Illustration by Tim Bobko
 

A portable spa decked out with hundreds of jets, an 80,000-BTU electric heater and a surround-sound LCD flat screen doesn’t exactly yell green.

Yet some of the most impressive improvements in energy efficiency have also come from manufacturers. Better insulation and equipment help conserve power, and sophisticated control systems can micromanage running times.

Cost is still a prohibitive factor, but as energy prices rise, spa designs will continue to get greener.

Insulation

Not surprisingly, the most critical element in saving energy in portable spas is heat retention. Given that nearly 75 percent of heat loss often can be attributed to evaporation, covers are crucial to the energy efficiency of hot tubs.

“The overwhelming majority of the industry uses a similar type of cover construction — it’s vinyl-clad with an EPS (encapsulated polystyrene) core,” notes Sam Collins, vice president of operations for Marquis Spas in Independence, Ore.

These covers prevent the vast amount of potential heat loss. However, they are still subject to moisture damage, as water seeps in and lowers the product’s R-value, or ability to retain heat. As such, manufacturers developed a vapor barrier wrap to prolong the life of the cover’s insulation.

The actual design of the cover also has become more important. Every crack or joint that exposes the heat to the open air drastically accelerates heat loss.

The physical insulation within the spa also has undergone improvements.

“We’ve seen a lot of change in insulation to blanket wraps, to foam insulation in the frame work, on the floor, and even some materials that aren’t as much traditional insulation materials, but more of a hybrid that would go in there,” says Brian Wiley, president of Premium Leisure in St. Petersburg, Fla.

The frame itself is now almost always supplemented with a hard bottom cover, which protects against both heat loss and permeation from outside elements, namely rain.

Being green has become an important marketing tool in selling portable spas. This is not just in saving energy through insulation, but also by advertising recyclable materials. Companies push hybrid materials to accent various styles.

Equipment round-up

Improved equipment has also been a key to energy-efficiency among portable spas. The single largest advance is in the motor efficiency and design of pumps. (Click here to see how filtration and hydraulics have helped improve efficiency.)

Many portable spas use separate pumps to operate the jets and filtration, allowing minimal energy usage for the latter.

“I’ve seen a change to more circulation pumps,” Wiley notes. “There’s a cost factor, but they’re made to require a lot less energy.”

Manufacturers who stand behind a single pump design utilize a large two-speed model, which is designed to run only during operation.

Some companies are even experimenting with variable-speed technology. These pumps allow minimal energy usage during normal filtration cycles. They can also be optimized to control the amount of amps used for different jet speeds.

However, because of the cost, portable spas with this technology are only available in high-end models, limiting their growth in the current economy.

“Where the market is today is geared toward mid-priced products,” Wiley says. “But I think it will grow when the market comes back.”

Variable-speed pumps have the additional benefit of allowing users to choose their massage settings. Presets can even be arranged for varying jet pressures during a single run.

The heater, however, remains a major source of energy consumption with no obvious solution. Electric models are the most convenient and least expensive products to buy. And even with operational savings, other styles of heaters just don’t make sense.

“We’re trying to provide a product as a manufacturer to anyone and everyone,” Collins notes. “Not everyone has … access to geothermal heat or solar heat on the roof.”

Mission control

Although typically associated with convenience, new control systems allow a more efficient distribution of energy usage across the hot tub.

“One of the bigger opportunities lies in the equipment and how the equipment is configured,” Collins says. “The changes in the last 10-15 years have been the advent of electronic controls, being able to configure the software.”

User-friendly software allows homeowners to program filter cycles, clean-up cycles and heater cycles. In an area where energy costs are higher during the day, because that’s when the main load is, you can program your spa to switch on and filter at night when the rate isn’t as high.

Controlling the pump has also paid major dividends. While some models are set to run all the time, the control system will actually moderate the pump use according to temperature. The circulation pump won’t run until it reaches 3 degrees under or over the set point.

“I think some of your energy savings are from the computers being smart enough to change the programming depending on your usage,” Wiley says.

While spa owners often prioritize comfort ahead of energy savings, the equipment and software are there for more green-conscious homeowners.