Model matematyczny bilansu energetycznego okien w budynkach mieszkalnych

The paper presents a developed mathematical model, made by the authors, which is used to calculate the energy balance of windows in residential buildings. There is presented an algorithm for calculating the components of loss and heat gain of the energy balance of the window, as well as the course of action while choosing variable parameters, which are the part of mathematical model and also are suitable to make the optimisation of windows, like: the window surface, heat-transfer coefficients U for the glass and the window frame, the permeability factor g and others. There is also suggested the programme of a calculation experiment.W prezentowanym artykule przedstawiony został opracowany przez autorów model matematyczny służący do określenia bilansu energetycznego stolarki okiennej w budynkach mieszkalnych. Przedstawiono algorytm obliczania strat i zysków ciepła przez okno, tj. składników bilansu cieplnego okna, a także tok postępowania przy wyborze zmiennych parametrów, wchodzących w model matematyczny oraz nadających się do optymalizacji rozwiązań stolarki okiennej: powierzchni okna, współczynników przenikania ciepła U dla szyby i ramy okiennej, współczynnika przepuszczalności g i innych. Zaproponowano również program eksperymentu obliczeniowego

Analiza rozwiązań złożonych mostków termicznych pod względem udoskonalania ich parametrów cieplnych

The article presents the analysis of complex thermal bridges solutions which occur in the fixing nodes of ventilated facade and the way of taking into consideration them in thermal calculations. On the basis of this analysis, a number of factors which may affect the thermal parameters of thermal bridges were detected. However they are not reflected in the formulas specified in current standards. Therefore, new approaches and correlations, that will precisely determine the physico-technical parameters of similar fixing nodes, should be looked for.Artykuł dotyczy analizy rozwiązań złożonych mostków termicznych, występujących w węzłach mocujących elewacji wentylowanych oraz sposobu ich uwzględniania w obliczeniach cieplnych. Na podstawie tej analizy wykryto szereg czynników, które mogą wpływać na parametry cieplne mostków termicznych, jednak nie są one odzwierciedlone we wzorach z aktualnych norm. W związku z tym należy szukać nowych podejść i zależności, które w sposób precyzyjny pozwolą określić parametry fizyko-techniczne podobnych węzłów mocujących

Impact of Changes in the Required Thermal Insulation of Building Envelope on Energy Demand, Heating Costs, Emissions, and Temperature in Buildings

Various methods can be used to reduce energy consumption in buildings. One of them is the tightening of energy requirements, which, like other methods, cannot result in a worsening of the indoor environmental quality. The article presents a study on the impact of changes in the thermal insulation of the building envelope on the energy demand, heating costs, and emissions. Mathematical models of the dependence of the index of annual usable energy demand for heating (EUH) of a residential house on the thermal transmittance coefficients (Ui) of selected building elements were developed. Values of Ui were adopted at three levels, corresponding to the maximum required values—as approved in Polish law for the periods from 2014, 2017, and 2021. The analyses were conducted for the location of the building in three of the five climate zones of Poland. It turned out that the differences in the energy demand in various locations in Poland amount to 32.6%. The change in Ui in the analyzed period causes a decrease of EUH by almost 27%. Financial savings and a reduction of emissions strongly depend on the fuel used in the building. Increasing the level of thermal insulation of walls increases the perceptible temperature in rooms by 1.2–1.5%

Ekonomiczne efekty zmian wymaganej izolacyjności cieplnej przegród budowlanych w Polsce

Thermal insulation on the external partitions of the buildings is a very usual strategy to reduce energy demand for heating. This paper presents an original study of the demand for usable energy QH, nd of a single-family residential building in different climatic conditions (milder conditions – Szczecin, national average – Lodz and more severe conditions – Zakopane) on the thermal transmittance coefficient of selected partitions: external walls, roof, windows and balcony doors, roof windows and doors. They were adopted at three levels, corresponding to the maximum required values, as approved in the Technical Conditions, for periods from 2014, 2017 and 31.12.2020. Based on the results of the computational experiment, three deterministic mathematical models were developed, and the effects of factors on the Y function for the assumed climate conditions were analyzed. Financial savings related to the introduction of stricter requirements for thermal protection of buildings in Poland were determined.Ocieplenie przegród zewnętrznych budynków jest bardzo typową strategią zmniejszania zapotrzebowania na energię do ogrzewania. W artykule przedstawiono oryginalne badanie zależności zapotrzebowania na energię użytkową QH,nd jednorodzinnego budynku mieszkalnego w zróżnicowanych warunkach klimatycznych (łagodniejszych – dla Szczecina, średnich krajowych – dla Łodzi i surowszych – dla Zakopanego) od współczynnika przenikania ciepła wybranych przegród: ścian zewnętrznych, dachu, okien i drzwi balkonowych, okien połaciowych oraz drzwi zewnętrznych, które zostały przyjęte na trzech poziomach odpowiadających maksymalnym dopuszczalnym wartościom, zatwierdzonym w Warunkach Technicznych, obowiązującym od 2014, 2017 i 31.12.2020 roku. Na podstawie wyników eksperymentu obliczeniowego opracowano trzy deterministyczne modele matematyczne tej zależności oraz przeanalizowano efekty wpływu czynników na funkcję Y dla przyjętych warunków klimatycznych. Określono oszczędności finansowe związane z wprowadzeniem surowszych wymagań w zakresie ochrony termicznej budynków w Polsce

