What is a hot tub?

What this means for your home project

1. For a California purchase, photograph the model and manufacture-date markings alongside the energy label so the proposed unit can be identified. Source: California Energy Commission, read 2026-11-06.
2. Match the cover model marked on the California energy label to the cover named in the written installation proposal; request its model identification if absent. Source: California Energy Commission, read 2026-11-06.
3. Request a written equipment list identifying the hot tub’s controls, heater and circulation equipment, so the supplied systems are explicit. Source: U.S. Department of Energy, read 2026-11-06.
4. Ask the installer to identify whether the proposed self-contained unit uses a cord connection or permanent wiring; have that method included in the scope. Source: U.S. Department of Energy, read 2026-11-06.

How does a hot tub work?

A self-contained electric hot tub combines heating, circulation and controls in the product. DOE’s 2022 document (read 2026-11-06) describes equipment as “an integral part of the product.” Ask the installer to identify those systems in the proposed unit rather than treating the tub as an empty vessel. (source)

“A factory- built spa in which all control, water heating and water circulating equipment is an integral part of the product.” (source)

What types of hot tubs are there?

Portable electric hot tubs include standard, inflatable, exercise and combination models. DOE’s 2023 definitions (read 2026-11-06) describe the inflatable body as “designed to be filled with air”; combination models have two reservoirs, each with its own water-temperature control. (source)

“A wide range of portable electric spa products are available on the market, including standard spas, exercise spas, combination spas, and inflatable spas.” (source) “Inflatable spa means a portable electric spa where the structure is collapsible and is designed to be filled with air to form the body of the spa.” (source) “Combination spa means a portable electric spa with two separate and distinct reservoirs, where-- (a) One reservoir is an exercise spa; (b) The second reservoir is a standard spa; and (c) Each reservoir has an independent water temperature setting control.” (source)

Hot tub vs swim spa: what is the difference?

A swim spa adds water flow for exercise, including “swimming in place”, according to DOE’s 2023 description (read 2026-11-06). California Energy Commission guidance distinguishes its temperature use from a standard spa: some exercise models operate cooler, while others can also function as a standard spa. (source)

“Exercise spa means a variant of a portable electric spa in which the design and construction includes specific features and equipment to produce a water flow intended to allow recreational physical activity including, but not limited to, swimming in place.” (source) “An exercise spa is also known as a swim spa.” (source) “Exercise spas are operated at a much lower temperature than standard spas, but some exercise spas are equipped to function as a standard spa.” (source) “Thus, the test procedure for exercise spas accommodates both exercise spas that have a maximum water temperature below 100 degrees Fahrenheit and those that have a maximum water temperature greater than or equal to 100 degrees Fahrenheit.” (source)

What drives hot tub energy cost?

Hot tub energy use includes maintaining water temperature, circulation and filtration between soaks. DOE’s 2022 description (read 2026-11-06) calls standby the “predominant mode of spa operation” under ANSI/APSP/ICC-14 2019 testing. Those ongoing functions belong in an operating-cost comparison, alongside the unit’s covered operating condition. (source)

“For portable electric spas measured according to the test procedure in ANSI/APSP/ICC-14 2019, standby operation is the predominant mode of spa operation and includes power use to maintain the set temperature and to circulate and filter the water.” (source) “Spa users typically leave a portable electric spa at the desired water temperature setting while the spa is operating in default operation mode with the cover on.” (source)

How do I choose a hot tub?

California buyers can start with the unit’s model, manufacture date and energy label. California Energy Commission guidance (read 2026-11-06) specifies “Section 1607(d)(14)(B)” labeling for portable electric spas manufactured from June 1, 2019. Check the displayed performance together with the cover combination used for that result. (source)

“In addition to the marking requirements in Section 1607(b), requiring products to be physically marked with manufacturer name, brand name, or trademark; model number; and date of manufacture, all portable electric spas manufactured on or after June 1, 2019, shall be marked by the manufacturer with the label specified in Section 1607(d)(14)(B).” (source) “If the spa has been tested with multiple spa covers, the label shall display the most recent performance data of the tested spa cover of the spa unit-cover combination that yielded the maximum normalized standby power test result obtained in accordance with Section 1605.3(g)(6)(B).” (source) “For standard, exercise, and combination spas, the label shall be affixed on a readily visible location on the shell or skirt panel of the unit.” (source) “For inflatable spas, the label shall be affixed on a readily visible location on the unit’s retail packaging.” (source)

How do I choose a hot tub cover?

A hot tub cover should be matched to the unit’s tested energy performance when comparing California listings. California Energy Commission guidance (read 2026-11-06) identifies the “tested spa cover model number” on the label. Request that exact cover identification in the written proposal rather than an unspecified cover. (source)

“All tested spa covers that allowed the portable electric spa to pass the standby power performance standard must be certified to the appliance efficiency database as separate listings to sell or offer for sale in California.” (source) “The checkbox of the tested spa cover model number and corresponding spa cover manufacturer coinciding with the performance data shall be marked on the label.” (source)

How does a hot tub plug in?

Self-contained spas can be permanently wired or connected by a cord; DOE’s 2022 document (read 2026-11-06) says they may be “permanently wired or cord connected.” Ask which connection the proposed model uses so the written scope identifies the connection method rather than assuming every hot tub plugs in. (source)

“Self-contained spas may be permanently wired or cord connected.” (source)

Sources

• Portable Electric Spas — U.S. Department of Energy; read 2026-11-06.
• 2022 portable electric spa determination: product descriptions — U.S. Department of Energy; published 2022-09-02; read 2026-11-06.
• 2023 portable electric spa test procedure: product categories and operation — U.S. Department of Energy; published 2023-06-13; read 2026-11-06.
• Portable Electric Spas Frequently Asked Questions — California Energy Commission; read 2026-11-06.