The residential tower blocks so prevalent in eastern Europe are known for consuming high amounts of energy. University of Kassel researchers have devised an economic way to make them energy efficient.
The prefab's future is looking rosier
Starting in the 1960s, virtually all new public housing projects in eastern Europe were pre-fabricated tower blocks. Millions of people continue to live in the buildings, which were built in an age when saving energy was low on the list of priorities. Now a group of researchers from the University of Kassel is doing their best to make the towers more environmentally friendly.
Engineer Hartmut Hübner and his colleagues have been working in Dunaujvaros, south of Budapest, to convert Communist-era high-rises into environmentally friendly housing. The high-rises aren't just inefficient in terms of energy consumption, they are also a potential source of social conflict, according to Hübner.
"Here in Hungary, as in other eastern European countries, heating costs are still subsidized," he said. "But that will change. And with rising energy costs, it'll be difficult for the people here to pay their heating bills."
In Germany, prefab high-rises are increasingly being demolished
The Solanova Project, of which Hübner is a part, has already succeeded in retrofitting a seven-story building in the small town. The biggest problem was that prefabricated components for the buildings no longer exist, so the engineers had to experiment with parts such as solar panels or energy-efficient windows.
"We've now tailored these components for a pre-fabricated eastern European building," said Hübner. "The process has to be completed in several steps. You have to see the interactions between the various components -- between windows on the northern and southern sides of the building, the ventilation system, the solar energy system. It took a lot of planning to develop a really integrated concept."
Before Hübner and Andreas Hermelink, who heads the project, got started, they discussed the plans with the building's residents. They determined that the low-energy technology only works if people understand and follow basic rules. So they began by asking what the residents wanted, and then attempted to fulfill those wishes as far as possible.
Most eastern European cities are surrounded, if not made up of, tower blocks
"To start with, we were pretty skeptical, because no one here knew anything about low-energy housing," said Piroschka Kanik, one of the building's residents. "Now everyone in the building is enthusiastic because we're saving so much energy and money."
The engineers installed a heat-exchanger and a fully automated ventilation system, which ensured a constant flow of fresh, temperate air. They also dealt with the problem of poor insulation by adding an extra insulating layer on the building's exterior and replaced aging windows with new, energy-efficient ones. Reflective Venetian blinds were put in between the double-glazed glass to keep the apartments from overheating in the summer.
Previously, the residents could only keep their apartments from becoming suffocatingly hot in winter by opening their windows, while the central heating ran constantly. So they had to learn to change their habits, too, as the new integrated ventilation system required that the windows remain closed most of the time.
Efficient and cheap
The engineers also installed a solar collector array as well as a central element in the basement to supply warm water and a special system to ensure that the energy delivered by the local power plant was used to optimum effect.
Solar energy is another key to the project's sucess
The engineers aim was for the building's overall energy consumption to be reduced by 80 percent. Measurements taken before and after the refitting showed that the converted building consumed about 20 percent of the energy it had previously and that it emitted almost no heat into the surrounding air. The low-energy renovation cost about 250 euros ($325) per square meter (11 square feet) of living space.
The feedback has been positive. Hübner and Hermelink were awarded the European Solar Prize by the non-profit European Association for Renewable Energy for the project in December. Meanwhile, a construction company in Dunaujvaros has been planning to refit several pre-fabricated high-rises along the lines of the team's model.
"The Solanova Project has shown that you can renovate prefabricated high-rise buildings affordably, and bring them up to standards in line with sustainability," said Hübner. "That should be our goal -- to refit entire complexes like we did this building, including the energy supply systems."