Various methods can be used to reduce energy consumption in buildings. One of them is the tightening of energy requirements, which, like other methods, cannot result in a worsening of the indoor environmental quality. The article presents a study on the impact of changes in the thermal insulation of the building envelope on the energy demand, heating costs, and emissions. Mathematical models of the dependence of the index of annual usable energy demand for heating (EU_H) of a residential house on the thermal transmittance coefficients (U_i) of selected building elements were developed. Values of U_i were adopted at three levels, corresponding to the maximum required values—as approved in Polish law for the periods from 2014, 2017, and 2021. The analyses were conducted for the location of the building in three of the five climate zones of Poland. It turned out that the differences in the energy demand in various locations in Poland amount to 32.6%. The change in U_i in the analyzed period causes a decrease of EU_H by almost 27%. Financial savings and a reduction of emissions strongly depend on the fuel used in the building. Increasing the level of thermal insulation of walls increases the perceptible temperature in rooms by 1.2–1.5%.

The paper presents the results of the compressive strength, splitting tensile strength, flexural tensile strength and elastic modulus testing of high strength concrete at 28 and 56 days of maturation, depending on two factors: the portion of 2/16 mm fraction gravel aggregate and the portion of 2/16 mm fraction boiler slag. The analysis and conclusions were justified by the results of laboratory experiments and developed mathematical models describing the dependence of the selected characteristics of the material obtained from the compound composition - the portion of boiler slag and gravel aggregate in the aggregate mix, as well as the observation results of the obtained material microstructure.

Deterioration of concrete due to surface scaling is a very serious durability problem faced by the construction industry in cold environments. The experimental results of resistance to scaling due to cyclic freezing and thawing in the presence of 3 % NaCl solution (de‐icing agent) of not air‐entrained concrete with and without bituminous addition are presented and discussed in the paper. The results have been analysed using the analysis of variance and regression to verify the effect of addition content, number of freeze‐thaw cycles and the sort of cement on concrete ability to scaling. The statistical analysis showed that the bituminous addition significantly improves the scaling resistance of Portland cement concrete.

This article deals with the determination of the impact of selected parameters on energy consumption for heating and cooling purposes and CO₂ emissions. Mathematical modelling combined with planning a computational experiment was adopted as the research method. The database for creating the models was developed using building energy simulations performed with DesignBuilder software. A single-family house with an area of 101 m² was the subject of this study. Four deterministic mathematical models for the estimation of annual energy demand for heating, cooling, total final energy demand, and CO₂ emissions were developed. Four parameters affecting the energy balance of the house: the area of the glazing system (three levels), U-value of windows (two-, three- and four-pane), U-value of external walls (0.1, 0.15, 0.2 W/m²K) and location (Warsaw, Berlin, Paris) were considered. The article discusses in detail the influence of individual factors on the energy demand and their common interactions. It was found that the level of thermal insulation of the glazing system plays the most important role in saving energy. This factor was the only one to show a stable and significant reduction in house energy demand, and thus a reduction in CO₂ emissions for all four objective functions.