Image Daniel Shipp

Adding plants to walls and roofs is all the rage in commercial property as a way to improve indoor environment quality. Now new research by RMIT and the University of Melbourne has quantified the effects of plants in the home – with an app developed to help users calculate the benefits of adding particular plants to a room.

The research looked at both the air quality and wellbeing benefits of plants by reviewing over 100 scientific studies from around the world, including NASA’s benchmark work on the benefits of plants in controlled indoor environments.

Dr Dominique Hes, director of the Thrive Research Hub at University of Melbourne, told The Fifth Estate the team considered a broad range of research because it was important that the findings could be applied across all types of geographies, climate zones and spaces.

“Spaceships are a very controlled environment,” she says. “We had to do the research for a real world context.”

The project arose out of a 202020 Vision campaign that canvassed ideas on how to achieve a goal of adding 20 per cent more plants to people’s lives.

Hes says the fact so many people voted for the concept shows there is a real appetite for having more plants around us.

The big issue was that there were “rumours around that plants are good for us” but no simple way for most people to access evidence-based information on why they are good, and how many, and what type, will deliver major benefits.

An app to help calculate benefits

An outcomes of the research, which was backed by Horticultural Innovation Australia, is an app that enables users to rate their rooms for air quality and wellbeing as they are currently, then add plants and have the benefits calculated.

Users can also gather some inspiration from seven different styling schemes for both indoor and outdoor spaces that will optimise wellbeing, created by landscape designer and founder/editor of The Planthunter, Georgina Reid. A list of chosen plants can then be emailed to take to a local nursery.

The website for the Plant Life Balance project also lays out the science on why plants are good for us.

The move to bring back nature

Hes believes some humans have lost touch with the benefits of having nature around because it has in the past been a threat – the source of plagues and epidemics, unsafe water or things might try to eat us.

“So we tried to keep it out of our lives.”

But in recent times the link between nature and wellbeing, including lower stress levels, feeling greater relaxation, improved cognition and enhanced productivity has become more appreciated.

“We have basically been one giant experiment on ourselves,” Hes says. “We only now realise nature is a critical part of our wellbeing.”

Plants inside also went out of style for some because they were seen as creating mess, collecting dust or because people “couldn’t keep them alive”.

The idea that a special “green thumb” is needed for gardening or keeping plants alive is not true, Hes says.

“You just need tenacity.”

Image: Daniel Shipp

A deep dive to give fine-grain results

The research team collected “a lot of data” in order to provide detailed guidance.

The research found that adding one medium-sized plant to a medium-sized space improved indoor air quality by up to 25 per cent. That is because plants filter out a range of pollutants including airborne particulate matter and airborne toxins, including volatile organic compounds (VOCs).

VOCs have been linked to health impacts including increased allergies, and also to bad moods and reduced productivity. They are present in carpets, paint and furniture in Australian homes, and research has shown their concentrations can be 10 times greater indoors than out.

“Based on the leaf area and the species’ ability to remove certain contaminants, we were able to calculate how many of our sample plants were needed to improve air quality and wellbeing in spaces of various sizes,” Hes says.

One plant in a medium-sized room will also make a minor contribution to wellbeing – but five plants of varying size, colour and leaf shape will improve air quality by 75 per cent and mental wellbeing by up to 60 per cent.

When you have 10 varying plants in the same space – there is up to 100 per cent improvement in both air quality and wellbeing.

Important for apartments

Using plants is important for people in apartments, Hes says, especially above the third or fourth floor where many windows only give a view of sky and city, not the green of natural landscape.

“It is critical from a wellbeing perspective.”

It is also important from an air quality perspective, she says, as many apartments are kept largely sealed up and relying on air conditioning.

Plants have even been shown to “grow fresh air” in a sealed space. Hes refers to a Ted Talk by Indian business owner and activist Kamal Meattle, who designed his New Delhi office park to rely entirely on indoor plants to improve air quality in the highly polluted city.

Hes says it is hoped the research and the Plant Life Balance campaign may also encourage more plants in buildings other than homes.

“What about prisons?”

She says studies have already shown that having a window and the ability to connect visually with the outdoors improves prisoner behaviour and chances of rehabilitation.

That is because nature is relaxing, allowing higher cognitive processes – like self-reflection, empathy and creativity – to function more effectively.

Hospitals are starting to get it, she says. Universities are also starting to bring in the plants.

It all comes back to our biophilic nature.

Hes says she relates the effect to having a good night’s sleep.

“A good night’s sleep helps you cope better with things. [Similarly] nature helps us function better.”

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