calendar 10.10. 2016

Swimming and skiing fun have their price

Indoor water parks and ski centres attract many visitors. But have you ever thought about how energy-efficient that really is? We try and answer the question of how much energy-saving potential there is for public swimming pools. And find out which need more energy per visitor: public swimming pools or indoor ski centres?

Tropical Islands south of Berlin is considered to be the second-largest indoor water park in Europe: according to the Global Attractions Report, roughly 910,000 visitors came to the park in 2014. An man-made paradise set in 66,000 square metres. The tropical landscape was set up in the former Cargolifter hall, the largest self-supporting hall in the world. From an energy efficiency point of view, that was not the best choice: its shell is made of steel and sheeting; the building is designed for an inside temperature of 19 degrees.

The hall is heated to 26 degrees for the swimming and bathing area – although large areas of the shell have no thermal insulation as thermographic images show. The images also show that the hot steam from the pools is simply discharged from the hall into the open air.

Energy costs a big item in the balance sheet

The technology was then modernised some years after the opening at the end of 2004. According to a company spokesman, whom the german magazine “Focus” quoted in December 2009, the heat is now recycled and used for heating. The founder Colin Au estimated the energy costs to be three million euros per year.

“The running costs for an indoor swimming pool are up to 500,000 euros a year. So a saving of 10 per cent is a very attractive proposition.”

Public indoor swimming pools generally do better – but by no means all of them: “Many indoor swimming pools were built more than 40 years ago. Back then, energy prices were still not very relevant, the focus was on architecture and value for money,” says Christian Dahm, engineer at EnergieAgentur.NRW, who advises local authorities and operators on energy-saving potential. “The average indoor swimming pool which we advise has one 335 square metre pool and uses some 1.3 million kWh of heat and 0.37 million kWh of electricity a year,” Dahm reports. As energy prices rise, so do the costs. Public swimming pools are often heavily subsidised, quite a few are under threat of closure because of the costs. “The costs for the swimming pools mount up to about 500,000 euros a year. So a saving of 10 per cent is a very attractive proposition,” Dahm explains.

The thermographic image of Tropical Islands shows large red and orange areas – those are areas without no heat insulation and high heat loss.

Energy saving – on a large and small scale

You just have to make a few simple organisational changes to cut consumption. Today, the water can be 1 degree colder than it used to be and that alone cuts the heat requirement of the pool by some 10%. “It is also worth taking a look at the times when the outdoor lighting is switched on,” Dahm advises. “Or you turn off attractions such as massage jets in the jacuzzi when they are not being used.” Converting a lighting system to LED or heat-insulating an outdoor slide can also be done at a manageable cost.

If operators are looking for greater savings, they face a complex challenge. Indoor and outdoor public swimming facilities have extensive equipment, for example for heating, ventilation and pool water. Therefore, such facilities are mostly modernised in conjunction with the refurbishment of the entire building.

What a successful refurbishment can look like is described by EnergieAgentur in an article on the Walter-Leo-Schmitz public indoor swimming pool in Wipperfürth. There, extensive renovation work involved replacing the roof, installing a solar energy system and a cogeneration plant and refurbishing the heating system. Today, the swimming pool only needs a heating capacity of 700 kW, compared with 2,300 kW before. And the CO2 emissions have been cut by some 250 tonnes a year according to the operator.

Nevertheless, it will always take a lot of energy to keep the water at a pleasantly warm temperature in the winter. However, the same applies if you want to turn water into snow in the summer. This is shown by the still relatively young history of the German indoor ski centres.

Skiing in midsummer?

The first German indoor ski centre opened in Neuss in January 2001. In the meantime, there are now six indoor ski centres in Germany with slopes up to 600 metres long. To enable people to ski the whole year, cooling loops are installed in the floor and the air temperature is permanently cooled down to -1 to -4 degrees. That requires powerful refrigerating and snow-making systems. Therefore, the halls are criticised, among other things, for their high energy consumption. But do they really need more energy than swimming pools?

According to an estimate by Bund Naturschutz in 2010, the indoor ski centre in Neuss uses some 5 million kWh a year and has had 840,000 visitors a year since its opening. That is an energy consumption figure of some 6 kWh per visitor.

Indoor ski centre beats swimming pool

By comparison, the average indoor swimming pool uses some 1.67 million kWh of energy a year and has between 50,000 and 100,000 visitors every year. If we assume 100,000 visitors, consumption per guest is therefore 16.7 kWh – nearly three times higher than for indoor ski centres.

Economically speaking, indoor ski centres are in a similar economic situation to public swimming pools. “In the six-and-a-half years we have been in operation, we have never made a profit and at best just barely managed to break even. That is above all because of the high energy costs,” said the managing director of the Snow Dome in Lower Saxony, Jakob Falkner, in an interview with the german magazine “Spiegel Online” in March 2013.

“In the six-and-a-half years we have been in operation, we have never made a profit and at best just barely managed to break even. That is above all because of the high energy costs.”

Faced with this situation, the operators invested in new technology. For example, the Snow Dome in Bispingen near Hamburg was closed for half a year in 2013 and comprehensively refurbished. The operators say the new refrigeration system is to cut energy consumption by roughly one third. The popularity of the indoor ski centres shows their high energy consumption does not deter the visitors. Many indoor ski centres have developed into alpine leisure parks with adjoining hotel facilities. They are now regarded as an important and permanent tourist attraction in their regions.



picture credits: ista, grasundsterne, Tropical Islands, allrounder