eDNA Method Allowed for Research on Bats in Cavity Wall Insulation

Insulating cavity walls is now easier thanks to the innovative research method eDNA. As of March 7, this method has been included as a recognized measure in the so-called Environmental Regulation. With the eDNA method, insulation companies can more effectively demonstrate whether bats are present in the cavity walls. The Minister of Housing and Spatial Planning and the Secretary of State for Agriculture, Fisheries, Food Security, and Nature state this in the letter to the House regarding the sustainability of the built environment, which was sent to the House of Representatives today.

The eDNA method allows for reliable year-round investigation of whether bats are present in cavity walls. If a negative eDNA test shows that there are no bats present, insulation can proceed without additional measures.

Bats often reside in cavity walls and use small openings to enter and exit. In doing so, they lose traces that contain DNA, such as skin cells and droppings. These traces are collected with a sponge or roller. They are then tested in a laboratory, which can demonstrate whether bat DNA is present or not. If no DNA material is found, insulation can proceed without additional measures.

If the eDNA test is positive, it means that bats may be present in the dwelling. To insulate the dwelling, a bat-friendly insulation method must be used to ensure that the animals are not killed or disturbed. Additional measures are taken. For example, insulation companies must install so-called exclusion flaps so that bats that may be present in the cavity wall can exit first. They must also adhere to the nature calendar to avoid disturbing the animals during the breeding and nursing season and hibernation. There are conditions associated with this requirements.

The eDNA regulation is a complement to the national approach to nature-friendly insulation, which works towards area-specific (pre)species management plans (SMPs). If there is an SMP, the use of the eDNA method is no longer necessary, as the nature-friendly measures have already been taken.

More information about the regulation has been published in the Official Gazette.