A new Dutch adaptive thermal comfort guideline

In practice, the commonly used Dutch design criterion for long-term thermal comfort in buildings-the weighted temperature exceeding hours method--often leads to confusion.The criterion is hard to understand for non-experts, and many doubt the validity of the present criterion : how sure are we that meeting the requirements really means that future occupants will be comfortable? A project was initiated in order to formulate alternative ways to predict, evaluate and communicate thermal comfort performance of buildings.The result is a new Dutch thermal comfort guideline for both design and evaluation purposes. Important properties of the new guideline are:- It distinguishes between buildings with a high versus a low degree of occupant control ('free running' versus 'centrally controlled'): type ALPHA versus type BETA.- Limits are set in terms of maximum and minimum allowable operative indoor temperatures. These change with increasing or decreasing average outdoor temperatures, anticipating adaptation effects. The maximum allowable temperature for type ALPHA buildings during warmer periods is substantially higher than for type BETA buildings.- A building's performance over time is characterized as the percentage of occupancy time that the 90, 80 and 70% acceptability lines are exceeded. Referring to CR 1752, a building is classij7ed as a class A building if the 90% lines are never exceeded, as class B if the 80% lines and class C if the 70% lines are never exceeded.