Anyone who has ever boiled a kettle knows how much energy it takes to raise the temperature of a small amount of water. But have you ever thought how much energy it takes to heat an Olympic sized pool in a swimming centre and what that costs?

Councils help people de-stress, stay fit and socialise by creating and maintaining parks and gardens to walk in, playgrounds for kids, sport grounds for the competitive, and bush walking trails for quiet contemplation. Some councils create and run specialist sport facilities like gymnasiums, and indoor sports stadiums. Councils also have a tradition of providing places for people to swim and importantly for island kids, a place to learn to swim.

City of Hobart - Doone Kennedy Aquatic Centre

Swimming pools and recreation centres are a popular community resource, but the energy bills to heat such large volumes of water can be extraordinary! The City of Hobart have used some fascinating techniques and a mix of energy sources to heat the Doone Kennedy Aquatic Centre to a comfortable temperature year-round, without costing the environment or residents too much.

City of Hobart has put in a unique system in place at the DKHAC using different energy sources to maintain a consistent and stable temperature for the pool, general heating and domestic hot water.

A combination of different energy sources and techniques are used, to ensure a stable and reliable temperature at the DKHAC, while allowing the City of Hobart to pick and choose which energy source it uses to effectively manage energy costs.

The first impressive engineering feature – which was part of the original design - is the capture and use of the heat contained in treated sewerage effluent! In a clever system using a heat exchanger, the heat is taken from the treated waste water, and stored in 300,000L of clean water. This thermal storage tank acts like a water battery in times of peak water demand, storing heated water for use by the water circuits helping heat the pools, space heating and hot water for the bathrooms.

The second engineering feature is the use of photovoltaic solar panels. Over 1500 solar panels were installed on the Aquatic Centre’s roof, in 2015 and 2017.  The annual solar power generation of this system is likely to be 370,000 kWhrs with all of the power being used on site. This level of generation results in an annual cost savings of approximately $130,000 and 12.5% total energy used at the pool. The installation should pay for itself in cost savings within six years’ time.

The third feature is the installation of new, condensing gas, water boilers. The new gas fired boilers will create 1,200kW of near instant heat energy, which is added in a much more direct and efficient manner than the earlier thermal storage tank design. This energy can serve as an important back up in the case of the failure of the electric heat pump system, the heat pumps are very efficient and will still be the main system used to heat the Aquatic Centre. The thermal storage tank system part of the system will be decommissioned. This will avoid the inevitable heat losses from the storage system and provide the council with an energy source when the sun fails to deliver enough solar energy.  Also, the storage system could only supply a few hours of heating for the Centre in an emergency, but the new gas boilers can supply constant heat!

With the option to use any combination of heat in treated sewerage effluent, solar electricity, Tasmania’s largely hydro-electricity, and gas, the City of Hobart can ensure a stable and reliable energy source to maintain heating systems, using two sources of renewable energy all year round. This also means the DKHAC can implement demand management to make the best use of the energy sources available and reduce energy costs while reducing the energy demand on critical infrastructure during peak demand periods for energy.  Through sophisticated design and engineering work, the City of Hobart has reduced its energy use at the Doone Kennedy Aquatic Centre by about 20% since 2010, with cost savings set to increase with the new work.