Using water more than once helps save energy
Saving energy through the use of an innovative filter technology in Vienna's public swimming pools
The water in Vienna's public swimming pools has to be changed frequently, a process that consumes great quantities of water and energy. Novel filter technology is being used to reduce the water changing intervals, thereby saving 50% of water and energy input while ensuring compliance with rigorous sanitary standards. Installation of the filters and supplementary energy-saving measures are carried out by private contracting partners who also guarantee that the equipment functions reliably and both water and energy consumption are reduced.
Contracting for energy-saving measures most frequently involves evaluating technologies used in building installations, such as ventilation, heating and the provision of hot water. Vienna's public swimming pools require huge quantities of heated and chemically treated water. To cover this need, the City Administration uses what it calls an "energy-saving contracting model". The first step in implementing this model was to invite a group of selected companies to participate in an ideas competition for a new technology that would effectively reduce water consumption. After the technology with the maximum reduction potential (a new filter system) had been identified, the contract was awarded and the new system installed in cooperation with the contracting partners.
The new filter technology meets Vienna's rigorous sanitary standards. Although the water remains within the pool-filter cycle for a longer period than previously, the filter performance remains undiminished. As impurities and combined chlorine are effectively removed in each cycle, the water needs to be changed less frequently. The central element of the filter equipment is a sand filter with an activated carbon layer. In this filter, impurities that are dissolved in the water attach themselves to the surface of the sand grains and are thus removed from the swimming pool water. Combined chlorine is eliminated by the activated carbon layer, and most of the water can be fed back into the cycle after this process. The speed of the filter process is regulated through pressure control (overpressure/negative pressure). The filters are automatically cleaned by backwashing at night. The backwash water is subsequently cleaned, and heat is withdrawn from it by a heat exchanger before it is used for lawn sprinkling or discharged to the sewer system.
The advantage of the new filter technology for Vienna's public swimming pools is that it reduces the need for water, energy and chemicals, so that both operating cost and the environmental footprint of the swimming pool are reduced.
Installation and maintenance of the necessary equipment are financed by the contractor, and repayments are made by the City Administration (Municipal Department 44, Municipal Swimming Pools) strictly in line with plant performance, i.e. the amount saved on energy and water. After the repayment period - approximately ten years - the savings become effective in the Municipal Swimming Pools budget.
Facts & Figures
- 38 public swimming pools
- 11 of which apply the "energy-saving contracting model"
- Total number of visitors per year: more than 4 million
- Capital investment of EUR 33 million in 2001-2011
- Annual savings: approx. EUR 3,36 million; energy saved: 25,240 MWh; water saved:
- Reduction of water consumption: approx. 55%
- Reduction of energy required for heating: approx. 50%
- Reduction of CO2 generation: 3,733 t/year
- Ideas competition (two-stage process, pre-selected group)
- Jury decision (preset evaluation criteria)
- 1-2 rounds of negotiations
- Assessment by the committee awarding the contract
Prizes and awards:
- 2001 "Energieprofi" Award of ÖGUT (Austrian Society for Environment and Technology) for the Simmering public swimming pool
- 2007 EU Energy Award (for the Floridsdorf swimming pool)
- 2007 Best European Energy Project of the EU (for the Brigittenau swimming pool)
- 2008 "Green Building Partner Award 2008" of the EU Commission (for the Floridsdorf swimming pool)
- Gesellschaft für Wassertechnik (GWT)
DI (FH) Volker Schaffler
Tel. +43 1 4000 84269
Fax +43 1 4000 7997