and artificial daylight help to improve staff well-being
That is the conclusion of research carried out by
scientists at universities in Norway and the UK.
It is already widely accepted that visual contact with plants
or other natural elements stimulates psychological well-being
and has beneficial effects on man. Indeed, a number of scientific
studies have provided convincing evidence that plants can
help to relieve stress and reduce absenteeism in the workplace.
these new studies suggest that the benefits are enhanced if
plants are supplied in combination with full-spectrum lighting
(FSL), which is closer to natural daylight than conventional
Most of the research has been carried out in Norway by Dr
Tøve Fjeld, who looked at the combined effects of plants
and artificial daylight on the health and well-being of the
occupants of a school, hospital department and a bank. Her
findings were reported at the Floriade International Horticultural
Exhibition in Amsterdam in 2002. Click
here to see a copy of her full report.
Fjeld’s research was prompted by the desire to find
a solution to poor indoor air quality (especially low humidity)
and seasonal affective disorder (often called winter depression
or SAD), which are especially common in northern latitudes
during the long winter months. Low light conditions and dry
atmospheres caused by hot processors and fans in modern office
IT equipment contribute to symptoms of stress, eye strain,
headache and throat irritation. Collectively this results
in increased rest breaks, low concentration levels and higher
Fjeld’s results indicate that bringing together the
psychological and physical effects of plants in offices with
more natural background light levels does have a beneficial
effect in northern latitudes. This is reinforced by the experiences
of Greentime, a small Norwegian company now owned by Rentokil
Initial. Since 1995 Greentime have installed plant and FSL
displays in more than fifty commercial buildings. All the
building managers seem convinced that there have been improvements
in staff well-being and some have seen dramatic reductions
Rather surprisingly, Fjeld found that FSL on its own had virtually
no impact on staff satisfaction with their working environment.
This ties in with a Canadian review of the effect of FSL alone
by Jennifer Veitch and Shelley McColl, who concluded that
“A few rigorous investigations of full-spectrum fluorescent
lighting have demonstrated small effects; however, few researchers
have taken up the challenge to replicate their work. These
small effects do not support the claims that full-spectrum
fluorescent lighting will produce better performance, mood,
or health in the general population.” Clearly plants
are an important part of the equation!
So much for Scandinavia, but what about lower latitudes, where
SAD is less of an issue? A start was made on this in some
very recent research carried out by Meredith Theeman as part
of an MSc at the University of Surrey, UK and supported by
Rentokil Initial's Research and Development department.
In Theeman’s main study, staff in two large offices
were asked to take part in a short trial to test their lighting
Participants’ age and gender were recorded. A colour
vision test was also conducted. Individuals were shown a sequence
of pairs of compact fluorescent lights of different intensity
and colour ranging from standard office lighting (correlated
colour temperature of 3000 K) to daylight quality lighting
(correlated colour temperature of 6000 K) and they were asked
to state which light they preferred in each case. The sequence
was then repeated with a colour stimulus.
The key results of this trial were:
- Daylight colour was preferred to standard office lighting.
- Brighter light was preferred to dimmer light.
- Men and women ranked light quality in the same order,
although the range of responses among women was less than
- The introduction of a colour stimulus reduced the range
of responses for both genders, but did not change the order
Rentokil Initial is planning further University-based research
for 2004, with the focus on plant and light combinations in
commercial buildings in the UK and the development of purpose-built
floorstanding and desktop displays.