4. The Long-Term Percentage of Dissatisfied

Following the analysis about the indices for the long-term comfort evaluation, carried out in the previous two chapters, in this chapter a new long-term discomfort index, called Long-term Percentage of Dissatisfied, is proposed, and its features are discussed. It is a symmetric and comfort-model based index, not depending on comfort categories, and it is applicable to both summer and winter assessments. This index is proposed in three versions, which differ in the way the hourly likelihood of thermal discomfort is evaluated, depending on the reference comfort model used for the assessment. The three versions weigh the zone hourly likelihood of thermal discomfort by the hourly occupancy rate in each thermal zone of the building. The first version of the new index is based on the Fanger comfort model, and its likelihood of thermal discomfort coincides with the Predicted percentage of dissatisfied. The second version is based on the EN adaptive comfort model, and its likelihood of thermal discomfort is calculated through the Nicol et al.’s overheating risk. The third is based on the ASHRAE adaptive comfort model, and, since a reliable likelihood of thermal discomfort was not identified in literature for this comfort model, it has been developed via a logistic regression analysis of the data collected in the ASHRAE RP-884 database. Therefore, the methodology adopted for deriving such new likelihood of thermal discomfort from the ASHRAE RP-884 data, and the result of the performed logistic regression analysis are presented. Then, the three versions of the index are calculated for the 54 building variants described in Chap.​ 1 and their results are compared. Finally, since the building performance simulation software used in this work, EnergyPlus, does not directly calculate the proposed new index, three computer codes have been written in the programming language EnergyPlus Runtime Language, and then integrated in EnergyPlus through the Energy Management System module.