ISHS Acta Horticulturae 797: International Workshop on Greenhouse Environmental Control and Crop Production in Semi-Arid Regions
A REAL-TIME ENERGY BALANCE MODEL OF A LARGE SCALE GREENHOUSE |
| Author: | G.G. Schoonderbeek |
| Keywords: | greenhouse, energy balance, model, training tool |
| Abstract:
A greenhouse is a controlled environment. Climate parameters like temperature and humidity are controlled by venting, heating and cooling. Shading light and dosing CO2 influence other growing conditions like light level and CO2-concentration. In a dry and hot climate like Arizona forced ventilation with evaporative cooling is used to maintain favorable growing conditions. Forced ventilation means full control over the amount of air exchanges. Together with known ambient conditions like temperature, relative humidity and incoming solar irradiation, all input data are available to model the energy flows in a greenhouse. The steady state balance between the energy input from the sun and the forced cold air is calculated and the result is shown as a temperature and relative humidity. The ‘cooling capacity’ of the crop on the greenhouse climate is part of the model. Characteristics of the greenhouse cover and the evaporative cooling can be adjusted. This model is presented in a user-friendly interface. It is realistically shown as a cross-section of a greenhouse with all relevant parameters visible, both input variables like ambient conditions and the resulting calculated values of the greenhouse climate such as temperature and humidity. The model calculates the greenhouse temperature and humidity under steady-state conditions. The model can be used as a learning tool for growers. All relevant ambient conditions can be used as input data to calculate the greenhouse climate. The model is validated using real data recorded on sunny days in May 2008. | |
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