Alertness, Visual Comfort, Subjective Preference and Task Performance Assessment under Three Different Light's Colour Temperature among Office Workers

Mohd Tamrin Bahri Shamsul,S Nur Sajidah,S Ashok

doi:10.4028/www.scientific.net/aef.10.77

Mohd Tamrin Bahri Shamsul, S Nur Sajidah + Show 1 more

Open Access

https://doi.org/10.4028/www.scientific.net/aef.10.77

Copy DOI

Abstract

Different CCT provided by different lighting are important in affecting human beings psychologically and physiologically, as well as visual and non-visual processes. This study aim in finding out the effects of warm white (WW) light (CCT=2700K), cool white (CW) light (CCT=4000K) and artificial Daylight (CCT=6200K) on workers alertness, visual comfort level, preferences and task performance. A repeated measure experimental study was conducted among 46 office workers under controlled environment. Alertness levels were measured by Karolinska Sleepiness Scale. Office Lighting Survey was used to evaluate visual comfort and preference. Typing speed and accuracy also were tested. Paired Sample T-Test was used and the results showed that there was significant reduction of subjective alertness level in WW light (p=0.001). In term of typing performances, subjects performed significantly better in term of typing speed under CW light and Daylight than WW light. Less typing errors were made under DL, followed by CW light. Meanwhile WW light lead to high typing errors. Besides, CW light is the most preferred whereas subjects feel most comfortable under Daylight. Subjects indicated that they can perform longer works in this coloured-lit environment. The CW light and DL light were more beneficial for office setting for computer-based task.

Highlights

Good lighting is required for good visibility of the environment
Statistical analysis shows that there was significant changes in alertness level of subjects when exposed under warm white (WW) light (Paired sample T-test, p=0.001
As a conclusion, subject working under the WW light recorded the highest reduction in level of alertness while cool white (CW) light and Daylight resulted with no significant changes of alertness level in the end of experiment

Summary

Introduction

Good lighting is required for good visibility of the environment. Lighting should ensure the luminous environment that is human-friendly and appropriate for the visual task performed. Various studies had been conducted in order to identify the effects of lighting condition towards human health, productivity, well-being and alertness level [1]. The right selections of CCT in an office environment will benefits occupants in term of visual comfort and reduction of daytime sleepiness. This will increase of productivity and prevention of health effects associated with inappropriate light’s CCT such as eye strain, or the effects towards emotion and human circadian rhythm [4]. The objective of this study is to identify the differences in term of alertness level, typing performance and subjective visual comfort and preferences among office workers when exposed under different light’s CCT (WW 2700K, CW 4000K and DL 6200K)

Objectives

Methods

Findings

Discussion

Conclusion