Why a longer stay doesn't necessarily make temperature matter more
The intuition is that discomfort accumulates: sit in a stuffy 29 °C room for ten minutes and you cope, but sit there for three hours and your work should suffer. The extended-U model, which these studies test, says something different. It proposes that human performance stays relatively stable across the wide band of temperatures typically found indoors, and only drops off near the extremes [1][2]. If that's right, then extending exposure inside the comfortable-to-slightly-warm band mostly extends the same flat performance, not a worsening one.
The 165-minute tropical office study is the clearest direct test here. Fifty-eight participants worked at four temperatures with humidity, clothing, activity level, and airspeed held constant, and performance on one cognitive test plus seven neuropsychological tests stayed constant across all four temperatures [1]. Notably, some participants reported thermal discomfort at the higher temperatures while their measured performance did not change — a gap between how people feel and how they perform that matters for interpreting comfort complaints.
Task difficulty may matter more than the thermostat
A separate climate-chamber experiment with sixteen office workers tested 22, 25, 28, and 31 °C across tasks of two difficulty levels, covering memory, math, executive function, planning, reasoning, decision-making, and motor skills [2]. Temperature variation had minimal effects on performance, and task complexity was a stronger predictor than temperature. The interaction between temperature and task difficulty was not significant, meaning temperature didn't meaningfully change how much harder the difficult tasks were [2].
That's a useful reframing for anyone tuning an office: the cognitive demands of the work itself may swamp the thermal setting, at least within the tested range. It also means a longer exposure to a mildly warm room is unlikely to suddenly convert an easy task into a hard one through temperature alone.
Where temperature does seem to bite
The picture changes at the edges. A review of temperature, humidity, and ventilation in office-like environments describes a concave dose-effect curve for temperature, with cognitive and work performance optimal between 22 °C and 24 °C in temperate or cold climates and deterioration at both higher and lower temperatures [4]. That review also links elevated temperatures to acute non-specific symptoms such as dry eyes and respiratory symptoms, and low humidity to dry, tired eyes that degrade work performance [4]. So temperature's effect on performance may run partly through comfort and symptom pathways rather than a direct hit on thinking.
This is where the sustained-exposure question gets interesting but under-resolved. If symptoms like dry eyes build up over a long day, longer exposure could matter more than short laboratory sessions reveal. The tropical study's finding that discomfort rose without performance falling suggests that pathway isn't automatic, at least over 165 minutes [1].
What the evidence can't yet settle
The honest answer is that direct tests of very long exposure are thin. One temperate-climate study notes that at the highest temperature tested, task performance did not differ, and it flags longer-duration exposure and more diverse occupants as areas needing attention [3]. That is a call for more data, not a demonstration that long exposure is harmless.
A lighting study offers a useful analogy for how exposure duration can be tested: it compared 5-minute and 90-minute test times and found no significant effect of light exposure duration on task performance [5]. That's about light, not temperature, so it can't be transferred directly — but it shows that in at least one office-environment domain, stretching exposure from minutes to an hour and a half didn't change the performance signal. Whether the same holds for temperature over a full workday remains an open question that current studies are too short to answer.
Sources used in this answer
The effect of indoor temperature on work performance of fifty-eight people in a simulated office environment
In a 165-minute simulated tropical office with 58 participants, work performance stayed constant across 23, 25, 27, and 29 °C despite reported thermal discomfort at higher temperatures, supporting the extended-U model.
The Effect of Indoor Temperature and Task Complexity on the Cognitive Performance of Office Workers
In a climate-chamber study of 16 office workers at 22, 25, 28, and 31 °C, temperature had minimal effects on cognitive performance while task complexity was a stronger predictor, with no significant temperature-by-difficulty interaction.
Indoor temperature and office work performance in a temperate climate
In a temperate-climate study of indoor temperature and office work performance, task performance did not differ at the highest temperature tested, and the authors note the need for longer-duration exposure and more diverse occupant data.
Health, work performance, and risk of infection in office-like environments: The role of indoor temperature, air humidity, and ventilation
A review reports a concave temperature dose-effect curve, with cognitive and work performance optimal between 22 °C and 24 °C in temperate or cold climates and deterioration at higher and lower temperatures, alongside symptom pathways such as dry eyes.
Effects of correlated color temperature of office light on subjective perception, mood and task performance
In an office lighting study comparing 5-minute and 90-minute test times, light exposure duration had no significant effect on task performance, though correlated color temperature affected perception, mood, and performance.