SkinOver Reed – a skin made of grass _ a contribution to climate change

IBBTE - Institute for Building Material, Building Physics, Building Technology and Design, Faculty of Architecture and Urban Planning, University of Stuttgart

Project description

The objective is to research the appropriateness of reed as facade and roof cladding material especially in high altitude alpine regions. Reed grows fast, forms a valuable biotope, generates better water quality and provides home for multiple animals. The dead standing part of the plant is going to be replaced by new plants every year. Only this dead part oft he plant is going to be harvested and can be used as cladding material for facade and roof without any further treatment. At the end of life reed is compostable and closes the material life cycle. Reed - also known as thatch - is in every sense a sustainable, renewable, carbon neutral resource and seems to be a perfect alternative renewable material fort he building envelope: rapid growth, short process chain with low energy demand and emissions, perfect life cycle, no pollutants, proved over generations. After two years of research and project development at the Institute of Building Technology and Design IBBTE at the University of Stuttgart we built in August 2019 the first thatched project in high alpine surrounding close to Mannheimer Hut (2600m) in Vorarlberg, Austria. The building envelope has been realized in local thatch and wood by reducing metal connections as far as possible and all other materials. The building guarantees the water supply of the main hut and needed a new appearance. We decided to use the existing stone building as foundation for the new wooden structure to minimize the intervention into this sensible environment. The design needed to be simple and appropriate to location and use. The main focus should be on the material itself with its architectural and manual – technical coordinated details. The integration of experiences thatch craftsmen in an early stage of planning was essential to develop simple and appropriate details for the material involved. A team of craftsmen, students and faculty staff developed and built balanced together. But how did we get to this material? This was a very formal approach in the beginning. We realized that in their design work for a mountain hut the students attempted to design the full envelope – facade and roof – out of a single material to generate a monolithic design. So we researched in a following student workshop materials which could be used in this way. Besides stone, concrete, wood and metal we rediscovered the material thatch which allows a very three-dimensional design analog to concrete almost. This fascinated us right away and led to further research and the idea of building a prototype thatched envelope. We also researched contemporary thatch architecture and found beautiful strong examples in France, Denmark and Sweden, which acknowledged what we had investigated. We would like to thank all people involved for their courage, faith and trust. This summer (2020) we will be back at SkinOver project to monitor and document the first winter and its impact on the material. In the long term we plan periodic and permanent measurements to gain more knowledge of appropriateness and aging. Why should we win in the category architecture - Sustainable & Green? How can we reach the goals we set up for climate change? What are the materials we should chose for our buildings? Are there alternative renewable materials for the building envelope? Together with students we found a way to use a material which has been proven its resource efficiency over generations but has disappeared one day. This has been an exciting experience for the students to work with a 'new' but also 'old' material and transfer it to our modern world. Their enthusiasm made us as research staff go further and investigate how other renewable materials such as wood and clay may have found their way back into contemporary architecture. Which are the qualities that made them come back as building material and how can thatch 'learn' from these experiences and may re-enter our modern building industry. This could happen because of changing needs, focus on embodied energy and emission, good life cycle ability but also because of changing regulations, possibilities of prefabrication, etc. This enthusiasm and connecting people already let to the first LCA for thatch as insulation material and we will go on working on the qualities of thatch and hope that more architects will see the beauty of the material.