Variable Speed Pump for Commercial Swimming Pools
Pool pumps: Variable-speed vs. Single-speed
Variable speed pumps on the filtration system of commercial swimming pools.
Item ID: 464
Process Loads & Appliances--Commercial and Residential Appliances
Commercial and public pools are required to meet rigorous water quality standards to ensure the health and safety of swimmers. Many commercial pools have single-speed pumps that are providing higher flow rates and turnover rates than those required by health authorities. Significant energy savings opportunities through replacing these older pumps with variable speed flow control. Many swimming pool pump manufacturers now offer variable speed high efficiency electronically commutated permanent magnet (ECPM) pump drive motors as standard offerings.
Pumps used in public pools are required to operate continuously while the pool is in use. They therefore can benefit from efficiency improvements to a greater extent than residential swimming pool pumps. The current industry standard is a six hour turnover rate, which is based on sequential dilution studies.
Energy savings are dependent upon pump oversizing, whether the existing pool has a single or two-speed pump, and on variations in swimming season length. When replacing a single-speed pump, a variable speed pool pump might reduce energy use by 50% to 75% (Building America Retrofit Alliance).
SMUD conducted a variable speed drive retrofit at a swimming center in 2012. The center initially operated a constant speed ¾ hp pump. Their goals were to verify that filtration would maintain water quality with reduced flow rates and to quantify energy savings when operating with a reduced flow regime. While expected energy savings were estimated at 60% of pumping system use, the demonstrated savings were only 34% of baseline pumping use (2,884 kWh/year). The reduction in savings was due to operating constraints posed by the chemical feeder, heater, and filtration system.
Baseline Description: Constant Speed Pump with 3/4 hp Capacitor Start Induction Run Motor
Baseline Energy Use: 8390 kWh per year per pool facility
The baseline pumps are installed at a 20,000 gallon indoor swimming pool and an outdoor pool. The 3.4 hp pumps are constant speed with on/off control and have input power requirements of 1.7 kW and 1.6 kW respectively. The smaller pool is operated for 1/2 days while the indoor pool pump is operated for 6 hours on weekends, 12 hours on weekdays, and 6 hours per day during the off-season. The estimated total annual pumping energy is 8,390 kWh/year. The indoor pool had a flow rate of 61 gpm while the outdoor pool operated at a flow rate of 54 gpm.
Manufacturer's Energy Savings Claims:
Savings Range: From 50% to 90%
Best Estimate of Energy Savings:
"Typical" Savings: 34%
Low and High Energy Savings: 30% to 75%
Energy Savings Reliability: 3 - Limited Assessment
The replacement ECPM or brushless DC motor driven pump (a Hayward Ecostar SVRS) offered variable speed capability (the study doesn't indicate the hp of the ECPM motor). The replacement pumps operate continuously (i.e. constantly) and cycle from a low speed of 32 gpm to satisfy pool heating requirements with high speed operation providing 60 gpm for a minimum of four hours per day. While the operating hours increased, the pool facility energy savings amounted to 34%. Constant pump use during the "off" season resulted in increased energy use during that time, but resulted in a benefit as the pool was constantly available for use and didn't have to be re-commissioned i.e. shocked with chlorine---at the start of the swimming season.
Energy Use of Emerging Technology:
5,537.4 kWh per pool facility per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
The 2014 NEEA "Northwest Commercial Building Stock Assessment" indicates the pool and hot tub area by commercial building type. Regional pool area is concentrated in the "Assembly", lodging, school, and "other" categories. The region has a total of 4,585,000 square feet (sf) of indoor pool area and 1,973,000 sf of outdoor pool area. The total regional pool square footage is 6,558,000 sf (Figure A.9.4, Appendix A).
The number of pools (and thus of pool pumps) will be estimated by assuming a surface area of 1800 sf per pool (30 ft x 60 ft). This assumption indicates a total of about 3,643 commercial pools in the Northwest.
Regional Technical Potential:
0.01 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Currently no data available.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.