Distributed moisture and leakage sensing in buildings

The goal of the project was to demonstrate the technical and commercial applicability of an innovative idea for moisture and leakage measurement over long lengths and large surfaces in wooden buildings. The idea is based on an innovative cable design where the optical loss in the cable is made sensitive to moisture or water penetration. The project has investigated a prototype in a lab environment and came to the conclusion that the
technology is suitable. However, we also found that the sensor concept is currently not commercially applicable in the wood construction industry.

The results from the lab tests clearly show that it is possible to detect water. By using an Raman-OTDR it has also been found that it is possible to locate where water is in contact with the sensor. By showing that the loss es in the sensor do not significantly depend on the wavelength of the light signal we have shown that it is possible to use commercially available low-cost light sources and detectors.

We investigated the needs of a fiber sensor in wooden building constructions through site visits, but as the needs of a distributed measurement technology were judged to be minor in the wood construction industry at the moment, no further efforts were made to develop concepts for installation. The develop ment and testing of a sensor in a lab environment indicate that continued development of the sensor, possibly focusing on the detection of substances other than water, is very promising.