Dehumidification Helps Pools

February 13, 2004
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GRAND RAPIDS — Indoor swimming pools are cutting through the fog and operating costs at the same time, thanks, in part, to dehumidification methods that have been incorporated in several recent high-end projects.

Paul McWaters, president of MacAire Inc., says his firm has provided swimming pool and natatorium dehumidification solutions for almost 300 pools in West Michigan. Those clients have ranged from the Holland Aquatic Center, which is one of the biggest natatoriums in the country, to hotel and residential pools.

While dehumidification devices prevent the buildup of condensation and help repel mold in indoor environments, they also can serve as a source for climate control.

“A lot has to do with how the air flow and duct work are designed,” McWaters said. “In a pool, it’s difficult to keep more than 75 percent of the people happy all of the time. The swimmers like it so they don’t get chilled when they come out of the water, but that will sometimes be too warm for spectators.

“Some places such as hotels and health clubs are able to control the year-round humidity and temperature control to keep occupancy up or keep membership up.

“The other part of it is in the winter to control humidity and condensation on the glass,” McWaters added. “But the worse-case scenarios are the things you can’t see, such as mold.

“We’re doing as many retrofits now as we are new installations. In retrofits, the mold we have found can be unbelievable.”

Dehumidification devices have been implemented in indoor pools for nearly a quarter of a century, according to McWaters. More recently, technology has enabled vendors to incorporate extreme energy savings into operating costs.

“Because of energy recovery, we’ve been able to recycle energy from the air and they are able to use that energy to either heat the air in the building or heat the pool water in some of the most efficient cases,” McWaters said.

The savings comes in the form of latent energy, which essentially recycles evaporated water in the air.

“Even in the summer, you can use it to heat the pool,” McWaters said. “The big difference is that in pools you need in the winter some fresh, cold outside air.

“They’re bringing in outside air, but they have to heat the surroundings in the winter and cool it in the summer.

“Historically — and even now — engineers don’t quite understand this.”

MacAire has provided dehumidification for swimming pools at state-of-the-art high schools in Grand Haven, Holland, Grandville and Hamilton, among others. MacAire is also involved in the Grand Rapids Downtown YMCA project.

“Almost all the pool water at those projects is heated with recycled energy in the form of latent energy from the air,” McWaters said. “There isn’t a set figure on the energy savings, but it is substantial.

“It’s important to consider operating costs at the very beginning when the buildings are being planned, because the school is funded by taxes and it’s important to consider operating costs at the same time as construction costs are being analyzed.

“Some of those huge schools that were built during the 1970s, ’80s and early 1990s are finding out now that it is becoming difficult to keep those schools operating because of rising natural gas costs and the like. And gas costs impact electricity costs.”

McWaters estimates that a system with latent energy recovery, compared to a system with outside air, can recover nearly half the energy costs.

“That can be a huge amount of money,” he said.

The most common form of air recovery is “sensible” recovery, he said. Sensible recovery, he expained, occurs when the temperature of the air that is leaving an area passes by the air coming in from the outside through a heat exchange; it represents about 50 percent efficiency. In essence, sensible recovery is using the temperature of the outside air to cool off or heat the inside.

Latent recovery, meanwhile, captures evaporating pool water and returns it to the pool. For every pound of water that evaporates, McWaters said that the pool loses 1,047 BTU of energy.

Recovering that evaporation — or latent energy — and returning that energy inside the facility can help either in climate control or pool heating.

“Since that energy came from the water in the first place, it is by far most efficient to put it back to the water when it needs it, and you don’t always need to heat that outside air,” McWaters said. “That is really important in facilities where they want year-round humidity control in places such as a YMCA, sports club or hotel, where occupancy or use is impacted by comfort.”

McWaters was a manufacturer’s representative for Dectron Inc. when MacAire installed a custom-built dehumidification device in the $6.5 million, 44,000-square-foot Grand Haven High School facility. The climate control device not only creates a more comfortable environment, but it substantially reduces the district’s operating costs in both the winter and summer.

“Grand Haven will have big swim meets and we have to look at how it is used in cooler weather and also the warmer weather,” McWaters said. “First off, you’ve got to talk to an engineer and determine how many people will be in there.

“In warmer weather, a pool is just for comfort with humidity control. At Grand Haven — and we’ve done this in more and more pools — we have the ability to bring in more outside air when there are more spectators there if they are there for more than three hours.

“But if we brought in that same amount of outside air all the time, it would cost a fortune. We have to work with the engineers and aquatic directors to come up with the best system for how they are going to use that pool.”

McWaters is the 2004 president of the West Michigan chapter of the American Society of Heating, Refrigerating and Air Conditioning Engineers.

MacAire has also represented several companies on downtown projects such as the Amway Grand Plaza, Eastbank and Plaza Towers, as well as the former Mackey’s World, which is now headquarters for the Grand Rapids Police Department.

The company is also involved in the development of the proposed Trowbridge Towers.

“We have to work with builder, architect, the electricians and plumbers and just about all the other tradesmen to make sure everything is done correctly,” McWaters said. “If somebody doesn’t do their job correctly, it can be a big problem.

“We’ve been pretty busy. The average engineer may only do one or two pools in his career, so there is a big learning curve and it takes a lot of experience to do them right.

“We’re usually involved real early in the project. For projects such as the YMCA and many of the big high schools, we get involved right away.”    

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