Hitzebeanspruchung und Leistungsfähigkeit in Büroräumen bei erhöhten Außentemperaturen - HESO. Abschlussbericht. (Heat strain and performance in offices at elevated outside temperatures. Final Report)

As a consequence of global warming, German office workplaces which have not been exposed to heat so far will be faced with a higher heat
load in the future. The German Ordinance on Workplaces calls for a “room temperature conducive to health” taking into account the working process, the physical strain of the workers and the specific use of the room during working hours. This requirement is depicted in the German Technical Rules for Workplaces ASR A3.5: Room Temperature which con-
stitutes that the air temperature shall not exceed 26 °C. In the case of high outside temperatures a step model defines the requirements for
acceptable higher room temperatures.
In a realistic office environment the impact of a high room temperature on the performance of 20 subjects carrying out office work during 4 ¼ hours exposure and during elevated outside temperatures was det
ermined. The room air temperature was controlled within three ranges
(23-26 °C as reference temperature range, 29-32 °C and 33-35 °C, comparable with the temperature ranges of the step model of the
German ASR A3.5). During the exposure physiological parameters and the subjective state of the subjects were recorded and different performance tests were conducted. Skin temperature, skin moisture and heart rate proportionally increase with the room temperature but stay in a
physiologically inoffensive range. The consumption of drinks increases with the room temperature, too. Contrary to expectations, alertness,
verbal and numerical thinking do not show significant changes at higher room temperature. However, the subjective acceptance of higher room temperature is significantly reduced, the subjects feel less relaxed and the
willingness to exert effort decreases. The results are summarised in an operative guideline.