Robotic pool cleaners save energy

Relative to other cleaner types, robotic cleaners save money in energy costs. Generally speaking, robotic cleaners are more expensive than hydraulically powered cleaners, but it is possible to see a return on the investment in a couple of years, after factoring in the energy savings.

In 2010, PG& E conducted a study that compared the energy use of the common automatic pool cleaners that are in use today. They published the results of that study in a paper published in 2012 called “Swimming Pool Sweep Technical Performance Assessment Offering Major Energy Savings and Program Opportunity.”

The main conclusion of that study is that robotic pool cleaners use significantly less energy than other automatic pool cleaners, such as those hydraulic cleaners powered by the filtration pump or booster pumps. In the study, they performed an extensive evaluation of 12 individual booster pumps and pool filtration pumps powered hydraulic cleaners, and compared their performance to that of 6 robotic cleaners.

Hydraulic cleaners are powered by moving water under pressure. The hydraulic power is provided by swimming pool filtration pumps or by additional booster pumps dedicated to serving the cleaners.

While these cleaners do not use electricity directly, they affect the power demand and energy use of the filtration and/or booster pumps that power them. In particular, they limit the extent to which filtration pumping can be accomplished at lower flow rates over a longer period of time, using two-speed or variable-speed pumps.

That is because hydraulic cleaner operations require greater flow than filtration alone, adding to the minimum total flow rate and pump speed. For example, filtration, skimming and directional inlet might be accomplished at 25 GPM of flow. Adding a hydraulic cleaner might double the flow requirement to 50 GPM. But this increase in flow is more significant than it might seem, because pump power increases proportionally to the cube of the flow. That means that adding the hydraulic cleaner to the filtration often requires double the flow, which results in 8 times the power requirement for the duration of the cleaning cycle.

Robotic cleaners operate directly from an independent low-voltage power source which eliminates the need to increase pump speed during cleaning cycles. This allows pool filtration pumping to be accomplished at the lowest flow for the longest time to

achieve maximum energy savings. The savings is even more significant for cases where the robotic cleaner replaces a hydraulic cleaner powered by a booster pump because the energy use of the booster pump can be entirely eliminated.

The study assumed cleaner operation of 3 hours a day, 365 days a year. The cost comparison assumed a rate of $0.30 per kWh since this was typical for residential pool owners. The following shows the annual energy use and cost of use for the cleaners tested.

Robotic: 197kWh, $59/year Filtration Pump (suction side): 1,675 kWh, $501/year Filtration Pump (pressure side): 1,675 kWh, $501/year Booster Pump Required: 2,989 kWh, $897/year In their report, PG& E stated that robotic cleaners offer high technical potential but still see low adoption due to a variety of market barriers.

The Consortium for Energy Efficiency (CEE) has said that the most significant market barriers to the sale and installation of efficient pool equipment are higher incremental price, lack of awareness of the benefits (among both consumers and contractors) and difficulties with explaining the benefits of high efficiency equipment to customers.

With that in mind, following are the benefits of robotic cleaners.

Robotic cleaners tend to be a bit more expensive than hydraulic cleaners. Depending on the manufacturer, a robotic cleaner can run between $500 to a couple thousand dollars. Meanwhile, popular pressure side cleaners cost between $500 to $800 and common suction side choices are cheaper at between $100 to $400.

Energy costs also vary a lot, dependi