How to reduce swimming pool running costs

When referring to running costs for swimming pools, one of the key elements is water consumption. Despite best endeavours, a pool needs a large volume of water, which can be multiplied depending on the way it is used and the treatment it goes through. The longer the existing water lasts, the less consumption––therefore less expense is incurred.

So, why do swimming pools consume water even after they have been filled? Here are the three main reasons:

• Evaporation. Regardless of the ambient temperature, some water loss will always occur through evaporation. The hotter it gets, the more this happens. Additionally, if your pool is outdoors, it will be used more during periods of good weather, when water will also evaporate more.
  • One way to prevent evaporation is to use a pool cover.

• Filtration. If using a sand filter, it must be cleaned regularly. This produces a lot of dirty water to be removed and replaced, which means additional water consumption.
  • Using an electric pool cleaner can save some of this usage, as it will have its own filter.
  • Another helpful addition is a pool cover, especially if the pool remains unused for a long period of time, in which case it would require less filtration.

• Water treatments. Adding new water to the pool leads to chemical imbalances. This can occur naturally from rainfall, when more chemical products need to be used to rebalance the water levels.

To avoid water waste in this scenario, automatic systems that control and regulate the level of chemical products can make a remarkable difference (e.g. Freepool2 and Neolysis).

Water renewal

Renewing the water is essential for swimming pools no matter how well maintained they have been throughout the year. Especially if the water has been treated for multiple seasons, it will need to be renewed. This is due to losses in its physical, chemical and aesthetic properties within time, which makes it increasingly difficult to be recovered without applying significant quantities of chemical treatments.

Moreover, using chemical products leaves traces (isocyanides) that accumulate year on year. Over time, even the safest combinations can become toxic and irritating. Overall, you should renew the water in your swimming pool every 5-6 years.

Pool maintenance

Periodic maintenance is important to keep the pool in perfect condition. In addition to renewing the water on a regular basis, you may have to refill the pool due to maintenance of the pool itself. For ideal maintenance, having access to the installation is crucial, since it will enable you to detect possible leaks and repair them on time, avoiding water waste.

Moreover, swimming pools can lose water through an incorrect installation. It is important, for example, to ensure watertight connections between accessories. An imperceptible 1 drop per second could lead to a loss of 8,000 litres per year––quite a huge difference to your pool’s water consumption!

Should you empty the pool during inactivity?

It is actually better to keep water in the pool when this is not being used. This not only avoids a significant volume of water being wasted, but it also contributes to maintaining the structure of the basin itself: the water presence modulates temperature differences, preventing cracks in the material caused by expansion.

However, an outdoor pool may freeze, so it is important to use “ice breaker” elements and purge part of the hydraulic installation. You should also carry out preventive regular maintenance on a pool that is not in use, so it can have a better performance when the season starts.

Using a cover will also help prevent the water from getting dirty. All in all, not emptying the pool saves a large volume of water and can yield a few additional benefits.

How do floating pool covers affect consumption?

Using a floating cover over a swimming pool that is not in use (which can still be 16-18 hours per day even in a full bathing season) can make a significant impact on evaporation, reducing it by up to 70 %. For a collective or public swimming pool, in which inactivity periods are shorter, you can still save up to 20 % of the evaporation losses.

Swimming pool covers also reduce energy consumption, especially for heated pools. They help keep the water temperature higher and to reduce heat loss through radiation and evaporation. You will not need to add quite as much new, cool water, that would need to be heated up to the ambient temperature. As a reference, heating 1 m3 of water from 15 to 25 degrees Celsius can use up to 12 kW/h.

What is the link between water temperature and evaporation?

The higher the water temperature, the more it will evaporate. Other factors that influence evaporation include relative air humidity, wind and its strength levels. A covered pool will be less impacted by these factors, so a 0.16 L/m2 of evaporation at 25 degrees Celsius will raise to 0.20 L/m2 at 30 C. Therefore, by increasing the water temperature 5 C evaporation will increase 25 %.

