The correlation analysis basically identified the most significant factors which were used to normalize the energy consumption [16].Correlation analysis is often used to investigate the relationship between two sets of variables based on the data obtained by observations or experiments [38]. Correlation coefficient is introduced to express the degree of correlation by numerical value. It is a measure of the strength of the linear relationship between two variables, which is usually expressed as r [39]. The range of correlation coefficient is |r| ≤ 1; the closer |r| is to 1, the stronger the correlation is. Generally, in the case of r = 0, there’s no correlation; while |r| < 0.3 means there is weak correlation; if 0.3 < |r| < 0.5, it exhibits a low correlation; 0.5 < |r| < 0.8, significant correlation; 0.8