Dynamic thermal modelling of a large plastic multi-span greenhouse: Calibrated simulation and energy retrofit

Open problems in the thermal modelling of greenhouses that are worth of investigation concern the modelling approaches, the thermal inertia of the envelope, the solar heat loads and their control, the fast dynamics and the evapotranspiration. Given this picture, the scope of this work is to apply a dynamic thermal model for the estimation of the indoor environmental conditions and the energy use of a large plastic multi-span greenhouse, to calibrate the model against a large dataset of monitored data and to apply the model for the estimation of energy retrofit measures. The present work deals with the simulation and calibration of an energy model of a 3 hectares plastic multi-span greenhouse in North-Italy. Dynamic energy simulations were performed by means of the EnergyPlus software tool. The energy model of the greenhouse was calibrated against monitoring data of the 2014 year, which were retrieved from the Building Automation System (BAS) of the greenhouse. At the end of the process, the simulation results matched with the real data gathered on field. The calibrated energy model allowed possible retrofitting solutions to be evaluated in terms of energy performance increasing and satisfaction of the environmental requirements for plants’ growth. Results of the simulated scenarios concerning possible measures of energy savings were particularly interesting. Indeed, they highlighted how effective energy savings were achievable with relatively simple technical solutions, such as an additional external screen that controls the solar radiation or the additional thermal insulation of the slab in contact with the ground.