Frankfurt: Capital of the Passive House | Darmstadt

In Frankfurt, the passive house has been used for 20 years. The trend is now towards the active house.

It was new, but not too experimental to try: Thirty years ago, the passive house standard revolutionized building. Suddenly living could be energy-efficient, yet comfortable and at the same time economical. What sounded too good to be true at the time will soon lead to a construction revolution in Frankfurt – and ultimately set a new standard. But is the model still up-to-date in the original sense? In the meantime, some people want to expand the concept in order not only to save energy, but also to generate it.

The warmth stays in

The passive construction concept, which is supposed to keep the heat inside a house through insulation, special glazing and a ventilation system, also uses incident sunlight, waste heat from electrical appliances and the body heat of the residents as energy sources. The heat does not have to be actively generated, but can instead be used purely passively. Ultimately, this can save 90 percent of the heating energy that a conventional building consumes. In the nineties, this way of thinking still caused disbelief and criticism, which, however, often turned out to be ignorance: It is now known, for example, that you can open the windows as usual and ventilate them. The remaining flaw: The construction-related additional costs compared to a conventional building. These would, however, be amortized over the service life and the saved heating costs, as Rosemarie Heilig (Greens) from the Frankfurt Environment Department replied to FR’s request.

In Frankfurt, public buildings have only been allowed to be built and refurbished as passive houses since 2007. This explains the increase in the usable floor space of the Passive House, from less than 100,000 square meters back then to almost nine times that value. Because the waste heat from the people who live and work in the buildings is used, the passive construction method is also suitable for public buildings such as schools, administrative buildings, fire stations and soon also for Europe’s first passive construction clinic – a total of 882,000 square meters in Frankfurt . The following applies: the larger a building, the better it can be implemented as a passive house.

The strong urban funding will soon bring Frankfurt the title of “Passive House Capital”. “What is certain is that Frankfurt has been in the top group for years,” explains Environment Secretary Heilig. Hamburg, Cologne and Nuremberg are now also promoting the energy-saving alternative to construction. However, according to Heilig, it depends on whether it is the absolute number of areas or the proportion of passive houses in the total building stock that counts. For Frank Junker, however, the case is clear: Frankfurt is still the passive capital of the republic. The managing director of the municipal housing association is one of the early supporters of the energy-saving house. ABG has been relying on the passive house standard for almost twenty years. ABG has built around 4,500 apartments, from social housing to owner-occupied apartments, all of these apartments correspond at least to the passive house concept. Junker also wants to dispel old prejudices. It is important to him to emphasize that this type of living does not require a complicated introduction: “These are perfectly normal apartments. There is a thermostat hanging next to the door, which residents can set as they wish. ”Operating instructions are not required. The housing association also strives for this normality when it comes to facades. “You shouldn’t stand in front of the building and think, Aha, this is a passive house! ‘”

generate energy

What is new is that one is breaking away from the much-vaunted basic principle of the passive house. Today, buildings should not only be as energy-saving as possible, they should also generate energy themselves. The city of Frankfurt has had photovoltaic systems installed on new public buildings since 2018, and since this year these have also been combined with green roofs. The ABG calls their project “Aktivstadthaus” – actually a passive house, to which, however, components such as a photovoltaic system and a waste water heat exchanger have been added. “Doing one does not mean leaving the other behind,” explains Junker. He still thinks the idea of ​​the passive house is good. They want to keep the basic principle. The distinction is also a conceptual subtlety: Environment Officer Heilig makes it clear that the expression active house actually means nothing other than that a building can meet its energy needs from renewable energy. A passive house is the ideal basis for this.

So even if new technology overtakes the original passive house in terms of energy balance and should be called an active house, one can only exist on the basis of the other. What once seemed revolutionary will, in this combination, also be the standard of urban construction in Frankfurt in the future.

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