The study found that putting one plant for every six cubic metres provided the best air quality – which is around 29 plants per classroom.
The school’s sixth form centre, complete with money-plants, palms, moth orchids and cheeseplants, was recreated at the Chelsea Flower Show and the school was given a Gold Award for its research into how plants improve air quality and the cognitive and mental well-being of students.
Headteacher Suzie Longstaff said: “I am amazed! I run a school not a garden.
“In the post-Covid world wellbeing has to be the number one priority. The biophilic classroom improves the girls’ cognitive and emotional wellbeing. It makes them feel better and healthier. Oxygen levels and humidity increase. They think more clearly and are happier and calmer.”
Ms Longstaff is now advising other teachers on how to introduce more plants to their classrooms. The school has produced a leaflet listing plants that they use which can remove chemical vapours, are easy to grow and maintain and are more resistant to insect infestation and have high transpiration rates. They include the Dwarf Palm, or ‘hamaedorea elegans’, which produces oxygen and reduces carbon dioxide at night, and the Spider Plant or Chlorophytum comosum, which improves indoor air quality.
The school now has several hundred plants, which are looked after by students and staff. There is a watering plan for the holidays and during lockdown Ms Longstaff took a large number of them to her home to look after.
Biophilic design is an approach to architecture that seeks to connect people with nature.
Putney High School conducted its research with a firm of sustainability architects and an environmental consultant.