Bat research in cavity walls with eDNA
The growing focus on sustainable construction and the legal obligations that come with it are clear. However, sustainability in construction doesn't always align with nature conservation. Take, for example, the insulation of cavity walls—a highly sustainable practice, but one that poses a serious threat to the protected bat. These creatures often nest in the cavities between walls.
It is mandatory to conduct thorough research to determine the presence of bats in cavity walls before any sustainable construction work begins. SGS has developed a new, innovative technique for detecting bats using Environmental DNA (eDNA).
Since March 7, 2025, eDNA research has been officially recognized as an approved method under the Dutch Environment and Planning Act (Omgevingswet). This technique enables the rapid and efficient detection of bats through DNA traces, without disruptive field visits.
eDNA research: faster and more efficient
This revolutionary bat research method based on eDNA is much faster and more efficient than traditional bat surveys and can be conducted year-round. Traditional methods typically involve multiple days of field visits by an ecologist to observe the bats, often using sound detectors capable of capturing the ultrasonic sounds bats produce. However, this type of research can only be performed during the months when bats are active and flying.
Benefits of eDNA bat survey
- Fast, time-saving, and cost-effective.
- Identifies bat species without direct observation or disturbance.
- Enables quicker execution of renovation and cavity wall insulation projects.
How does an eDNA bat survey work?
A bat survey always includes sampling and laboratory analysis. Based on the results, additional research or mitigation measures may be required.
- Sampling: specially prepared rollers are used to collect samples under roof edges and around entry and exit points.
- Analysis: samples are analyzed in our laboratory for bat DNA using the qPCR method. This determines whether bat DNA is present and whether it concerns common pipistrelle, serotine bat, or other (rare) species.
- Species identification: if bat DNA is detected, further analysis using metabarcoding can precisely identify the species. It can also reveal the presence of other animal species (such as house sparrows or swifts).
How does traditional bat research work?
Traditional bat surveys are carried out by ecologists and typically involve multiple field visits. Detection is based on direct observation and acoustic monitoring using bat detectors that capture ultrasonic sounds.
This method is only possible during the active season (April to September) and often takes several months to complete.
What if bats are detected?
If the result is positive (bat DNA detected, then insulation can not proceed under standard procedures. The property owner must apply for an environmental permit and often carry out additional ecological research. In case of a negative result, then you can proceed with insulation without additional measures.
Our services
SGS Search offers a complete service for eDNA bat research, including:
Full service
We carry out the entire process—from sampling to analysis—through certified specialists (in accordance with BRL 5110).
Self-sampling option
Certified insulation companies can perform sampling themselves. SGS supplies the required materials and conducts the laboratory analysis.
To support this process, we have developed a free application that enables fast and efficient registration and analysis of results. Test results are typically available within a few days.
Training: eDNA bat sampling
To ensure high-quality research, SGS offers a dedicated training program. Participants learn about bat species, behavior, and how to collect eDNA samples in a standardized and reliable way.
Frequently asked questions
What does a bat survey cost?
Costs depend on the method and building type. For residential properties, a full eDNA bat survey with qPCR analysis typically costs between €250 and €400. Traditional ecological surveys are generally 5 to 10 times more expensive.
How long does a bat survey take?
An eDNA-based survey takes up to two weeks and can be carried out year-round. Traditional surveys typically take around five months.
When is a bat survey mandatory?
A bat survey is mandatory for any building modifications that may disturb or harm bats, such as renovation, demolition, or insulation works.
Want to know more?
If you would like more information about eDNA bat surveys or the sampling protocol, please contact us.
