A solar cover in use as a pool heater

Pools are an excellent addition to any home, but they can be expensive and inefficient. In addition, what brings hours of fun and refreshment can cause equal amounts of stress to keep running. Luckily, there are several ways to heat your pool efficiently and save money in the process. 

Whether you already have a pool or are looking to install one, this guide should provide all the information you need to maximize efficiency and savings when heating the pool. 

What Is Pool Heater Efficiency?

Pool heater efficiency is the effectiveness of a pool heater in converting the energy it consumes into heat for your swimming pool water. It’s a measure of how efficiently the heater can raise the pool water temperature while minimizing energy waste and operational costs.  

According to the Department of Energy, the efficiency of a pool heater refers to the ratio of heat output to energy input.

The efficiency of pool heat pumps is determined through the Coefficient of Performance (COP). COP represents the ratio of heat output to the electrical energy input. 

Therefore, the higher the COP, the more efficient the pool pump transfers heat from the surrounding air to the pool water. 

Most gas pool heaters have a COP of between three and seven, translating to between 300% and 700% efficiency.

An efficient pool heater comes in handy when you want to save on operational costs while maintaining your pool’s ambient temperature.

A COP of between three to seven means you get between three and seven units of heat for each unit of electricity you use to operate the heater’s compressor. Thus, a higher COP will save you more money in energy costs because the heater uses less electricity to generate more heat.

Let’s consider a baseline of a 55% efficient pool heater. In this case, if you install a 95% efficient pool heater, how much will you save for every $1,000 in annual cost of heating your pool? The table below shows the savings:

Current EfficiencyAnnual Cost in USDAnnual Savings W/95% ($)
Table 1: Annual pool heater savings based on efficiency based on the formula by the Department of Energy.

Understanding BTUs and Pool Heater Efficiency

A British Thermal Unit (BTU) is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit. So, why is this important when it comes to pool heater efficiency?

Well, let’s assume your pool has 21,000 gallons of water. Since each water gallon weighs 8.34 pounds (3.78 kg), you’ll need approximately 175,100 BTUs to raise its temperature by one degree.

With that explanation, is a pool heater with a higher BTU more efficient?

While a pool heater with a higher BTU is more powerful and will heat the pool quicker, it consumes more energy than necessary. Therefore, it’s important to size the options based on your pool’s size to get the best pool heater for efficiency.  

Low Cost, High-Efficiency Options

You can make some simple changes or additions to your ground pool that can immediately help increase your pool’s efficiency.

Although these actions have a lower initial investment, they can still significantly affect the operational and maintenance costs of heating your swimming pool. 

Heating During the Ideal Time of Day 

The time of day you heat your inground pool can significantly impact its cost and efficiency, which is especially important if you have a heat pump heater. 

Heat pump heaters utilize the ambient air around them, so running it in the middle of the day, around noon, when it is warmest out, can increase the heater’s efficiency. The warmer the air is, the less work the heater has to do to help heat the pool. 

To implement this cost-saving method, you can use a timer or program the filtration system and heat pump to run simultaneously. 

Solar Pool Cover

One of the most critical tasks is to limit the evaporation from your pool. Experts estimate that a pool loses 50-70% of its heat through evaporation. 

Solar pool covers can be one of the most cost-effective and practical solutions for evaporation reduction to increase your pool’s efficiency. They can be a bit cumbersome to use but have huge benefits.

Solar covers are typically made of plastic and look almost like bubble wrap. They limit evaporation while simultaneously allowing the sun to heat the pool naturally. Solar covers are hands down one of the highest impact upgrades you can make to your pool.

Suppose you cannot put the cover on yourself. In that case, you can get one that automatically deploys and retracts, which is more expensive but is still a good option for many people.

It is essential to have the pool cover on when your pool is not in use, including during the hottest and coldest parts of the day.

Evaporation occurs fastest during the hottest part of the day, while heat loss is highest at the coldest part of the day. 

A solar cover in use as a pool heater
Tried and tested. The sun cover is often the traditional choice for low-cost and high-efficiency options for pool heating efficiency.

Solid Pool Blanket

If you have ever winterized your pool, a solid pool blanket is like a hybrid between the winter cover you put on the pool and the solar cover described above. 

This pool blanket does not allow sunlight through and eliminates almost all evaporation. So, while the pool doesn’t actively get heated by the sun with a pool blanket, very little heat escapes, maintaining the pool temperature well.

An added benefit is solid pool blankets are pretty strong. It is like having a built-in safety feature because they can handle the weight of a dog or a child without collapsing. 

Solid pool covers are more expensive than some other options. But they provide some excellent additional bonuses like their strength, and some come with automatic deployment features. 

Liquid Pool Cover

If a solar cover or solid pool blanket is not in your budget at the moment or simply not something you want to invest in, a liquid pool cover is an alternative option.

Liquid covers are the most budget-friendly but least efficient of the three pool cover options. However, it is better than not doing anything at all. 

A liquid pool cover is a chemical additive you can pour into your pool that helps prevent evaporation. The chemical is designed for pools specifically and does not alter the overall chemistry of the pool.

It is also safe to swim in pools where a liquid cover has been added. With this product, it is crucial to know the volume of your pool to ensure you use the appropriate proportional amount. 

Solar Sun Rings

Solar sun rings are mobile versions of a solar pool cover. They are floating disks that you lay on your pool that use the same material as solar pool covers.

Because they do not cover the entire pool, they are not quite as efficient as a solar pool cover or a solid pool blanket. However, they do help minimize evaporation and heat the pool. 

Solar sun rings are more affordable than other pool cover options and are easier to use and store. In addition, they are great for pools with a unique shape because they can be fitted into curves quite easily. 

