Online cost calculators: The first step to reducing pool operating costs

April 4, 2016

By Mike Fowler

Knowing the potential savings that can be achieved by simply upgrading the pool equipment is the first step in renovating a mechanical room.

Every year, aquatic facility managers review their operating costs and usually find their electricity bill to be one particular expense that never seems to get cheaper. For an aquatic facility, there is so much equipment that uses electricity that the simply ideology of ‘turning off the lights’ does not help to lower these costs. Everyone realizes an aquatic facility’s mechanical room consumes a lot of electricity; therefore, it is the logical place to start when looking for ways to reduce operating expenses.

Today, there are many new cost calculators in the marketplace which allow facility operators to pinpoint where the most electricity is being consumed in the mechanical room. Thanks to these online tools, an increasing number of operators are using them to evaluate their facilities. For instance, the figures generated by a cost calculator can be used as the basis for presenting the need to upgrade or modernize a facility’s mechanical room with more efficient equipment (such as a variable frequency drive [VFD] pumps). Cost calculators can also show prospective saving capabilities to utility companies when seeking possible rebates.

Knowing the potential savings that can be achieved by simply upgrading the pool equipment is the first step in renovating a mechanical room. However, the decision to do so becomes more definite once an aquatic facility operator sees on paper just how much the facility can save in terms of electricity costs (between $300 and $1000 a year, sometimes more).

What is the cost calculator?

As the name implies, cost calculators are set-up to determine the cost of electricity for one particular piece of equipment in the mechanical room. Pumps are typically the first place to start because they can consume a lot of electricity. The calculator will start by asking questions about the aquatic facility—so operators must be ready to input various information (e.g. the pool’s total water volume and the pump’s turnover rate). (See Table 1 below). Calculators will also ask if there is a minimum required flow rate along with the number of days the pool is open per year, how long the equipment runs, and pool’s hours of operation.

To start this process, operators should have an electricity bill handy to enter the cost per kilowatt hour (kWh), as well as know the horsepower (hp) of the facility’s pump(s). Cost calculators will even take into consideration the size of the suction and return pipe, and the estimated flow rate.

By entering this information, the facility’s power demand, energy use per day and, more importantly, cost per annum, can be quickly identified. Comparing the figures of a facility’s electrical consumption using its current equipment to that of a new, energy-efficient pump, for instance, will show the savings in black and white (see Figure 1 above).

What does the cost calculator compute?

Figure 2: Pump curve

Online cost calculators have pre-loaded formulas that make it easier and faster for facility operators to get the figures they require to make key operative decisions. Ultimately, the calculator shows how reducing pump speed can save energy by a cube factor. The computation takes kWh and revolutions per minute (rpm) to determine the savings.

kWh = Energy

The ‘quantity’ of energy consumed.

For example, if the unit price for electricity is $0.125 per kWh then:

Cost calculators have integrated pump affinity laws into the computation. This allows an aquatic facility operator to demonstrate that lower pump speeds save energy by a cube factor.

For example, reducing pump speed (rpm) by 20 per cent automatically reduces flow (litres per minute [lpm]/gallons per minute [gpm]) by 20 per cent. (See Table 2 on page 46). Energy consumption, however, is reduced by a cube factor. Therefore, a 20 per cent reduction in flow will provide almost a full 50 per cent reduction in energy (e.g. 0.8 x 0.8 x 0.8 = .512). Even a 10 per cent reduction in speed can reduce energy consumption by more than 25 per cent. (see Figure above).

Commercial aquatic facilities and utilities

Using an average figure of $0.0583 per kWh with a 7.63-hp pump per every 37,8541 L (100,000 gal) of water, a 20 per cent reduction in speed for one hour would free up four medium-sized power plants. If pump speed was reduced by 50 per cent for one hour, aquatic facility mechanical rooms could possibly free up seven medium-sized power plants.

Each year, there are an increasing number of reports discussing the energy crisis that North American electricity grids increasingly face. So much so that many regions (in Canada and the U.S.) have implemented the use of smart meters to track electricity use by the hour, while some areas have had to endure brown-outs and/or rolling black-outs. With an aging infrastructure and constrained capacity, utility providers in the U.S. are looking for ways to get rapid reductions in the amount of power they need to provide.

That said, with more than 300,000 commercial aquatic facilities in the U.S.[6], pumping 265 billion litres (70 billion gallons) of water, utilities are looking at commercial aquatic mechanical rooms
as an area where they can get quick reductions with respect to power demand. In fact, the aquatics industry could make a huge impact in this regard. For instance, using an average figure of $0.0583 per kWh with a 7.63 hp pump per every 37,8541 L (100,000 gal) of water, a 20 per cent reduction in speed for one hour would free up four medium-sized power plants. If pump speed was reduced by 50 per cent for one hour, aquatic facility mechanical rooms could possibly free up seven medium-sized power plants.

