Enhancement of Mediterranean Greenhouses Facilities: Heat Power Pump Assessment for Bedding Plant Production by Coaxial Basal Heating

Protected horticulture is a highly energy-consuming sector where optimizing energy use and cost for heating facilities is strategic to achieve high environmental and economic sustainability. The paper main aim is to present the use of a heat pump (HP) for basal heating as an alternative technology to produce bedding plants. The experimental test was carried out by bedding plant production for the early spring market. The adopted greenhouse, located in Tuscany, Central Italy, consisted of a frame made of galvanized iron, roofing in polycarbonate slabs, and walls of polyethylene sheets with a fully automatized opening system equipped with twelve concrete benches. The benches were isolated from the ground with polystyrene and a substrate of volcanic lapilli. Then eight benches were provided with a basal heating system based on four couples of coaxial pipes circulating warm water, while four were not heated. Cuttings of Impatiens Walleriana ‘Buddha F1 Carmine’ were transplanted in 1.2 L pots and subsequently grown by comparing basal heating of 16 °C with no basal heating conditions for a total of 960 potted plants. According to requirements, all the plants underwent the same agronomic care (fertigation and pest control). The microclimatic conditions and the energy consumption were acquired. The experimental results show that the heat pump ensures suitable thermal conditions for such cultivation in the winter period, confirming the possibility of using a conventional heat pump in horticulture as a simple installation in an existing Mediterranean greenhouse.