University of Surrey Research Reveals How Indoor Plants Improve Buildings

Most people spend far more of their day indoors than they may think. At home, in schools, workplaces and shopping centres, buildings are where the majority of our waking lives take place.

Research from the University of Surrey suggests that bringing plants inside offers benefits beyond visual appeal.

Indoor plants and sophisticated greening systems may enhance comfort and air quality, while also helping buildings respond more effectively to heat.

Researching indoor plant systems

Scientists have extensively examined outdoor trees and green spaces. Parks in cities and trees beside roads can lower urban temperatures and remove pollutants from the air.

Indoor planting systems, by comparison, have received less detailed attention. Researchers therefore sought firm evidence on the ways plants influence genuine indoor settings.

A wide-ranging investigation led by the University of Surrey’s Global Centre for Clean Air Research considered the issue in detail. It involved 35 specialists from the UK, Europe, USA, Australia, India and Brazil.

The international collaboration was carried out through the GREENIN Micro Network Plus project, which aims to improve indoor environments as the climate warms.

Comparing indoor greening systems

Researchers developed a framework of ten questions to assess the real effects of indoor plants.

It considered technical performance, microbiology, health impacts, social and economic considerations, and the importance of location. By taking this approach, the experts could assess indoor greening from multiple perspectives rather than concentrating on a single advantage.

The researchers compared 26 types of indoor greening system, ranging from ordinary potted houseplants to indoor living walls and hydroponic towers.

Living walls place plants across vertical surfaces. Hydroponic towers cultivate plants without soil, instead using water enriched with nutrients.

The comparison offered practical direction for building managers and designers, while identifying areas that still require further study.

How indoor plants cool and clean air

One important finding was especially straightforward: larger indoor planting systems can make a space feel up to two degrees cooler.

Although the temperature recorded by a thermometer may not change, the room can seem cooler and more comfortable. This may lessen the oppressive, stale sensation often experienced in warm rooms.

Plants indoors release moisture into the atmosphere. Dry conditions are frequent during winter and in air-conditioned buildings. As plants raise humidity levels, breathing may become more comfortable, and the additional moisture may ease dryness in the nose and throat.

Certain purpose-designed plant systems can also purify indoor air. They may reduce fine particles, which are small forms of pollution, as well as harmful gases called VOCs. VOCs can be released by paint, furnishings and cleaning products.

Yet these effects require thoughtful planning. Plant numbers, lighting and the wider design each have an influence. A carefully designed green system performs far better than several plants randomly positioned in a poorly lit corner.

Indoor plants and the indoor microbiome

The research also identifies preliminary evidence that indoor greenery could diversify the indoor microbiome. This microbiome consists of the microscopic organisms found in indoor air and on surfaces.

By bringing in microbes associated with natural outdoor surroundings, plants may support a healthier, more balanced indoor environment, though additional research is required to establish long-term health consequences.

The researchers highlighted shortcomings in earlier studies as well. A number of previous experiments involved unrealistic quantities of plants or small laboratory chambers.

These conditions do not represent actual homes, schools or offices. Future studies need to be conducted over longer periods in real buildings, where lighting, ventilation, occupancy and maintenance all affect the performance of indoor greening.

Placement and maintenance matter

“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,” said Professor Prashant Kumar, lead author of the study.

“Our collaborative work shows that indoor greening can make a meaningful difference in certain situations – not just to how buildings feel, but to how they cope with heat, humidity and pollutants.”

“But these benefits don’t happen by accident. They rely on using the right systems, in the right way, with the right lighting and maintenance.”

Indoor plants require careful planning

Achieving meaningful results depends on considered planning and ongoing maintenance. Without suitable lighting and regular care, plants may fail to survive or deliver their potential benefits.

“Treating greening as environmental infrastructure, rather than decoration, as well as filling substantial research gaps in the topic area, will be key to unlocking its full potential,” noted Professor Kumar.

This underlines an important point: indoor plants are not merely decorative features. Effective design, appropriate lighting and consistent care are needed if they are to provide genuine environmental gains.

Greener, healthier indoor spaces

“Indoor planting is a fantastic way to bring the benefits of plants, and people’s interaction with them, into urban homes, schools and any other spaces where nature is not easily accessible,” said study co-author Dr. Tijana Blanusa.

“This paper lays strong foundations by providing evidence of the conditions needed to achieve the greatest impact on air quality, wellbeing and more.”

Indoor plants cannot address every environmental problem on their own. Nevertheless, when professionals regard indoor greening as a significant element of building design, plants can contribute to healthier, more comfortable and more climate-resilient everyday spaces.