Cost Calculators

Every year, facility managers sit down to review their operating costs and every year there is a huge figure that never seems to shrink:  the electricity cost.  There is so much equipment that uses electricity and trying to simply “turn off the lights” doesn’t seem to help reduce that figure.  Everyone realizes that an aquatic facility’s pump room are big consumers of electricity so it’s a logical place to start when looking at ways to reduce operating expenses.  Luckily, there are now many new ‘cost calculators’ in the marketplace that allow a facility manager to get to the detail about where exactly that electricity is being used in the pump room.  Today’s aquatic professionals are turning to these cost-calculators to start this evaluation.  Many pool professionals use the figures they generate from these cost calculators as the basis for presenting the need to upgrade to more efficient equipment or add a variable frequency drive, and also to show prospective savings capabilities to an electric company to be approved for possible rebates for using more energy efficient products or VFD’s.  Knowing the potential savings that will come from upgrading equipment is the first step in renovating an aquatic facility pump room.  When an aquatic facility sees on paper that they can save from $300 to $1,000.00 a year in electricity costs, or in some cases potentially more, it becomes much easier to decide there is a need to upgrade pump room equipment.

What is the cost calculator?

As the name implies, cost calculators are set up to calculate the cost of electricity by one particular piece of pump room equipment.  Pumps are a great place to start because they are big electricity users.  The calculator will start by asking questions about the aquatic facility—so be ready to know how many gallons of water are in the pool and the turnover time of the pump.  Calculators will also need to ask if there is a minimum required flow rate and the number of days the facility is open per year, and how long per day the facility is open and equipment runs..  Be sure to have an electric bill handy to enter the cost per kWh of electricity and the horsepower of your existing pump.   Calculators will even take into consideration the suction and return pipe size and the estimated flow rate.  By entering this information these ‘cost calculators’ can quickly identify the power demand and energy use per day and more importantly, the cost by year.  Comparing the figures of current equipment to the electricity usage figures of a new, energy efficient pump will puts the savings figures in black and white. 

What does the cost calculator compute?

Cost calculators have pre-loaded formulas to make it easier and faster for aquatic professionals to get figures they need to make decisions.  Ultimately the calculator shows how reducing pump speed saves energy by a cube factor.  The computation takes kilo-Watt hours and rpm to determine the savings.

kWh:  kilo-Watt hours = Energy

The ‘quantity’ of energy consumed


If the unit for pricing electricity is $0.125 per kWh

1kW x 1 hr = 1kWh or 1kW x 2 hrs = 2 kWh

1.5 Horsepower pump on average uses 2,000 watts

2.0 kW x 8hrs/ day = 16kWh/day x $0.125/ kWh = $2.00/ day

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

For example, by reducing the speed (RPM) of a pump by 20% automatically reduces the flow (GPM) by 20%.  However ENERGY CONSUMPTION is reduced by a cube factor!  So a 20% reducing in Flow provides almost a full 50% reduction in energy: 

0.8 x 0.8 x 0.8 = .512

Even a 10% reduction of speed saves over 25% of energy!

Commercial aquatic facilities and utilities

The news continues to point out that the US electrical grid is stressed.  With an aging infrastructure and constrained capacity, utility providers in the US are looking for ways to get rapid reductions in the amount of power they need to provide.  With over 322,000 commercial aquatic facilities in the US, pumping 70 billion gallons of water, utilities are looking at commercial aquatic pump rooms as an area where they can get quick reductions in the amount of power demand.  In fact, the aquatic industry could, in fact, make a huge impact on demands of power providers.  If you assume an average figure of $0.0583 per kW with a 7.63 HP per every 100,000 gallons of water, a 20% speed reduction for 1 hour, would free up 4 medium sized power plants.  If you reduced the pump speed by 50% for 1 hour, aquatic facility pump rooms would free up 7 medium sized power plants. 

