In order to achieve its climate targets, the German government has advised homeowners to reduce their energy consumption. Most are responding by insulating their building façades with polystyrene panels.

By Julian Kuper

Steeplejack Benjamin Seider (right) and Thorsten Nitzsche are fighting against the damages caused by woodpeckers.

Benjamin Seider is making sure that Helga Zemke can once again sleep in peace. The steeplejack leans his ladder against the wall of the house, grabs a green haul bag full of wool insulation, and climbs up towards the gutter. Just below the roof he finds a gaping hole, 20 centimetres in diameter and so perfectly round that it looks like it must have been made with a pair of compasses. This is the second time that the woodpecker has pecked a hole in the façade of this building, and it regularly returns to continue with its work. The noisy bird has been the cause of many a sleepless night for tenant Helga Zemke. “I kept hearing knocking, but when I went to the door there was nobody to be seen,” says Helga. She explains how it was only after days of this annoying tapping that she spotted the woodpecker sitting outside.

The block of flats in Erpmannstieg, Hamburg, is an easy target for the woodpecker, as the outer wall is covered in a polystyrene-composite thermal insulation system. This is the cheapest and therefore most widely used insulation method in Germany. These panels, made of insulating material, mortar, fastening elements and plaster, ensure that less heat is lost through the walls of the house, saving energy for the homeowners who invest in it. But the panels also attract woodpeckers, as they sound very similar to the dead, hollow wood where the birds are used to making nests and looking for insects. The fact that woodpeckers are now hunting for food in these insulation panels also shows that their natural habitat is disappearing. “The city is prettying up all of its green areas, so rotting or dead wood is immediately removed,” says Torsten Nitzsche, head of company Ropeworx. Sometimes he and his employees come across holes where their arms could vanish up to the elbow.

These holes are a serious problem for the insulation systems. Either animals like squirrels or blackbirds will move in, or the hole will remain empty and fill up with rain water. As a result, the building façade and the plaster will get wet inside, and then, when it freezes, the wall will no longer be able to expel the moisture and could crack.

Currently, Nitzsche’s company repairs somewhere between 150 to 200 woodpecker holes a year. This number is growing, as there is high demand for thermal insulation in Hamburg. One reason for the demand is the city’s large number of old houses. “The numerous old buildings from the post-war era are in an especially poor condition from an energy point of view,” says Edgar Badenius, an expert on heat insulation with Hamburg’s city government. Around 900,000 flats in Hamburg are in older buildings, and only a third of these have medium to good insulation systems; the rest are either poorly insulated or have no insulation system whatsoever.

“He only knocks when I’m at home.” Helga Zemke, tenant

Saga, Hamburg’s biggest housing association, has already equipped almost 60 percent of its 130,000 properties with a thermal insulation system, either of polystyrene or mineral wool. Between 1990 and 2009 these measures lowered the properties’ energy consumption for heating by 39 percent. Heat insulation expert Badenius agrees that insulation is an easy way to make existing buildings more energy efficient. Efficient thermal insulation is also one of the key points in the federal government’s energy concept, drawn up in 2010. Germany’s Reconstruction Loan Corporation (KfW) is supporting investments in improving energy efficiency by providing grants and low-interest loans. This financial support also goes towards the thermal insulation of exterior walls.

However, these polystyrene panels are facing increasing criticism. Although they are certainly cheap and offer good insulation, if tenants do not air their flats well, they can lead to mould or a build-up of lichen on the exterior wall. To avoid this, tenants must either radically change their ventilation behaviour or install a heat exchanger, which consumes a lot of electricity.

Benjamin Seider cuts the insulating block to size, fills in the gaps with grout, and the woodpecker’s hole is sealed. But these repairs are not covered by insurance.

And mould is not the only problem. Polystyrene does not catch fire easily, but when it does, it burns ferociously. “I imagine this will lead to some fatalities in the future,” says Heinrich Stüven, chairman of the Hamburg landowners’ association. The integrated fire barrier should restrict the flames, but Stüven claims it is insufficient. He is also sceptical about whether the material really lasts between 20 and 30 years, as the manufacturers promise. And when the thermal insulation reaches the end of its lifespan, what do we do with it then? Polystyrene is hazardous waste, so disposing of it is a problem, not least because the individual components have to be separated first. “We clearly need good insulation systems for our homes, but the systems we currently have in place are not properly developed,” says Stüven. He hopes that these insulation systems will evolve considerably in the next few years.

Steeplejack Benjamin Seider prefers to trust his own judgement. He picks up a small saw and cuts a rectangular shape around the woodpecker’s hole. Flakes of white polystyrene flutter to the ground. He then fills the resulting hole with mineral wool from his sack to restore the insulating properties, and closes it up with a ready-made insulating block. Ten minutes later, the wall is fully sealed. Whether or not it stays that way remains to be seen; woodpeckers are keen-sighted and intelligent birds. Ropeworx manager Nitzsche says woodpeckers tend to be very territorial – once they have found an appropriate habitat, they stay put. And it would seem this particular woodpecker has decided that insulated houses are its ideal pecking ground.



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