Greenhouse with fan and pad cooling system – best suited for hot dry climatic conditions such as Northern plains where temperature goes above 30 oC,. The system is working on the principle that when water evaporates and heat is absorbed from surroundings. This is possible by drawing cool air into greenhouse through wet pad located at one end of the wall, where hot air is replaced by co-axial fans mounted on the opposite end of wall. The excessive temperature causes various damages to the morphology and physiological processes of plants such as flower shedding, leaf scorch, poor fruit quality, excessive transpiration, shortened life span of the plants and low net photosynthesis due to excessive respiration etc. Hence, it is important to maintain air temperature inside the greenhouse ranging between 20 oC to 28 oC for better crop growth..
Fan and pad system is controlled by a thermostat. Thermostatically controlled fans let the outside air into the greenhouse and remove inside air out of it. The capacity of fan should be 1m3 for each m3 of greenhouse volume per minute so as to ensure a complete renewal (or at least three quarters of it) or (50 to 60 renewals per hour) under tropical conditions.
The orientation of the multi span greenhouse with fan & pad cooling system should be made in such a way to take advantages of prevailing wind direction. Wet pad should be mounted on the wall of greenhouse facing winds and fan on the leeward side. The temperature gradients inside the greenhouse decide the need for Fan & Pad system. The root vents should be on the leeward side to prevent structural damage to the greenhouse.
Production of vegetable crops.