Issue 3/2026

The article addresses the phenomenon of flutter echo, a common acoustic issue that can significantly impair sound quality in a wide range of indoor spaces. It relates this phenomenon to standard construction practices and illustrates it through case studies of three school gymnasiums. For two of them, the applied acoustic remediation measures are described in detail. The reader also has access to unique online audio samples that demonstrate the flutter echo effects in the presented spaces.

The aim of this artic le is to point out tha t the design of an air -to-water heat pump is a sensitive task, where unnecessary oversizing increases capital costs without delivering substantial operational savings. The main output of the study are design curves that show the percentage coverage of heat demand and the proportional heat pump electricity consumption depending on the bivalence temperature or the sizing of the heat pump’s output. The curves were generated using a simulation model developed in Matlab/Simulink, applied to simulate IVT AIRX and Heliotherm heat pumps. Simulation results indicate that even a significantly undersized heat pump (35–60% of the heating capacity at the temperature of -12 °C) is capable of covering more than 80% of the annual heating demand in regions with a design outdoor temperature of -12 °C, across a range of supply wa ter temperatures.

Is a mechanical constant air volume regulator more environmentally friendly, or is an electronic variable air volume regulator better? The Environmental Product Declaration for these regulators – as for other ventilation components – only partially answers this question due to the prescribed methodology. The remaining part of the answer can be found (or should be found) in a realistic estimate of the energy consumption of the ventilation unit fan, based on the air flo w rates and pressure losses of the system.

The article presents experience with the operation of HVAC systems, focusing on the control of supply air parameters in ventilated and air-conditioned spaces, with an emphasis on optimum indoor environmental comfort and maximum opera tional efficiency.

The article addresses the issue of moisture recovery. It analyses moisture recovery in office and residential buildings, including the influence of boundary conditions. Based on the analyses, the applications, advantages, and benefits of moisture recovery in the assessed buildings are discussed. The paper presents a calculation methodology that enables evaluation of the effectiveness and suitability of moisture recovery in different applications.

The article describes a supporting web tool designed for the effective decarbonization of urban district heating systems through the integration of Power-to-Heat technology, primarily heat pumps. The tool was developed within a project by the Technology Agency of the Czech Republic and is designed to support decision-making in the early stages of planning the integration of heat pumps into district heating systems. The tool is based on an extensive simulation knowledge database created in the TRNSYS environment, enabling the interpolation of results, visualization, and economic evaluation of scenarios. The article presents the structure of the web tool, its functions, and its benefits for planning decarboniza tion strategies.

The article provides an overview of respiratory protective equipment, including its basic classification, components, and representative examples. The second part describes self-contained breathing apparatus and escape breathing apparatus, including the related current ČSN EN standards. At the end of the article, suitable personal protective equipment for working with asbesto s is presented.