Among different engineering projects, there are ones intended to improve the energy-saving properties of buildings. Both new and much older buildings undergoing refurbishment can be involved. Broadly understood energy-saving projects increasingly often entail renewable energy installations. Every implementation of such an investment project needs to be preceded by an assessment of its economic efficiency. Although the literature provides examples of methods which can serve this purpose, a coherent methodological approach seems lacking. In this article, the author proposes methodology based on several simple and compound methods combined into a schematic assessment procedure. The methodology is presented as applied in a case of typical photovoltaic roof installation to generate electricity for a single-family house. The assessment procedure consists of a few steps leading from a preliminary to a more detailed appraisal. The first stage is an How to cite this article: Szafranko E. Assessment of the economic efficiency of energy-saving projects, methodology based on simple and compound methods.