Putting the science of biophilic design to the test: why does wood equal wellness?

We’ve recently been writing about the benefits that wood in our built environment can have on our wellbeing, emotions and productivity. But what is the science behind these claims?

We’ve recently been writing about the benefits that wood in our built environment can have on our wellbeing, emotions and productivity. But what is the science behind these claims?

To understand why wood lowers stress and enhances wellbeing and productivity, we spoke to Bill Browning, a founding partner at Terrapin Bright Green and one of the leading practitioners and researchers in this field.

What does Terrapin Bright Green do?

Terrapin Bright Green is a research and consulting firm focussing on green building practices. We are interested in biomimicry, innovation inspired by nature, and in how buildings impact people both physiologically and psychologically and how that translates into productivity and economics. Our work on productivity is focused around the field of biophilia, the human connection with nature.

How do you define biophilia?

I will paraphrase Ed Wilson from Harvard because he’s the one who gave us the working definition. It’s an innate connection to nature that has definite psychological and physiological results or impacts. Biophilic design is translating those experiences of nature into the built environments.

When did your interest in biophilia begin?

In the mid-90s we were collecting case studies for a book on green real estate. We kept coming across impressive improvements in worker productivity, in sales per square foot, drops in defect rate in manufacturing, faster sorting speeds in mail sorting facilities. These were serious case studies that really contradicted the notion that the only way you get gains in productivity is to change how you manage people. The buildings themselves were clearly leading to the gains in productivity. We gathered the case studies together and published Greening the Building and the Bottom Line, one of the first papers about productivity in green buildings.

Then at the Rocky Mountain Institute, we went on to support a US Department of Energy study on furniture manufacturer Herman Miller who was moving a 700-strong workforce from a windowless box to a new factory that was beautifully daylit with views out onto a restored prairie. The study showed significant gains in productivity on the day shift and none on the nightshift. We worked with Judith Heerwagon, an environmental psychologist who is now at the US General Services Administration as an expert on green buildings and is a professor at the University of Washington in Seattle. She introduced us to the concept of biophilia.

How has awareness of biophilia grown since then?

There’s a growing interest. It was named as one of the top trends in hospitality design for three years, there’s a growing interest in the commercial architecture world and very strong interest from the tech firms. We are part of a team that developed the biophilic design standards for Google’s spaces and campuses worldwide, a version of which is now available to download from the International Living Future Institute website.

During COVID, we saw that many people got an intuitive sense of how important connections with nature are because they were stuck in the same space for a year or maybe two. So, during that timeframe, we have seen a huge acceleration in interest and in the work coming in too. We’ve even seen biophilia mentioned in adverts for furniture and interior design – it is becoming common parlance.

Can you summarise the findings in your latest paper, The Nature of Wood?

We wanted to explore why we seem to prefer wood. There has been a fair amount of research on this going back to the 1970s and strong body of evidence for a preference for wood over other materials. We wanted to look at what evidence was out there and find the science that explained why we respond to wood in this way.

We looked at all the senses including our visual responses to wood; our haptic responses to touching wood and the way it feels; and the smell of wood and its impact on us, for example some woods have a very distinctive scent. To date there is very little research available on our acoustic response to wood.

The research showed that typically our strongest response is due to our visual processing. Work done by the neuroscience team at the Salk Institute in California examined how we visually process collinear patterns, like those found in the grain in wood. The research shows that with a surface where the pattern is collinear and the lines are moving roughly in the same direction, it is much easier for the brain to process. One set of neurons process the lines in one direction but if others move in another direction, a different set of neurons processes it. So, if I have a surface where the pattern is moving roughly in the same direction is much easier for the brain to process. Anytime it takes less effort for the brain to process something, you get a positive response.

The brain is also constantly looking for patterns so while some timbers may have a very fine grain made up short segments of lines, the brain will find the contours and connect the lines together.

