Repsol YPF

Greenhouses

Heating in greenhouses started developing in the decade of the 1970s. Findings from trials in greenhouses that used heating indicated a 20% increase in production.

In greenhouses with heating, it may be interesting to use a floor heating system, due to the favourable response that it produces in crops, both during the germinating and rooting of cuttings phases, and during the phase of growth until it becomes marketable. However, factors such as the demand in terms of machinery and the labour that is needed to bury the tubes, and problems when it comes to working the ground when the tubes are not buried at great depth, negatively affected the development of heating systems buried in the floor. The reduction of surfaces dedicated to the growing of crops on the ground over the last two decades has contributed to the parallel development of underground heating or of  heating that was located at the level of the cultive tables.

The heating systems that are most often used, are warm air generators (cheaper) and systems of heating by low-temperature water conduction (30-40ºC). The former have a high thermal efficiency, greater still in the case of direct combustion, that push the combustion gases into the greenhouse, than those that use exchangers, which are very useful to maintain a minimal thermal shift or in cases of emergency (freezing), because their response to changes in the greenhouse's air temperature is very quick.