The Economic and Environmental Impact of Greenhouse Heating Pipe Insulation

This study aimed to determine the effect of optimum pipe insulation thickness on energy savings and air pollution under greenhouse conditions. In this regard, an optimization model based on a Life Cycle Cost (LCC) analysis was carried out using the P1–P2 method. Three fuel types, coal, natural gas, and fuel oil, were tested with nominal pipe sizes ranging from 25 to 65 mm, and hot water was used in the system. Our findings showed that the highest insulation thickness (0.807 m), the greatest energy savings ($62.351/m), and the lowest payback period (0.502 years) were achieved with a 65 mm pipe size for fuel oil. Overall, the insulation minimizes heat loss through the heating pipelines, resulting in economic and environmental benefits. Fuel oil was determined as the best option for savings in this study. Hence, for fuel oil utilization, the emissions of CO2 varied from 2.762 to 3.798 kg/m and SO2 from 0.014 to 0.020 kg/m for pipe thicknesses ranging from 25 and 65 mm, respectively.

Aspects Regarding the Optimal Insulation Thickness, the Cost and Energy Savings for Cold Storage in Romania

The paper presents a technical and economic analysis regarding the sandwich panels with polyurethane insulation layer (PUR) used in cold stores’ construction. 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 maintained as well 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 in operating energy is decreased by 6.7%. The SEC has an average value of 54.83 kWh·m3/yr for cold storage and 74.55 kWh·m3/yr 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.

Optimization of insulation levels from an environmental perspective: impact of HVAC controls and Personal Comfort Systems

Today, strict insulation requirements apply. Nevertheless, the inverse correlation of thermal conductivity with insulation thickness leads to decreasing energy savings with increasing insulation packages. Therefore, a balance between potential energy savings and environmental impact due to additional materials using Life Cycle Assessment (LCA) needs to be strived for. This balance is sought for a case study called ‘The Mobble’ i.e. a flexible, modular, and circular building system developed by a student team from Ghent University. Through an iterative design process supported by LCA, comfort and dynamic energy simulations efforts are made to design an energy-efficient and low impact module with an agreeable indoor environment. First, material choices are made based on LCA and the material impact of a 5-module home is calculated. Second, energy calculations are executed in Modelica/Dymola. For this, three possible energy reductions are explored: insulating the building, altering the working regime of the HVAC system and lowering the setpoint temperature while maintaining comfort by using personal comfort systems (PCS). The results support PCS as a possible energy conservation measure and indicate that reducing operational energy does not shift the environmental burden to the additional materials’ production. However, these environmental saving effects decrease as the operational share decreases.

Effect of Heat Transfer between Potable Water Cold and the Environment Inside Building on Water Quality

In the face of a coronavirus pandemic, many buildings or facilities are closed. The sudden closing of schools, factories or offices has caused a reduction in the water consumption inside buildings. The lack of chlorinated water flowing through the pipes, combined with temperature changes, poses a real risk to potable water from the bacteria multiplication point of view. The contribution focuses on the requirements for the temperature of potable water cold (PWC) in the water pipeline system inside buildings. The main goal of the research is to evaluate the effect of heat transfer between the PWC and the surrounding air during the water stagnation. Temperature differences between the PWC and the indoor air in building are leading to the heat transfer by convection. The result of the heat transfer is an undesired increase of the PWC temperature. The paper assesses the increase in PWC temperature over time using two methodologies - mathematical analysis and computer simulation. The results show that with an increasing pipe diameter and insulation thickness, the temperature of PWC during stagnation increases more slowly. The article points out the fact that the first 10 mm of insulation has the greatest impact on preventing the heating of PWC from the surrounding environment. Regarding the material design of the pipeline, only small deviations in the results were calculated between steel and plastic pipe. Mathematical analysis and computer simulation show that the issue of PWC stagnation in the pipeline has a significant effect on the temperature and thus the quality of water in buildings.

Energy and Economic Sustainability of a Trigeneration Solar System Using Radiative Cooling in Mediterranean Climate

The spreading of nearly zero-energy buildings in Mediterranean climate can be supported by the suitable coupling of traditional solar heating, photovoltaics and radiative cooling. The latter is a well-known passive cooling technique, but it is not so commonly used due to low power density and long payback periods. In this study, the energy performance of a system converting solar energy into electricity and heat during the daytime and offering cooling energy at night is assessed on the basis of a validated model of a trifunctional photovoltaic–thermal–radiative cooling module. The key energy, CO2 emission and economic performance indicators were analyzed by varying the main parameters of the system, such as the spectral emissivity of the selective absorber plate and cover and thermal insulation thickness. The annual performance analysis is performed by a transient simulation model for a typical residential building and two different climates of the Mediterranean area (Trapani and Milano). For both climates, glass-PVT–RC is the best solution in terms of both overall efficiency (electric + thermal) and cooling energy capacity, even better with a thicker insulation layer; the annual electrical, heat and cooling gains of this system are 1676, 10,238 and 3200 kWh for Trapani, correspondingly (1272, 9740 and 4234 kWh for Milano, respectively). The typical glass-PVT module achieves a performance quite similar to the best ones.