Dimming strategies for open office lighting: User experience and acceptance

Abstract

Sensor-triggered control strategies can limit the energy consumption of lighting by considering the presence of users in the office and dimming lighting down when it is not needed. In multi-user offices, the application of occupancy-based dimming at room level limits the energy saving potential. However, zone or desk-based dimming may affect the comfort of co-workers due to its dynamics. This paper reports the assessment by 17 participants (30 to 50 years of age) of occupancy-based dimming in a mock-up office, using different dimming speeds. Participants consisted of co-workers experiencing changes triggered by others, and actors triggering these light changes. While the participants performed an office-based task, the luminaire above the actors' desk was dimmed from approximately 550 lx to 350 lx (average horizontal illuminance), and vice versa. The participants evaluated the dimming conditions regarding their noticeability and acceptability. The study showed that the noticeability of light changes due to dimming, increasing when fading times become shorter. Dimming with a fading time of at least two seconds was experienced as acceptable by more than 70% of the participants. The results of this experiment provide insights to system behaviour that does not compromise user experience while addressing the energy efficient use of electric lighting.Address for correspondence: Sanae Chraibi, Philips Lighting B.V., High Tech Campus 7,

A Randomized Controlled Trail for Comparing LED Color Temperature and Color Rendering Attributes in Different Illuminance Environments for Human-Centric Office Lighting

“…2021, 11, x FOR PEER REVIEW 3 of 14 [36] is in the range of 150-300 lux. For LED office lighting, past psychophysical experiments were conducted under a single illuminance level between 150 and 300 lux [37,38].…”

Energy Saving Potential for Integrated Daylighting and Electric Lighting Design via User-Driven Solutions: A Literature Review

“…A further set of studies investigated the perception of dimming speed (up and down) in automatic systems. A study showed that more than half of individuals might not notice a 20% reduction of illuminance (Chraibi et al, 2018). In addition, the detection of changes increased when the speed of dimming went from 5 lux/s to 50 lux/s.…”

“…When the fading-out is slower than 1 lux/s, an illuminance reduction above 20% might still not be detected (Akashi and Neches, 2005). While these studies are based on individual responses for personal lighting, Chraibi et al (2018) tested dimming speed in open plan offices, whereby the variation of illuminance from a ceiling luminaire placed above a desk would also be perceived by other occupants. The authors dimmed up or down the illuminance on a desk between 543 lux to 345 lux at different speeds (0 s / ≈ 800 lux/s -2 s / 133 lux/s -5 s / 45 lux/s).…”

A New Trend for Indoor Lighting Design Based on A Hybrid Methodology

“…In [16], a micro-IoT architecture is used for LED lighting and diming control in smart homes and in [17], it is used in street lighting aided by video vehicle detection and lightdependent resistor (LDR) to control lighting on the streets to increase the safety and power saving. In [18], sensor-triggered control strategies are used to save consumption lighting power depending on the acceptance of seventeen (17) participants on the dimming fading time through their experiences and experiments. The research in [19] indicated a greater circadian stimulus and power saving by desktop overhead rather than overhead luminaires of ceiling lighting systems.…”

“….1. Application with fixed lifetime valueBy using Eqs (12)(13)(14),(18),(33)(34)(35)(36),. the calculated values of illuminances for two light sources "variation with luminaire numbers" are as follows: =…”