Issue 5/2025

The article focuses on fire safety requirements for ventilation ductwork, particularly at the points where ducts penetrate fire-separating building structures. It outlines the legislative framework and relevant standards, design principles, and technical solutions for penetrations with or without fire dampers. Special attention is paid to the issue of fire sealing of ductwork without dampers and the importance of selecting appropriate materials and systems tested according to EN 1366-1. The article highlights shortcomings of commonly used sealing methods tested according to EN 1366-3 and proposes an approach based on correct normative procedures and realistic fire beha viour of duct systems.

The article compares various normative approaches to the design of mechanical ventilation systems in residential buildings. Using five case studies of single-family houses of different sizes, the design airflow rates specified by applicable standards are analysed and compared. The paper also presents minimum ventilation rates, intermittent airflow rates, and highlights common design errors in design of residential ventilation systems.

The article presents and analyses computational methods suitable for determining the noise levels of industrial fans and compares them with the values provided by manufacturers in their documentation. Three types of industrial fans were compared – axial, radial with forward-curved blades, and radial with backward-curved blades. The analysis includes both a numerical comparison and a graphical representation of frequency cur ves across octa ve bands.

The use of geothermal energy from depths of several kilometres is a dynamically developing field in Europe, applied mainly in district heating systems. The paper presents various types of geothermal systems and their implementation in Europe, with different temperature levels and application of extracted geothermal energy.

The article addresses the issue of flexibility in the power sector and its practical use for cost savings and stabilization of the power grid. Flexibility is understood here as the ability to adapt electricity consumption or generation to current market and grid conditions. The paper first explains the principles of spot prices and ancillary services, specifically automated frequency reserves. It then discusses two levels of the flexibility application. The first level is the management of domestic heating systems involving thermal storage, battery storage, and predictive consumption control. The second is the use of district heating for providing system ser vices and efficiently utilizing surplus electricity.

The design and verification of a flue system are carried out using standardized thermal and hydraulic calculations in accordance with ČSN EN 13384-1 and 13384-2. These calculations demonstrate the functionality and reliability of the entire system and constitute a mandatory part of the inspection report both upon commissioning and when addressing doubts regarding proper operation.