Biophilic Design

Case Study

The Importance of Daylight

While many people prefer to be in spaces with abundant daylight, a critical question is to what extent the benefits of daylight matter to those who spend the majority of their time indoors, particularly in an office setting.

View Case Study

Despite the fact that humans have lived primarily in built environments for thousands of years, there still lives within the human psyche an evolved propensity to affiliate with living organisms and natural systems. We still feel the tug of nature in backyard gardens, street trees, bird feeders, flowers, or the changing patterns of light indoors as the sun makes its pathway across the sky. An extensive body of research shows that our desire to affiliate with nature also is good for us. The following sections address why nature is so important to us, what we know about the benefits of nature, and how biophilia is being applied in buildings, particularly in urban settings. It is not intended to be an extensive review of the research literature, but rather to highlight how biophilia can be integrated into the built environment, hand in hand with sustainability, to enhance human health, performance and well-being.

Why is nature important to us?

In his influential 1984 book, Biophilia, E.O.Wilson defines biophilia as “the tendency to focus on life and life-like processes.” Wilson argues that because the brain evolved in a biocentric world, humans should be especially tuned to features and attributes of nature that have had consequences for survival – either in a positive or negative way. For biophilic design, it is important to understand how to draw on the survival and well being benefits of nature to enhance human experience of place and to reduce or eliminate environmental features that create health or survival risks.

The Savannah Hypothesis

Behavioral ecologist Gordon Orians argues that humans are intrinsically attracted to features and spatial patterns that mimic the African savannah, the presumed site of human evolution.¹ Savannah features and spatial patterns include:

• A rich diversity of plant and animal life
• Clustered trees with spreading canopies for refuge and protection.
• Open grassland that provides easy movement and clear views to the distance
• Topographic changes for strategic surveillance to aid long distance movements and to provide early warning of approaching hazards
• Scattered bodies of water for food, drinking, and bathing
• A “big sky” with a wide, bright field of view to aid visual access in all directions
• A home base to support food preparation, social life and safety at night around a campfire

Savannah “mimics” are obvious in many of our modern built spaces, especially public areas such as lobbies and atria that are meant to evoke positive emotional experiences. These spaces often have large plants, flowers, indoor trees, expansive views, water features, daylight, multiple view corridors, an interior “big sky” atrium, and comfortable retreats.

Geographer Jay Appleton independently developed the prospect-refuge theory of landscape preferences that is closely related to the savannah hypothesis.² Appleton argues that people prefer to be in places where they have good visual access to the surrounding environment (high prospect), while also feeling protected and safe (high refuge).

How Do We Know Biophilia Enhances Health?

Khoo Teck Puat in Singapore
2017 Kellert Biophilic Design Award Winner

Interest in biophilia within both the research and design communities has grown rapidly since E.O. Wilson’s 1984 book on biophilia. A 2018 Google search on the term “biophilia” provided 1,760,000 hits while “biophilic design” produced 619,000 hits. Not surprisingly, research on the topic has also grown considerably, especially on the human benefits of connection to nature, and more recently, on issues of how urban biophilia can help mitigate climate change while also supporting public health goals.

This section provides an overview of key findings on the links between human health resulting from a variety of biophilic applications – from indoor vegetation and daylight to window views and water features. The focus is primarily on biophilia in the built environment.

Due to the extensive body of research on biophilia, this section is intended to identify key findings relevant to building design rather than to provide a detailed review. Recent reviews are identified in the bibliography for those wanting more information.

Table 1. Links Between Biophilic Elements and Health Outcomes

Daylight Matters

In addition to creating a visually pleasant environment, indoor daylight can also enhance mood, improve cognitive functioning, reduce stress, and reduce the use of strong pain medicine in hospital settings.

Daylight Reduces Stress, Improves Cognitive Function, and Helps Sleep

Indoor skylight "street" at a Herman Miller facility in Michigan

Research by Walch and colleagues in a Pittsburgh hospital assessed the relationship between indoor daylight levels and variation in health outcomes.³ The research team studied 89 patients who had elective cervical and spinal surgery. Half of the patients were located on the bright side of the hospital while the other half were in a hospital wing with an adjacent building that blocked daylight entering the rooms. The study team measured medication types and cost as well as psychological functioning the day after surgery and at discharge. The results showed that patients in the brighter rooms had 46% higher intensity of sunlight, took 22% less analgesic medicine/hr and experienced less stress and marginally less pain. This resulted in a 21% decrease in the costs of medicine for those in the brightest rooms.

