Roosting bats and other protected species are holding up an insulation programme to make homes more sustainable, insulation sector organisation Venin has warned.

Some 2.5 million homes are set to be made more energy efficient in the coming years. However, the programme is likely to be delayed because of the presence of bats, swifts and sparrows and a lack of ecologists to evaluate the situation, Venin spokesman Piet-Jan Dijkstra told the Telegraaf.

Local councils and the provincial authorities are in a hurry to start, now that government money for the programme has been earmarked. Last winter’s high energy prices also mean insulation is a priority. First in line in the programme are 1.5 million homes with an E, F, or G energy label, followed by a million housing corporation houses.

“Local councils have to abide by the nature protection rules and that means the programme is coming under pressure,” Dijkstra said.

Finding out if the bats and other animals and birds are living in roofs and cavity walls will take a lot of time and there are not enough ecologists to do the job, Dijkstra said. With the number of experts now available, it could take from three to 17 years before the work can even start, he told the paper.

The cost of an investigation by ecologists triples that of the insulation itself, the association of local councils VNG told the paper.

“We are in talks with the government and the provinces to reach a pragmatic solution. We are thinking of checks which look at an entire neighbourhood rather than individual houses,” a spokesman said.

That approach is also favoured by the home affairs ministry.

However, it is unlikely a sweeping approach will find favour with ecologists who recently won a case against an insulation company in Utrecht which, local officials said, did not do enough to check for bats before installing cavity wall insulation.

That case is now being studied by the high court.

In the case of bats, for instance, builders usually insert a camera into a wall for a look around, but, ecologists say, that is not enough to exclude the possibility of bats having made their home there. To find out if bats are present, the wall cavity or roof has to be observed for many months, they argue.

“We have proposed putting up nesting boxes on public buildings. But we first have to see if bats and birds use them, and that will cause more delays,” Dijkstra said.