AN OFFICE POINT OF VIEW

Iain Carlile looks at three of the latest papers published online by Lighting Research and Technology, all of which focus on issues in the workplace

eople spend up to 90 per cent of

Ptheir time indoors, say Batool et al, and the visual connection to the outside provided by windows plays an important role in ensuring a person’s physical and psychological wellbeing. They present a study to define suitable methods and metrics to measure view performance in an urban environment. Participants in the study observed three different photographic views in laboratory conditions. The data collected was based on eye-tracking, subjective preference and verbal reasoning.

A link was found between the preference for a scene and a greater degree of visual exploration, with a greater number of saccades (rapid movements of the eye that abruptly change the point of fixation) and higher occurrence of fixations. Views containing people, well-maintained buildings and ordered colours were typically preferred, while green and natural elements led to higher preference ratings.

The authors suggest that this pattern of eye movement could guide the criteria for framing views and window design, although they note that in a real world setting other factors such as the position of the person in the interior, internal view, dynamic quality of daylight, long-term exposure and so on may also have an influence on a person’s preference of view.

Considering a different aspect of views from the interior to the exterior, Pierson et al examine discomfort glare caused by daylight. The authors note that none of the 20 existing models for predicting discomfort glare from daylight accurately predict it. They suggest that the addition of different factors may help to improve the models’ predictions, one such factor being the socio-environmental context of the observer. They conducted an evaluation of discomfort glare from daylight in office buildings from four different socioenvironmental contexts in Chile, Belgium, Japan and Switzerland. Evaluations included both subjective assessments and physical measurements made from the office desks of 211 participants.

The results revealed that the socioenvironmental context did not appear to influence the perceived daylight discomfort glare experienced by the participants. This suggests that the results from discomfort glare research from around the world could be globalised and compared without being influenced by this factor.

Van Duijnhoven et al’s paper presents the findings of a field study which looks at office workers’ personal lighting conditions. Over a period of 10 days in spring 2017, 62 Dutch office workers aged 49.7 (+/- 11.4) years were continuously measured, and self-reported activities and locations. Personal lighting conditions were interpreted based on four factors which may initiate non-visual effects of light, namely light quantity, spectrum, timing and duration of light.

Large individual differences were found between the subjects’ measurements for daily luminous exposure, illuminance, correlated colour temperature and irradiance. The average illuminance (for all participants) peaked three times across the course of the day, in the morning, during lunchtime and at the end of the afternoon. It was also found that on average the participants were only exposed to an illuminance above 1000 lux for 72 minutes a day. The authors note that while the study is limited, the findings give an in-depth insight into the possibilities for interpreting personal lighting conditions and their effects beyond vision on office workers.

t

Typical view conditions in Chile, Belgium, Japan and Switzerland (Pierson et al)

Iain Carlile, FSLL, is a past president of the SLL and a senior associate at dpa lighting consultants

Lighting Research and Technology: OnlineFirst

In advance of being published in the print version of Lighting Research and Technology (LR&T), all papers accepted for publishing are available online. SLL members can gain access to these papers via the SLL website (www.sll.org.uk)

View preference in urban environments

A Batool, P Rutherford, P McGraw, T Ledgeway and S Altomonte

Is there a difference in how people from different socio-environmental contexts perceive discomfort due to glare from daylight?

C Pierson, B Piderit, T Iwata, M Bodart and J Wienold

Personal lighting conditions of office workers: An exploratory field study

J van Duijnhoven, MPJ Aarts and HSM Kort