This section aims to give the reader an insight on statistical concepts related to regression analysis for better understanding of the literature review, and it is based mainly on references [13–17]. Multiple methods and regression algorithms are available for regression analysis, and specialized software, such as SPSS [18], SAS [19], SIMCA [20], STATISTICA [21], R [22], STATGRAPHICS [23] and NCSS [24] are used for applications. In building energy analysis the most common method used for regression analysis is the least squares method