The aim of the study was to determine the effect of a temperature of 29°C on performance in tasks involving different cognitive demands and to assess the effect on perceived performance, subjective workload, thermal comfort, perceived working conditions, cognitive fatigue, and somatic symptoms in a laboratory with realistic office environment. A comparison was made with a temperature of 23°C. Performance was measured on the basis of six different tasks that reflect different stages of cognitive performance. Thirty-three students participated in the experiment. The exposure time was 3.5 h in both thermal conditions. Performance was negatively affected by slightly warm temperature in the N-back working memory task. Temperature had no effect on performance in other tasks focusing on psychomotor, working memory, attention, or long-term memory capabilities. Temperature had no effect on perceived performance. However, slightly warm temperature caused concentration difficulties. Throat symptoms were found to increase over time at 29°C, but no temporal change was seen at 23°C. No effect of temperature on other symptoms was found. As expected, the differences in thermal comfort were significant. Women perceived a temperature of 23°C colder than men.

The aim of this laboratory experiment was to study the effects of ventilation rate, and related changes in air quality, predominantly bioeffluents, on work performance, perceived indoor air quality, and health symptoms in a typical conditions of modern open-plan office with low material and equipment emissions. In Condition A, outdoor air flow rate of 28.2 l/s person (CO level 540 ppm) was applied and in Condition B, outdoor air flow rate was 2.3 l/s person (CO level 2260 ppm). CO concentration level was used as an indicator of bioeffluents. Performance was measured with seven different tasks which measure different cognitive processes. Thirty-six subjects participated in the experiment. The exposure time was 4 hours. Condition B had a weak negative effect on performance only in the information retrieval tasks. Condition B increased slightly subjective workload and perceived fatigue. No effects on health symptoms were found. The intensity of symptoms was low in both conditions. The experimental condition had an effect on perceived air quality and observed odor intensity only in the beginning of the session. Although the room temperature was controlled in both conditions, the heat was perceived to impair the performance more in Condition B.

a b s t r a c tThe aim of this study was to investigate how irrelevant speech, temperature and ventilation rate together affect cognitive performance and environmental satisfaction in open-plan offices. In Condition A, neutral temperature (23.5 C), low intelligibility of speech (high absorption and low masking sound level) and high fresh air supply rate (30 l/s per person) were applied. This was contrasted to Condition B with high room temperature (29.5 C), highly intelligible speech (low absorption and high masking sound level) and a negligible fresh air supply rate (2 l/s per person). Sixty-five participants were tested. In Condition B, performance decrement was observed especially in working memory tasks. Based on subjective assessments, mental workload, cognitive fatigue and symptoms were higher and environmental satisfaction was lower in Condition B. It was concluded that special attention should be paid to the design of whole indoor environment in open-plan offices to increase subjective comfort and improve performance.