Many companies have been working on to reduce energy consumption these days. However, it could also reduce efficiency of office work because the office environment becomes uncomfortable by the energy saving. Thus, it is necessary to save energy and keep workplace productivity at the same time. Since quantitative analyses about certain effects of workplace environment to office productivity have been already done in conventional studies, the degree of each environmental effect can be compared. It is however unclear how the environmental condition affects their productivity. The purpose of this study is to propose a systematic combination of various expert statistical methods as a framework of mechanism analysis of productivity changes. The proposed framework was also tested by case studies of some different varied environmental factors.