PL
The article provides the empirical analysis of thermo-insulation layer thickness (expanded polystyrene – EPS70) of the typical wall detail and its investment payback period in the traditional new construction single-apartment residential and net-zero energy building. On the basis of the results a simple payback period was calculated. Geographic region of Lithuania and Poland was chosen as the research object. The research results are important for building investors, designers, also for the auditors and experts of buildings energy consumption.