Considering the imperative reduction in CO₂ emissions, both from household heating and hot water producing facilities, one of the mainstream directions is to reduce hydrocarbons in combustibles by replacing them with hydrogen. The authors analyze condensing boilers operating when hydrogen is mixed with standard gaseous fuel (CH₄). The hydrogen (H₂) volumetric participation in the mixture is considered to vary in the range of 0 to 20%. The operation of the condensing boilers will be numerically modeled by computational programs and prior validated by experimental studies concluded in a European Certified Laboratory. The study concluded that an increase in the combustible flow with 16% will compensate the maximum H₂ concentration situation with no other implications on the boiler’s thermal efficiency, together with a decrease in CO₂ emissions by approximately 7%. By assuming 0.9 (to/year/boiler), the value of CO₂ emissions reduction for the condensing boiler determined in the paper, and extrapolating it for the estimated number of boilers to be sold for the period 2019–2024, a 254,700-ton CO₂/year reduction resulted.

The building sector plays an important role in the global climate change mitigation objectives. The reduction of CO2 emissions and energy consumption in the building sector has been intensively investigated in the last decades, with solar thermal energy considered to be one of the most promising solutions due to its abundance and accessibility. However, the discontinuity of solar energy has led to the study of thermal energy storage to improve the thermal performance of solar thermal systems. In this review paper, the integration of various types of phase-change materials (PCMs) in transpired solar collectors (TSC) is reviewed and discussed, with an emphasis on heat transfer enhancements, including nanomaterials. Thermal energy storage applied to TSC is studied in terms of design criteria, materials technologies, and its impact on thermal conductivity. This review highlights the potential of nanomaterial technology integration in terms of thermal performance improvements. The utilization of nanomaterials in solar walls holds the potential to significantly enhance their performance. The integration of diverse materials such as graphene, graphite, metal oxides, and carbon nanoparticles can pave the way for improving thermal conductivity.

The increasing concerns about CO₂ emissions and climate change have pointed out the urgency of promoting sustainability in the building sector. One promising solution to enhance the energy efficiency of buildings and diminish environmental impact is the integration of phase-change materials (PCMs) into ventilated façade systems. This review article critically examines the current state of research on this innovative approach, with a particular focus on fire safety considerations. The paper explores the integration of PCM into ventilated façades, highlighting the potential for significant improvements in energy consumption, thermal comfort, and reductions in CO₂ emissions. However, the flammability of PCMs introduces substantial fire safety challenges that must be addressed to ensure the safe application of this solution. The fire safety of both ventilated façades and PCMs is approached, followed by specific fire safety concerns when PCMs are integrated into ventilated façade systems. The conclusion states that while the integration of PCMs into ventilated façades offers substantial environmental benefits, attention to fire safety is essential. This necessitates the implementation of rigorous fire protection measures during the design and construction phases. By addressing both the environmental advantages and fire safety challenges, this review aims to provide a comprehensive understanding of the potential and limitations of PCM-integrated ventilated façades, offering valuable insights for researchers, engineers, and policymakers in the field of sustainable buildings.

Silica aerogel has remarkable properties, particularly its translucence/transparency, extremely low thermal conductivity and density. Due to these properties, it can be used for the thermal insulation of buildings for energy saving, cost saving, and enhanced comfort. In this context, aerogel products such as aerogel blankets have already started to demonstrate their effectiveness in retrofitting projects and the development and adoption of aerogel glazing systems and aerogel-enhanced renders is promising. Other products, for example, through the incorporation of silica aerogel granules in cement and lime renders were obtained, with high thermal insulation properties, to achieve energy efficiency on buildings facades. This research aims to come up with new aerogel particle composition insulation plasters at cost-effective rates for application in building insulation. Their physical apparent mass density, mechanical–flexural and compressive strengths, thermal conductivity, and properties were investigated. As an experimental study, the thermal conductivities of six sets of cement and lime plasters with aerogel particles (0.1–4.0 mm) were investigated and it was concluded that the thermal conductivity of cement and lime plasters with 80% aerogel was 0.2287 W·m⁻¹·K⁻¹, about 3.4 times smaller than the respective value of traditional lightweight plasters of 0.76 W·m⁻¹·K⁻¹, while the cement and lime plasters with less than 40% aerogel showed a thermal conductivity value as low as 0.3172 W·m⁻¹·K⁻¹. It was confirmed that the end product plasters’ mechanical qualities included low apparent mass densities, no apparent shrinkage, and mechanical strength values that matched those of the prepared compositions. This suggests that the obtained plasters are suitable for use in both new constructions and renovation projects.

Cotton textile waste (CW) and crushed bricks (CB) are wastes generated by the textile and construction industries that cause adverse effects on the environment. This paper explores the effect of adding 1, 2, 5, and 10 wt.% of CW and CB, instead of natural sand under 1 mm (50 to 100 vol.%), on the properties of concrete. The study included the analysis of workability, density, water absorption, thermal conductivity, mechanical strengths, and electron microscopy. The results show that the presence of CW and CB increased the water required to obtain the same slump value as reference, R. Concretes with CW provided better performance in terms of density, water absorption (for 1 wt.%), and splitting strength (for 1 to 2 wt.%). The 28 days of compressive strength decreased with increasing CW (33.3 MPa for R and 26.9 MPa for 2 wt.% of CW). The partial substitution of sand decreased the workability and density and increased the mechanical strength of concrete. The presence of both CW and CB decreased workability, density, and mechanical strengths. Regarding the ability of concrete to transfer heat, the addition of CW and CB decreased the thermal conductivity value (e.g., 0.32 W/(m·K) for 1 wt.% of CW compared to 0.37 W/(m·K) for reference).

The purpose of this research is to design an energy-efficient off-grid vending machine that has a refrigeration system powered by an environmentally friendly refrigerant. The paper presents details from the equipment’s design phase in terms of the resistance structure, photovoltaic panels area dimensioning, but also in terms of the necessary cooling load to be provided by the refrigeration system. The refrigerant chosen was R290 following a comparative analysis, which showed that it has an efficiency 6.6% higher than R134a. During the monitoring periods, the outdoors temperature varied between −4–28 °C, the relative humidity between 22–100% and yet only a slight indoor temperature variation of ±1.5 °C compared to the set value was recorded. The battery module managed to store enough energy from the photovoltaic panels to keep the vending machine functional through three consecutive days with adverse environmental conditions, as evidenced by the low variation of indoor temperature