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.

Recently, heat and mass distributions within a greenhouse were assumed to be homogeneous. Heat is gained or lost in absolute terms, and crop contribution in a greenhouse or its effect is not considered. In this study, statistical analyses were conducted to establish the significance of heat and mass variation at sensor nodes in two single-span and multi-span greenhouses. Three greenhouses were used in this study, 168 m² floor area a single-layered (SLG), double-layered (DLG) single-span gothic roof type greenhouses, and 7572.6 m² floor area multi-span greenhouse (MSG). The microclimatic parameters investigated were temperature (T), relative humidity (RH), solar radiation (SR), carbon dioxide (CO₂), and vapor pressure deficit (VPD). To check their horizontal distribution, all microclimate data collected from each sensor node in each greenhouse were subjected to descriptive statistics and Tukey honestly significant difference (HSD) test. The lowest minimum temperatures of 2.93 °C, 3.33 °C and 10.50 °C were recorded at sensor points in SLG, DLG, and MSG, respectively, whereas the highest maximum temperatures of 29.17 °C, 29.07 °C and 27.20 °C were recorded at sensor point, in SLG, DLG, and MSG, respectively. The difference between the center and the side into the single-span was approximately 0.88–1.0 °C and in the MSG was approximately 1.03 °C. Significant variation was observed in the horizontal distribution of T, RH, SR, and VPD within SLG, DLG, and MSG. Also significant was CO₂ in the MSG. Estimating the energy demand of greenhouses should be done based on the distribution rather than assuming microclimatic parameters homogeneity, especially for T, with VPD as a control parameter. Such estimation should also be done using a crop model that considers instant changes in air and crop temperature.

Strawberry cultivation is highly dependent on environmental parameters and energy during the winter. Two gothic greenhouses with different glazing material combinations, polyolefin–thermal screen (PoTS) and polyolefin–thermal screen–polyethylene (PoTSPe), were used for strawberry cultivation. The energy-saving capabilities of the two configurations and their impact on the microclimates of the greenhouses were investigated. The temperature, relative humidity, vapor pressure deficit, leaf temperature, carbon dioxide concentration and solar radiation over the experimental period in the PoTS greenhouse were 13.0 ± 2.3°C, 75.8 ± 6.5%, 0.4 ± 0.1 kPa, 13.6 ± 1.7 °C, and 168.8 ± 82.3W/m2, respectively, whereas those of the PoTSPe condition were 13.1 ± 2.3 °C, 80.0 ± 5.7%, 0.3 ± 0.1 kPa, 13.5 ± 1.6 °C, and 183.1 ± 90.5 W/m2. The mean fuel consumption by the PoTS and PoTSPe greenhouses were 5.5 and 3.5 L, respectively. The performance analysis shows that both greenhouses were able to maintain the environmental parameters and leaf temperature within the recommended ranges, although more energy was consumed in the PoTS. More yield was obtained in the PoTS greenhouse, however, not significantly different from PoTSPe yield.

The implementation of renewable energy systems (RESs) in the agricultural sector has significant potential to mitigate the negative effects of fossil fuel-based products on the global climate, reduce operational costs, and enhance crop production. However, the intermittent nature of RESs poses a major challenge to realizing these benefits. To address this, thermal energy storage (TES) and hybrid heat pump (HHP) systems are integrated with RESs to balance the mismatch between thermal energy production and demand. In pursuit of clean energy solutions in the agricultural sector, a 3942 m² greenhouse in Yeoju-si, South Korea, is equipped with 231 solar thermal (ST) collectors, 117 photovoltaic thermal (PVT) collectors, four HHPs, two ground-source heat pumps (GSHPs), a 28,500 m³ borehole TES (BTES) unit, a 1040 m³ tank TES (TTES) unit, and three short-term TES units with capacities of 150 m³, 30 m³, and 30 m³. This study evaluates the long-term performance of the integrated hybrid renewable energy and thermal energy storage systems (HRETESSs) in meeting the greenhouse’s heating and cooling demands. Results indicate that the annual system performance efficiencies range from 25.3% to 68.5% for ST collectors and 31.9% to 72.2% for PVT collectors. The coefficient of performance (COP) during the heating season is 3.3 for GSHPs, 2.5 for HHPs using BTES as a source, and 3.6 for HHPs using TTES as a source. During the cooling season, the COP ranges from 5.3 to 5.7 for GSHPs and 1.84 to 2.83 for ASHPs. Notably, the HRETESS supplied 3.4% of its total heating energy directly from solar energy, 89.3% indirectly via heat pump utilization, and 7.3% is provided by auxiliary heating. This study provides valuable insights into the integration of HRETESSs to maximize greenhouse energy efficiency and supports the development of sustainable agricultural energy solutions, contributing to reduced greenhouse gas emissions and operational costs.

This study analysed the performance of a hot-water pipe (HWP) and fan-coil units (FCUs) in controlling microclimate conditions in a net-zero energy greenhouse (NZEG). The performance of a previously developed TraNsient SYstem Simulation (TRNSYS) model for the NZEG was enhanced to include a crop model and several HWP emission standards, and the improved TRNSYS model was used to analyse heating, ventilation and air-conditioning (HVAC) systems for different greenhouse sizes in the Republic of Korea. Further, an economic analysis was conducted. The model validation showed excellent agreement between the measured and simulated values, with Nash-Sutcliffe efficiency of 0.98. The presence of crop in the simulation model reduced the total heating load by 14.5 MWh and increased the cooling load by 4 MWh. The capacity of the FCU was increased as the outside temperature rose from 33.4[ ] to 36.4[ ] in summer, and the diameter of the HWP was decreased from 25A to 10A as the outside temperature rose from −21.7[ ] to −12.2[ ] in winter to maintain the greenhouse at the desired temperature of 15[ ]. Notably, the payback period was reduced by 9 years when the annual savings in heating energy costs and revenue from carbon trading were considered as a part of the net economic cash flow.