Civil Engineering Reference
In-Depth Information
High
200-260
26
23
Very high
>260
24
19
Adapted from International Standards Organization (1989).
The PMV can be used to predict the percentage of dissatisfied (PPD) office users (Figure
12.6). The results of this research gives credence to the saying, “You can't please
everybody.” Regardless of the temperature setting in an office at least 5% of the office
workers will be dissatisfied. The International Standards Organization suggests that the
temperature be chosen so that the PPD is less than 10%. This means
TABLE 12.3
Measures to Reduce Heat Stress in
Hot and Humid Environments
Reduce the relative humidity by using dehumidifiers
Increase air movement by using fans
Lower the temperature by using air conditioners
Remove heavy clothing; permit loose-fitting wide clothing
Provide for lower energy expenditure levels
Schedule frequent rest pauses; rotate personnel
Schedule outside work so as to avoid high-temperature periods
Select personnel who can tolerate extreme heat
Permit gradual acclimatization to outdoor heat (2 weeks)
Supply cool, refrigerated vests (containing cooling elements)
Install local cold spots; e.g., refrigerated rooms for rest breaks
Maintain hydration by drinking water and taking salt tablets
FIGURE 12.6
The predicted
percentage of dissatisfied (PPD) users
