A wetland roof is a green roof with a rich variety of hydrophilic plant species that are otherwise only known as pond edge vegetation, e.g. purple loosestrife, marsh marigold, water irises, rushes and sedges, etc. - and not with drought-resistant succulents as in extensive standard green roofs
Contrary to a regular green roof, a wetland roof is equipped with a permanent irrigation system during the summer months: Rainwater from the roof or yard areas is collected in a cistern and pumped back to the roof at temperature-dependent intervals, programmed in terms of time and quantity (irrigation computer). A large part of the supplied water evaporates - and cools the roof by radiation cooling, evapotranspiration and convection - excess water flows back into the cistern via the gutters.
The marsh plants (helophytes) are usually precultivated on a water-storing vegetation carrier mat for at least one year before they are installed on the pitched or flat roof.
Some of our application examples and references you will find under the following downloads:
Download 1: Wetland roofs, a versatile and innovative type of green roof
Download 2: Realized wetland roof in Zofingen, Switzerland
Download 3: Wetland Roof in Jena, Germany
Our latest publications on this topic are:
Blumberg, M. (2020): Wetland roofs -a multifunctional green roof type - Basics and perspectives from engineering practice. Long version presentation "Closed Cycles and the Circular Society", Symposium in Wädenswil, Switzerland, 2. - 4. September 2020. Organizer: Zurich University of Applied and International Ecological Engineering Society (IEES). www.researchgate.net
Zehnsdorf, A., Willebrand, K. C. U., Trabitzsch, R., Knechtel, S., Blumberg, M., Müller, R. A. (2019): Wetland roofs as an attractive option for decentralized water management and air conditioning enhancement in growing cities - A Review. In: Water 2019, 11(9), 1845; https://doi.org/10.3390/w11091845.
Zehnsdorf, A., Blumberg, M., Müller, R. A. (2018): Helophyte mats (wetland roofs) with high evapotranspiration rates as a tool for decentralised rainwater management – process stability improved by simultaneous greywater treatment, Water Science and Technology: Water Supply, December 2018.