Glare and light distribution matter more than how bright the room is
The most direct field comparison of photometric quality and productivity found that the two lighting systems produced no difference in illumination levels, yet workers clearly preferred one. Under a ceiling-suspended, lensed-indirect uplighting system, computer workers reported fewer screen glare problems and fewer problems with tired eyes and eye focusing than under a parabolic downlighting system [2]. They also said productivity was less hindered, and they rated lighting quality and satisfaction significantly higher [2]. Because the illumination was the same, the difference in reported efficiency tracks the quality of the light distribution—how it reaches the eye and the screen—rather than the quantity of light.
That distinction matters for anyone interpreting photometric metrics. A lux reading tells you how much light lands on a surface; it does not tell you whether that light creates veiling reflections on a monitor or a bright source in the field of view. The field study suggests that the glare-related and distributional aspects of lighting quality are the ones that workers actually feel as help or hindrance to their work [2]. About two-thirds of workers said they preferred the lensed-indirect system, which is consistent with the idea that the preference is driven by visual comfort rather than brightness [2].
Satisfaction with lighting and how much people care about it pull in opposite directions
One counterintuitive field finding is that ratings of lighting satisfaction and ratings of lighting importance were inversely related [2]. In other words, workers who were more satisfied with their lighting tended to rate lighting as less important to them, and vice versa. This is a useful caution when reading self-reported productivity: people who are unhappy with their lighting may inflate how much they believe lighting matters, while people in comfortable conditions may discount it. The study does not establish why this happens, but it means a simple satisfaction score is not a clean proxy for photometric quality.
The same study measured environmental variables including illumination, air temperature, and relative humidity alongside questionnaire data on health symptoms, job stress, and self-reported productivity [2]. That design lets the lighting comparison be separated from at least some other workplace conditions, but the productivity outcome itself was self-reported rather than an objective count of output. So the field evidence supports a link between light distribution, glare, and perceived hindrance to productivity—not a measured change in units of work completed.
Newer human-centered metrics track alertness, but not the classic photometric numbers
A 2024 field study in an open-plan office at Istanbul Technical University tested lighting defined by Circadian Stimulus and Equivalent Melanopic Lux—metrics intended to capture how light affects the body's daily rhythms—using two beam distributions from LED sources [1]. Sixty office workers completed visual cognitive performance tests, proofreading tasks, and the Karolinska Sleepiness Scale to measure alertness, along with comfort feedback [1]. This is the kind of design that could connect lighting to efficiency, but the study does not analyze traditional photometric quality metrics such as illuminance, uniformity, or glare [1]. Its preliminary findings concern energy efficiency and meeting WELL and UL design guidelines, with optimization deferred to a second part [1].
The practical implication is that the field literature is split. One strand measures classic photometric quantities and self-reported productivity [2]; another measures circadian metrics and cognitive test performance but not the classic photometric quantities [1]. Neither strand yet gives a clean dose-response curve linking a specific lux level, uniformity ratio, or glare index to a measured change in worker output.
Mock-up and review work points the same way, with weaker field grounding
A dissertation using a mock-up office rather than a live workplace monitored vertical illuminance at the eye and luminance while video display terminal users performed tasks, pairing objective performance measures with ocular behavior and subjective assessments [5]. Its stated aim was to move past rigid design approaches toward human-centric lighting for computerized offices [5]. Because the setting was a mock-up, this supports the general idea that photometric quantities and task performance are related, but it is not a field study of real workers doing their own jobs.
A narrative review of lighting in industrial and shift-work environments discusses lighting quality and working efficiency in office settings, but as a review it synthesizes rather than adds new field measurements [4]. An older paper on lighting quality for offices reports effects of lighting on the performance of workers assembling components in a specially prepared setting, again outside a normal office field context [3]. Taken together, these sources are consistent with the field finding that lighting quality affects comfort and perceived performance, but they do not supply the missing quantitative link between specific photometric metrics and measured efficiency in real offices.
Sources used in this answer
A Field Study of Individual, Energy-Efficient, and Human-Centered Indoor Electric Lighting: Its Impact on Comfort and Visual Performance in an Open-Plan Office Part 1
A field study of Circadian Stimulus and Equivalent Melanopic Lux lighting in an open-plan office measured cognitive performance, proofreading, alertness, and comfort in sixty workers but did not analyze traditional photometric metrics such as illuminance, uniformity, or glare.
Effects of lensed-indirect and parabolic lighting on the satisfaction, visual health, and productivity of office workers.
In a pre/post renovation field study, a lensed-indirect uplighting system produced fewer screen glare and eye problems and less hindrance to self-reported productivity than parabolic downlighting, despite no difference in illumination levels between the systems.
Creating high-quality workplaces using lighting
The paper reports effects of lighting on the performance of workers assembling components in a specially prepared setting, without explicit photometric lighting quality metrics for office field studies.
Lighting in Industrial and Shift-Work Environments and Occupational Health: A Narrative Review
A narrative review discusses lighting quality and working efficiency of workers in office and shift-work settings, synthesizing rather than adding new field measurements.
Experimental studies on revealing the relationships between luminous environment characteristics and cognitive, ocular and psychological changes
In mock-up office experiments, vertical illuminance at the eye and luminance data were monitored while video display terminal users' task performance, ocular behavior, and subjective assessments were recorded, supporting a relationship between photometric quantities and task performance outside a real workplace.