Once used only to describe algae contamination, green has become a welcome adjective in the aquatics industry.

Walk into the 6,600-square-foot natatorium at the two-year-old Health & Fitness Center at Washtenaw Community College - on the way, you'll pass a large U.S. Green Building Council plaque recognizing the building's status as a LEED Gold-certified facility - and you'll be impressed by what you won't notice. "You don't smell chlorine when you hit the doors here," says Greg Hanby, the center's executive director.

That's because the five-lane, 25-yard lap pool, whirlpools and large activity/therapy pool are sanitized with a saltwater system that produces its own chlorine - one reason why the center (which is open to the general public) is the only LEED-certified facility on the Ann Arbor, Mich., campus. Saltwater chlorine generation eliminates the need to purchase, handle and store chlorine. Instead, salt is added directly to the pool (the standard dosage is 50 pounds per 2,000 gallons), which receives chlorine that is automatically generated by electrolysis.

Hanby hears few complaints about itchy skin and eyes, and many swimmers tell him they feel faster and more buoyant in the saltwater. "There are no other commercial pools in our area that use saltwater chlorination, and we are the largest commercial pool in the state to use a saltwater system," he says. "I can tell you we have members who chose us because of our green building. I can't say definitively how many, but the pool has drawn people here. Ann Arbor is a swimming town, and swimmers talk."

"Green is the new blue," says Randy Mendioroz, a principal with Aquatic Design Group, an architecture and engineering firm in Carlsbad, Calif. "That's our latest marketing phrase. Previously, you didn't want green associated with your pool."

But recent advancements in technology - and relatively quick returns on investment - make chemical-reduction strategies and energy-saving options more appealing than they were even two or three years ago. "Equipment gets more efficient every day," Mendioroz says. "If you look at pool heaters 10 years ago, they were 75 to 80 percent thermal efficient, at the most. Now they're up to 95 percent thermal efficient."

"The green movement has matured to different extents in different segments," says Thomas Lachocki, chief executive officer of the Colorado Springs, Colo.-based National Swimming Pool Foundation. "The pool industry is very much in the curiosity stage right now. Once you have an existing facility, making infrastructure changes costs money. People aren't going to go buy a heat exchanger tomorrow because they learned about one today. But they can say, 'That's something we need to be budgeting for, exploring and discussing with different vendors.' And next year's budget cycle might reflect that."

In virtually any aquatics operation, energy consumption is the primary expense. "You're trying to attack the heat; that's the big target," Mendioroz says, explaining that the majority of costs associated with maintaining pool water come from natural gas, followed by electricity. "So anything you can do to reduce the costs of heating the pool is smart."

Some of those things - the use of high-efficiency pool heaters and pump systems, for example, and automated filtration systems - have been championed for years as part of good pool design. But many pool operators still are not taking advantage of even the simplest options available to help them conserve both cash and energy.

Consider thermal blankets. Concerns about the labor involved with covering pools every night and then uncovering them the next morning keep some facility owners from realizing up to a 40 percent savings in natural gas costs for an outdoor pool. With a low price per square foot - well-insulated blankets for a standard 25-yard-by-50-meter pool can be had for $30,000 - thermal blankets can pay for themselves in less than 12 months, and probably closer to six. For indoor pools, the cost savings aren't quite as dramatic, but the use of thermal blankets still helps trap moisture - preventing it from escaping and thus giving the building's mechanicals a break from working as hard when the facility is not in use.

One item that facility operators invariably specify on new construction these days (and one that has seen the most advancements in both quality and capability) is a variable-frequency drive (VFD). This automated device, which costs between $10,000 and $15,000 but reduces by up to 50 percent the energy costs associated with electric motors that operate over extended periods of time, can pay for itself in one or two years.

In many jurisdictions, state and local health departments mandate pool circulation pump sizes to function adequately in even the worst possible circumstances - an excessively dirty filter, say, or a clogged pump strainer - so the pump is actually oversized for most pool conditions. For example, Mendioroz explains that even though a 40-horsepower pump might be stipulated, the actual design condition for 95 percent of the pool's operating time probably requires only a 30-hp pump. But a VFD package, which connects to the pump motor and a digital flow meter (to provide input back to the VFD), sets the flow rate required by the health department while controlling voltage to the pump motor based on actual conditions. If the filter is clean and the pump strainer is empty, the pump motor does not have to work as hard to deliver the required flow rate - resulting in considerably greater motor efficiency.

A VFD also incorporates a "soft start," which means the motor powers up gradually, a process that eliminates a sharp spike in energy usage. The device is easier to specify in new construction but also can be added to an existing facility, provided the pool uses a premium-efficiency motor.

Eco-friendly energy-saving methods that go beyond basic design and implementation are becoming more commonplace in some aquatics applications, too. Among the more popular are passive thermal solar systems, which use the existing circulation pump to discharge water through a series of solar collectors, where a transfer of heat from the sun to the pool water occurs. On the discharge side of the pool filtration system (but before the pool heater), a bypass routes pool water into solar collectors. Because the heater is activated by low pool-water temperature, the solar system can provide the necessary set-point water temperature and not activate the pool heater.

