Air-conditioning and Cooling technology Page 4

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Too dramatic temperature differences between room air and outside air are thereby avoided, and thus also the danger of heat shock. In addition, this measure results in a savings of cooling energy.

Fig. 2 Sliding room temperature in summer

English translation of technical terms and sentences in Fig. 2:

t1 Room air temperature
t2 Outside air temperature

1.1.2 Radiation temperature (Wall temperature)

Because the temperatures of the surfaces surrounding a room (walls, doors, windows, ceiling, floor) are generally lower than the surface temperature of the human body (25 ... 27C), it constantly radiates heat to these relatively cooler surfaces. This has the effect that spaces with normal air but low wall temperatures are found to be uncomfortable. The average temperature of the surrounding surfaces, the radiation temperature, thus has a considerable influence on comfort levels.
In order to ensure comfort, the temperature of the surfaces surrounding the room should lie within a range in which the heat dissipation of the body is neither restricted nor increased. A room temperature of 20 ... 22C is generally only suggested as the most favourable where the average wall temperature is either identical or at least quite similar to the air temperature (Fig. 3). Where the wall temperature is significantly lower than the air temperature, as is the case, for example, when warming a room in winter, a room temperature of 20C will be felt to be too cold.

Fig.3 Radiation influence and level of comfort at a room air temperature of 21C

The following factors should be considered with respect to the average temperature of surrounding surfaces:

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