Analysis of already created heat metering and billing systems are made. Lacks and advantages of existing systems are overlooked and considered for add-on model development. Heat metering and billing functions are described and solution is presented. MS Navision and MS SQL Server technologies usability aspects where analyzed. The functionality of MS Navision where compared with described heat metering and billing functions and the fit-gap where made. Product was built as a specific add-on module for MS Navision Attain. The most important goals of product where heat energy billing integration with financial management and flexible data model for program adaptation to methodology changes of heat energy billing. Data model flexibility analysis where done and compatibility to requirements was established. MS Navision and MS SQL server functions performance testes where run and recommendations for choosing platform are made.