With the rapid development of economy,huge civil public buildings have been constructed rapidly recent years,such as office buildings,commercial malls,luxury hotels.However,many personnel in charge of property management confirm that there exist commonly in public buildings in service relatively low load rates of transformers(generally 30%~50%),resulting in poor ecologic efficiency.Lots of factors can be attributed to this situation.The present work made an attempt to determine the causes by exploring the process of load calculation in the period of constructional drawing design.The paper also comparatively describes some actual cases,in order to provide useful information and support for similar proj ects.