The energy refurbishment process involves an initial data collection which is mandatory during the building diagnostics phase. In this paper we address the building construction and materials, technical parameters, building location and form. The main goal is to set up a framework through examples of data collection methods for holistic energy refurbishment. The subjects of this study are two social housing buildings which belong to the 8th district Municipality in Budapest, consisting of 109 and 100 individual dwellings. On-site data was collected and building material samples were tested in the laboratory. The testing included measurements of the overall thermal transmittance of walls and heat transfer coefficient of a brick. The monitoring was conducted during a 72-hour period on-site using a heat flow meter. The research discusses the measurement process and laboratory testing results to formulate further steps and milestones during the energy renovation process of these specific and similar buildings.