How To Reduce All Spas And Hot Tubs Energy Expenditure

For any prospective or current owner of a spa or a hot tub to make a well-informed decision while thinking to buy or upgrade a tub, reliable information about energy-efficiency features is needed. It may sometimes seem like the right choice to go for the lowest retail price right away, but this may often lead to higher monthly electric bills and adverse financial effects in the long term. Fortunately, some features of all Spas and Hot Tubs will help you reduce energy expenditure and save a chunk of cash in the long run.


The National Spa and Pool Institute has stated that an average of 2,514 kWh per year is consumed by a single spa, which means that 250$ a year is spent simply on heating it. A spa study done by the Davis Energy Group revealed that spas are almost always the biggest electrical culprits in the house. It was only recently that unbiased information on spa energy use become readily available since even the Consumers Union (a publisher of Consumer Reports) has not rated spas.

all Spas and Hot Tubs

How All Spas and Hot Tubs use Energy

It is vital to understand how spas and hot tubs use energy to reduce their operating costs. Typically, electricity is used to heat and continually circulate the water around the tub, while a small amount of electricity is consumed for lighting. 95 percent of the time, tubs remain cover and unused, yet this is actually the time where 75 percent of energy is consumed. Therefore, energy conservation starts at this “steady-state” mode and attempting to reduce heat loss from the cover and walls. While heating requires a significant amount of energy, pumping also consumes a chunk of its own.

Heat loss increases six-fold or even more when the cover is removed, and the tub is in use. Heat loss is further increased if a few people get into the tub and the jets are activated, due to evaporative heat losses from the surface of the water. The pumps use a lot more energy for the high-speed jets than employed by the circulating pumps. Heat loss is increased far beyond the capacity of most heaters by air pumps or bubblers, and water temperature quickly begins to drop.

Three elements are key to conserve energy efficiently on all spas and hot tubs. They are the cover, the tub wall insulation, and the pump system efficiency.


Cover – Regarding overall energy use, it is important to pay attention to the insulative value of the cover, as well as the tightness of its seal around the tub. The perfect cover provides excellent insulation, tight air sealing, and is also light enough for one person to handle. Between the cover and the hot water, the humid air is rich in energy, and a small air leak in the seal would cause evaporation from the water surface, bypassing insulation and increasing heat loss within the tub. It is therefore vital to have a good-quality cover made of closed-cell foam that will not absorb water. It should also be properly supported so that it does not sag around the middle while being light enough for one person to lift.


Tub Walls – We can often find tub walls that aren’t insulated at optimum levels and can be a primary source of energy loss. Thermal insulation can perform two different functions: decreasing heat loss and physically supporting the tub if the insulation foam is rigid enough. The thicker the insulation, the more energy is conserved relative to its cost. These incremental benefits make the optimum thickness of the foam somewhere around six inches, depending on average ambient temperatures and energy costs.

In many cases, users will place fiberglass insulation over a two-inch layer of rigid foam insulation, which can save a few dollars in the short term. However, the fiberglass eventually gets wet, and the insulation value drops to almost zero; ultimately adding a chunk to your electric bill.


Pumps – During the earlier mentioned “steady-state,” water is continuously circulated through a filter and heater by the circulator pump(s). Some tubs will have motors options for water circulation; a low-speed mode during the “steady-state,” and a high-speed mode when the jets are activated. While these pumps are usually not very efficient, they are especially so during the steady-state since the motor is loaded very lightly and is also running at low efficiency most of the time.

Moreover, getting rid of the waste heat from the motor can be troubling as well since these are air-cooled motors. While initially slightly more expensive, it is recommended to purchase tubs with separate pumps for circulation and jets. This will help optimize the circulation pump and will eventually earn you significant savings during steady-state operation.

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