12.1.2.1-3 Effective Temperature

The temperature in the control room should be maintained in the comfort zone of its users.

Additional Information: The temperature metric used to determine the control room climate under “Ambient Temperature” above represents the dry-bulb temperature and should be used as the primary criterion for determining temperature conformance in the control room. However, the dry-bulb temperature metric has certain limitations with regards to human comfort. Calculating individual heat balances in the workplace is difficult. If the dry-bulb temperature metric proves to be inadequate, or if a more in-depth analysis is needed, for certain types of control room climate conditions, especially as regards extremes in relative humidity and air movement, the more comprehensive effective temperature (ET) metric should be used. The ET considers dry-bulb temperature and wet-bulb temperature (and derived relative humidity), as well as air movement, to more accurately determine the comfort zone, which itself can vary depending on user clothing, workloads, and acclimatization. The optimum range of ET for accomplishing light work while dressed appropriately for the season or climate is 21–27 degrees C (70–80 degrees F) in a warm climate or during the summer, and 18–24 degrees C (65–75 degrees F) in a colder climate or during the winter. More information on the ET metric may be found in

ANSI/ASHRAE 55 (2013).HFDS