A Human Spaces report in 2015 on biophilic design showed that,
globally, nearly two-thirds of workers have no plants in their
workspaces. Those spaces which incorporated plants and other
natural elements reported 15 percent higher well-being and
creativity, and six percent greater productivity. A 2014 study by
the University of Exeter supports this, showing that just a few
plants introduced into a work environment can increase
productivity 15 percent.
Studies in Texas, Washington State, and England showed that
employees in environments with plants were 12 percent more
productive than those not exposed to interior plants. Visual
exposure to plants helped to reduce blood pressure, and recovery
from stress within five minutes. A 2010 study by the University
of Technology in Sydney quantified several reductions in workplace
stress, just from plants. They found reductions of 37 percent in
anxiety, 58 percent in depression, 44 percent in hostility, and 38
percent in fatigue. Since green is a calming color, this too
should have some effect.
Perhaps some of the increased productivity with plants arises
from the reduction in office noise, another factor well-documented
in studies. For instance, a small indoor plant hedge around a
workspace can reduce noise by five decibels. Plants absorb sound,
rather than just insulate against it. A 1995 study from London
South Bank University showed a positive effect on noise reduction
from large plants placed along wall edges and in corners.
Surveys and studies have verified the positive effect of plants
on employee perception and disposition. A key incentive for firms
to have interior plant design and maintenance contracts is this,
as well as employee retention. Plants have been shown to reduce
employee absenteeism by 14 percent. It is cost effective to keep
employees happy, this asset valued at ten times a building
operating cost and 100 times the energy cost.
Plants cool by the process of “transpiration”, releasing moisture
into the air. A USDA estimate is that proper use of plants could
decrease air temperature in an office by as much as ten degrees.
Plus, the moisture released by these plants helps maintain indoor
humidity in the human comfort zone of 30 to 60 percent, and helps
prevent materials such as wood from cracking when dried out.
Similar to outdoor plants, indoor plants improve the perceived
value of spaces, in addition to enhanced aesthetics. A study in
England reinforces that indoor plants have a positive effect on
perception, while costing less than most other choices for
corporate décor. Clients and employees perceive interior spaces
with plants as more welcoming, relaxed, and upscale.
An often cited example of the positive effect of plants on
perception and value is the study of the Opryland hotel in
Nashville. Its occupancy rate is considerably higher than the
national average. A scientific case study found that the main
factor accounting for this high occupancy is the significant
investment (over $1 million) in interior plants, in fact one of
the largest investments in indoor plants in the country. This
hotel was planted with 12 acres of indoor space, containing about
18,000 indoor plants representing over 600 species.
A more recent investment in indoor plants, topping this one, was
the opening in January 2018 of the glass domed “spheres” at the
Amazon headquarters in Seattle. These contain 40,000 indoor
plants, representing over 400 species. This mirrors the trend
with many other corporate firms adding plants, although on a
smaller scale, to their interior environments. They are learning
that the concept of “biophilia”—the innate human connection to
nature—can make workplaces healthier and happier.
A pioneering study during the 1980’s was perhaps the first to
show that interior plants can have a positive impact on “sick
building syndrome.” This is the condition found in many tight,
energy efficient buildings from indoor pollutants. These are the
toxic chemicals from building components such as carpets, paints,
and synthetic construction materials. Toxins include such
compounds as xylene and benzene, with the most commonly found in
EPA tests being formaldehyde at 0.173 micrograms per liter of air.
Such tight buildings can be ten times more polluted than air
outside or in “leaky” environments. An adequate installation of
plants in sealed U.S. offices could save, by one estimate, $258
Rooms filled with plants were shown to have 50 to 60 percent
fewer molds and bacteria in the air than in rooms where no plants
were present. These, and toxins, both are absorbed in the soil,
and into plant leaves. Toxins may be translocated down into the
root and used there as plant food, or destroyed through a process
called “metabolic breakdown”.
Plants grown in potting soil have been rated for their relative
removal rate of toxins, such as formaldehyde. For this compound,
Boston fern can remove 1863 micrograms per hour, bamboo palm 1350,
Janet Craig dracaena 1328, English ivy 1120, peace lily 939, areca
palm and corn plant 938 for examples. All the details of how
plants clean such air, and how to use them for this, are in the
classic paperback book “How to Grow Fresh Air” by the
researcher B.C. Wolverton.
“Living walls” of plants have become more common in buildings,
including modular units one can even install in a home. A company
in Sydney (Australia) has partnered with the University of
Technology there to quantify the positive effects of what they
term “breathing walls” to remove carbon dioxide and volatile
organic compounds from interior air. U.S. researchers Fisk and
Rosenfeld of the Berkeley National Laboratory have quantified a
$58 billion annual savings from sick-building illness with the use
In a small but important study by university professor Tove Fjeld
in Oslo, Norway, plants were shown to improve employee health in
offices, schools and hospitals. When plants were present,
ailments such as fatigue, headache, sore throat, coughs, and dry
skin were all reduced. The mean reduction of 12 ailments with
plants present was 23 percent.
For office workers, just having a plant on the desk can improve
the six to eight cubic feet of “personal breathing zone” where
most the day is spent. Jay Naar, author of “Design for a
Livable Planet”, suggests that only 15 to 20 plants can
clean the air in a 1,500 square foot area. A good minimum would
be two large (10- to 12-inch pots) plants per 100 square feet of
Whether you have a workplace, or just home, consider adding some
indoor plants if you don’t have them already. Main considerations
in choosing plants are their light, humidity and water needs.
Most people prefer plants that are low maintenance with few, if
any, pests and problems. Some good choices for bright, indirect
light are spider plant, dracaena, and begonia. For lower light,
consider peace lily, pothos, Chinese evergreen, or snake plant.
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