Ready for occupancy: It pays to live in the efficiency house!
If every homeowner produced his own energy, the supply would be secured in the long run. A new housing area in Friedberg-Hügelshart is the first to implement such a concept on a large scale.
The sun has long since set on this autumn evening, but its power still supplies the entire house – the sophisticated storage system makes solar power available even in the evenings. There is a rice pan on the stove in the kitchen, and more excess electricity is being used in the garage to charge the electric car – the vision of a home that produces more energy than those who reside there need, has become reality. This has long been technically possible, but there was one sticking point: economic efficiency. In cooperation with BayWa AG, Augsburg-based asset bauen wohnen gmbh has now managed to build an entire housing area in Friedberg-Hügelshart that is remarkable for its excellent energy balance and reasonable sales prices. The first homeowners have already moved in. They are pleased that the nine single-family homes and four semi-detached houses not only meet the Federal Ministry of Construction “Efficiency House Plus” criteria, but also produce enough electricity to feed what is not immediately consumed or cannot be stored into the public grid.
Green housing projects as the one in Hügelshart are setting the bar high in terms of energy efficiency. © BayWa AG
From model project to housing area
“It was a long way to the inauguration ceremony,” recalls Bernhard Jakob, asset bauen wohnen gmbh’s managing director. “One research project made it much easier: The Schlagmann/BayWa Efficiency House Plus in Burghausen, funded by the ‘Zukunft Bau’ [‘Future Building’] federal initiative. For two years, it provided important data that served as the basis for the houses in Friedberg-Hügelshart.” The result should be a new type of home. Its benefits for the tenants are a solid and energy efficient construction at a reasonable price. Different simulation szenarios were needed to find the most efficient and economic solution. At the heart of the houses is the photovoltaic system on the south side’s extended roof. In single-family houses, it consists of 44 solar modules and produces an average electricity yield of 14,200 kilowatt hours (kWh) per year. “This is considerably more than the families themselves consume,” explains Mr Jakob. “Their average demand is about 6,600 kWh.” But of course there are days when the sun does not shine. Provision is also made for them. “Some of the self-produced electricity charges a powerful storage battery,” Mr Jakob says. “An air-water heat pump, operated primarily with electricity from the photovoltaic system, moves the heat thus generated to interim storage in a thermal water tank.” The heated water is distributed through an air-handling ceiling in the house, heating the rooms. The heat thus comes from above as radiant heat, much like the sun’s. In addition, there is hardly any convection – that is, air turbulence familiar from conventional heating systems – which is a boon for allergy sufferers. If required, the ceiling can even cool the house. “The complex interaction is automatically controlled, which is very convenient for the residents,” Mr Jakob says with pride. All in all, the energy self-sufficiency reaches 70 percent, including electricity for the house and its inhabitants. “Their interests were at the top of the list in all areas. That is why we have taken into account all conceivable parameters for each house – from the quality of the floor slab to the overall economic analysis of the individual property to the foreseeable demand for household electricity associated with a family of four.”
Low-cost brick construction
This also includes the exterior walls. Such a system is efficient only if no energy is lost. The single-shell brick construction ensures that this is the case. “The stones have a core of natural volcanic rock, highly thermally insulating in itself, which requires no additional insulation,” explains Mr Jakob. “The windows are equipped with triple thermal insulation glazing. Energy efficiency is further enhanced by a ventilation system with heat recovery.” The appearance was also carefully considered: Thanks to the modern architecture that is also typical of the region, the houses are very attractive.
Healthy living as a model for the future
“We want people to really feel at home here,” Mr Jakob says. So he took another concern into account in his planning – health. Energy-efficient buildings are characterised by low air exchange rates. Heat – or cool air in summer – should remain in the rooms. As a result, toxins that can escape in small quantities from building materials may accumulate in the air. “We have avoided this by using only tested, low-emission materials,” Mr Jakob says. “We have each house tested by TÜV Rheinland and have the good values for residential health confirmed. The central ventilation system also ensures low carbon dioxide levels and pleasant room hygiene." On the bottom line, the flexible concept could serve as a blueprint for other settlements and buildings. Bernhard Jakob is convinced that Friedberg-Hügelshart will become a reference project for the future. The housing development has now been occupied, and the residents agree. The Bavarian State Secretary for Economic Affairs Franz Josef Pschierer is regarding the project as paramount: “A modern construction and cutting-edge technology as presented here in Hügelshart will have a special importance for the future of our energy supply.“