Plants 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.

However, 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 office lighting.

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 absenteeism.

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 in absenteeism.

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 preferences.

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 for men.

• The introduction of a colour stimulus reduced the range of responses for both genders, but did not change the order of preference.

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.

Author: Mike Lothian