Reuse of rainwater in Roskilde

CLIMATE ADAPTATION

Rainwater in Roskilde

As part of an innovations project, our climate engineers will work with the recycling potential of rainwater flowing through rockwool. The idea is that green rockwool facades will collect, delay and rinse rainwater that can then be reused.

One of the project goals was to make the recycling of rainwater visible. Once rockwool has been installed on facades, it is possible to plant plants and give it a green appearance both functionally and visually. The idea behind the new concept is that the rockwool can rinse water from roofs when led from gutters vertically through a rockwool facade much like a coffee filter. Then, the water can be reused for things such as toilet flushes and floor-washing.

MOE’s climate engineers now need to document how long the rockwool’s capacity will last. Rockwool has a high porosity. However, because water is rinsed by removing minerals, it is essential to find out how long it will take for the filter to be filled, so to speak, and estimate how often the rockwool would need replacement.

Bioponds for biodiversity While rainwater occasions indoor activities, it is not a given that rain equals floor-washing. Thus, it is necessary to somehow store the water. For this purpose, the engineers are working with bioponds that would allow for biodiversity in small wetland areas. If kept in local ponds, the water would be of use while simultaneously remaining at disposal to domestic purposes. Bjørn M. Nielsen Project Director in Drainage & Climate explains:

Conceptually, the idea is that you should be able to see the water, point and say; here is the water that we will eventually flush down the toilet and it came from this roof here. It is about showing part of the water’s cycle to challenge the idea that rainwater is something that should simply disappear.

Rockwool has great potential compared to the material's relative simplicity because it is possible to attach it to all facades with an exterior drainpipe. Additionally, it is easy to replace every five or ten years, depending on how long the rockwool remains efficient. In all regards, the method gives rise to a greater recycling of rainwater than what is seen today.

Most people expect rainwater to go down a drainpipe and run off this is a waste of water as a resource. We now help develop methods that make the recycling process a lot easier, more accessible and financially advantageous. The recycling of rainwater is something that we will be seeing a lot more of in the future.

Bjørn M. Nielsen Project Director Drainage & Climate Copenhagen

The innovation project Client Roskilde Kongrescenter, CORO Co-lab Roskilde and Fors A/S Collaborators The Technical University of Denmark (DTU), Bacticon, Rockwool and ARK LAND.