In issue 9/2025

Słowa kluczowe: Two-phase loop thermosyphon, cryogenic thermosyphon, heat pipe, condenser, evaporator, filling stage

Streszczenie:
The article describes a technical solution called a thermosyphon. Types of thermosyphons were characterized. The basic parameters affecting the operation of thermosyphons are discussed. The literature on research on thermosyphons and their potential application in practical solutions was also reviewed. The issues addressed in the article were also the subject of two engineering works [1], [2] carried out at the Department of Air Conditioning and Heating of the Faculty of Environmental Engineering of Warsaw University of Technology.

Słowa kluczowe: energy transformation, thermal modernization, heat pump, building energy class

Streszczenie:
The article presents an analysis of the energy transformation of a historic tenement house in Wroclaw performed in the context of the EPBD 2024 Directive and the European Union's goals until 2050. The aim of the analysis was to compare the energy effects of modernizing the heat source with connection to a district heating network, the use of an air and ground source heat pump and electric heating. Three sub-variants were developed for each variant, differing in the extent of thermal modernization and the use of photovoltaic installation. Simulations of the heat demand profile were performed in the EDSL TAS program, determining the annual demand for usable energy in an hourly step. Final energy and non-renewable primary energy consumption were determined in accordance with the current Polish methodology for determining the energy performance of a building and the draft amendment to this methodology. On this basis, energy classes A+ to G were assigned. The initial state (W0), prior to the 2020 thermomodernization, is characterized by EP >500 kWh/(m²-yr) and class G. Performing partial insulation of the building (W1), means improving the class to F. After full insulation and the introduction of PV (W1.2), a class of D is achieved. The use of an air source heat pump (W2) improves the class to E, a ground source heat pump (W3) to D. Variants with PV and full insulation (W2.2, W3.2) achieve class A. Electric heating (W4) remains in class G, and in the best case of insulation (W4.2) in class E. The article points out that the best results were obtained for a ground source heat pump with PV and full insulation. It also stressed that it is necessary to choose the optimal path of thermal modernization and implement it consistently.

Słowa kluczowe: circulator, nursing homes, energy efficiency, CO2 reduction

Streszczenie:
In social care facilities with residents requiring continuous care, domestic hot water (DHW) consumption is higher than in typical residential buildings, resulting in high heat demand. The article presents an analysis of the potential for reducing energy consumption and CO2 emissions associated with the operation of a domestic hot water system by using a circulating pump with automatic control instead of a continuously operating pump. The case study includes a comparison of the two solutions. The analysis showed significant energy savings and CO2 emission reductions after implementing the new solution.

Słowa kluczowe: drying, heat pump, solar energy, refrigerants, hybrid systems

Streszczenie:
The growing importance of renewable energy sources in the context of the energy transition is contributing to the rapid development of solar-assisted heat pump (SAHP) technologies, especially in drying. This article, a continuation of the previous part of the review, discusses advanced SAHP systems, such as hybrid systems, the use of alternative refrigerants and the prospects for implementing SAHPs in industry and agriculture. Particular attention was paid to the problems of using natural and low-carbon refrigerants, such as HC, CO2 and HFO, which can replace traditional substances with high greenhouse potential. Directions for future research were also presented, including the application of heat/cool storage technologies and novel design solutions. The results of the review indicate significant potential for further development of SAHPD systems, despite current technological limitations.

Słowa kluczowe: residential buildings, ventilation system energy assessment, ventilation heat transfer coefficient

Streszczenie:
The article presents and systematizes the methodology for determining the heat transfer coefficient of ventilation in residential buildings, in accordance with the 2015 Regulation of the Minister of Infrastructure and Development on the methodology for determining energy performance. The calculation algorithms used to describe gravitational ventilation, mechanical exhaust ventilation and supply and exhaust ventilation with heat recovery are discussed. Special attention was paid to hybrid ventilation, the current methodology of which does not provide a clear way to calculate. A practical engineering approach has been proposed, dividing the calculation year into periods of operation of gravitational and mechanical ventilation, based on the selected limit temperature of +12°C. The analysis is supplemented by important requirements for ventilation systems, which are derived from the regulation on technical conditions to be met by buildings and their location. Purpose: To explain, critically analyze and systematize the methodology for determining the heat transfer coefficient of ventilation in residential buildings in light of the current Polish regulations. Methods: The regulation on the methodology of determining energy performance and related Polish Standards were critically analyzed. The basic ventilation systems used in residential buildings were characterized, and then the calculation algorithms in each case were interpreted and presented. In the case of hybrid ventilation, due to the lack of formal guidelines, a calculation model is proposed that uses design criteria and an available typical meteorological year. Conclusions and reference to practical applications: The main practical application of the presented algorithms is the preparation of energy performance certificates for residential buildings. The current method of determining the ventilation heat transfer coefficient is very simplified due to the monthly balance method adopted for the energy assessment of buildings. The analysis carried out showed significant gaps in the methodology, especially with regard to hybrid ventilation.