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Based on the monitoring campaigns, we have evaluated the indoor microclimate in a church. Most church buildings are characterised by low thermal comfort due primarily to their architecture, heating huge volume of air. The CFD tools was used for thermal comfort evaluation in case of the existing heating system during the winter season. The simulation model was validated with experimental data and it was used for thermal and air velocity profiles in the occupancy zone of churchgoers. The aim of the paper is the study the feasibility of maintaining the heritage values of the churches while achieving the significant improvement of the thermal comfort.

This paper presents a CFD Heat Transfer Analysis of an originally designed system for heat recovery in the building sector. The heat exchanger has a dual role, which means it will produce simultaneously hot water and warm air. The key to the efficiency of the heat exchanger is the heat pipe system which recovers thermal energy from residual hot water and transfers it to the secondary agents. The paper includes a case study structured by different mesh distributions and flow regimes. The purpose of the heat exchanger is to reduce the costs of producing thermal energy and to increase the overall energy efficiency of buildings.

The aim of the study is to develop a system for converting, accumulating, and delivering solar energy that is based on the development of an innovative solar panel with heat pipes and a heat storage wall, for the construction of passive structures. The novel aspect of this experiment is the utilization of concrete walls that have different recyclable materials added to their structure in various proportions. The solar energy from the sunny façades is transformed by this system into thermal energy, which is then transferred by integrated heat pipes in a massive element with high thermal inertia. Using insulated shutters, thermal energy can be stored during the day and released at night to keep the room at a comfortable temperature. In order to integrate the modules into the solar recovery system, four concrete samples were cast with a blend of standard and waste aggregates. Four heat fluxes of 100 W/m 2 , 150 W/m 2 , 200 W/m 2 , and 250 W/m 2 were applied to each global system. Thermal imaging data and numerical simulations both supported the findings of temperature sensors. The most effective mixture, fly ash and chopped PET, delivered temperatures that were, on average, 3.3% higher at the end of the charging cycle than those measured for the control sample. The discharging cycle of the concrete block with fly ash and sawdust was the most effective, with an average temperature loss of 5.0 °C as compared to 5.5 °C for the control sample, on average.

The continuous growth of the concrete industry requires an increased quantity of cement and natural aggregates year after year, and it is responsible for a major part of the global CO 2 emissions. These aspects led to rigorous research for suitable raw materials. Taking into account that these raw materials must have a sustainable character and also a low impact on environmental pollution, the replacement of the conventional components of concrete by residual waste can lead to these targets. This paper's aim is to analyze the density, compressive strength and the thermal conductivity of nine concrete compositions with various rates of waste: four mixes with 10%, 20%, 40% and 60% chopped PET bottles aggregates and 10% fly ash as cement partial substitution; a mix with 60% waste polystyrene of 4-8 mm and 10% fly ash; a mix with 20% waste polystyrene of 4-8 mm, 10% waste polystyrene of 0-4 mm and 10% fly ash; a mix with 50% waste polystyrene of 4-8 mm, 20% waste polystyrene of 0-4 mm and 20% fly ash two mixes with 10% fly ash and 10% and 40% waste sawdust, respectively. Using 60% PET aggregates, 60% polystyrene granules of 4-8 mm, or 20% polystyrene of 0-4 mm together with 50% polystyrene of 4-8 mm led to the obtainment of lightweight concrete, with a density lower than 2000 kg/m 3 . These mixes also registered the best results from a thermal conductivity point of view, after the concrete mix with 40% saw dust. Regarding compressive strength, the mix with 10% PET obtained a result very close to the reference mix, while those with 20% PET, 40% PET, 30% polystyrene, and 10% saw dust, respectively, registered values between 22 MPa and 25 MPa, values appropriate for structural uses.