Optimization of the Selected Parameters of Single-Family House Components with the Estimation of Their Contribution to Energy Saving

Knowledge of the influence of factors determining energy consumption in buildings is very important for the possibility of effective energy saving. This article describes the results of an original study on the analysis of the annual energy demand for heating (QH;nd), cooling (QC;nd), and annual usable energy demand (QH/C;nd = QH;nd + QC;nd) assumed as objective functions of a designed single-family building, which can be classified as a typical representative of currently built houses in Poland. It was assumed that the object of study was located in the climatic conditions of north-eastern Poland. The study takes into consideration three groups of selected parameters: architectural/spatial, structural, and physical properties of windows. The research was carried out in a single-family building, as energy consumption in residential buildings accounts for a significant part of the total energy consumption in buildings. In the group of architectural/spatial parameters, the height of rooms in the building (h) and the window area change coefficient (k) were taken into consideration. The design parameters pertained to the solutions of building components: the density of the material of the inner layer of the external walls (ρ1), the density of the material of internal walls (ρ2), and the thickness of internal walls (d). In the third group of parameters, the heat transfer coefficient of the glazing (Ug) and the total solar transmittance of the glazing (g) were considered. Deterministic mathematical models of these dependencies were developed on the basis of the results of a computational experiment, obtained by performing a simulation with the use of the DesignBuilder software, based on the EnergyPlus computational engine. The models allowed the authors to estimate the degree and nature of the influence of the examined factors on the building’s energy demand. As a result of the optimization of parameters according to the energy criterion, the contribution of each of the three groups of parameters to energy saving was determined. Deterministic numerical optimization using MATLAB was applied. It turned out that the factors from the first group played the most important role in energy savings (40.0%), and the factors from the third group contributed slightly less (25.7%). The contribution of the characteristics from the second group was 4.2% of the total value of energy saving. This information can be useful to scientists, as well as engineers and policymakers, in making correct decisions when designing new residential buildings

Influence of air-entraining admixture on strength development of cement composites containing fly ash addition

The results of laboratory investigation concerning the influence of the air-entraining admixturecontent [i]d[/i]/[i]C[/i], the [i]W[/i]/[i]C[/i] ratio, and the time of curing[i] τ[/i] on the compressive strength [i]f[sub]c[/sub][/i] of cement mortarssamples are presented in the paper. On the basis of the results, a mathematical model was elaborated.The character and the influence grade of each factor were analyzed. It was determined that with increasein the content of air-entraining admixture, the compressive strength of cement mortars containingfly ash decreases. However, there is a limiting dosage of the admixture above which the increase in itscontent does not cause the decrease in the strength.[b]Keywords[/b]: civil engineering, cement composites, air-entraining admixture, fly ash, mathematicalmode

Surface scaling resistance of concrete modified with bituminous addition

Deterioration of concrete due to surface scaling is a very serious durability problem faced by the construction industry in cold environments. The experimental results of resistance to scaling due to cyclic freezing and thawing in the presence of 3 % NaCl solution (deâ€icing agent) of not airâ€entrained concrete with and without bituminous addition are presented and discussed in the paper. The results have been analysed using the analysis of variance and regression to verify the effect of addition content, number of freezeâ€thaw cycles and the sort of cement on concrete ability to scaling. The statistical analysis showed that the bituminous addition significantly improves the scaling resistance of Portland cement concrete. First Published Online: 14 Oct 201

Evaluation of concrete resistance to chloride ions penetration by means of electric resistivity monitoring

