Darmstadt: The world’s first passive house is celebrating its birthday

  • fromClaudia Kabel

    conclude

30 years ago, Wolfgang Feist developed a house that protects the climate. Today the idea from Darmstadt is spread all over the world.

In Darmstadt, Wolfgang Feist developed and built the world’s first passive house 30 years ago. The energy-saving pioneer still lives with his family in the row house in Kranichstein today. Since there is still an anniversary coming up – the 25th International Passive House Conference, initiated by the Passive House Institute (PHI) in Darmstadt, is currently underway – Feist is too busy to present his house to the Frankfuter Rundschau. He is the director and founder of the institute, which now oversees the construction of passive houses all over the world.

But there are other passive houses very close to Feist’s house. One of them belongs to Berthold Kaufmann, a research assistant at the Passive House Institute. Visually, his house is no different from other houses in the K6 residential area in Kranichstein: It looks like an ordinary terraced house. But it floats on a 20 centimeter thick plate made of polystyrene, is actually wrapped in a 25 centimeter thick layer of insulating material and has no heating in the conventional sense. “Our cellar is 20 to 22 degrees warm in summer and winter,” says Kaufmann. It doesn’t have to heat until the end of October or the beginning of November, and only to a small extent.

He points to a small white box below the ceiling: Fresh, filtered air from the outside constantly flows out of the ventilation system. This is warmed up in the heat exchanger in the basement by used exhaust air. If this is no longer sufficient, district heating is used. He says he only uses one and a half liters of heating oil per square meter per year. An old building needs ten times as much

When Wolfgang Feist implemented his idea together with three other clients in 1991, he was laughed at by many. The necessary components, such as insulated and triple-glazed windows, had to be specially made.

Since then, the idea of ​​a completely packed house without cold bridges, which saves 90 percent of the heating energy of a conventional house, has spread around the world: the PHI has so far certified 29,000 residential units worldwide. The database lists 79 passive houses in Darmstadt and 46 in Frankfurt – many of them multi-storey residential buildings. Certification is not mandatory. Builders can have it carried out in order to receive funding or to ensure that everything has been installed perfectly and works, says Kaufmann.

Build and renovate

The passive house is the consistent further development of the low-energy house: The unnecessary heat losses through walls, roofs and windows are reduced to such an extent that the heating becomes completely insignificant; only around 1.5 liters of heating oil equivalent per square meter per year are required.

A well-planned passive house According to its inventor Wolfgang Feist from Darmstadt, the investment is not significantly more expensive than a conventional house.

The insulation materials used such as polystyrene, fiberglass, cellulose or rock wool are considered recyclable and non-toxic. Even polystyrene, which is made from crude oil, has a good CO2 balance in the form of insulating material, since a passive house saves more CO2 over its useful life of 50 to 100 years than simply burning crude oil.

Corononatauglich is the passive house thanks to its ventilation system: unlike mobile air purifiers, the room is permanently supplied with fresh, filtered outside air.

Construction information and the renovation according to the passive house standard is still available until September 16 at the passive house exhibition, which is currently accessible free of charge to everyone at: https://passivehouseconference.expo-ip.com/

Infos about the 25th International Passive House Conference and the presentation of the Passive House Award at: https://passivhaustagung.de

Passive houses are currently massively funded. The funding programs of the State of Hesse can be found at www.energieland.hessen.de/foerderung. Federal funding can be found at: https://www.bafa.de

View Passive houses can be found on the open days from November 5th to 7th, 2021. The organizer is the Passive House Institute, which also advises and informs: https://passiv.de cka

Sometimes the ventilation system, which also serves as heating, has to be readjusted until it works properly, explains Kaufmann. As the efficiency of the passive house is being further researched, its house is equipped with sensors that monitor the functionality.

A prejudice that is often mentioned is that you should not or cannot ventilate a passive house. Not true, says the physicist: “The windows can be opened like in a normal house. Our windows are open in summer. ”In winter, if necessary. Ventilation is not necessary, but it is also not prohibited. Even if you open the window for half an hour when it is below zero, the room heats up again just as quickly afterwards. This is due to the surfaces, which thanks to the good insulation of the walls do not cool down so quickly. With the development of the first passive house, Feist, who was then working at the Institute for Living and Environment (IWU) in Darmstadt, wanted to tackle the problem of energy consumption at the roots, as he says. Because a third of our consumption is spent on heating. With the consistent use of passive houses, one could enormously advance the achievement of the CO2 saving targets.

Nevertheless, only one percent of the building space is energetically renovated every year, complains Michael Hörner, energy consultant at the IWU. It makes little difference whether a house is renovated or built according to the passive house standard or according to the standards of the low-energy house KfW-40. “You save a similar amount of energy,” says Hörner. In contrast to a passive house, a low-energy house has no ventilation with heat recovery and is less well insulated. But it complies with the energy saving ordinance.

The declared goal of the city of Darmstadt is to build new municipal buildings in accordance with the KfW 40 standard with passive house components. The crux of the matter: “Climate protection is not decided in the new buildings, but in the existing buildings,” says Hörner. Now old buildings urgently need to be renovated in a climate-friendly manner. And this is also possible according to the passive house standard. The IWU building on Rheinstrasse is an example of this: the owner, Stadtische Bauverein AG, has been persuaded to implement this. Although the attempt was successful, it unfortunately stuck to this single example.

The city’s Climate Protection Advisory Board, of which Hörner is a member, is currently also concerned with this topic. It is true that the current coalition agreement between the Greens, CDU and Volt stipulates that they will become climate-neutral by 2035, “but more should be done and faster,” says Hörner. “The city government must now let more ambitions flow into the implementation.”

Energy-efficient construction and renovation are currently being subsidized by the federal and state governments with up to 45 percent of the costs. “Anyone who does not call up the subsidies now is giving away money.” Because, Hörner is certain: The heating costs will rise drastically in the future due to the rising CO2 taxes, so that the slightly higher investment costs for a passive house would be worthwhile. According to Kaufmann, you have to reckon with additional costs of 100 euros per square meter for new buildings and 150 euros per square meter for renovations. Kaufmann also insists that housing associations in particular should start building passive houses.

Berthold Kaufmann can see how much the outside air is heated in the cellar.

© Michael Schick

Passive houses can also be ventilated normally, as Berthold kaufmann demonstrates.

© Michael Schick

Construction elements of the wall insulated with cellulose and fiberglass and a window with triple glass.

© Michael Schick

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