Energetic and economic analysis for improving greenhouse energy efficiency

Abstract

Protected agriculture is one of the prominent agricultural techniques. It allows for creating an adapted microclimate to the plant growth, which leads to high quality and off-season production. Instead, a significant amount of energy is required. This study aims to provide the potential of energy saving based on the optimal selection of the greenhouse design under Fez City’s climatic conditions (Morocco). For this purpose, a dynamic model of a gothic-arch-shaped greenhouse is created in EnergyPlus environment. The impact of four different orientations (0°, 90°, 45° and - 45°) on greenhouse energy needs is first investigated. The selected design is further improved by using a thermal insulation blankets system operating during the coldest months and deploying from the sunset to sunrise. To define the prospect of the energy saving, two variables were primarily evaluated: the greenhouse inside air temperature variation and thermal loads prompted by creating the optimum microclimate for tomato plant. Finally, an economic analysis is performed. The results show that 0° relative north (longer axis) is the optimal orientation for a gothic-arch greenhouse and that the thermal insulation blankets allow for reducing 17 % of the greenhouse heating needs under the climate conditions of Fez