||The presidential commission on architecture policy promotes happy house center service. One of the main service of happy house center is energy performance assessment of existing dwellings and renovation scenario's economic evaluation. In this study we have developed software(beta version) and its manual which would be used energy performance assessment of existing dwellings and its renovation consulting. If the software development would complete with taking stable root of happy house center service, we can expect systematic performance of energy performance assessment of existing dwellings which is carried out happy house center service. And developed program would be used in diversity fields beside happy house center service. The process of this study is as in the following : (1) The survey of existing detached dwellings, (2)The comparative analysis of existing energy performance programs, (3) The setting up the developing way of a program, (4) The analysis of theories which are related to development of a program and the development of algorithm, (5) The development of the program system, (6) The verification of the developed program.