Solar sun rings in use as a pool heater
Solar sun rings may be for you for a more affordable and easy-to-store option. Courtesy of Solar Sun Rings.

Lower the Pool Temperature

Have you ever heard that lowering the thermostat in your home in the winter by just one degree can significantly impact energy usage? The same is true for heating pools.

The higher the water temperature, the more energy it takes to heat and maintain the heated pool. You want your pool to be comfortable, but if you keep it at a higher temperature and are looking for ways to cut costs, lowering it by a few degrees can immediately impact it. 

In fact, for each degree warmer you want your pool, it could increase your operating costs by 15 to 18%. 

Existing Pool Design Improvements (That Also Work for New Builds)

Suppose you have or are building a pool but are looking for a more substantial investment to reduce energy usage and maintenance costs.

In that case, some installations and more significant projects can have an even bigger impact on the efficiency of heating your pool. 

Heat Pump Pool Heater

Heat pump pool heaters are highly efficient and can help lower energy costs sustainably in the long term.

No matter where you live, a heat pump heater can add a lot of value to your pool. 

Heat pump water heaters use the ambient air to heat the pool efficiently,  which is incredibly cost-effective and has an excellent return on investment. 

A standalone heat pump unit
Not all pool heaters are equal. Be sure to consider the Coefficient of Performance.

The great thing about heat pump pool heaters is they can be effective in any climate.

Unlike other heat pump technology, which is most efficient in warmer temperatures, pool heat pumps can be used in any environment because pools in cooler climates are typically closed in winter. 

Pair a heat pump pool heater with a solar cover or other technology, and your heating efficiency will be through the roof.

By using warm air, heat pump pool heaters reduce a significant amount of the energy needed to warm pool water. 

When looking for a pool heater, it is essential to look at the Coefficient of Performance (COP). The COP is a rating that measures the efficiency of a heat pump pool heater.

The higher the COP, the more efficient the unit is. By looking at the COP, you can find the most efficient heat pump for your budget. 

Hydronic Solar Panels

Using renewable energy to heat your pool, such as solar power, can reduce energy usage and heating costs.

In addition, it is environmentally friendly and requires little maintenance, especially in warmer climates. While a solar pool heating system may not be logical for everyone, especially those farther north, it can be a great solution.

Hydroponic solar panels are used as a pool heater
Using hydronic panels may be a bit more challenging for residents in areas with scarce sunlight.

Hydronic solar panels run the water from the pool through the panel itself to maximize heating efficiency.

Of course, pumping the water from the pool to the solar pool heating system requires an additional cost. However, the amount of savings a hydronic solar pool heater presents is far more substantial than the cost of pumping the water. 

Wind Protection

Wind can be a significant factor in heat loss.

The small waves or ripples created by wind in a pool increase the surface area of the water, which in turn increases the rate at which heat is lost from the pool.

 If you live in an area with a lot of wind, you can install wind covers or barriers to help limit the wind’s impact on your pool. 

Other Pool Heaters

There are a plethora of pool heaters on the market, including:

  • Gas pool heater taps into natural gas as the energy source for heating.
  • Heat pump pool heater is an electric pool heater that transfers heat into the pool.
  • Solar pool heater uses solar energy for heating.
  • Propane pool heater utilizes propane for pool heating.

Unfortunately, it is not always feasible to purchase the most efficient option; however, there are some steps you can take to ensure that the water heater you use maximizes efficiency within your budget or constraints. 

Ultimately, you need to find the best pool water heating system for you, but there are still ways to prioritize efficiency no matter what type of heater you purchase. For example, some pool heaters work more efficiently with specific pumps.

By doing research and finding out the efficiency of the heaters ahead of time, you can find the best fit for your pool and budget. 

Considerations When Building or Upgrading a Pool

If you haven’t built a pool yet or are looking to do some serious upgrades to your current pool, these crucial considerations will ensure maximum heating efficiency for years to come!


Choosing the right location for your pool is of the utmost importance. You do not want to put it in an area with a lot of shade. 

The best location is anywhere the sun will have direct access to the pool for the most extended timeframe.

In addition, direct sunlight is the best to raise and maintain a reasonable temperature in the pool. 

If possible, you also want to avoid super windy areas. As described above, the wind is one of the worst things for heat retention in a pool. Any area protected from the wind is an ideal spot for the pool.

Pool Color

The color of your pool’s liner is critical in heat retention. The darker the color, the more heat it will absorb.

Dark-colored liners are a great way to heat your pool naturally.

Black absorbs the most heat but is not aesthetically pleasing or easily accessible. Dark blue options are great because they look nice and absorb heat well. The lighter the color, the less heat it will absorb.

Pool Insulation

If you are relining your pool or installing a new one, additional insulation prevents the ground from absorbing heat. 

While the pool loses most of its heat from evaporation or wind, the soil also naturally absorbs heat.

Installing rigid insulation between the pool wall and the liner prevents heat from being lost from the pool into the ground.

A diagram demonstrating how insulation works as a pool heater
A diagram showing the build of an insulated ICF swimming pool. Courtesy of Build Block.

Installing pool insulation is expensive but can save you money in the long run. Heat absorption by soil is like a slow leak. It does not have a significant impact at any specific moment or in the short term but can cause long-term inefficiencies within the pool system. 


Pools are fun and a great addition to homes in any location. But, unfortunately, they are expensive to maintain and heat.

Luckily, great options to heat your pool efficiently include different covers, heaters, and design considerations.

In addition, each home and situation is unique, so you can use one or multiple heating techniques mentioned above to save money and increase the efficiency of your pool.

For more ways to save on costs and make your pool more energy-efficient, you can view our articles on All About ICF Pool Construction and Variable Speed Pool Heat Pumps.

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