Commercial Buildings Economic Analysis of Different Improvements Investment Return Return Time Management $1 $10~20 1~2 months Replace Fans and Pumps $1 $0.8≈1.0 1~1.2 years Add Automatic Control Systems $1 $0.3≈0.5 2~3 years Retrofit Whole Systems $1 $0.2~0.4 3~5 years Retrofit Construction Material $1 $0.1~0.2 5~10 years Source:Tsinghua Tongfang Human Environment Engineering CompanyCommercial Buildings Economic Analysis of Different Improvements Investment Return Return Time Management $ 1 $ 10~20 1~2 months Replace Fans and Pumps $ 1 $ 0.8~1.0 1~1.2 years Add Automatic Control Systems $ 1 $ 0.3~0.5 2~3 years Retrofit Whole Systems $ 1 $ 0.2~0.4 3~5 years Retrofit Construction Material $ 1 $ 0.1~0.2 5~10 years Source: Tsinghua Tongfang Human Environment Engineering Company