A study of 109 workers in 5 federal office buildings addressed whether indoor daylight could have health and well-being benefits through the circadian system.⁴ The research team from Rensselaer Polytechnic Institute found that study participants who had the most circadian stimulus during the day, and especially in the morning, fell asleep earlier at night and had better overall sleep quality than study participants who received less light. Circadian stimulus was measured by a device (called a daysimeter) worn around their neck for 3 days, both at work and at home. The daysimeter measures characteristics of the light (spectrum, intensity, duration, timing) as well as activity levels. The combination of light exposure and activity shows a person’s degree of entrainment to the local day/night cycle on earth. Someone who shows high levels of entrainment is most active during the day when circadian stimulus is the highest and less activity at night as it gets dark.

The study also found that the amount of daylight entering the windows does not guarantee high circadian stimulus due to interior design features that may block daylight penetration or limit the amount of light reaching the eye. This includes high workstation partitions, shade use, seating orientation with respect to the windows, and other factors such as reflectance of surfaces.

Window Views of Nature Make a Difference

While much research on windows has focused on reduction of glare and heat gain, the health benefits of views is an active area of research. Results show that views of trees and vegetation reduce stress, enhance mood, improve the recovery process in hospitals, and enhance cognitive performance in work settings compared to views lacking natural features.

Views Can Improve Health, Cognition, and Psychological Well-being

Window view of nature

The first well-controlled empirical test of the therapeutic hypothesis was published in 1984 by Roger Ulrich.⁵ Using data from hospital records, Ulrich tested the effect of window views on patient outcomes. Half of the patients had a window that looked out onto a brick wall while the others viewed an outdoor landscape with trees. All patients had the same kind of surgery, with the two different view groups matched for age, gender, and general health conditions. Ulrich found that patients with the view of trees used less narcotic and milder analgesics, indicating lower pain experience. They also stayed in the hospital for a shorter time period and had a more positive post surgical recovery overall than did patients who had the view of the brick wall.

In two studies of office workers, Heschong and colleagues⁶ found that those with full window views, especially views of trees, performed better on a number of work tasks than workers who had only partial views or views of buildings without nature. One of the studies, conducted in a call center, found that workers with seated window views of nature performed 6-7% faster (e.g., were able to handle more calls) than those without window views. The other study, a field experiment, also found positive impacts of nature views on memory and attention tasks. Those with full, high quality views with natural vegetation performed 10-25% better on these tasks than those with a view of buildings.

In a similar study of office workers in a Midwest building, Rachel Kaplan⁷ found that those who had a window view of trees and vegetation scored higher on measures of well being than those doing similar work whose view consisted of a parking lot or buildings without nature. Workers with the natural view also had lower levels of stress, experienced less frustration, were more patient, and had more positive outcomes on a measure of overall life satisfaction.

Although the mechanisms of impact for window views are not known, researchers argue that nature is very effective at switching attention from current concerns to a state of rest and calmness that refreshes the mind. Views of nature through the window may thus provide mini mental breaks by switching attention from on going work activities, which may demand high cognitive output, to relaxed viewing which reduces cognitive load and physiological arousal.

Indoor Plants and Flowers Are More than Decorations

Plants have long been used to enhance the appearance of indoor spaces. Research on the benefits of plants also shows reduced respiratory symptoms likely linked to improved air quality. In addition to green plants, flowers are also associated with positive outcomes, especially increases in positive emotional functioning.

Indoor Plants have Physiological and Psychological Benefits

A study conducted in Norway⁸ provides evidence for the health benefits of indoor plants including reduced fatigue, cough, sore throat and dry skin when plants were present in the office.

The research team in Norway studied 60 office workers who each experienced both a plant and no plant condition (this is referred to as a cross over study) during the spring months. In the first year, half of the subjects had a planter installed on their windowsill and a large floor plant near their desks, while the other subjects experienced their standard office conditions without plants. In the second year, the conditions were reversed and the plants were moved to the workspaces of the no-plants group. The results showed that:

• Neuropsychological symptoms were reduced by 23% when plants were present. Fatigue reduced the most – by 30%.
• Mucous membrane symptoms were reduced by 24% overall when plants were present. Cough decreased by 37% and dry throat by 25%.
• Dry or flushed skin was reduced by 23% lower with plants in the workspace.

