Many energy performance assessment methods are available. There are both dynamic and steady state methods, of which initial data may be based on statistics or physical models. However, many of the tools are not suitable in refurbishment projects because of the difficulties in defining the input values for the building and user behaviour. The objective of the study was to review the existing energy performance assessment tools and make conclusions for the new type of tools needed especially by small companies in refurbishment projects. The study concluded that the right combination of ease-of-use and accuracy is important. This can be achieved with the help of dynamic calculation engine, carefully defined local data and well-selected default values and − on the other hand − with the help of openness which enables the users to access the default values and give detailed true data when that is available. This combination enables both rough estimations in early phases and more accurate assessment when better information is available. The research developed a new tool based on these principles and carried out a wide survey among potential users. The survey supported the preliminary understanding and highlighted further needs of SMEs in refurbishment projects.