Swimming pool running costs have steadily reduced through advances in the technologies used to treat the water, heat it, and maintain it. Compared to 25 years ago, pools today use 1/9 of the energy they needed to run properly. One area in which running costs can be reduced is water heating.

Most swimming pools today have a heating system, although options such as thermal covers are an alternative to prevent the water from cooling down. Heat pumps have reduced energy consumption, as well as heat exchangers and other systems; e.g. thermal covers that conserve calories from the pool water.

Heat exchangers

A heat exchanger continuously transfers heat from one medium to another. There are two main types:

• Direct heat exchanger. Both media are in direct contact and it is assumed they do not mix. Examples of this are cooling towers, where water is cooled through direct contact with the air.
• Indirect heat exchanger. Both media are separated by a wall through which a heat transfer occurs.

There are multiple types of indirect heat exchangers: plate, shell and tube, spiral, etc. The most efficient happens to be a plate heat exchanger, thanks to its ability to provide the widest pressure and temperature limits.

Heated swimming pool key criteria

When designing a heated swimming pool, regulations impose certain requirements to ensure that an adequate temperature and humidity level can be maintained on premises. Basic aspects are covered in the Regulation of Thermal Installations (RITE):

• The temperature of the vessel must be between 24 and 30 degrees Celsius, while the air temperature will need to be 1-2 C above that, with a maximum of 30 C.
• Humidity of the premises must be under 65 % to avoid condensation.
• Adequate ventilation is needed to ensure air circulation and to recover the thermal energy from evacuated air (through heat recovery units).

Furthermore, the Technical Building Code requires solar energy to be used for heating the water in the pool, with a minimum contribution of 30-70 % depending on where is located your pool. If you don’t have access to enough solar energy, you can resort to boilers, heat pumps, or other equipment.

Tip: You can save up to 30 % of energy use by employing air conditioning instead of conventional gas heaters. See below for an illustration of air conditioning use volumes through years:

Heat pump costs

Using a heat pump for your swimming pool water can cost a varying amount. The weather conditions in your area and whether the pool is indoors or outdoors, the presence of a pool cover, the operation hours for the pool and the heat pump power itself all influence the running cost.

For an air-water type heat pump, you can expect average consumption costs per season to range between €2.50 and €3.70 per cubic meter of water heated.

A large part of the running costs for operating a swimming pool are electric. These apply to the filtration pump and the hydraulic system, equipment cleaning, and lighting.

Filtration pumps and the hydraulic system

These two pieces of equipment are essential for running a swimming pool. They must be of the right size for the volume of water. For example, it has been shown that filtering for a longer time at lower speeds with a lower-powered pump achieves better quality than a shorter filtration at high speeds with more powerful equipment. For that reason, consider installing a smaller engine, which uses less energy than a larger one.

Hydraulic networks are designed to facilitate water movement by limiting pressure drops. This will optimise filtration as well. Additionally, having different speed drives can also contribute to rationalise energy consumption as it provides the power the pump needs based on what the system actually requires.

A variable speed water pump offers different levels of speed, adjusting it and the flow and energy consumption taking into account the requirements of the pool. This means it only turns on when needed. It also features a number of different integrated programs, removing the need for manual adjustments––it will simply regulate itself as required. Additionally, a variable speed pool pump has a longer lifespan than its counterparts, thanks to running for less time.

On an annual basis, the cost difference between a variable speed pump and a traditional one may look like this:

• “Classic” fixed speed pump with intermittent operation – working 11 hours a day: €287.44 per year
• Variable speed pump – working 24 hours a day: €65.75 per year.

This equates to an 80 % reduction in electricity consumption in addition to also improve the pool treatment.

Pool cleaners

Cleaning the pool is part of essential maintenance activities, ensuring end user satisfaction and more durable use of the pool itself. While hydraulic pool cleaners have been used widely thanks to using the pool’s filtration system, they have some important drawbacks which lead to recommending electric pool cleaners.

Hydraulic pool cleaners do not lead to using less energy, as they have to use the filtration pump. Moreover, by using the filtration system, hydraulic cleaners make it so the dirt removed from the pool water remains in the filter. This means a filter wash is required regularly to maintain the cleaning capacity. Water is then removed from the pool and needs to be topped up, which leads to water waste––therefore additional consumption.

