Councillors voted to install new heatpump equipment at the St Clair Salt Water Pool and the Mosgiel and Port Chalmers community pools at last week's non-public extraordinary council meeting.
The new system, which will replace heating elements used to heat water at the pools, will cost about $443,000.
The heatpump equipment will be paid for in part by a Electricity Commission grant of $170,000.
The new system is due to be in place by October this year, and swimmers are not expected to notice any difference in pool temperatures.
However, the council's investment was expected to deliver immediate financial results, with operating costs at the three pools cut by 72% immediately, council energy manager Neville Auton said yesterday.
That was because the greater efficiency of the heatpump technology meant the amount of electricity needed to heat the pools to the same temperature would be dramatically reduced, he said.
That would reduce operating costs across the three pools by $44,000 in the first year, with most of the money used to service the loan debt, he said.
A small saving of just under $4000 would remain once the first year's debt was serviced, and would be returned to the council's consolidated fund.
The annual saving would rise to just over $17,000 by year 10, as the loan was steadily repaid, and then jump to over $60,000 a year once the loan repayments ceased the following year, he said.
Over 15 years, savings totalling $420,290 were expected, with the money helping ease pressure on rates, he said.
The immediate and growing positive cashflow meant the project was a "no-brainer", he said.
The technology was in used in pools elsewhere in New Zealand, and had been considered before for use in Dunedin, Mr Auton said.
The difference now was the combined impact of improved technology, higher energy prices and the Electricity Commission grant, which combined to make the project more attractive.
Honeywell, the company installing the pumps, also guaranteed the savings as a condition of its contract with the council, meaning the company would fund the difference if savings were not achieved, Mr Auton said.
The heatpumps were essentially the same as those used to heat homes, except "instead of pumping heat into the room, it actually pumps heat into the water", he said.
The pumps would be housed within 3m x 2m x 1.5m cages outside the pools, with existing pipes carrying water between the pools and existing filters and heating units extended to pass through the new pumps, he said.
The "nasty" environment at the open-air St Clair pool meant the heatpump equipment for that pool would also feature freshwater spray units and other design features to reduce problems arising from salt water, he said.
Pool heating
• Heatpumps to be installed at St Clair, Mosgiel and Port Chalmers community pools, replacing less efficient heating element systems.
• Equipment to be installed by Honeywell New Zealand at cost of $443,000.
• Funded by Electricity Commission ($170,000 grant) and Dunedin City Council ($273,000 loan).
• New technology will cut electricity use at pools by 72% and slash operating costs.
• Small annual savings until loan repaid over 10 years, rising to more than $60,000 a year once repaid.
• Total projected savings for council of $420,290 over 15 years.
• Money returned to council's consolidated fund.
