The energy saving tendencies, in reference to residential buildings, can be recently seen in Europe and in the world. Therefore, there are a lot of studies being conducted aiming to find technical solutions in order to improve the energy efficiency of existing, modernized, and also new buildings. However, there are obligatory solutions and requirements, which must be implemented during designing stage of the building envelope and its heating/cooling system. They are gathered in the national regulations. The paper describes the process of raising the energy standard of buildings between 1974–2021 in Poland. Therefore, the objective of this study is to show energy savings, which can be generated by modernization of thermal insulation of partitions of existing buildings and by the use of different ways of heat supply. The calculations are made on the selected multi-family buildings located in Poland, with the assumption of a 15 years payback time. It is shown that it is not possible to cover the costs of the modernization works by the projected savings with the compliance to the assumption of 15 years payback time.
The article aims to evaluate the Portuguese building stock energy policies and strategy for energy saving in buildings among the EU members. It was found out the average heat transfer coefficients of the main structural elements of Portuguese Buildings and analyzed the U-values of this elements considering different time periods. The fundamentals of this study were funded by the Agency for Development and Innovation (ADI) and co-financed by the European Regional Development Fund (FEDER) through the Operational Program for Competitiveness Factors (POFC) assigned to the Building Physics and Construction Technology Laboratory with the reference SB Tool SPT_2011_4.