Low-carbon indoor greening helps cool, clean and cushion buildings, study finds
low-carbon is a growing focus for building design, and a new international study led by the University of Surrey's Global Centre for Clean Air Research (GCARE) finds that houseplants and engineered plant systems can raise indoor humidity, boost thermal comfort and help create healthier, more climate-resilient buildings. The analysis, published in Building and Environment, gives designers clearer guidance on which indoor greening systems actually perform in real spaces.
Low-carbon indoor greening and building performance
The review assembles evidence from 35 experts across the UK, Europe, the USA, Australia, India and Brazil through the GREENIN Micro Network Plus project and introduces a ten-question framework to evaluate indoor greening systems. The study compares 26 different indoor greening systems — from simple houseplants to living walls and hydroponic towers — and finds larger systems can make spaces feel up to two degrees cooler while improving perceived comfort even when air temperature stays the same.
What the researchers measured and what changed
Published in Building and Environment, the paper reports that some engineered plant systems helped reduce fine particulate matter and volatile organic compounds, though those effects depended on plant density, lighting and overall design. The authors also point to early evidence that greenery can enrich the indoor microbiome by introducing more environmentally derived microbes. The study cautions that past lab experiments often used unrealistic plant numbers or controlled chambers that do not reflect real homes or offices.
Design guidance, not decoration
Professor Prashant Kumar, lead author and founder of Surrey's GCARE, framed the findings around practical use: "People spend around 90 per cent of their lives indoors, but surprisingly, we still understand very little about how indoor plant systems can reshape those environments, " he said, adding that benefits rely on "using the right systems, in the right way, with the right lighting and maintenance. " That concrete admonition steers indoor greening toward environmental infrastructure rather than simple decoration.
The study’s ten-question framework covers technical, microbiological, health, socio-economic and place dimensions, giving building managers and designers a clearer picture of which systems are likely to deliver measurable improvements in air quality and comfort. By laying out evidence on 26 systems, the paper helps teams match plant density and lighting choices to desired outcomes.
Next steps: long-term, in-building trials
Authors call for long-term, in-building studies that consider lighting, ventilation, occupancy and maintenance — the practical realities that determine whether indoor greening performs over time. That next step is explicit in the paper: the research community must move from lab chambers to occupied buildings to test performance under real conditions.
For practitioners and policymakers focused on low-carbon building practices, the study provides an evidence-based starting point: it clarifies when indoor greening can cool spaces, reduce some pollutants and alter indoor microbial communities, and it specifies the conditions needed to do so. The confirmed next step is clear — field trials in real buildings that track lighting, ventilation, occupancy and maintenance over extended periods.
