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Lake water for heating and bathing

Lake water for heating and bathing

In 2014/2015, Knie's Kinderzoo completed the largest expansion in its history with the expansion of the zoo area to include an area of a football field.

  • Other building
  • Renovation
  • Gas

Initial situation and challenges

A modern elephant park and the new Thai restaurant Himmapan have been built on the plot overlooking the lake. The expansion increased the water requirement for the new swimming pools for the animals and required an expansion of the heating system. Knie's Children's Zoo wanted to use the lake water as much as possible for this purpose. Existing plans for a heat pump system using seawater were then further developed by Energie 360° and the functionality of the overall concept was optimised.

One challenge was the complexity of the system, which, in addition to heat generation, also included the distribution of seawater on the grounds of the zoo – the latter a novelty for an energy service provider such as Energie 360°. The schedule was also challenging: the plant had to be completed in just eight months from the start of construction to commissioning.

We have a long-standing professional partnership with Hoval.

(Martin Weber, Energie 360°)

The Energy 360° solution - together with Hoval AG

In order to be able to meet the tight deadlines and to protect flora and fauna, the pipes to the lake were laid underground using the flush drilling method. The water is collected about 340 metres from the shore at a depth of five to seven metres, coarsely filtered and led to a compensation basin on the zoo grounds. With the help of a pump, it is transported from there to the heat pump via a second filter system. It thus serves as the main heat source for the heating system and is then fed into another balancing basin. From there, it either flows back into the lake in its natural state or can be used to fill the pools for elephants, penguins and other animals, as well as for the service water network to clean the zoo grounds. The heating system currently consists of a heat pump with an output of 280 kW and supplies the elephant house and the Himmapan restaurant with hot water and heat. The energy centre offers space for two additional heat pumps and another Hoval gas condensing boiler – which enables the system to be expanded in a modular manner. To store the thermal energy, three storage tanks, each with a volume of 6800 litres, have been installed. For peak times and as a fallback level, a Hoval UltraGas (720) Gas Boiler Available. The entire plant was planned, implemented and financed by Energie 360° as a contractor. The contracting contract runs for 30 years – during this time, Energie 360° is responsible for operation and maintenance as well as energy and water supply around the clock.

Ecological benefits

Thanks to the use of lake water, a significant amount of fossil energy can be saved. This not only brings an economic benefit, but also a great ecological advantage. With a coverage ratio of around 89% of its energy requirements, Knie's Children's Zoo saves a good 100,000 litres of heating oil per year and thus reduces the burden on the environment by 272 tonnes of CO2 per year – this corresponds to the emissions generated by heating around 225 apartments in accordance with the Minergie standard per year.

The special feature of the solution

Since the lake water usually has a constant temperature in deeper layers (approx. 4.5 degrees in the Obersee in winter), it is ideally suited as an energy medium. The current lake water supply for the children's zoo is 36 litres per second, which is only equivalent to the flow rate of a very small stream. The water used returns to the lake cooler, but still natural, and does not affect the biological balance of the water. Until now, however, the large ecological energy reserves of Swiss lakes have rarely been used – the Rapperswil Children's Zoo, Energie 360° and Hoval have implemented an innovative solution with this facility.

(Source: energie 360°)