Moss covered surfaces are a promising way to mitigate the urban heat island effect. A layer of moss on a building’s façade reduces heat absorption during summer, hence passively cooling the building and its surroundings. The startup Respyre wants to offer such moss layers as a commercial product. A bio-gel mixed with moss fragments is sprayed on a porous concrete outer layer. This is irrigated for several months until the wall is covered by a layer of living moss.

The aim of this project is to rethink the existing irrigation system, since it gives a bad water distribution, resulting in high water usage and uneven moss growth.

First, the context was analysed. Literature study and an interview with an expert provided a better understanding of what role moss has in mitigating the urban heat island effect and what moss needs from a biological perspective. Further research revealed what solutions for providing moist already exist. A stakeholder analysis provided insight into who has something to say about the irrigation system. All these findings together resulted in a list of requirements.

During a brainstorm, a set of ideas was sketched to find as many out-of-the-box solutions as possible. This is a mix of new ideas, existing ideas found during the analysis, and combined ideas.

The brainstormed ideas that are feasible were developed into concepts. They were prototyped and their water distributing performance was tested by irrigating them in a green house. The concepts have been assessed on (among others) water distribution, estimated costs, minimum water pressure, ease of installation, and the need for developing new parts.

Five promising concepts were further developed and tested on a larger prototype. Their water distribution was quantitively tested, and costs estimated.

The finally chosen solution was further improved and detailed in the last stage. The end result is a design and prototype of an irrigation system that gives a slightly more uniform water distribution at a significantly slower rate for comparable costs.