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This study investigates the thermal behavior of a building in Zone 4 (Ifrane) using TRNSYS, focusing on the impact of envelope parameters on energy consumption. Different insulating materials (wood wool, glass wool, expanded polystyrene, and wood fiber) and insulation thicknesses were evaluated to reduce heat losses and enhance thermal comfort. Simulations show that both the type of material and its thickness significantly affect thermal performance, with low thermal conductivity and adequate thickness improving indoor temperature stability and reducing energy use. Results indicate that optimal insulation can increase indoor temperatures by up to 6 °C, substantially lowering heating demand. Expanded polystyrene (EPS) was selected for its favorable cost-performance ratio. The study emphasizes the importance of a comprehensive energy management strategy, integrating building orientation, window performance, and HVAC efficiency, to minimize energy consumption while ensuring optimal occupant comfort.

•A novel phase change radiator (PCR) integrates heating and thermal energy storage.•PCR maintains indoor temperature above 16 °C during nighttime heating interruptions.•Solar fraction increased from 39.0 to 53.5 % in January with PCR integration.•Annual primary energy savings reach 33.2 %, with 2098.30 kg of CO₂ emissions reduced.•Payback period is 5.27 years, indicating strong economic and environmental benefits. To meet the low-cost heating demand in solar-rich regions, we utilized phase change thermal storage technology to temporarily store excess solar heat during the day and release it at night to improve the energy efficiency. The optimal placement of phase change material was explored, and a phase change radiator (PCR) was proposed. The heating performance of the PCR under typical winter operating conditions was verified through experiments. Using a standalone building in Lhasa as a case, the TRNSYS simulation was employed to assess the economic and environmental benefits of the Solar-PCR heating system under intermittent heating conditions in winter. The results show that the PCR effectively slows down the indoor temperature drop under intermittent heating and maintains the room temperature above 16 °C at night. An increase in the supply water temperature can shorten the phase change time and accelerate the rate of room temperature rise, whereas supply water flow rate has a smaller impact on indoor temperature. Furthermore, in January, the PCR application in solar heating systems improves the solar fraction compared to a conventional radiator (CR) from 39.0 % to 53.5 %, with an annual energy saving rate of 33.2 % and a reduction in CO2 emissions by 2098.3 kg. [Display omitted]

TRNSYS is a common tool that has been recently used to model and simulate greenhouse energy demand and utilization using building energy simulation (BES). Previously, a single thermal point was used for validation, ignoring the distribution of greenhouse climate parameters, especially the temperature. Temperature variation often leads to thermal stratification, prompting researchers to propose volume discretization in dynamic greenhouse simulations. In this context, the effect of envelope characterization on the accuracy of discretized TRNSYS BES model was developed to determine the best BES model under a free-floating regime. The combination of the number of layers [double (D) and single (S)], geometry mode [3D and manual (M)], and layer type [massless (M) and no glazing window (W)], led to the development of five models: D_3D_M, D_3D_W, D_M_M, S_3D_W, and S_M_M. The simulation was performed in a standard radiation mode, and the output parameters were temperature and relative humidity (RH). R2 and the root square mean error (RSME) were used to check the fitness and degree of deviation, respectively, to validate the models. Analysis of variance (ANOVA) was employed to investigate the significant differences among the models, whereas contour plots were used to compare the distribution pattern between the significant models and experimental data. Validation of the models showed that the obtained R2 values ranged from 0.86 to 0.95, and the RSME values for the temperature were between 2.64 °C and 3.91 °C. These values were 0.91–0.93 and 19.72%–30.32% for RH. The ANOVA (p < 0.05) result exhibited significant differences between the S-scenario models and experimental central points in temperature and RH. The D- and S-layer scenarios with a 3D geometry and massless layer showed similar distribution with their corresponding experimental greenhouses. Hence, 3D_M was regarded as the best combination in the discretized BES model.

The thermal efficiency corresponding to an earth-to-air heat exchanger (EAHE) of d = 40 mm diameter, in the temperature climate zone similar to Beni Mellal, has been presented. This paper’s focus to determine the exact length of pipe that is required to reach desired comfort conditions in the exit of this system. TRNSYS software is used for detailed simulation of these summer characteristics. The results are encouraging; on the hottest day in July, EAHE reduces the air temperature at the inlet from 44.6 °C to an outlet temperature of about 27.85 °C producing a total cooling around 16 °C.

Buildings consume approximately ¾ of the total electricity generated in the United States, contributing significantly to fossil fuel emissions. Sustainable and renewable energy production can reduce fossil fuel use, but necessitates storage for energy reliability in order to compensate for the intermittency of renewable energy generation. Energy storage is critical for success in developing a sustainable energy grid because it facilitates higher renewable energy penetration by mitigating the gap between energy generation and demand. This review analyzes recent case studies—numerical and field experiments—seen by borehole thermal energy storage (BTES) in space heating and domestic hot water capacities, coupled with solar thermal energy. System design, model development, and working principle(s) are the primary focus of this analysis. A synopsis of the current efforts to effectively model BTES is presented as well. The literature review reveals that: (1) energy storage is most effective when diurnal and seasonal storage are used in conjunction; (2) no established link exists between BTES computational fluid dynamics (CFD) models integrated with whole building energy analysis tools, rather than parameter-fit component models; (3) BTES has less geographical limitations than Aquifer Thermal Energy Storage (ATES) and lower installation cost scale than hot water tanks and (4) BTES is more often used for heating than for cooling applications.

