Advancement of Energy Management Systems (EMSs) for building facilities is becoming more important for sustainable development. The Service Oriented Architecture (SOA) will be a powerful approach for these systems. Distributed type building air-conditioners, which are dominant in Japan, have many distributed raw state variables required by an EMS. This makes it difficult to apply the SOA to those EMSs. We have introduced our concept of state variable integration that realizes loose-coupling and proper-granularity in Web services of an SOA-EMS. We have confirmed the effectiveness of our state variable integration in a field test with an office building. In this case, our integration services provide 4 integrated state variables from 172800 raw data for a day. Auto Regressive (AR) system identification with our integrated state variables has been carried out using a time series of the field test data for 60 days.