Spatial, Temporal, and Vertical Variability of Ambient Environmental Conditions in Chinese Solar Greenhouses during Winter

Abstract

The monitoring and control of environmental conditions are crucial as they influence crop quality and yield in Chinese solar greenhouses (CSGs). The objectives of this study were to assess the spatial, temporal, and vertical variability of major environmental parameters in CSGs during winter and to provide greenhouse climate/microclimate characteristics in order to facilitate the monitoring and control of greenhouse environmental conditions. A wireless sensor network (WSN) was deployed in two CSGs: one with crops and one without. Sensors were placed at different locations inside and outside the greenhouses, and the air temperature, humidity, CO2 concentration, light intensity, solar radiation, and wind conditions were measured and analyzed. Significant variability in the spatial, temporal, and vertical distribution of environmental factors was observed in both greenhouses. The average minimum and maximum temperatures and humidity inside the CSG with crops were 9.96 °C (4:00 h) and 24.5 °C (12:00 h), and 32.6% (12:00 h) and 92.1% (5:00 h), respectively. The temperature difference was 2.2 °C between layers in the CSG without crops and 1.4 °C between layers in the CSG with crops. The CO2 concentration in the different layers inside the CSG with crops was highest at night. The average maximum light intensity inside the CSG with crops was 32,660.19 lx, 36,618.12 lx, and 40,660.48 lx (12:00 h to 13:00 h) in the bottom, middle, and top layers, respectively. Sensor positioning in the greenhouse was evaluated by considering the sensors’ data variability. The findings of this study could aid in the development of a better monitoring and control system for CSG’s microclimate during winter. More research is needed on greenhouse microclimate control systems based on this variability analysis, which could improve crop quality and yield in greenhouses.

Parametric Analysis of a Radiant Gas Heating System for Controlled-Environment Agriculture with Preheated Ventilation

“…The choice of artificial heating methods for buildings and structures is only part of the energy conservation solution [9,13,[17][18][19][20][21][22]. In conjunction with this, there is a need for optimal architectural and planning solutions [15,[23][24][25][26][27][28], and the implementation of modern innovative technologies aimed at reducing the consumption of non-renewable fuel and energy resources [24,[29][30][31][32][33]. Therefore, within the context of addressing this problem, research on the impact of various factors on the energy balance of cultivation structures is required, consequently affecting the thermal regime of the premises and the calculated power of the adopted heating system.…”

Impact of Environmental Factors on Indoor Air Temperature in Gas-Fired Radiant Heated Cultivated Structures

“…Practical horticulture is only feasible when creating favourable temperature and humidity conditions within cultivation structures throughout the entire cold period of the year. To achieve this, various heating systems are employed in winter greenhouses and conservatories, including water (or steam), air, combined water or steam and gas-air systems [9][10][11][12][13][14][15]. The heating of cultivation structures can also be accomplished through the use of electrical energy.…”

“…The heating of cultivation structures can also be accomplished through the use of electrical energy. In addition to the mentioned traditional heating systems, alternative methods for providing thermal comfort to cultivation structures are organized, such as through heat pumps [1,15] or solar collectors (solar greenhouses) [2,6,[10][11][12][13][14]. Currently, for several reasons [3]: artificial source of infrared radiation; the absence of the need for a boiler installation, thermal networks, and related engineering equipment; automation of the technological process; even distribution of thermal energy on the soil surface; possible application of carbon dioxide (CO2) for plant fertilization, obtained from fuel combustion products when using gas infrared emitters -gas radiant heating systems are of significant interest in agriculture [16][17][18][19][20][21][22][23][24][25].…”