Această lucrare analizează integrarea sistemelor de fața de adaptabile în clădirile cu pereti cortină, având ca obiectiv îmbunătățirea eficienței energetice, a performanței termice și a confortului vizual. Având ca punct de plecare versatilitatea geometrică a hexagonului și fiind inspirat de principiile de pliere din origami, studiul propune un sistem de umbrire exterioară cu mecanism cinetic, capabil să reacționeze în mod dinamic la schimbările radiației solare. Designul este ghidat de principii de biomimetism și urmărește să contribuie atât estetic, cât și funcțional la anvelopa clădirii.

Cuvinte Cheie: design sustenabil, anvelopă adaptabilă, teselare hexagonală, fațade ventilate, stare de bine.

This paper explores the integration of adaptive façade systems in curtain wall buildings as a means to enhance energy efficiency, thermal performance, and visual comfort. Starting from the geometric versatility of the hexagon and drawing inspiration from origami folding principles, the study proposes a kinetic external shading system capable of responding dynamically to variations in solar radiation. The design is inspired by principles of biomimicry and aims to contribute both aesthetically and functionally to the building envelope.

Keywords: sustainable design, adaptive envelope, hexagon tessellation, ventilated façades, wellbeing.

Betonul armate dispers reprezintă o soluție prin care se pot înlocui o parte din armăturile convenționale din oțel prin adăugarea de fibre în masa betonului. Betoanele armate dispers cu fibre de oțel sunt clasificate pe baza rezistenței și a ductilității. În funcție de cantitatea de fibre, comportarea poate fi de slăbire sau întărire. În articolul de față, rezultatele individuale arată o comportare specifică de întărire. Cu toate acestea, betonul armat dispers este încadrat într-o clasă cu comportament de slăbire, din cauza variabilității rezultatelor experimentale.

Cuvinte Cheie: beton armat dispers, slăbire, întărire, rezistență, ductilitate

Fiber reinforced concrete is a solution whereby some of the conventional steel reinforcement can be replaced by adding fibers to the concrete mass. Steel fiber reinforced concrete is classified based on strength and ductility. Depending on the amount of fiber, the behavior can be softening or hardening. In the present paper, individual results show a specific hardening behavior. However, this fiber reinforced concrete is classified into a class with weakening behavior due to the variability of experimental results.

Keywords: fiber reinfored concrete, softening, hardening, strength, ductility

The paper analyzes the performance of an air-to-water heat pump installed in a single-family home in the hilly area of Romania, during the cold season.Based on in situ measurements and simulations, COP values between 2.90–3.54 for heating and 1.71–2.62 for DHW were obtained.The results confirm the efficiency of the system in low temperature conditions and reveal the importance of correct sizing and intelligent control.The study supports the use of heat pumps as a sustainable solution for residential buildings in cold climates.

Keywords: heat pump, heating, energy efficiency, renewable energy

Geopolimer celular pe bază de cenușă zburătoare cu caracteristici adecvate fizico-termice și de rezistență mecanică a fost preparat utilizând perborat de sodiu ca agent de expansiune, ulei de palmier ca surfactant pentru stabilizarea spumei, montmorillonit ca o nanoargilă pentru creșterea rezistenței geopolimerului și un activator alcalin compus din soluții de hidroxid și silicat de potasiu. Rezultatele au arătat excelente proprietăți termoizolante (densitate între 438-502 kgꞏm-3 și conductivitate termică în intervalul 0,077-0,103 Wꞏm-1ꞏK-1), precum și rezistență la compresiune și încovoiere până la 5,4 și respectiv, 4,1 MPa, fiind interesante excelentele valori ale rezistențelor obținute timpuriu, după numai 7 zile.

Cuvinte Cheie: geopolimer, porozitate, izolație, agent de expansiune, spumă

Cellular fly ash-based geopolymer with suitable physico-thermal and mechanical strength characteristics was prepared using sodium perborate as an expanding agent, palm oil as a surfactant for stabilization of the froth, montmorillonite as a nanoclay for growing the strength of geopolymer , and an alkaline activator composed of potassium hydroxide and silicate solutions. Results showed excellent thermal insulation properties (density between 438-502 kgꞏm-3 and heat conductivity in the range of 0.077-0.103 Wꞏm-1ꞏK-1) as well as adequate compression and flexural strength up to 5.4 and 4.1 MPa respectively, being interesting the excellent strength values obtained at early age only 7 days.

