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 (EUH) of a residential house on the thermal transmittance coefficients (Ui) of selected building elements were developed. Values of Ui 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 Ui in the analyzed period causes a decrease of EUH 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 rapid growth of sustainability has created a plethora of options for expanding zero-energy buildings (ZEBs) and energy efficiency in all aspects of life. In recent years, there has been a rise in interest in ZEBs, and many countries have adopted ZEBs as future energy targets to promote the sustainable development paradigm. The primary goal of this paper was to conduct a bibliometric review of current research on ZEBs and energy efficiency. The first part of this paper identifies new knowledge gaps as well as practical demands in the field of sustainable development. Furthermore, bibliometric analysis was performed using the Scopus database (i.e., 2592 articles) and a screening process was undertaken, with the result being 252 papers. This study draws attention to a body of knowledge by reviewing trends and patterns, major research topics, journals, countries, new approaches, emerging trends, and future directions for sustainable development. This study is unique in that it provides a comprehensive, updated review of ZEBs and energy efficiency trends. Moreover, this study could help identify limitations for future policymakers, practitioners, and academics. The empirical section of this paper, through a case study, presents an example of a low-energy single-family building located in Poland.

The study presents an investigation of thermal energy consumption for heating in an educational building located in the north-eastern part of Poland in 2017–2020, after deep thermomodernization. An evaluation of the actual energy effects was made based on measurements carried out over a 4-year operational period. They were compared with the results of theoretical calculations included in the energy audit and an attempt was made to describe the reasons for the discrepancies. The planned and achieved economic efficiency indicators were assessed and the amount of reduction of pollutant emissions was determined. The performed analysis allowed for an assessment of the impact of deep thermomodernization in terms of reducing heat energy consumption for central heating purposes, as well as reducing greenhouse gas emissions such as CO2, SOx, NOx and benzo(a)pyrene to the atmosphere. The implementation of thermomodernization in buildings led to savings of about 43% in terms of heat energy consumption for heating and a reduction in pollutant emissions. The theoretical savings based on the audit were 50.4%. The obtained results show that deep thermomodernization contributes to the improvement of energy and ecological efficiency in educational buildings, however, without the possibility of using subsidies, the investment is unprofitable. All the obtained results were discussed with the available literature sources and have been summarized with appropriate conclusions.

Abstract. Rational use of energy in buildings, their maintenance and proper exploitation are important issues, because they determine the standards of life and health of the population. In existing buildings, it is necessary to carry out ongoing repairs or modernization to maintain proper technical condition as well as to reduce energy consumption and CO 2 emissions. This is part of the global activities aimed at increasing energy efficiency and care for the natural environment. Retrofitting may involve the building envelope, ventilation system, heating system, hot water preparation, lighting and the use of renewable energy. The best results are achieved because of comprehensive deep thermal modernization. The paper analyses the possibilities of energy consumption reduction because of deep thermal modernization and the use of renewable energy in few public buildings in rural areas in north-eastern Poland. This is a case study based on energy audits. Energy consumption decreased by 46-65 % and CO2 emissions by over 80 %. The share of renewable energy from solar collectors and photovoltaic panels was not high (from 3 % to 15 %). The cost of saving the energy unit during deep thermomodernization in the test sample was higher than its current price.

This work presents the results of analysis of the final energy demand (Qk) for a single-family house in a pandemic situation and accompanying self-isolation of residents. It was assumed that the object of study is located in Bialystok (Poland). This analysis covers the impact of various factors such as specific periods of the active pandemic phase, the length of the inhabitants’ self-isolation period, the number of residents at home, and the type of energy source used in the building. Based on the results of computational experiments, a deterministic mathematical model of the relationship between these variables was developed, and the effects of the selected factors on the final energy demand were analyzed for the typical meteorological year (TMY) weather data. It turned out that the change in the length of the self-isolation period from 0 to 31 days caused an increase of Qk by about 6.5% for the analyzed building. When the number of inhabitants changed from 1 to 4, Qk increased by 34.7%. A change from 4 to 7 people causes an additional 26.7% increase in Qk. It was found that the structure of energy demand for this building operation during the period of inhabitants’ self-isolation also changed. With the increase in the length of the self-isolation period from 0 to 31 days, the electricity demand (Eel) increases by about 40–42%, while the demand for energy related to fuel consumption (Qg) decreases by about 7–10%. The article also presents an analysis of the impact of residents’ self-isolation on indoor air quality (IAQ) and thermal comfort. The simulation results showed that the use of variable air volume ventilation allows the CO2 concentration to be kept significantly below the limit value.

Many buildings have considerable thermal bridges at the junction of balcony slabs with walls. To achieve the new EU directive targets related to energy efficiency, greater attention should be paid to such design details. This study analyzes the efficiency of traditional balcony slab modernization methods, the use of modern insulation materials and a new alternative system: an added self-supporting light balcony system (LKBD) in retrofitted large-panel buildings. The main objective was to capture cost-effective renovation methods from both the heat loss reduction perspectives and risk of surface condensation. The analyses, carried out in four buildings, have shown that at current costs, the thermal modernization of balconies is not economically efficient (SPBT>98.4 years). However, it is necessary because leaving the balcony slabs without insulation or only insulating them from the bottom carries the risk of surface condensation. The most cost-effective renovation method is to insulate the balcony slabs from below and above with the thickest possible XPS layer (SPBT = 98.4 years; 107.4 years). Replacing XPS with modern material increases SPBT by almost 50%, for the LKBD system, SPBT = 269.2–281.5 years. More favorable energy and economic effects related to the reduction of balcony thermal bridges were achieved in the wall with lower insulation.

Many factors affect energy demand, and knowing their impact is very important for being able to design a low-energy building. In this group of factors, there are those that cannot be changed and improved after the building is constructed, so taking them into account when choosing a project is important for energy savings. This group includes geometric parameters. We propose a geometric method of assessing the energy demand of a single-family house. The idea is to predict the level of energy demand by calculating the values of simple geometric parameters in the first stage of design. Based on the analysis of 30 realistically designed single-family houses, we show that the geometric indicators expressed by the base area Af, and perimeter P at a fixed building wall height h, perfectly characterize the amount of energy, both usable and final. Moreover, we show linear relationships between the nominated A/V and non-nominated EWA/FA, RCcd compactness ratios. This relationship allows one indicator to be measured with another. As a result, we show how a designer can use a simple calculated index RCcd to find out the level of energy demand.

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