The main objective of this paper is to demonstrate the effectiveness of increasing the thermal capacity of a residential building by using traditional building materials to reduce the risk of its excessive overheating during intense heat waves in a temperate climate. An additional objective is to show that the use of this single passive measure significantly reduces the risk of overheating in daytime rooms, but also, though to a much lesser extent, in bedrooms. Increasing the thermal mass of the room from light to a medium heavy reduced the average maximum daily temperature by $2.2$$\mathrm{K}$ during the first heat wave and by $2.6$$\mathrm{K}$ during the other two heat waves. The use of very heavy construction further reduced the average maximum temperature for the heat waves analyzed by $1.4$$\mathrm{K}$, $1.2$$\mathrm{K}$ and $1.7$$\mathrm{K}$, respectively, giving a total possible reduction in maximum daily temperatures in the range of $3.6$ °C, $3.8$ °C and $4.3$ °C. A discussion of the influence of occupant behavior on the use of night ventilation and external blinds was carried out, finding a significant effect on the effectiveness of the use of both methods. The results of the study suggest that in temperate European countries, preserving residential construction methods with heavy envelopes and partitions could significantly reduce the risk of overheating in residential buildings over the next few decades, without the need for night ventilation or external blinds, whose effectiveness is highly dependent on individual occupant behavior.

The paper proposes an alternative approach to the problem of district heating monitoring parameters selection, based on conditions, taken, for instance, from a specific real district heating network supplemented with tests data and expert knowledge.

Energy efficiency is extremely significant for industrial processes and technologies. Rising energy prices, depleting fossil fuels, as well as tightening regulations that impose the need to reduce GHG emissions incentivize companies to look for energy-efficient solutions. This also applies to wastewater treatment plants, which, on the one hand, are consumers of very large amounts of energy, and on the other hand, have significant potential to retrieve waste energy in the form of heat accumulated in wastewater. The authors of this publication have recognized the benefits of managing this heat. However, they have also pointed out several problems and difficulties associated with this process. By means of measured data, this publication provides a comprehensive analysis of the heat that can be recovered from wastewater treatment plants. As a result of the analyses, the locations of sites for collecting heat from wastewater have been determined, and potential technologies for this purpose have been identified. Moreover, the impact of the proposed heat recovery technology on the process of biological wastewater treatment has also been analyzed. As a result of the research, the authors developed generalized guidelines for selecting an optimal heat recovery site and the technological system designed for this purpose.

In the EU countries, almost 50% of the produced energy is used in residential buildings. More than 25% of this energy is used to produce domestic hot water, of which almost 80% is used to heat water in domestic hot water circulation systems. This is due to high expectations on the part of residents based on their comfort, in particular regarding the supply of heat for heating and domestic hot water. In the course of their long-term research conducted on real systems, the authors confirmed that the operation of domestic hot water distribution systems causes significant costs, mainly due to heat losses. Therefore, typical variants of energy optimization of such systems were analyzed. Tests have shown that selected solutions, such as the use of control automation, are not sufficient, and recommended additional thermal insulation may not be applicable due to technical reasons. With an aim of finding a solution to the problem, the publication analyzes operational data from an existing heat source and domestic hot water circulation system in a residential building. On the basis of these analyses, a solution was proposed to reduce energy consumption within the installation by means of its hydraulic optimization. The reduction of heat losses in domestic hot water installation by means of a method presented by the authors is estimated at approximately 20%.