Developing Active Green Walls for Classrooms

University of Birmingham

This project is funded by the Royal Horticultural Society (RHS) and will pursue a multi-scale approach to establish the potential of active green walls to improve environmental quality in classrooms. Building on our recent work on indoor air quality (IAQ) impacts of single potted plants (Gubb et al., 2018-2022) and people’s preferences for plant shape/form and its impact on perceived wellbeing (Berger et al., 2022), we plan to establish the key performance parameters of more effective, active green walls. We will first carry out laboratory experiments to optimise the IAQ performance of different planting combinations joined in modular active green wall system. Research will use AQ instrumentation available at UoB and expertise in soil science to investigate how heterotrophic microorganisms in substrate affect pollutant removal e.g. via reduction of NOx to N2. Choices of plant combinations and design of the active green wall will also benefit from the industrial co-supervisor with extensive experience in award-winning green wall design, maintenance and application in the built environment. After identifying the most promising plant-growing media combinations and understanding contributions of various plant and substrate mixes to deliver particular purposes (e.g. plants with hairy/rough leaf surfaces for particulate removal; physiologically active plants for CO2/RH regulation), we will also optimise energy consumption of the active green walls by optimising light levels (using LEDs and exploring the limits of varying plants’ pairings to maximise light interceptions though combining light-leaved plants, and use of reflective surfaces). In addition, we will investigate the impact of lower temperatures (12-18 C) on plant function considering the predicted energy crises and winter-time temperature reductions of minimal temperatures in buildings.

For deployment of the optimised active green wall systems, we will use the RHS links to an extensive network of over 30k schools across the UK (who already participate in the RHS’s Campaign of School Gardening) with ongoing AQ work with within one partner school. This will allow us to move from model lab-based assessment to deployment of newly-developed, energy efficient, active green wall solutions. This will be integrated in the school curriculum (linked to teaching within KS4 Biology/Science and Geography) to ensure student and teacher engagement, co-design and optimisation of the green wall system based on the feedback from the students. Thanks to the links to industry and especially the direct involvement of the UK’s leading Living Wall company, our findings will be widely shared with the real possibility to develop an approach and/or product as direct project outcome.

Impact of project:

IAQ is of massive importance given we spend 90% of our time indoors in poorly constrained environments in particular when considering private homes and densely occupied environments. We will develop an energy efficient, active, indoor green wall – while we test specifically in schools, this wall can be deployed in any indoor location, so potentially has a wide impact. The fundamental insight gained in the laboratory part of the project will enhance our understanding of plant and soil science with potential wide impact for the indoor greening community in particular. Direct link to industry brings our project particularly close to application and substantially increases its chance to lead to commercially viable products: Kenneth Freeman is currently chair of the UK interior landscaping trade association, Plants at Work, and has connections with several of the world’s leading commercial interior landscaping companies and many of their customers – including early years education settings – through employment and consultancy work.

Details of the PhD project’s funder:

The Royal Horticultural Society (RHS) is UK’s largest and best-known horticultural charity. It prides itself on providing evidence-based practical advice to gardeners, but increasingly also to planners and policy makers on matters relating to landscape and environmental horticulture. Its Science Department hosts a vibrant cohort of PhD students. Outputs of the project will enable RHS to refine the advice it is able to provide via different channels, not least via its Campaign for School Gardening programme (which encompasses over 30,000 schools in the UK). The outputs of the project will feed directly into campaigns with the aim of launching post-project initiatives to increase the use of indoor planting in schools. The direct involvement of an industry partner, Biotecture, had been enabled by the RHS. Biotecture has worked specifically on the ability to harness the power of plants to mitigate for poor air quality and will provide expertise in terms of design, previous test results and data as well as test materials in the form of plants and living wall systems (

Relevant links:

Gubb et al, 2018-22:

Berger et al, 2022:

Person Specifications:

We are looking for an enthusiastic student with a 2.1 or higher BSc or MSc degree in the area of Environmental Science, Chemistry, Soil Science or related disciplines with a genuine interest in the relationship between plants, soils and the growing environment.

For informal enquiries, please get in touch with project lead Dr Christian Pfrang ().

To help us track our recruitment effort, please indicate in your email – cover/motivation letter where ( you saw this posting.

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