Energy and economic analysis for the selection of optimal greenhouse design: A case study of the six Morocco’s climatic zones

Abstract

Early in the greenhouses' development, energy optimization must be taken into account. Without a doubt, the greenhouse's design and location affect the amount of energy it requires for heating and cooling. As a result, for a particular type of cultivation and under a specific set of environment conditions, the design of the greenhouse should be chosen to preserve its best possible microclimate conditions. The purpose of this study is to assess various greenhouse designs (shape, envelope material and orientation) in order to choose the most appropriate one for each Morocco’s climatic zone. For that, different shape/ envelope material combinations are considered, namely nine shapes (uneven span, single slop, standard even span, modified IARI, mansard roof, quonset, gothic arch, modified quonset, and modified gothic arch) and four materials (low-density polyethylene, bubbled polyethylene, ethylenevinyl acetate and glass). After the selection of the suitable combination, four orientations were investigated, namely 0°, 90°, 45° and −45° (longer axis vs North-South axis). Further improvements have been made to the greenhouse's energy efficiency by utilizing natural controlled ventilation to reduce the requirement for cooling, and nocturnal thermal insulation that operates during the heating season period. Different parameters are considered to determine the potential for energy savings and to choose the more adequate design in each climatic zone: the greenhouse heating and cooling thermal loads, the incident solar radiation on the greenhouse floor, depending on the considered plant needs, and the yearly air-conditioning cost.