Conversely, electric pool cleaners represent a better choice. They normally use less electricity and require fewer hours of operation to achieve the same levels of cleaning as hydraulic cleaners. They also have their own filter, which can be emptied and cleaned when full, without using the pool’s filtration system.

In conclusion, electric pool cleaners are autonomous, low-consumption and efficient, which makes them the best technology on the market. Such as the Zodiac® VORTRAX^TM series, which are an ideal solution as they efficiently suck up all types of debris by using powerful cyclonic suction.

Lighting

Many swimming pools feature lighting systems, which can be an additional running cost to reduce. Nowadays, LED lighting is the best option in terms of cost savings as well as sustainability and environmental impact. They use less energy, have a longer life, and generate a well-balanced light.

By using an LED projector, you could use about 10 times less than a traditional 300 w projector, given that LED bulbs only use around 24-30 w. With their longer life (c. 100,000 hours) LED pool lights also last 100 times longer than the old halogen pool lamps.

All in all, this type of electricity consumption can be reduced by more than 90 % while adding superior durability.

Operating a swimming pool involves ensuring the optimal chemical balance for the pool water, which represents an additional swimming pool running cost.

The consumption of chlorine can be affected by lots of different aspects:

• Type of pool. Outdoor pools need more chlorine than indoor ones because of the sun rays acting on the water;
• Water temperature. Chlorine will be evaporated quicker at higher temperatures (a 1 C increase leads to 15-20 % of chlorine loss);
• Solar radiation. UV rays convert chlorine into inactive chlorides, which makes it difficult to maintain adequate levels of chlorine in outdoor pools in the summer. Stabilized chlorinated products such as isocyanurate derivatives will help with this;
• Stabilized chlorine products. Using them reduces the consumption level of chlorine;
• Adequate filtration. More chlorine will be used if the organic matter in the water passes through filters without being retained, as chlorine is used to oxidize it;
• Use of the pool. Each person using the pool pollutes and absorbs a certain percentage of chlorine.

Swimming pools are starting to be equipped with other disinfection systems, such as saline chlorination, ultraviolet disinfection, hydrolysis, etc. Those are other ways for reducing the use of chemical products, directly impacting the quality of water and the sustainability of the pool, and to ultimately reduce the need for topping up water volumes.

A final element in the cost calculations related to swimming pools is linked to staff and associated activities such as cleaning and other services.

The cost of cleaning and maintaining a swimming pool at a routine level is influenced by a number of factors, including:

• Labor. Periodic maintenance services can be hired on a daily, weekly or monthly basis. This includes cleaning residues in the water, checking and adjusting the pH, disinfecting, cleaning of glass and perimeter area, emptying and checking filters. This costs, on average, €120 per service.
• Pool dimensions. The bigger your pool is, the more hours of labor will be required for cleaning and maintaining. And the more products will need to be used, as well as more water will be needed for topping up.
• Cleaning intensity. A thorough cleaning is needed when the pool has been out of use for some time, or alternatively, when it is being used intensively. The budget will grow by including extra tasks such as cleaning the bowl without emptying or cleaning filters and gaskets.
• Additional services. Separate jobs like fully emptying and cleaning the pool, or repair work, raise the budget for your swimming pool running costs. For example, repairing a crack can cost around €300, while a full overhaul and start-up can be €200. These costs are also influenced by the size and needs of each pool.
• Full empty and refill. For each bathing season, if you plan to empty the pool or to top it up, these are additional costs to be taken into account. Costs depend on the size of the pool, water supply prices or the method used (the price is higher with a tanker, for example). You should budget at least €100 to €180 additional one-off costs for this activity, but could be much higher.

Knowing what to expect from your swimming pool running costs is essential to create a budget for operating a pool all year round. Thanks to a wide range of options and technologies available, some significant cost savings and an improved environmental impact can be achieved by choosing the right tools and materials and operating your pool in a more sustainable manner.