The biggest obstacle is finding enough space for the solar panels, which need to be positioned close to the pool in order to be effective. This technology works particularly well at high schools or colleges, where a gymnasium roof can house the solar collectors. A distance of 50 to 100 feet from the pool is ideal, while 300 to 400 feet is the maximum distance, according to Mendioroz. Otherwise, pool water must be pumped farther, increasing energy use.

The cost per square foot of non-metallic solar panels (typically polypropylene or EPDM collectors) runs between $15 and $20, and although the exact number of panels required varies by region, coverage equivalent to 80 percent of the water surface area is usually sufficient for pools in all but the most sun-challenged spots of North America. Years ago, when natural gas cost 55 cents per therm in California, the ROI for a passive thermal solar system was between eight and 10 years. Now, with the cost of natural gas hovering around $1 per therm in that state, the estimated ROI is four to six years. "Back then, you were basically using solar in the name of political correctness," Mendioroz says. "But as energy costs have gone up, solar has become more and more attractive."

Not to be confused with passive thermal solar systems, photovoltaic electricity generation systems convert sunlight into electricity. Initial capital costs are high, and historically payback on PV systems has been as long as 40 years. The systems work best in facilities powered by electricity, as opposed to aquatics applications in which the major energy source is natural gas. That said, the Georgia Tech Aquatic Center, which hosted swimming and diving events during the 1996 Olympics, operates with a roof-mounted system consisting of nearly 2,900 PV modules - the largest such system in the world at the time of the Games. But even the operators of that facility have acknowledged that the PV system will never pay for itself during the expected life of the facility.

Looking ahead, a technology that uses thin-film solar cells and is commonly referred to by the name of the startup company pioneering it (Nanosolar) is positioned to become the third generation of solar-power technology. The San Jose, Calif.-based firm claims to have developed a proprietary process using inkjet technology that makes it possible to produce significantly thinner, less bulky solar cells faster and cheaper than current production standards, generating electricity for everything from pools to cars. "That's the direction in which we need to head," Mendioroz says.

Unlike some other green strategies, many elements of sustainable pool design allow operators to easily quantify the eventual (and often significant) cost savings - which helps justify the initial capital outlay. "The benefit in the pool and spa segment, and the reason I think it's becoming more common for people to talk about ways they can make their facilities greener, is that there is a direct positive relation to cost," Lachocki says. "It's a relatively simple calculation to verifiably say that you'll lose this much money upfront but you'll save this much money over time."

"People are going to make an investment when it makes sense," Mendioroz adds. "They're going to look at the ROI, and if it's up to two years, they'll do that in a heartbeat. If it's up to four to six years, they might think about it a little bit more."

"The recession is a double-edged sword relative to the greening of aquatic facilities," Lachocki says. "On one edge, money is more precious now, and as a result people are questioning the spending of more money now to save more later. Conversely, the recession also challenges people to look at their world a little more imaginatively, creatively and innovatively to find ways to do things better. Their business survival is at stake."

In addition to the automated chlorine generation system, the natatorium at the WCC's Health & Fitness Center uses ozone purification in its three whirlpools and carbon dioxide to control the pool water's pH. The building's heating, cooling and ventilation system is 20 percent more efficient than a conventional system, there is no use of particleboard (which can contain formaldehyde) and all walls are covered with low-VOC paint.

"A lot of green strategies can be started with minimal investment," Hanby says, referring to recycling programs and lighting sensors that shut off when an activity space or office area is unoccupied. The use of recycled wood, rubber, tiles and other surfaces on the deck and in locker rooms - as well as low-flow plumbing fixtures for showers, toilets and sinks - also are steps that aquatic facility operators can take.

Mendioroz points out that while no LEED standards exist specifically for pools, many sustainable-design strategies in natatoriums fall under LEED's "innovation in design" category and can result in as many as four points. The key, he says, is getting facility operators to better understand those strategies and the impact they can make.

To that end, Ft. Lauderdale, Fla.-based Keiser University's eCampus aquatic engineering degree program (the only one of its kind) requires students to write essays about nearly every aspect of green pool operation - including heating, pumps, chemistry, filtration, lighting and even landscaping. And for the first time this October, the NSPF will host an all-day session dedicated to sustainability and emerging green technologies at the sixth annual World Aquatic Health Conference in Atlanta. Topics include filtration, chemical automation and general energy-conservation strategies. A related two-day session will focus on helping aquatic facilities become more profitable, which in turn will provide them more financial resources for sustainable design practices. "Ultimately, if pool operators want to be green, they have to be profitable," Lachocki says. "Otherwise, they're not going to be able to invest in efficiency improvements or greener technologies. When you can benefit the world and your bottom line, people are motivated to move faster."