Personal lighting conditions of office workers: An exploratory field study

Abstract

Light enables us to see and perceive our environment but it also initiates effects beyond vision, such as alertness. Literature describes that at least six factors are relevant for initiating effects beyond vision. The exact relationship between these factors and alertness is not yet fully understood. In the current field study, personal lighting conditions of 62 Dutch office workers (aged 49.7 ± 11.4 years) were continuously measured and simultaneously self-reported activities and locations during the day were gathered via diaries. Each office worker participated 10 working days in spring 2017. Personal lighting conditions were interpreted based on four of the six factors (light quantity, spectrum, timing, and duration of light exposure). Large individual differences were found for the daily luminous exposures, illuminances, correlated colour temperatures, and irradiances measured with the blue sensor area of the dosimeter. The average illuminance (over all participants and all days) over the course of the day peaked three times. The analysis of the duration of light exposure demonstrated that the participants were on average only exposed to an illuminance above 1000 lx for 72 minutes per day. The interpretation of personal lighting conditions based on the four factors provides essential information since all of these factors may be relevant for initiating effects beyond vision. The findings in the current paper give first in-depth insight in the possibilities to interpret personal lighting conditions of office workers.

The identification of variables influencing personal lighting conditions of office workers

“…These sub groups are explained in more detail in a prior publication. 8 First, an overall likelihood ratio test was performed to test the influence of the subgroup on the model parameters. In the case this test was found to be significant, individual variables were judged at the significance level of p ¼ 0.05.…”

“…The current article describes a field study including 62 participants (mean age: 49.7 AE 11.4 years) in a Dutch office. 8 The office building consisted of five floors with fully glazed facades and an atrium situated at the south fac¸ade. The workspaces of the office workers participating in the field study were on average 5.1 AE 4.0 m away from the nearest window.…”

“…the office environment, the study deign, the objective measurements with the Lightlog, the participant sample, or the recruitment process) can be found in a prior publication. 8…”

“…The current article describes a field study conducted in a Dutch office. 8 The main purpose is to identify predictors of personal lighting conditions of office workers (e.g. similar to the results of the study of Heil and Mathis where they also identified determinants for bright light exposure).…”

“…A previous article describes the interpretation of personal lighting conditions based on four of these factors of light. 8 The term personal lighting conditions was introduced as continuously measured lighting conditions at the individual level (i.e. light that enters the individual's eyes).…”