The researchers suggest that health improvements were likely due to two mechanisms: improved air quality and the psychological value of being in a more pleasing environment. The presence of plants may have created a microclimate effect that resulted in increased moisture (which could influence mucous membrane systems) as well as a cleansing of the chemicals in the air.

Flowers, in addition to green plants, also have psychological and social benefits. A series of experiments by Haviland-Jones and colleagues⁹ explored people’s emotional responses to a gift of flowers versus other living elements (fruit) and non-living items (a pen or a candle). The researchers used a similar paradigm in three related experiments. They presented people with gift of a flower or another item (such as a pen or an apple) and recorded their facial expressions and comments. The results showed that only the recipients of the flower showed a “true smile” – one that engages the zygomatic muscles in the cheek and the small muscles around the eye. The true smile is difficult to fake and is considered a valid indicator of emotional pleasure.

In one of the experiments, the researchers also looked at social behavior. The experiment was conducted in an elevator in a university library. The experimenter and a colleague randomly selected individuals who approached the elevator by themselves and entered the elevator with him or her. Once inside, three conditions were tested: the subject was given a gift of a flower or a pen, no gift, or passive exposure to flowers in a basket carried by the experimenter. The researchers recorded facial expressions and comments made by the subject. The results showed that only the recipients of the flower gave a true smile. In addition, they talked more to the experimenters than those receiving a pen, no gift or passive contact with the basket of flowers.

Although we know intuitively that people like flowers and are willing to spend considerable sums of money to plant flowers in their yards or purchase bouquets (especially on Mother’s Day), the reason for our attraction to flowers is not clear. In a chapter in The Adapted Mind, Orians and Heerwagen¹⁰ speculate that our attraction to flowers may have evolved because they are indicators of high value food (especially fruit) that can be harvested in the future.

Nature Photos and Videos Can Be Effective Surrogates

Health benefits can also be achieved indirectly through the use of photos or videos of nature. Research shows both physiological and psychological responses to nature versus urban scenes. The findings show strong support for more positive benefits with nature-based visual stimuli.

Adaptations to Windowless Environments Using Nature Decor

Although people have a strong preference for working in spaces that have windows, there are many windowless work environments. Research shows that people in such spaces often decorate their workspaces with nature posters or plants, perhaps as a way to compensate for lack of connection to the outdoors.

People in Windowless Spaces Enhance Their Well Being with Nature Images

Posters of nature from a windowless work area

Research by Heerwagen and Orians¹³ explored how people adapted to being without a window. They hypothesized that people in windowless, compared to windowed environments would use more visual décor to enhance their personal workspaces and that the décor would be dominated by nature themes due to their disconnection to the outdoors.

The hypothesis was tested by gathering information on the number and content of items used to decorate the walls in 75 windowed and windowless offices on a university campus in Seattle. The data gathering included only items that were judged to be of aesthetic value (e.g., photos, posters, crafts versus work schedules or other typed materials). The number of items at each work station were identified and classified as a landscape, cityscape, non-landscape natural (e.g., trees, flowers, animals) or other (which included things such as macramé hangings and other crafts).

Results showed that occupants of windowless rooms used twice as many items (primarily posters and photos) to decorate their offices than those in windowed offices and three times more nature-dominant visual materials. Furthermore, the majority of the posters and photos were placed directly in the occupant’s field of view, where they could be seen as people were working.

A recent partial replication of this study in an office building in Sweden found that workers compensated for lack of views to the outdoors by decorating their work spaces with more indoor plants than those who had a view to outdoor vegetation.¹⁴

The Psychological Value of Water

Given its importance to human life, studies on the health benefits of water are surprisingly scarce compared to the extensive research on water-borne health problems. However, researchers have begun to focus on the qualities of water that influence people’s preferences. A review of human responses to a variety of water features (referred to as “blue space”) concludes that water is clearly a component of preferred landscapes.¹⁵

Water: The Unifying Element of Nature

Haworth Office in Merchandise Mart

Landscape preference studies tend to omit water from visual stimuli because researchers believe that water features are so positively regarded that they dwarf response to other aspects of the landscape. As noted by Mador,¹⁶ water is “the unifying element of nature,” essential to life itself. Yet it is surprisingly ignored in biophilia and especially research on health benefits. The focus to date is on the negative health effects of pollution.