For example, CPS Energy, a local utility provider in San Antonio, Texas, is one energy company that is looking for ways to reduce power usage. As Texas is one of the largest states with respect to the number of commercial aquatic facilities, with nearly 30,000 installed pools as of 2012[7], the city of San Antonio worked with the utility provider to conduct an energy audit using tools similar to those of an aquatic facility cost calculator. As a result, it was determined that retrofitting 22 city-owned pools with updated equipment, the utility would experience a dramatic reduction in energy demand and the city would get a payback on the project in less than a year.

This project primarily focused on reducing pump speeds at the 22 aquatic facilities, whereby replacing older pumps with new VFD equipment. The total project cost, for equipment and labour, was $137,000; however, annual electrical savings were $63,000 and CPS Energy gave the city an $87,000 rebate. As a result, the city’s initial costs were paid back within nine months and a five-year return on investment (ROI) of 530 per cent is expected.

Using the cost calculator for proposals

Table 2

Using an online cost calculator is the first step in getting an aquatic facility to consider upgrading or retrofitting its mechanical room. It is an easy tool that can be used to close a deal with a facility that might be hesitant in replacing its outdated equipment. By showing operators how much money can be saved in energy costs alone, it can be a game changer with respect to approving any mechanical room upgrades. When electricity costs can be reduced at an aquatic facility from $1000 to $300 per year, the question then becomes, what will the facility do with the extra money?

Similar to what was experienced in San Antonio, several years ago, the city of London, Ont., hired an auditor to perform a cost-benefit analysis of reducing energy consumption on all city-run facilities, which included six aquatic facilities. The calculations were powerful enough that the city decided to retrofit a myriad of systems to lower energy consumption, including the installation of VFDs on all pumps used by the municipal pools.

Hollandia Pools, also of London, performed all of the retrofit work at the aquatic facilities, which included the installation of VFDs and ultraviolet (UV) disinfection systems; the latter was included with the intention to help reduce pool chemical consumption as well.

Another factor in the city of London’s case was the ‘redundancy’ designed into all of its aquatic facilities. For instance, the city mandates two pumps on every body of water. One pump is in operation on the pool and the other acts as a backup. Both pumps are plumbed and ready to go and they switch on/off between pumps every month. As a result, Hollandia installed one VFD on every two pumps. For example, one of the city’s aquatic facilities contains two bodies of water—a lap pool and a wading pool. Each has two pumps—one operational and one in reserve—and they switch the pump being used on a monthly basis.

Hollandia Pools & Gardens’ Richard Deakins says it is important to note the VFDs should always have a flowmeter to keep the VFD properly calibrated as the filtration system loads. Flowmeter automation is an integral part of the VFD’s functionality. Without it, the VFD is just an expensive light switch.

Deakin says a typical pool in the city of London is classified as ‘Class A,’ which means it requires a turnover rate of six times per day or once every four hours. (The city requires its pools to operate 24-7). During this period, the pumps are pulling and pushing water through the filtration system and as the filters get dirtier, the pumps need to speed up or slow down to meet the flowrate requirements. By putting a flowmeter with the appropriate set points on the VFDs, they can then be controlled by the flowmeter readings.

As a result of this project, the City of London recognized an overall cost savings of 30 to 60 per cent on energy consumption.

Deakin understands the power of cost calculators and regularly shows prospective customers the positive results achieved with his previous customers. In fact, the cost calculator has become so integral to his business that he has the program installed on his laptop.

“I look at the pump sizes, flowrates, etc., and I have the client pull out their electrical bill to enter the rate which they are being charged per kilowatt hour,” says Deakin. “It’s very easy to show them a comparison of what they are paying now and how their costs would decrease should they install a VFD and flowmeter on all their pumps.”

Food for thought

Online cost calculators have pre-loaded formulas that make it easier and faster for facility operators to get the figures they require to make key operative decisions.

Lately, everyone is pushing for energy-saving products and the pool industry is no different. Facility operators who are looking for money to invest in new programming, but are not sure where to get it, should start at the heart of their facility—the mechanical room. Whether it means replacing an old pump or motor or switching out pool, spa/hot tub, and/or water feature lights with energy-efficient light emitting diodes (LEDs), there are savings to be found. Further, these savings continue annually because the replacement products and/or equipment will last much longer and operate with increased efficiency.

One question facility operators should ask themselves when considering this kind of mechanical room upgrade is: “What is the cost of doing nothing?” For a concrete answer, those facility operators who use a cost calculator will soon learn the tremendous potential to save money at their aquatic facility.

Fowler_Headshot[10]Mike Fowler is the commercial marketing/sales for Pentair Commercial Aquatics in Sanford, N.C. He has been with Pentair since 1992, starting his career in the technical services department at Purex Pool Products. Fowler has held many managerial roles within the company, including marketing, accounting and products. He can be reached via e-mail at[11].

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