This contribution investigates whether the use of the MATLAB Optimization Toolbox on a parameter identification problem for a TRNSYS model provides better performance in iteration time. It presents the development of a framework connecting the MATLAB Optimization Toolbox with TRNSYS on the one hand and coordinating the optimization process of a TRNSYS model by GenOpt through MATLAB on the other hand. A benchmark framework in MATLAB was created to link TRNSYS and MATLAB and to configure the optimization process of GenOpt and the MATLAB Optimization Toolbox. Using this framework, a comprehensive comparison of the optimization solvers in GenOpt and the MATLAB Optimization Toolbox for the identification of the overall heat transfer coefficient of a TRNSYS heat exchanger model regarding the optimization time and number of iterations is presented as a use case. The results for the given problem show that GenOpt gives slightly better results in optimization time, whereas MATLAB has more potential and flexibility.

Water scarcity remains a global challenge that directly affects rural communities. The objective of this study is to design, build, and validate a pyramid-shaped solar distiller using appropriate technology for the decentralized supply of fresh water in Bucaramanga, Colombia. We combined a nine-day experimental campaign (April 1-9, 2025) with a TRNSYS (Type 66a-EES) simulation, evaluating two simulation models: a simplified energy balance model (MS01) and a variant that includes the efficiency of the Hottel-Whillier-Bliss (HWB) collector (MS02). Ambient temperature, direct normal irradiance (DNI), and four internal temperatures were measured every five minutes with calibrated sensors during the experimental process. The prototype reached tank/steam temperatures of 42-49 °C and produced 225-750 ml/day, with a total of 3,861 ml; the peak of 750 ml on a day of low irradiance was due to thermal inertia and reduced losses. Both simulation models reproduced the thermal and production trends with relative errors between ±0.012 and ±0.040. The cumulative yield on April 9 was 3765 ml (?2.5%) for MS01 and 3995 ml (+3.5%) for MS02. In summary, MS01 adjusted the tank/steam temperature values slightly better, while MS02 improved the distillation output prediction and offers greater calibration potential through the HWB parameters (FR, UL, (??)e). The results indicate technical feasibility and scalability for rural contexts, and point to simple design improvements (sealing, leak control, thermal management) to increase daily production. Overall, passive desalination is a practical alternative.

Ground-coupled heat pumps (GCHPs) have a great potential for reducing the cost and climate change impact of building heating, cooling, and domestic hot water (DHW). The high installation cost is a major barrier to their diffusion but, under certain conditions (climate, building use, alternative fuels, etc.), the investment can be profitable in the long term. We present a comprehensive modeling study on GCHPs, performed with the dynamic energy simulation software TRNSYS, reproducing the operating conditions of three building types (residential, office, and hotel), with two insulation levels of the building envelope (poor/good), with the climate conditions of six European cities. Simulation results highlight the driving variables for heating/cooling peak loads and yearly demand, which are the input to assess economic performance and environmental benefits of GCHPs. We found that, in Italy, GCHPs are able to reduce CO2 emissions up to 216 g CO2/year per euro spent. However, payback times are still quite high, i.e., from 8 to 20 years. This performance can be improved by changing taxation on gas and electricity and using hybrid systems, adding a fossil-fuel boiler to cover peak heating loads, thus reducing the overall installation cost compared to full-load sized GCHP systems.

The energy demand in greenhouses is enormous, and high-performance covering materials and thermal screens with varying radiometric properties are used to optimise the energy demand in building energy simulations (BES). Transient System Simulation (TRNSYS) software is a common BES tool used to model the thermal performance of buildings. The calculation of the greenhouse internal temperature and heating demand in TRNSYS involves the solution of the transient heat transfer processes. This study modelled the temperature and heating demand of two multi-span glass greenhouses with concave (farm A) and convex (farm B) shapes. This study aims to investigate the influence of the different BES longwave radiation modes on greenhouse internal temperature in different zones and the heating demand of a conditioned zone. The standard hourly simulation results were compared with the experimental data. The results showed that the standard and detailed modes accurately predicted greenhouse internal temperature (the Nash–Sutcliffe efficiency coefficient (NSE) > 0.7 for all three zones separated by thermal screens) and heating demand (NSE > 0.8) for farms A and B. The monthly heating demand predicted by the simple and standard radiation modes for farm A matched the experimental measurements with deviations within 27.7% and 7.6%, respectively. The monthly heating demand predicted by the simple, standard, and detailed radiation modes for farm B were similar to the experimental measurements with deviations within 10.5%, 6.7%, and 2.9%, respectively. In the order of decreasing accuracy, the results showed that the preferred radiation modes for the heating demand were standard and simple for farm A, and detailed, standard, and simple for farm B.

Phase Change Materials (PCMs) offer a promising pathway toward net-zero energy buildings by enhancing thermal energy efficiency. By absorbing and storing heat during the day and releasing it at night, PCMs can reduce reliance on active heating and cooling systems. While PCMs have been widely studied both experimentally and numerically, limited research exists on configurations where PCM containers are in direct contact with surrounding air. This study developed a novel “PCM-in-container” component in TRNSYS 18 to simulate energy gains from such direct interactions. The component was integrated with greenhouse and weather modules in TRNSYS and validated experimentally using three model greenhouses containing air, water, and Vaseline as PCM substances. Model performance was assessed using R-squared (R²), correlation coefficient (CC), root mean square error (RMSE) and mean absolute error (MAE). For water-based PCM, values of R² = 0.97, CC = 0.99, RMSE = 2.01°C, and MAE = 1.33°C were obtained, demonstrating strong model accuracy. The results showed that PCM-filled containers (e.g., structural or railing pipes) could increase nighttime greenhouse temperatures by up to 7°C. The developed component enables energy gain simulations and nighttime heating predictions, offering a valuable tool for greenhouse energy demand evaluation. Although the current model does not account for hysteresis, future work may incorporate this through modifications in the TRNSYS Fortran environment.