Energy Efficient Pools


By Rebecca Brennan
Thursday, 13 December, 2012



Energy Efficient Pools

With the cost of energy rising rapidly, many consumers may be hesitant to install that pool they have been dreaming of. However, armed with the right information, you can inform them on all of the savings that are now possible with an array of energy efficient pool products available in the market.

Swimming pools and spas can use a lot of energy. A swimming pool will typically use around 2,000kWh to 3,000kWh of electricity per year depending on:

  • the type and size of the pump
  • how long the pump is run for each day, and
  • if the pool is heated.

Running costs are typically between $800 and $1,200 a year at 2012 prices.

A typical backyard swimming pool using 1.5kW pool pump can add up to 17% to an electricity bill. This cost can be entirely offset by installing solar panels, while adding value to a home and slashing a household's carbon footprint.

The cost of a 1.5kW home solar power installation in Sydney can be recouped in 5 - 6 years through electricity savings and the system will then go on to save many thousands of dollars more over its life.

Swimming pool and spa pool running costs

Swimming pools

The majority of energy used for swimming pools is for pumping water through the pool filter. Energy is also used to heat the water for the pool. This is usually achieved using a gas water heater, or the water may be heated by a solar system, which typically has its own pump. Comparatively small amounts of energy are used to operate cleaning appliances, lighting and the equipment that converts salt to chlorine in a salt water system.

Spas

Spas typically have a water volume ranging from 1,000 - 2,000 litres. Water in a spa is usually heated to between 34°C and 38°C and pumped through multiple nozzles at high pressure. The cost of heating water is the main running cost, and a gas heater is typically used. Gas heaters cost from $2 to $8 to run per hour.

Determining the energy use and running costs for a spa pool is difficult because it depends on:

  • How often the spa pool is used.
  • Whether the water is heated from cold or from the household's hot water system.
  • Whether the spa is kept filled with water or emptied after use.
  • How much heat the water loses to the environment.

For pools and spas, running costs can be calculated using the power consumption of the electric pumps or gas water heaters and the length of time they are operating. Source: the Government of South Australia Website, www.sa.gov.au

How to Make Pools and Spas More Energy Efficient

Pumps

Dr George Wilkenfeld, head of George Wilkenfeld and Associates, has been a consultant on energy efficiency policy since 2004. He has been working on domestic pools energy use for the Department of Climate Change and Energy Efficiency (DCCEE), which administers the national Equipment Energy Efficiency (E3) program, along with with State and Territory energy agencies. The E3 program manages energy labeling and minimum energy performance standards (MEPS) for a wide range of appliances and products.

Dr Wilkenfeld is chair of the Standards Australia committee, which prepared AS 5102, Performance of household electrical appliances - swimming pool pump-units.

After AS5102 was published, DCCEE set up a voluntary system to allow pump-unit suppliers to test their products and label them, provided they followed the guidelines. By October 2012, voluntary labels had been approved for 30 pump-units, from 9 suppliers

"As expected, suppliers have only chosen to label their most energy-efficient products. The ones registered so far range from 5.5 to 8 stars on a 10 star scale," said Dr Wilkenfeld.

The E3 program is now considering the next stage - mandatory energy labeling for all pump-units despite their level of energy-efficiency, so all buyers get the information they need to make a properly informed choice about energy efficiency and running costs.

A review of the standard is being conducted by a Working Group with over 20 participants, before the E3 program progresses to the next stage. The review is likely to result in proposals to revise AS5012. The industry as a whole will see the results of the evaluation when the proposed revisions to the standards are published, probably early in 2013. There will be the usual 6-week public comment period and EL-58 will then consider any submissions and hold a ballot on the final standard.

"Changes to the standard will not in themselves make much difference to the industry. However, if compliance with the standard becomes mandatory then buyers would see that there are many 1 to 3 star models on the market, not just 6 to 8 star models. This would create market pressure on suppliers to increase the energy-efficiency of their entire model range. Higher MEPS levels in the standard might also remove the least efficient models, so even buyers who ignore the energy labels would end up getting more energy-efficient products than otherwise," said Dr Wilkenfeld.

Pool pumps participating in the voluntary labeling scheme can be viewed here.

Heating

Heating a swimming pool doesn't have to be expensive - it can be as easy as collecting the energy that falls on your roof everyday and simply redirecting it to the pool.

Heating a pool with electricity or gas comes at a huge cost. Not only will it be the most expensive appliance in the house to run, but it will also have a damaging effect on the environment. Enough solar radiation falls on an average roof each day to heat 3 or 4 swimming pools, so the sensible approach is to harness some of Mother Nature's free energy to heat pool water in a responsible way.

In Australia we are blessed with abundant sunshine so why burn tons of coal just to keep our pools warm when we can collect the free energy falling on the roof of the house.

Pool Covers

In addition to saving water (by reducing evaporation) and reducing cleaning time, pool covers are a great way for pool owners to save on power. Regardless of how pool water is heated, solar blankets act as a barrier between the colder air and the warmth in the pool water. Acting as an insulator, the cover stops the natural process of hot and cold attracting each other commonly known as convection.

According to the CSIRO Division of Mechanical Engineering, the water temperature in an unheated swimming pool depends on the total solar radiation absorbed in the water and on the rate of heat loss from the water. In an open pool exposed to sunshine, the water temperature is normally close to the mean air temperature. Although it's very much subject to personal preference, the CSIRO concludes that the minimum acceptable water temperature for swimming is around 20°C - and the desired level is about 25°C.

Using the CSIRO minimum swimming temperature as a guide, a pool cover would double the swimming season in Melbourne, for example, from just 3 months to 6 - with no cost for heating.?Elsewhere, owners may gain 3 to 4 months additional use from their pool, just depending on their own temperature preference.

"Wherever you live in Australia, a pool blanket can warm your pool by up to 8°C and significantly extend your swimming season. If your pool is heated, it can cut your heating energy costs by 50 to 70%. It does this primarily by insulating against heat loss, effectively eliminating evaporation, therefore saving a huge amount of water," said Derek Prince, Managing Director of Daisy Pool Covers.

Next time you build, maintain or repair a pool, ensure the owners are aware of the benefits of pool covers. There are covers to suit every style and budget.

Top 10 Tips to Reduce Pool and Spa Energy Consumption

  1. Cover swimming pools and spas to prevent heat loss and water evaporation. Thermal covers will keep the pool clean, reduce water loss and contain the warmth.
  2. Consider turning off heating and using only when necessary.
  3. Install a heat pump or solar heating system.
  4. Don't run the pool pump longer than necessary. Reducing the running time will minimise energy use and cost. Check the operating manual for recommended operating times.
  5. Check with the energy supplier to see if the pump can run on the off-peak tariff overnight. This will reduce the running cost but not the amount of energy used.
  6. Timer switches can help owners reduce energy bills through the programming of an efficient operating regime.
  7. Follow manufacturer's instructions and maintain the pool or spa to ensure it is always operating at its highest efficiency.
  8. Reducing water use can also help to keep costs for pools and spas down.
  9. Installing an efficient water management system will mean that pumps and filters need to be run for shorter periods of time.
  10. Replace old equipment that has been superseded with energy efficient models.
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