Saving Energy in a Fun Place


Although working in the public sector is usually stereotyped as somewhat dull and monotonous, my own experience is totally different. For a little over 10 years now, I have been working for the city administration of Laatzen, a city with about 40,000 inhabitants close to Hannover, Germany. As a state-certified environmental technician, my responsibilities include a broad range of issues within the administration: technical environmental and health issues, regular industry surveillance, waste disposal, and energy consumption. Additionally, I am responsible for public outreach and education on environmental issues.

The old bath on fire in July 1996.

The development of specific technical concepts is one of the "extra assignments" I do once in a while. In the past 2 years, I have worked on a project that required a lot of energy, from early ideas to final realisation. It began in 1996, when a huge fire destroyed the city's public bath--as much of a paradox as it may sound, the bath burned fairly well and not much more than the foundation walls were left. Immediately after the fire, a discussion about rebuilding the bath was initiated. In times of tight budgets, publicly funded pools and baths are critical issues. It is not possible to operate a small facility without taking huge losses each year, and a big facility with more features could be considered an unnecessary waste of public expenditures.

After the city had decided it wanted to build a new and modern bath, I developed a concept for a new, low-energy facility that puts a heavy focus on low energy consumption, rational energy provision, and the use of renewable energies. The unusual feature of this concept was combining several energy-saving technologies which were all considered state of the art, but which had never been realised in a major project such as a large public bath. After the mayor's and the city council's approval for the concept, detailed planning was begun in cooperation with Lower Saxony's energy agency (Niedersächsische Energie-Agentur).

During construction, solar panels become visible on the rooftop.

The project's objective was to reduce energy consumption by as much as 40% compared to "regular" baths, as well as to implement an innovative water-saving concept. It is interesting to take a look at the individual features of the energy concept, yet the whole may well be greater than the sum of its parts: It proves that energy-saving, swimming, and sauna-going can happen at the same time--the latest technologies can be applied to a place where people come to have fun.

Special insulation materials and heat-shield glass help to reduce transmitted heat to about 60% below the allowed limits. Highly efficient heat exchangers are used to reduce the heat loss in ventilation and water loops. Within the ventilation system, up to 80% of lost heat can be regained. Revolution-controlled fans and intelligent pump controls, in combination with a well-planned heat conduction system, help reduce electric power consumption by 25%.

The sun as an energy source is being used in four different ways: A 350-square-meter air collector generates about 220 MWh of solar energy annually. Solar panels have been used to replace common roof tiles on 480 square meters in the sauna area. They are used to heat up the showering water and generate about 310 KWh per square meter per year. The biggest part is a 600-square-meter field of unglazed solar collectors (solar swimming pool absorbers) which heats the water of both the outdoor and indoor pools. A technical highlight of solar energy features can be found in the little children's area--the so-called transparent heat insulation system collects the warmth of the sun in glass capillaries, especially in the winter months. Through the bath's walls, the heat is directed into the interior--solar heat for the children's area at zero cost. Energy-saving light bulbs and an on-site co-generation power plant round out the low-energy components.

The water concept includes the bath's own well for providing the water and an outdoor pool where the use of chlorine is not necessary because the biological water treatment methods allow reusing the water and reduce the amount of wastewater.

Aside from the technical planning, I was also put in charge of acquiring federal and state grants because the energy-efficiency measures had to be put on solid financial grounds. About ?1.7 million had to be invested to implement the proposed concept. In the end, several institutions committed to support the project, among them the local energy provider and the State of Lower Saxony. In early 2001, the now-called "aquaLaatzium" opened its doors for the first time and already has acquired a reputation for both its energy efficiency and its value for leisure. My duties have now shifted toward the optimisation of all operating devices and guided tours through the technical areas for interested experts and citizens.

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