The chlorideâ€induced corrosion of reinforcing steel is the major reason for the premature deterioration and degradation of field concrete structures built in a saltâ€laden environment. The results of investigation of the bituminous addition effect on Portland cement concrete resistance to chloride ions penetration are presented in this paper. Chloride penetration was simulated by subjecting samples to cyclic loading with salt solution and drying. Concrete resistivity development was monitored during 12 months. The test results have been analysed to verify the effect of addition content, the time of exposure in aggressive environment, as well as the sort of cement on chloride ion permeability of Portland cement concrete. The statistical analysis showed that bituminous addition significantly improves the concrete resistance to chloride salt solution penetration. Betono atsparumo chloro Jonų skvarbai įvertinimas stebint elektrinÄ—s varžos kitimÄ… Santrauka Betono ir gelžbetonio atžvilgiu chloro jonai yra agresyvus veiksnys, skatinantis armatÅ«rinio plieno ir betono korozijÄ…. Pateikiami bituminio priedo betone įtakos tyrimų rezultatai chloro jonų skvarbai jame. Siekiant įvertinti betono pasiprieÅ¡inimÄ… tokiems difuzijos procesams, remtasi eksperimentiniais medžiagos elektrinÄ—s varžos matavimo rezultatais. Taikant statistinius tyrimų metodus, atlikta rezultatų dispersinÄ— ir regresinÄ— analizÄ—, aiÅ¡kinantis betono elektrinÄ—s varžos kitimo tendencijas priklausomai nuo panaudoto cemento rÅ«Å¡ies, bituminio priedo kiekio, NaCl vandeninio tirpalo, skirto bandiniams įmirkyti, koncentracijos, ir agresyvaus priedo poveikio trukmÄ—s. StatistinÄ— analizÄ— patvirtino gana teigiamÄ… ir naudingÄ… bituminio priedo betone poveikio įtakÄ… ribojant chloro druskų tirpalų skvarbÄ… į betonÄ…. Raktiniai žodžiai: betonas, chloro jonai, elektrinÄ— varža, struktÅ«rinÄ— apsauga, bituminis priedas, dispersinÄ— analizÄ—, regresija. First Published Online: 14 Oct 201

Wielokryterialna analiza porównawcza – narzędzie do oceny jakości użytkowej mieszkań

Choosing (buying) flats is a multistage, complicated decision which many elusive factors affect. Mathematical methods allow for construction of the measuring tool letting for making these processes more objective. It requires distinguishing features affecting the decision making in this process by specific groups of users and determining their importances.Wybór (zakup) mieszkania to wieloetapowa, skomplikowana decyzja, na którą wpływa wiele trudno uchwytnych czynników. Metody matematyczne pozwalają na budowę narzędzia pomiarowego pozwalającego na zobiektywizowanie tych procesów. Wymaga to wyodrębnienia cech mających wpływ na podejmowanie decyzji przez określone grupy użytkowników oraz określenia ich wag w tym procesie

Analysis of the Impact of Self-Isolation of Residents during a Pandemic on Energy Demand and Indoor Air Quality in a Single-Family Building

This work presents the results of analysis of the final energy demand (Qk) for a single-family house in a pandemic situation and accompanying self-isolation of residents. It was assumed that the object of study is located in Bialystok (Poland). This analysis covers the impact of various factors such as specific periods of the active pandemic phase, the length of the inhabitants’ self-isolation period, the number of residents at home, and the type of energy source used in the building. Based on the results of computational experiments, a deterministic mathematical model of the relationship between these variables was developed, and the effects of the selected factors on the final energy demand were analyzed for the typical meteorological year (TMY) weather data. It turned out that the change in the length of the self-isolation period from 0 to 31 days caused an increase of Qk by about 6.5% for the analyzed building. When the number of inhabitants changed from 1 to 4, Qk increased by 34.7%. A change from 4 to 7 people causes an additional 26.7% increase in Qk. It was found that the structure of energy demand for this building operation during the period of inhabitants’ self-isolation also changed. With the increase in the length of the self-isolation period from 0 to 31 days, the electricity demand (Eel) increases by about 40–42%, while the demand for energy related to fuel consumption (Qg) decreases by about 7–10%. The article also presents an analysis of the impact of residents’ self-isolation on indoor air quality (IAQ) and thermal comfort. The simulation results showed that the use of variable air volume ventilation allows the CO2 concentration to be kept significantly below the limit value