Keywords: geopolymer, porosity, insulation, expanding agent, foam

Regardless of the precision or complexity of the reliability analysis method used, the quantitative assessment of the reliability of a system requires knowledge of the values of the reliability indicators of the component elements. Obtaining realistic results for the reliability of the system is conditioned by the credibility of the values of the reliability indicators of the elements. Information on the reliability of the elements is useful both for beneficiaries (for the purpose of optimizing maintenance) and for manufacturers (for the purpose of applying corrections in design and manufacturing).

Keywords: water supply, systems, operational reliability

The night ventilation process is carried out in order to reduce the energy consumption required to cool the space during the day. This process proposes a sustainable approach to generate a comfortable indoor environment, with relatively low energy consumption. Following an extensive study documenting existing research in the field, the paper aims to describe the elements that influence night ventilation and the impact of these elements on energy efficiency and thermal comfort.

Keywords: night ventilation, energy efficiency, thermal mass, air changes per hour, climate zones, thermal comfort

This paper presents the relation between indoor air quality (IAQ) and the efficiency of ventilation systems in indoor spaces, given their impact on the health and comfort of occupants. In the context of urbanization and modern construction trends, in which the tightness of buildings has increased significantly, inadequate ventilation can lead to the accumulation of internal pollutants, such as carbon dioxide (CO₂), volatile organic compounds (VOCs), fine particles, and biological agents (molds, bacteria). The paper presents the different types of ventilation systems used in homes (natural, mechanical and hybrid ventilation), analyzing their effectiveness in maintaining a healthy indoor environment. The study highlights that proper ventilation not only prevents the build-up of pollutants, but also helps to improve occupant performance, reducing risks to respiratory and mental health. In conclusion, this paper highlights the need for a balance between energy efficiency and occupant health protection by implementing sustainable and smart ventilation solutions in modern homes.

Keywords: indoor air pollution, IAQ, heat recovery technologies (HRV), indoor pollutants, ambiental comfort, ventilation systems, healthy environment, mechanical ventilation, natural ventilation, hybrid ventilation, CO2 concentrations,

The growing global population necessitates sustainable energy solutions to meet escalating energy demands. Geothermal energy, abundant and continuous, ranks as a leading alternative after solar energy. Integrating geothermal energy into building systems requires specialized structures. For shallow geothermal applications, thermo-active piles offer a cost-effective and efficient solution regarding both investment and operational expenses. Distinct from traditional piles, these energy piles enable thermal exchange between the pile and surrounding soil, supporting building heating, cooling, and hot water needs. Their design mandates a coupled thermo-hydro-mechanical analysis. This study presents a numerical model of a field-scale energy pile experiment conducted in Houston, Texas, validated through stress and temperature data collected during the experiment.

Keywords: geothermal piles, experiment, solar energy

Realizarea simulărilor CFD are un rol important în domeniul proceselor de transfer termic, permițând analiza mecanismelor transferului de căldură prin conducție, convecție și/sau radiație, identificarea punctelor critice in sistemele de izolație termica, estimarea evoluției unor parametri ai sistemelor în care au loc procese de transfer termic, optimizarea proiectării sistemelor de transfer termic și eficientizarea energetică a acestor sisteme. Intre sistemele bazate pe fenomene de transfer termic, sistemele de refrigerare necesită unele din cele mai ridicate consumuri de energie. De aceea, una dintre cele mai utile metode de reducere a costurilor acestor sisteme este asigurarea unei optime izolații termice a pereților. Simulările CFD pot fi un instrument foarte util in evaluarea parametrilor de funcționare ai unei camere frigorifice, respectiv temperatură, umiditate, dar și pentru identificarea zonelor critice în care pot apărea punți termice generând fluxuri termice necontrolate.

