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21 pages, 8130 KiB

Open AccessFeature PaperArticle

Ventilation Methods for Improving the Indoor Air Quality and Energy Efficiency of Multi-Family Buildings in Central Europe

by Joanna Ferdyn-Grygierek and Krzysztof Grygierek

Energies 2024, 17(9), 2232; https://doi.org/10.3390/en17092232 - 6 May 2024

Cited by 5 | Viewed by 2179

Abstract

In Poland and other countries in Central Europe, residential buildings from the second half of the 20th century dominate, which have recently undergone deep thermomodernisation. Research on the retrofitting of residential buildings has focused mainly on energy efficiency, with only a few studies on indoor air quality. The aim of this study was to present a comparative analysis of the impact of five ventilation scenarios (three natural and two mechanical) on CO₂ concentration and energy demand for heating and ventilation in residential spaces of a multi-family building located in Poland. The analyses were based on the results of building performance co-simulation using the EnergyPlus and CONTAM programs carried out under dynamic conditions with a 5 min time step for the entire heating season. The calculations took into account the instantaneous occupancy variability of twenty apartments. In the buildings equipped with new tight windows, the natural ventilation system provided extremely low air exchange (on average 0.1 h⁻¹) and poor indoor air quality (average CO₂ concentration at the level of 2500 ppm). Opening windows to ventilate the rooms generated a multiple increase (up to 8 times) in heating demand during these periods, but average CO₂ concentration was on the level of 930 ppm. The use of mechanical ventilation was profitable both in terms of energy savings (at the level of 50%) and improvement in the indoor air. Full article

(This article belongs to the Special Issue Thermal Comfort, Environment Quality and Energy Consumption)

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16 pages, 11862 KiB

Open AccessFeature PaperArticle

Numerical Study on Sensitivity of Turbofan Engine Performance to Blade Count of Centrifugal Compressor Impeller

by Arkadiusz Bednarz, Kirill Kabalyk, Robert Jakubowski and Rafał Bartłomowicz

Energies 2023, 16(14), 5251; https://doi.org/10.3390/en16145251 - 8 Jul 2023

Cited by 6 | Viewed by 2667

Abstract

The aim of this publication was to investigate the effects the blade count of a high-pressure centrifugal compressor’s impeller has on the performance of the DGEN 380 turbine engine at take-off. The study began with the development of a zero-dimensional thermo-fluid model of the engine. The model was matched with experimental data from the WESTT CS/BV virtual test bench for the baseline count and then implemented to analyse the engine behaviour at alternative counts. The corresponding changes in the compressor pressure ratio and efficiency were modelled in a commercial 3D CFD software and transferred to the zero-dimensional model with proper scaling. The results proved that the baseline design lied in the optimal range of thrust-specific fuel consumption. The increase in the blade count led to a crisis of the aerodynamic loading at the splitters, so that no further rise in the pressure ratio could be achieved. The results of the study could be implemented by mechanical engineers while solving the tasks of the maintenance and modernisation of gas turbines with radial compressors. Full article

(This article belongs to the Topic Decarbonised Powertrains and Emission Control in Transportation)

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19 pages, 3012 KiB

Open AccessArticle

Building Thermo-Modernisation Solution Based on the Multi-Objective Optimisation Method

by Małgorzata Basińska, Dobrosława Kaczorek and Halina Koczyk

Energies 2020, 13(6), 1433; https://doi.org/10.3390/en13061433 - 19 Mar 2020

Cited by 19 | Viewed by 3008

Abstract

This study presents a multi-objective optimisation of building thermo-modernisation for multi-family buildings. The applied model has considered alternative solutions for insulation materials, with different thicknesses and different types of windows. The weighted sum method was applied to find a solution considering the minimisation of global cost, primary energy ratio and CO₂ emissions. The solutions were compared for a building equipped with natural ventilation, and with mechanical supply—exhaust ventilation. In reference to the two considered types of ventilation, we analysed how the modification of an insulation thickness, its type and the type of installed windows, can be converted into individual evaluation criteria. The weights of the considered criteria were changed; however, this had no influence on the optimal solution. If the aim is to achieve the standards of zero-energy buildings, natural ventilation cannot be applied, despite the high value of thermal insulation of the building envelopes. Alternative solutions exist for buildings with natural ventilation and mechanical ventilation with heat recovery, where the primary energy ratio is the same for both, but the global costs are different. The additional energy and environmental input for the production of materials and elements to be replaced are insignificant in comparison to the savings brought about by thermo-modernisation. Full article

(This article belongs to the Special Issue Low and Zero Energy Highly Performing Buildings)

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29 pages, 14113 KiB

Open AccessArticle

Evaluation of the Criteria for Selecting Proposed Variants of Utility Functions in the Adaptation of Historic Regional Architecture

by Małgorzata Fedorczak-Cisak, Alicja Kowalska-Koczwara, Krzysztof Nering, Filip Pachla, Elżbieta Radziszewska-Zielina, Grzegorz Śladowski, Tadeusz Tatara and Bartłomiej Ziarko

Sustainability 2019, 11(4), 1094; https://doi.org/10.3390/su11041094 - 19 Feb 2019

Cited by 30 | Viewed by 4067

Abstract

In this article, the authors propose ways to evaluate the criteria for the considered variants of utility functions in the adaptation of historic regional architecture. The proposed set of assessment criteria (thermo-modernisation criteria, comfort of use, financial considerations, criteria of social benefits, and protection of cultural heritage) emphasises the multidimensional character of the problem of choosing a new function for a historic building. Some of the criteria are measurable while others are difficult to measure, which requires an expert approach to their assessment. The evaluation of the criteria was performed on the example of the historic building ‘Stara Polana’ located in Zakopane. The benchmark for the analysis was the existing condition of the ‘Stara Polana’ building, which is used as a hostel. The authors conducted a series of interdisciplinary studies specifying the potential of the new utility functions considered for the object in the context of the proposed criteria. The evaluation of individual criteria developed in this article is based on the multi-criteria analysis to be performed in the future and support the selection of a new function for the building in question. Full article

(This article belongs to the Special Issue Multi-Objective and Multi-Attribute Optimisation for Sustainable Development Decision Aiding)

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