However, there is some available research on the benefits of water. For instance, a study by Coss¹⁷ shows that people respond very positively to specific features of water – sparkle, reflections and surface movements. Coss suggests that early humans may have used visual sparkle, in particular, as a cue to the location of water. Sparkle can be seen in the distance, whereas reflections and water surface movement can only be seen on closer inspection. Coss also speculates that reflection and movement may have been used as indicators of water quality. Volker and Kistenmann also identify sound, color, motion, and clarity as key elements of preferred water features.¹⁵

Prospect and Refuge

Landscape design intuitively uses prospect (long distance views) and refuge (places of protection), with multiple long distant views often to the horizon, coupled with subspaces that offer protection and hiding.

The co-occurrence of prospect seems to be so obvious that research on the topic is scarce. However, one compelling study of human response to landscape scenes shows that those with both long distance views and places of refuge stimulate the opioid centers of the brain, creating a sense of relaxed enjoyment that may encourage movement and exploration.¹⁸

Non-Visual Sensory Systems

Environmental experience is multi sensory, not just visual. Yet less attention has been paid to other sensory systems in biophilia research. However, research in other fields such as acoustics and thermal comfort address conditions relevant to biophilia.

For example, recent work on sound looks at the health impact of soft nature sounds (birds, water, breezes) versus annoying sounds such as traffic, construction work, and people talking on cell phones.¹⁹ The authors conclude that quiet sounds linked to nature are indicative of safety and thus reduce stress and restore attentional capabilities allowing for high level cognitive functioning, including creativity. Louder, annoying sounds are more indicative of danger, and thus narrow attentional scope to focus on dealing with the danger.

Other researchers are exploring how thermal transitions can create momentary pleasure and result in greater satisfaction overall than constant indoor temperature conditions.²⁰ Whether such transitions could also create a sense of pleasure for other sensory stems is not known. However, the high variability in natural light across the day suggests that more indoor variability – especially in windowless environments – could generate feelings of pleasure also.

Overall summary of Research Findings

Research on biophilia shows that many different elements of nature, from daylight to plants and flowers, have consistent positive benefits on human health and well point to positive outcomes linked to attention restoration and stress reduction – both of which can enable more focus and greater use of executive functions associated with more complex cognitive performance.

Key conclusions from this research, as summarized in a review by Beute and de Kort are:²¹

1. Biophilic benefits have validated pathways of impact - including psychological mechanisms (preference, psychological stress reduction, emotional functioning, cognitive processes, and to a lesser extent social behavior) and physiological mechanisms (circadian entrainment, serotonin production, alertness, and physiological stress reduction).
2. The aspects of nature associated with these outcomes are consistent across diverse research projects and include large trees, plants, distant views, refuge, sunlight, and water.

Implementing Biophilic Design

Biophilic design translates our evolved propensity to affiliate with nature into strategies for improving health, well-being, and performance in the built environment. The brief review above shows that biophilic features have numerous positive benefits including stress reduction, enhanced emotional functioning, improved cognitive performance, social engagement, and better sleep.

In addition to elements and spaces that enhance experience of place, it’s important to also avoid spaces associated with danger or illness – a condition often referred to as “biophobia” because of the unease and stress associated with being in a space that can harm rather than heal. Like biophilia, the sense of biophobia is considered an evolved response intended to elicit avoidance or escape behaviors.

Features associated with biophobia include:

• Darkness
• Loud or uncontrollable noise
• Unkempt or hazardous spaces
• Presence of vermin and/or unpleasant odors
• Dead or dying plants due to lack of care
• Poor wayfinding leading to feeling trapped or lost

The Biophilic Design Continuum

One way to think about biophilic design is to see it as a continuum as shown below. As one moves from a biophobic to a biophilic space, there is an in-between space (bio-indifference) that eliminates the negative aspects of biophobia, but does not contain the natural features and attributes that promote health. Many current building spaces are likely to fall in the “bio-indifference” category where harmful elements are largely eliminated, but health-enhancing benefits are not present. An infographic from the Washington Post illustrates the concept.