We also looked at fake wood and found that it can have the same effect, but as soon as the brain sees a repeating pattern it realises the material is not natural. Natural wood also has a different response to light than replicas. Because it is cellular, the light penetrates the top layer and then gets scattered so that, if I change the angle at which I am viewing wood, the way it looks changes in a way that none of the replicas do.

A second element which is to do with the larger processing elements in the brain is called associative or semantic processing. This is where the brain subconsciously associates wood with trees and nature. We think that our response to wood is probably a combination of the above.

Is there more research to be done?

We’d like to see more work done on our fractal response to wood. We have previously done papers on fractal patterns which are visual, mathematically repeating patterns. These can be sometimes exact, sometimes not, like the dappled light under trees, the flames in a fireplace, or the repeating pattern in a snowflake. These patterns are so prevalent in nature that when we see them in human-designed objects, it’s much easier for the brain to process so the neuroscientists actually call that fractal fluency. And that lowers our stress and makes us happier as beings.

We would like to see a fractal analysis done of wood patterns to see if we get the same fractal response in the brain. We expect it would be the case but would love to see that research formally done. In addition, we would love to see an extension on the work on collinear patterns and the neural processing around that.

Will net zero goals, sustainability or wellbeing effects due to biophilia drive changes in design?

All of the above. It’s a confluence of factors. As we become more aware of carbon, we can see that using mass timber for larger structures can lead to a negative carbon footprint; buildings that are sequestering carbon rather than creating a big carbon debt. But we are also getting more evidence about why people love being in environments constructed of wood and the benefits of that.

For instance, Portland International Airport chose wood for a floating canopy that stretches over a 44,000 m² area for several reasons: it will resist a Richter 9 earthquake which the airport is likely to experience due to its location; there are strong cultural and economic reasons to use wood in the state of Oregon; and the authority wanted to use biophilic design to lower the stress levels of passengers as they came through the airport.

What would fast-track biophilic design into the mainstream?

We are really trying to promote the fact that biophilic design should be for all market segments, for everybody, for all ages. It can improve productivity in offices and factories, it can positively impact on medical care and it can boost learning. We were part of a team that did a year-long study in an inner-city school in Baltimore, Maryland, showing that minimal interventions in a 6th grade classroom reduced student stress and improved academic performance. You can read more about this in The Impact of Biophilic Learning Spaces on Student Success.

What advice would you give architects who want to use more wood?

Use wood so that you can see the grain. If it’s highly lacquered or painted over, we can’t tell whether it’s plastic or wood. But don’t cover every surface in wood. Studies have shown that the optimum percentage for wooden surfaces is between 40 to 50%.

We have produced multiple publications over the years which might be useful. 14 patterns of design sets out a way of codifying the patterns of nature that can be translated into the built environment. Economics of biophilia talks about the economic benefits of making a connection with nature in buildings. Nature Inside is a biophilic design book that we produced with the Royal Institute of British Architects (RIBA), working up from individual items like wallpaper and hardware, through different building and space types up to community interventions. We have also written papers on psychoacoustics and how the brain processes nature sounds and on how to work with fractal patterns which are mathematically repeating patterns found in natural elements such as dappled light under a tree, flames in a fireplace or snowflakes.

To hear more from Bill Browning about Terrapin Bright Green’s latest paper, The Nature of Wood: An exploration of the science of biophilic responses to wood, watch him speaking at our recent Health and Wellbeing webinar here. You can also download the paper here.

Bill Browning, BED Colorado University, MSRED MIT, Hon. AIA, LEED AP., is one of the green building industry’s foremost thinkers. Terrapin Bright Green is an environmental strategies research and consulting firm. Browning’s clients include Disney, New Songdo City, Lucasfilm, Google, Bank of America, Marriott, the White House, Interface, and the Sydney 2000 Olympics. Browning is a founding board member of the USGBC. He is a coauthor of the Economics of Biophilia, 14 Patterns of Biophilic Design, and Nature Inside: A Biophilic Design Guide.