The Methods Used to Decrease High Temperatures in Greenhouses

Vaporpressuredeficitandthehightemperatureemergedduringthesummer months in thecountrieswithMediterraneanclimate, resultsin decrease of thequantityandthequality of theproductsproduced in greenhouses. Duringthisperiod, toreducetheplantstressand in ordertoprovidehighqualityproductstothe market, greenhousesarerequiredto be cooled. Inordertoreducethetemperatures in greenhouse, naturalventilation is thefirstmethodconsidered. Althoughnaturalventilation; is cheaperthantheotherforced methods in terms of thefirstinvestmentandoperatingexpenses,it is not enough to reduce the high temperatures in the greenhouse during the periods when the temperatures are starting to increase.The advantage of the forced ventilation methodwith fansis the higher amount of air exchange ratio and the ability to control ratio compared to natural ventilation.This method, too, is insufficient in the summer months to reduce the high temperatures inside the greenhouse.Anothermethod is theshadingmethod; whichhelpsto lowerhightemperatures in theinside thegreenhousebyreducingtheradiationreachingthegreenhouse. Inthismethod, reduced temperaturelevelinside thegreenhouse is insufficientforplantgrowth, andalsoimproperuse of thismethodcausesreduced use of sunlightby plants.One of the most effective solutions for cooling the greenhouse during these periods when natural ventilation, forced ventilation and shading methods are inadequate is evaporative cooling.Inthisstudy, ventilation(natural and forced), shading and evaporative cooling methods, used toreducethe effect of high temperature that occursin greenhouses, and advantages and disadvantages of these methods have been evaluated.