Greenhouse gas emissions continue to rise due to the construction and operation of buildings and the increasing surface sealing of urban areas is contributing to urban heating and the loss of biodiversity. One approach to tackling these challenges is large-scale façade greening.

»Façade greening has a beneficial effect on the urban microclimate. It complements the thermal building envelope and can be used to retain rainwater. It can even be used for water treatment. In addition, they also provide new habitats for plants and insects«, explains Maria Hartmann from the Bauhaus-Universität Weimar. Researchers in Weimar are taking an innovative approach to watering the plants: Slightly contaminated wastewater, for instance from showering, bathing, hand washing, or laundry, is treated using an integrated cleaning substrate and reused for irrigation. Suspended moveable photovoltaic elements generate energy and protect the plants from heat, wind, and heavy rain. 

A prototype of the vertical climate treatment plant, or »VertiKKA«, has been operating in Weimar since September 2024. Long-term testing under real conditions is intended to optimise the cleaning performance and development of the system’s technology. The research is being carried out as part of the »GrayToGreen« project launched in 2025 by junior researchers Maria Hartmann and Gloria Maria Kohlhepp through the Building Physics Professorship and the Urban Water Management and Technologies for Urban Material Flow Utilization Professorship. Gregor Biastoch from the Professorship of Resource Management is also carrying out a comprehensive life cycle analysis and analysing the wastewater for microplastics.

Alongside the Bauhaus-Universität Weimar, the »IAB-Institut für angewandte Bauforschung Weimar« is involved in the project. The project is receiving funding from the European Social Fund Plus as part of the State of Thuringia’s »Thüringen MOTIVation« programme. 

GrayToGreen Reallabor: Decarbonising Through Energy Efficiency and a Circular Economy 

Project Management:
Bauhaus-Universität Weimar
Faculty of Civil and Environmental Engineering
Prof. Dr.-Ing. Conrad Völker, Dr.-Ing. Hayder Alsaad (Professorship of Building Physics)
Prof. Dr.-Ing. Silvio Beier (Professorship of Urban Water Management and Technologies for Urban Material Flow Utilization)

Cooperation Partners:
»IAB-Institut für angewandte Bauforschung Weimar« non-profit GmbH
Dipl.-Ing. Robert Fetter

Funding Amount: 
765,750.56 euros 

Funding Organisation: 
TAB (funded by the Free State of Thuringia through the European Social Fund Plus) as part of the »Thüringen MOTIVation« programme

In case of questions, please contact Maria Hartmann, Bauhaus-Universität Weimar, Professorship of Building Physics, via e-mail: maria.hartmann[at]uni-weimar.de or by phone at: +49 (0) 3643/584849. 

Greenhouse gas emissions continue to rise due to the construction and operation of buildings and the increasing surface sealing of urban areas is contributing to urban heating and the loss of biodiversity. One approach to tackling these challenges is large-scale façade greening.

»Façade greening has a beneficial effect on the urban microclimate. It complements the thermal building envelope and can be used to retain rainwater. It can even be used for water treatment. In addition, they also provide new habitats for plants and insects«, explains Maria Hartmann from the Bauhaus-Universität Weimar. Researchers in Weimar are taking an innovative approach to watering the plants: Slightly contaminated wastewater, for instance from showering, bathing, hand washing, or laundry, is treated using an integrated cleaning substrate and reused for irrigation. Suspended moveable photovoltaic elements generate energy and protect the plants from heat, wind, and heavy rain. 

A prototype of the vertical climate treatment plant, or »VertiKKA«, has been operating in Weimar since September 2024. Long-term testing under real conditions is intended to optimise the cleaning performance and development of the system’s technology. The research is being carried out as part of the »GrayToGreen« project launched in 2025 by junior researchers Maria Hartmann and Gloria Maria Kohlhepp through the Building Physics Professorship and the Urban Water Management and Technologies for Urban Material Flow Utilization Professorship. Gregor Biastoch from the Professorship of Resource Management is also carrying out a comprehensive life cycle analysis and analysing the wastewater for microplastics.

Alongside the Bauhaus-Universität Weimar, the »IAB-Institut für angewandte Bauforschung Weimar« is involved in the project. The project is receiving funding from the European Social Fund Plus as part of the State of Thuringia’s »Thüringen MOTIVation« programme. 

GrayToGreen Reallabor: Decarbonising Through Energy Efficiency and a Circular Economy 

Project Management:
Bauhaus-Universität Weimar
Faculty of Civil and Environmental Engineering
Prof. Dr.-Ing. Conrad Völker, Dr.-Ing. Hayder Alsaad (Professorship of Building Physics)
Prof. Dr.-Ing. Silvio Beier (Professorship of Urban Water Management and Technologies for Urban Material Flow Utilization)

Cooperation Partners:
»IAB-Institut für angewandte Bauforschung Weimar« non-profit GmbH
Dipl.-Ing. Robert Fetter

Funding Amount: 
765,750.56 euros 

Funding Organisation: 
TAB (funded by the Free State of Thuringia through the European Social Fund Plus) as part of the »Thüringen MOTIVation« programme

In case of questions, please contact Maria Hartmann, Bauhaus-Universität Weimar, Professorship of Building Physics, via e-mail: maria.hartmann[at]uni-weimar.de or by phone at: +49 (0) 3643/584849.