ChileanJAR

Reduced night temperatures during winter months at the Pampa Húmeda, Argentina, limit the production of certain crops. It is therefore necessary to protect those crops with covers and heating in order to establish a temperature gradient between internal (crop optimum) and external temperatures, and also to evaluate the costs of such heating systems. This study assessed the fuel consumption required to heat greenhouses with tomato and pepper crops during the months of July and August in the following localities: Rosario, Buenos Aires, Mar del Plata and Bahía Blanca. A simple model was applied which considers the losses of heat by convection, conduction and radiation with fixed parameters of the greenhouse structure, using external temperature data. Double-roofed greenhouses reduced fuel consumption by approximately 13.5% and a reduction of 27.5% was observed for a total transmission coefficient k =3.5 W m^-2 K^-1 with respect to k =5 W m^-2 K^-1. Even though fuel consumption was not closely related to the number of air renovations per hour within the greenhouse, variations in consumption connected to their geographical location were observed. There was an increase in the income for both crops using a heating system, due to greater and better productions, and also to their earlier arrival at the market.