Table 2. The Biophilic Design Continuum

	Biophobia		Bio-Indifference		Biophilia
Factors associated with the biophilic design continuum	Safety hazards Health hazards Absence of nature Windowless High discomfort Lack of comfort control Lack of spatial choice Uncontrollable noise Conditions outside recommended comfort zones		Absence of safety hazards Absence of health hazards Absence of biophilic features Lighting meets standards Thermal conditions meet stds Sound meets standards Imbalance of refuge & prospect		Health promoting design Indoor nature elements Water sounds for acoustics Equitable daylight distribution Light for circadian functioning Views to outdoor nature Outdoor green space Sensory variability Comfort controls Ambient transition zones Balanced prospect & refuge
Health & well-being consequences	Increase risk of illness Increase risk of accident Discomfort Low motivation High stress Rumination/worry Low overall satisfaction		Reduced health risks Reduced safety risks Improved satisfaction Improved comfort		Increased well being Enhanced mood Reduced stress Enhanced cognitive performance Enhanced sleep High satisfaction High comfort Enhanced social engagement
	Dark hallways		High Partitions		Hallway with lights and plants

Table 3 below summarizes the components of biophilic design in terms of specific elements, natural attributes, and spatial patterns. This is just one way to characterize biophilia. Others categorization schemes and practice approaches are presented in the 14 Patterns of Biophilic Design by Terrapin Bright Green¹⁹ and in The Practice of Biophilic Design by Stephen Kellert and Elizabeth Calabrese.²⁰

Table 3. Components of Biophilic Design

Using the Biophilic Design Elements

The most biophilic buildings incorporate multiple features that are revealed in the building façade, lobby, interior design, and surrounding landscape. The intent is to create an interior habitat of features that go together in a harmonious way drawing on the features and attributes of the climate and landscape where the building is located.

A biophilic design does not need to contain all of the desired elements and attributes, but rather the components that make the most sense given the context – which, in addition to climate and landscape, include the building purpose (office vs hospital), the organizational culture and mission, and occupant needs and characteristics.

Federal Center South, Seattle

Federal Center South

The new Federal Center South building in Seattle exemplifies an approach to biophilic design that links sustainability, organizational mission, and connection to nature indoors and outside. The building houses the US Army Corps of Engineers (USACE).

Biophilia was used as a framework for the overall design. The design includes expansive views across the building and to the outdoor landscape in all directions, an interior atrium with a meandering riverbed of rocks and plants, views to the Duamish River, extensive indoor daylight, and use of recycled wood for the interior walls. The building also has a well developed and balanced approach to prospect and refuge that includes open interior views coupled with numerous places for refuge without feeling totally enclosed.

Federal Center South received a LEED Platinum rating for its sustainable design and received the American Institute of Architects COTE award and COTE+ award for its stewardship of the environment.

Concluding Remarks

The research on biophilic benefits cited in this article come almost exclusively from adult populations. It is worth stepping back a bit and asking what would children say? The two images below come from children who were visiting a Herman Miller manufacturing plant in Holland, Michigan. Before the visit to the building, the teacher asked them to draw a picture of a factory. The photo on the left was typical of the drawings – they looked grim and dark. Hardly an exciting place to work. After the tour, when the children returned to class , the teacher asked them to draw another picture. The one shown here has happy people and the interior street lined with plants and wooden animals, including a snake and giraffe. Clearly, the experience had a powerful, positive emotional effect.

Children's factory drawing		Children's factory drawing after visit to Herman Miller Building

Additional Suggested Readings

• Appleton, J. 1977. The Experience of Landscape. London and New York: Wiley.
• Browning, W, Ryan, C. and Clancy, J. 2014. 14 Patterns of Biophilic Design. Terrapin Bright Green LLC.
• Gillis, K. and Gatersleben, B. 2015. A review of psychological literature on the health and well being benefits of biophilic design. Buildings, 5: 948-963.
• International Living Future Institute
• Kellert, SR. 2018. Nature by Design: The Practice of Biophilic Design. New Haven: Yale University Press.
• Kellert, SR and Calabresse, EF. 2015. The Practice of Biophilic Design. Biophilic-design.com
• Kellert, SR, Heerwagen, J and Mador, M. 2008. Biophilic Design: The Theory, Science and Practice of Bringing Buildings to Life. New York: Wiley.
• Sturgeon, A. 2018. Creating Biophilic Buildings. Ecotone Publishing.
• Wilson, E.O. 1984. Biophilia. Cambridge, MA: Harvard University Press.