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Our overview of collected spa models can be found here or under menu title "Benchmark".

Detailed information about energy consumption of spas in our publshed article (German).

Environment Friendly Spa?

What describes an environment friendly spa?

Well, mainly it is referred to its energy efficiency, meaning, its demand for energy for standby and spa usage. Although this will be widely covered by this website, evaluating environment friendliness should not only consider energy consumption of a product during its life time, but also its production, or even at an earlier stage, its development. It should also involve the product's packaging, its shipment and delivery, the maintenance during its lifetime and finally, its recycling, if there is any!

As environment we specifiy all the resources around us, such energy, space, climate, materials, fauna and flora and also - not to mention - ourselves, being also part of the environment.

We consider environment friendliness the overall approach to avoid unnecessary waste of resources and the application of possible resource conserving means during the product's life cycle.

Better designed spas are sophistically insulated, come with efficient electrical components (such as pumps and heaters) and offer low maintenance, durability and cost effective recycling. An energy efficient spa such as our test spa (standard version) was tested to consume 2000 kWh/a in standby for an average ambient temperature of 9°C plus approx 2,31 kWh per each spa usage. If spa owners use their spa every day for 30 min than the total energy consumed amounts to approx 3000 kWh/a electrical energy?

How much are 3000 kWh of electrical energy? 

To obtain 3000 kWh electrical energy approx. 3 times as much primary energy (energy mix) or 9000 kWh are required for generating and supplying this amount pf electrical energy. Mostly still coming from fossil energies.  Electrical energy is therefore not only expensive, it consumes valuable primary energy and produces significant CO^₂. To be multiplied with 20 years life expectancy (as promised).

For the purpose of a relative comparison 9000 kWh primary energy represent

• 900 l of heating oil or 900 m³ natural gas
• 1800 kg heating pellets (which is the annual pellet consumption of our 200m² sized show home demodomo in Germany!)
• 13000 km (@7 l/100 km) or 8000 miles (@34 miles/USgallon)  
• 1600 bathtubs of 160 l @ 40°C 
• ...

Therefore, our investigations focus on the reduction of valueable primary energy for the operation of spas.

General

The abbreviation "spa" derives from the Latin "sanus per aquam", meaning "health through water". Spas are also commonly referred to as "hot tubs" or "whirlpools" and are very popular for relaxation and their hydrotherapeutic massages. Portable spas are supposed to be moveable (if not put into a decking) and easy to install. They are often placed out side in the backyard.

The water temperature of a spa is normally set around the body temperature, slightly higher at 39°C for colder ambient temperature and slightly lower at 35°C for warmer ambient temperature. The temperature may even be set lower. However, the maximum water temperature should not exceed 40°C due to medical reasons.

Jet pumps force circulating water through a number of nozzles directed to different body sections and administer a hydrotherapeutic massage. Additionally, air bubbles blown through the nozzles into the spa by e.g. an additional blower cause a further stimulating and refreshing effect.

Keeping the spa water at the constant set temperature requires a heating device which generally is operated by electrical power. The amount of energy could be significant, especially if a non-efficient spa is operated in a colder climate.

Additional water filtration by a 24/7 operated circulation pump or by temporarily activated jet pump in combination with an ozonator and/or UV-light and chemicals keep the spa water clean and fresh.

In many households the outdoor spa constitutes the biggest electrical load.

Investment

The costs to acquire a portable spa (normally outdoor whirlpool) depend on the country the buyer lives in. Generally, the prices in Europe as well as in Canada are significantly higher than in the US. Sales prices are discussed in internet forums and make it relatively easy to compare. A model sold in the US for 8.000 US$ may be priced more than 15.000 € in Europe including the same accessories.

The installation of a spa incurs further costs for a foundation, a GFCI¹⁾ and electrical wiring if the spa does not come with a simple "plug-in" connector.

¹⁾ Ground Fault Circuit Interrupter

Operating Costs

Running costs can be significant especially in colder climates and buyers should ask for information about energy consumption and/or trustworthy energy certificates. Most of the energy data presented so far seem to aim towards the psychological threshold costs of 1 US$ or 1 € or 1 £ per day. Since no common test standards have been established yet, test conditions are often amended accordingly to meet this threshold. Independent tests report energy consumptions from as little as 1900 kWh/a to more than 7000 kWh/a for maintaining the water temperature at 39°C at an average ambient temperature of 10°C. These figures just represent the energy demand in standby, hence, energy loss while spa is used is not included.

Running a midsized spa which fulfils the CEC-standard (California Energy Commission) may exhibit a heat loss in standby of 337 W resulting in an energy consumption of 8,1 kWh/d or approx 3000 kWh/a (for average German climate, see calculation). A spa usage of 30 min with 10 min jet pumps has been tested to consume further 2,31 kWh/usage (test report) adidtionally to the standby costs. It has to be noted that longer usage and jet pump(s) operation will increase the energy consumption.

Chemicals and filter replacements for water purification add further costs of about 300 € to the yearly spa bill. Costs for the renewal of the spa water every three to four month (6000 ltr. per year) seemed to be negligible. 

In the long term the accumulated running costs can be higher than the purchasing costs of the spa, especially for not well insulated spas. Further increase in energy costs will even aggravate this effect.