###### Abstract
The temperature difference becomes greater than 5 \({}^{\circ}\)C if the continuous current exceeds 39 A. A CFD numerical simulation is performed for steady state conditions at the maximum experimental current rate in order to better understand the thermal and flow behavior. Overall, the numerical and experimental results are in good agreement, with a temperature deviation of less than 10%. Energy efficiency also applies to cold storage. In their article [11], [PERSON] et al. present a technical and economic analysis of sandwich panels used in cold stores' construction, equipped with a polyurethane insulation layer (PUR). The authors determine the optimal thickness of the insulating layer (OIT), corresponding to the 5 climatic zones in Romania. The operating and investment costs for cold and frozen storage in these 5 climatic zones have been assessed. The results obtained from the analysis show that, regardless of the climatic zone, the OIT for cold storage is 150 mm and for frozen storage is 180 mm. The investment cost increases by 41% and the expenditure on operating energy decreases by 8.3% for 180 mm for cold storage in comparison to OIT. Moreover, this tendency is also maintained in the other case of frozen storage, where, by increasing the thickness above OIT at 200 mm, the investment cost is increased by 20% and the expenditure on operating energy is decreased by 6.7%. The SEC has an average value of 54.83 kWh-m\({}^{3}\)/year for cold storage and 74.55 kWh-m\({}^{3}\)/year for frozen storage, respectively. The average values obtained in the paper were compared with those presented in the literature and resulted in deviations of about 1.58% for refrigeration, and hence 4.1% for freezing. One of the mainstream directions for CO\({}_{2}\) emissions reductions, both from household heating and hot water-producing facilities, is to lower the levels of hydrocarbons in combustibles by replacing them with hydrogen. The authors of the article [12] analyze condensing boilers which operate when hydrogen is mixed with standard gaseous fuel (CH\({}_{4}\)). The hydrogen (H\({}_{2}\)) 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 modeledby computational programs and prior validated by experimental studies concluded in a European certified laboratory. The study concluded that an increase in the combustible flow by 16%, together with a decrease in CO2 emissions by approximately 7%, will compensate the maximum H2 concentration situation without further implications for the boiler's thermal efficiency. By assuming 0.9 (to/year/boiler) as 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 resilience of the built environment is reflected in its capacity to provide a healthy and safe ecosystem for its occupants. In this context, two papers were dedicated to fire safety. Indeed, statistics show that most fires occur in civil residential buildings. Most casualties in such circumstances are due to the inhalation of hot air, loaded with smoke, leading to intoxication with substances harmful to the human body. Paper [13] aimed to develop a CFD model that relates the operation of the sprinkler system to the operation of the ventilation system through the air temperature in a specific point close to the sprinkler position. A real-scale experiment was carried out, and a CDF model was developed. Several parameters of the CFD model (thermal conductivity of the experimental test room walls, numerical grid elements' dimensions, burner heat release rate variation) were imposed onto the model, so that the resulting entire time variation of the temperature next to the sprinkler location corresponds to the real measured variation. Two other experiments were used to validate the numerical model.