CPS Energy, a local utility provider in San Antonio, Texas, is an example of a utility looking for quick reductions in power usage.  Texas has one of the largest installed number of commercial pools in the nation with well over 30,000 installed pools as of 2012.  The City of San Antonio worked with CPS Energy to reduce the city’s energy usage.  After doing an initial energy audit of the city, using tools similar to those of a typical cost calculator, the city determined that by retrofitting 22 city owned pools, the utility would experience a dramatic reduction in energy demand and the city would get a payback on the project in less than 1 year!  The 22 city pools primarily worked to reduce the speed of their pumps.  They did this by replacing older pumps and installing variable frequency drives.  The total project cost, for equipment and labor, was $137,000.00.  However the annual electrical savings was $63,000.00 and CPS gave the city of San Antonio a rebate of $87,000.00.  This gave the city a payback on the project of just 9 months and a five-year return on investment (ROI) of 530%

Using the cost calculator for proposals

Using the cost calculator is the first step in getting an aquatic facility to consider upgrading or retrofitting its pump room.  It’s an easy tool to close a deal with a facility that might be hesitant to upgrade equipment.  By showing them on paper, you can open the eyes of a facility to see just how much will be saved.  When you can go from a $1,000.00 power bill in 1 year to a $300 power bill after upgrades, it’s a real no-brainer.  Then the question becomes, what will the facility do with that extra money?  Programs?  Other?

Hollandia Pools & Gardens in Ontario, Canada has also had a similar experience to that of San Antonio but with the City of London, Ontario.  Several years ago, the entire city hired an auditor to do a cost-benefit analysis of reducing energy consumption on all city-run facilities that included 6 municipal pools.  The calculations were powerful enough that the City undertook to retrofitting a myriad of systems to lower energy consumption that included installing variable frequency drives on all the pumps of all the municipal pools in the city.

Hollandia Pools was the company that won the bid to do the swimming pool pump retrofits.  The City of London, Ontario put VFD units on all their swimming pool pump and they also installed UV on all their pools with the intension of reducing their overall ‘consumption’ footprint on the planet as UV reduces chemical usage.

“Not only did they want to reduce their energy consumption, they also wanted to reduce their chemical consumption so they installed UV systems on all their pools as well VFDs on all the pool pumps,” noted Richard Deakin of Hollandia Pools & Gardens.

In the case of the City of London, there is a ‘redundancy’ designed into all of their systems.  They have a mandate to have 2 pumps on every body of water.  One pump is in operation on the pool and the other pump acts as a backup.  Both pumps are plumbed and ready to go and they switch on and off between pumps every month.  As a result, Hollandia installed one VFD on every 2 pumps.  As an example, one of the local community pools has two bodies of water:  a lap pool and a wading pool for children.  Each body of water has 2 pumps—one operational and one in reserved and they switch the pump being used on a monthly basis.  “These municipal pools have really high bather loads and cannot afford to be down at any point,” says Deakin

Deakin points out that it’s important to note that the VFDs should also always have a flow meter to keep the VFD properly calibrated as the filtration system loads.  The flow meter automation is an integral part of the VFD in order to be functional.  Otherwise, your VFD is just an expensive light switch.

Deakin explains that a typical pool in the City of London is a Class A pool which requires that the water turn over 6 times per day or once every 4 hours. The city does require that the pool operate 24/7.  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 mandated city code flow rates.  By putting a flow meter on the VFDs with the appropriate set points input into the flow meter, the VFD is then controlled by the flow meter readings.

Deakin understands the power of the cost calculator.   He regularly shows prospective customers the results of previous customers.  The City of London, Ontario, for example, has recognized an overall cost savings of 30-60% on energy consumption.  In fact, the cost calculator has become central to his business and has the program permanently installed on his lap top computer.  He regularly pulls out his computer with a potential client and inputs all the variables with the client sitting at his side.  “I just look at the pumps sizes, flow rates etc and I have the client pull out an electrical bill to enter the rate which they are being charged for the kilowatt hour.  It’s very easy to demonstrate what they are paying now and to show them how that rate will decrease by installing a variable frequency drive and flow meter on all their pumps.”

For the last several years, we’ve seen everyone push for energy savings products and the swimming pool industry is no different. Remember when you’re looking for money to put into that new program at your facility and not sure where to get it; start at the heart of your Aquatics Facility pool, the equipment room. Whether it’s an old pump or motor that needs to be replaced, or the many lights you find in a pool, spa, or water feature, there are savings to be obtained and the same time the savings would continue annually because these new energy saving products will last much longer than standard products that have been in place sometime for years. Just ask yourself a popular question when looking into changing to energy efficient products, “What’s the cost of doing nothing?” Think of that answer while counting up the savings in your head, and using these cost calculators to assist with the tremendous savings potentials that are out there for your aquatics facility or commercial body of water.

Mike Fowler is the commercial marketing and sales manager 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, Customer management, accounting and products. He can be reached via e-mail at