water reuse.

Of concern with either direct or indirect potable water reuse is the prevalence of pharmaceutical and illicit drugs in the wastewater. Studies have shown that wastewater treatment plants do not effectively remove these pollutants, so they would be found in reused water. This is indeed a concern with potable water reuse, but it is also a concern with conventional public water supplies—from both surface water and groundwater sources. Pharmaceuticals are entering our aquifers as well as our rivers, creating a problem with no simple solutions.

Desalination

Desalination is the process of removing salts (and other impurities) from seawater or brackish water. Ninety-seven percent of the world’s water is saline, so tapping this resource as a freshwater source has long been attractive. While there are a few systems in the world that use seawater directly for toilet flushing and certain other nonpotable uses (see sidebar), the highly corrosive nature of seawater makes this impractical; desalination is required for widespread use of seawater.

Interest in desalination emerged at least as far back as the 1700s. As secretary of state, Thomas Jefferson considered a plan in 1790 to install desalination systems on ships, and a British patent was issued in 1852 for a desalination device. The first desalination plant on land was built on the island of Curaçao in the Netherlands Antilles in 1928. Saudi Arabia built its first plant in 1938.

Worldwide desalination capacity gradually grew from almost nothing in 1960 to about 9.5 billion gallons (36 million m3) per day in 2005, according to the Pacific Institute, a California-based think-tank focused on water issues. Half of this capacity was in the Middle East, where inexpensive energy makes the process more feasible; the U.S. is also one of the largest users of desalination.

While early desalination plants relied on evaporation and condensation, most plants rely on reverse osmosis (RO), a less energy-intensive technology using selective membranes. One of the largest desalination plants in the U.S.—run by Tampa Bay Water, Florida’s largest wholesale water supplier—produces about 25 million gallons (95 million l) per day using an RO system.

From an energy and environmental standpoint, desalination has a number of drawbacks. First, it is energy intensive, even where RO technology is used instead of evaporation. Current best practices with RO require about 12 kWh per 1,000 gallons (3.2 kWh/1,000 liters); with this energy intensity, between a third and a half of the total cost of desalination goes to energy. The figure below shows the relative energy intensities of various freshwater sources in San Diego, California. The high energy intensity of desalination in San Diego is comparable to that of Tampa Bay’s plant, which uses approximately 4,476 kWh/acre-foot (3.629 kWh/m3).

Second, along with producing freshwater, desalination also produces brine with about twice the salinity of the source water. The concentrated brine also often contains elevated levels of constituents found in seawater, such as manganese, lead, and iodine, as well as chemicals from urban and agricultural runoff. When brackish groundwater is desalinated, the resultant brine is usually deposited into evaporation ponds, reinjected into the ground through deep wells, or piped to the ocean.

When seawater is desalinated, the brine is usually piped some distance out to sea, though it may be mixed with treated wastewater or power-plant cooling water first. If it is not diluted first, the desalination brine is more dense than seawater, so it sinks, creating plumes of higher-salinity seawater on the ocean bottom—where sea life is concentrated. Few studies have been conducted to determine the risk of brine discharge into the ocean, and potential risks are significant.

Desalination is also well suited to solar-thermal power plants, according to a study by the German Aerospace Center, “Aqua-CSP: Concentrating Solar Power for Seawater Desalination.” In response to the heavy environmental impacts of conventional desalination systems, the researchers analyzed the use of concentrating solar power (CSP) to support desalination measures in urban centers throughout the Middle East and North Africa. They determined that implementing large-scale CSP desalination systems in those areas would not only avoid some environmental impacts from conventional desalination methods but would also become cost-competitive with desalination plants fueled by nonrenewable energy sources.

Final Thoughts

Future water shortages in the U.S. and internationally will necessitate reducing demand and increasing supply. The starting point, almost always, should be water conservation, but using unconventional supplies should not be overlooked. This article has introduced some of the options.

Relative to green building, the most exciting alternative sources are those that can be harvested onsite: especially rooftop rainwater, graywater, and air-conditioner condensate. Beyond these site-specific options are municipal water sources, including treated wastewater and desalinated water. Using these sources appropriately and continuing to maximize water conservation opportunities will help us stave off the water shortages looming on the horizon.

Published April 29, 2008

Energy Modeling For Sustainability

Feature

Energy Modeling For Sustainability

Published April 1, 2008