Indoor plants can improve comfort and air quality, new study shows

A University of Surrey-led review published in Building and Environment evaluates indoor greening systems and reports that larger installations can make spaces feel up to 2°C cooler and that some engineered plant systems can reduce PM2.5 and VOCs.

Researchers at the University of Surrey's Global Centre for Clean Air Research published a comprehensive review in Building and Environment that examines how indoor plant systems affect indoor environments. The team created a ten-question framework to assess technical performance, microbial interactions, health effects, socio-economic aspects and spatial factors. The review covers small houseplants as well as larger systems such as hydroponic towers and living walls. Authors note the topic is timely as climate change and declining outdoor air quality increase the importance of indoor environmental quality. Key findings: - Larger indoor greening installations can make spaces feel up to 2°C cooler through evapotranspiration, without changing measured ambient temperature. - Some engineered plant systems, when designed with appropriate density and lighting, showed measurable reductions in fine particulate matter (PM2.5) and volatile organic compounds (VOCs). - Indoor plants may introduce environmental microbes that increase microbial diversity indoors, with potential implications for immune-related health outcomes. - The review was produced by an international team of 35 researchers under the GREENIN Micro Network Plus project and was funded by the EPSRC. - The authors caution that many previous studies used artificial settings and call for long-term, in situ studies and clearer design and maintenance guidance. Summary: The review presents indoor greening as a multifaceted approach that can influence humidity, thermal perception, pollutant levels and the indoor microbiome. Translating these observations into routine building practice will rely on deliberate design choices, maintenance strategies and further long-term, real-world research. The ten-question framework is offered as a tool for researchers, designers and policymakers to guide future studies and practical applications.