The thermal energy demand during the production period in greenhouses is important for determining the production economics and feasibility studies to be carried out. This is because evaluating future investments in the greenhouse sector requires accurate estimates of energy demand and costs. For this purpose, the heat energy required in the greenhouse and the heating costs were calculated, taking into account the meteorological conditions of the region, the optimum temperature demand of the plants and the technical specifications of the greenhouse. Two different cover materials were used to determine the heat energy requirement: polyethylene sidewalls and roof (PE) and polycarbonate sidewalls + polyethylene roof (PC+PE). In addition, calculations were made for 8 different greenhouse combinations, including different insulation statuses (poor, medium and good insulation) of these greenhouses without thermal screen and with thermal screens. As a result of the study, it was calculated that the amount of energy consumed was reduced by 4.5% when PC covering material was used instead of PE covering material as covering material for the greenhouse side walls. In greenhouses covered with PE and PC+PE covers, if well-insulated thermal screens are used, the amount of energy consumed will decrease by 23.1%-22.4%, respectively, compared to PE and ...
In Türkiye, greenhouses without regular heating typically begin cultivation in March due to ecological reasons. However, low temperatures that occasionally occur during these months negatively impact cultivation. This study aimed to monitor inside climate parameters in high-tunnel greenhouses and evaluate measures to be taken. To this end, inside and outside temperatures, relative humidity, dew point temperature, canopy surface temperature, water condensation on the canopy's inner surface, light intensity, solar radiation, and photosynthetic active radiation were measured in March in the high-tunnel greenhouse and evaluated for cultivation. Data logger measurements revealed outside temperature and relative humidity values ranging from -5.7 to 11.0 °C and 53.4% to 91% throughout the trial. Inside temperature and relative humidity values ranged from -4.7 to 27.7 °C and 52.4% to 85.9%. Considering the low temperatures and high relative humidity values encountered during these periods, heating and ventilation of greenhouses becomes essential. Otherwise, the cover surface temperatures will drop below the dew point, causing condensation. Depending on the difference between inside and outside temperatures, water condensing on the inner surface of the cover can reach up to 90.1 g/m²/h. Furthermore, this condensed water on the cover surface has been determined to promote fungal diseases and reflect 67% ...
In regions with Mediterranean climates, high indoor temperatures, particularly during the summer months due to high solar radiation, limit plant growth in greenhouses. Due to the inadequacy of natural ventilation and shading practices commonly used to reduce indoor temperatures during these months, evaporative systems have become widely used in recent years. However, in regions where water is scarce, the high water volumes required for evaporative cooling are an issue that greenhouse operators should not overlook. The aim of this study was to determine the cooling effect, relative humidity effect, cooling efficiency, and water consumption of fan and pad cooling systems under Mediterranean climate conditions. For this purpose, measurements were taken in a Gothic-roofed greenhouse between June and September, when temperatures are high. The pad area used in the greenhouse was 7.5 m2, the water flow rate was 10 L per minute per meter of pad, and the air change rate was 0.066 m3m-2s-1. The average cooling effect, relative humidity effect, cooling efficiency, and water consumption in June were determined as 7.9 °C, 19.4%, 60.7%, and 9.82 L·m-2, respectively. In July, these figures were 5.6°C, 21.9%, 52.1%, and 9.73 L·m-2, respectively; in August, 5.4°C, 14.5%, 50.9%, and 10.2 L·m-2; and in ...