Cuvinte Cheie: CFD, camere frigorifice, refrigerare, punte termică, Ansys, transfer termic, flux termic, simulare transfer termic, convecție, conducție

The CFD simulations play an important role in heat transfer processes field, enabling heat transfer mechanism the analysis through conduction, convection and/or radiation, identifying critical points in thermal insulation systems, predicting the evolution of certain parameters in systems where heat transfer processes occur, optimizing the heat transfer system design, and improving their energy efficiency. Among the systems based on thermal transfer phenomena, the refrigeration systems require some of the highest energy consumption. Therefore, one of the most effective methods for these systemțs cost reducing is ensuring an optimal thermal insulation for the walls. CFD simulations can became a very useful tool in cold room parameters evaluation, such thenperature and humidity, as well as for critical areas identifying, where thermal bridges may occur, with results in uncontrolled thermal flows.

Keywords: CFD, computational fluid dinamics, cold room, refrigeration, thermal bridge, Ansys, thermal transfer modeling, convection, conduction

Evolutia tehnologica in industria agentilor refrigeranti bazata pe limitarile impuse de REGULAMENTUL (UE) 2024/573 AL PARLAMENTULUI EUROPEAN ȘI AL CONSILIULUI din 7 februarie 2024 privind gazele fluorurate cu efect de seră, de modificare a Directivei (UE) 2019/1937 și de abrogare a Regulamentului (UE) nr. 517/2014 s-a aliniat acestui regulament si impreuna cu producatorii de echipamente frigorifice au inceput introducerea in piata europeana a refrigerantilor cu GWP (Potential de Incalzire Globala ) mai mic de 150 unitati. Prezenta lucrare prezinta o metoda de modernizare a instalatiilor frigorifice comerciale de puteri mici si medii ce utilizeaza refrigeranti precum R448A sau R449A , cat si implicatiile tehnice care trebuie luate in considerare in procesul modernizarii .

Cuvinte Cheie: Retrofit, refrigerare comerciala, R449A,R448A, R455A, GWP

Technological developments in the refrigerant industry based on the limitations imposed by REGULATION (EU) 2024/573 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 7 February 2024 on fluorinated greenhouse gases, amending Directive (EU) 2019/1937 and repealing Regulation (EU) No. 517/2014 have aligned with this regulation and, together with refrigeration equipment manufacturers, have begun to introduce refrigerants with a GWP (Global Warming Potential) of less than 150 units into the European market. This paper presents a method for the modernization of small and medium-sized commercial refrigeration installations using refrigerants such as R448A or R449A, as well as the technical implications that must be taken into account in the modernization process.

Keywords: Retrofit, commercial refrigeration, R449A,R448A, R455A, GWP

Rezultatele fabricării cu asistența microundelor a sticlei celulare cu porozitate fină utilizând un agent de spumare carbonic lichid (glicerol) împreună cu apă de sticlă sunt prezentate în această lucrare. În condițiile desfășurării procesului în atmosfera oxidantă a cuptorului, rolul apei de sticlă a fost evitarea arderii premature a carbonului rezultat după descompunerea glicerolului. Utilizarea versiunii proprii a autorilor privind încălzirea cu microunde aplicată in ultimele experimente a reconfirmat viabilitatea soluției și remarcabila sa eficiență energetică. De asemenea, ca o măsură tehnică originală, proporția apei de sticlă in amestec a fost crescută la 8=12 % conducând la creșterea fineței porozității probelor.

Cuvinte Cheie: porozitate înaltă, sticlă celulară, microunde, glicerol, apă de sticlă

Results of microwave-assisted manufacturing fine porosity-cellular glass using a liquid carbonic foaming agent (glycerol) together with water glass are presented in this paper. Under the conditions of developing the process in oxidizing atmosphere of the oven, the water glass role was to avoid the premature burning of carbon resulted after glycerol decomposing .The use of authors’ own version of microwave heating applied in the last experiments reconfirmed the solution viability and its remarkable energy efficiency. Also, as an original technique measure, water glass proportion in the mix was increased to 8-12 % leading to growing the fineness of specimen porosity

Keywords: high porosity, cellular glass, microwave, glycerol, water glass.