FAN VENTILATION OF GLASSHOUSES - PRACTICAL ASPECTS
In Britain, glasshouse ventilation by extractor fans was first used by flower crop growers, particularly those growing carnations and year-round chrysanthemums. These growers had imported the method from the United States of America where, in certain areas, wet-pad cooling is used. This initial influence is evident from the fact that the most widely used propellor fan for glasshouse ventilation is similar in design to that of the original American machines. At present, it is estimated that 50–60 acres (20–24 hectares) of glass in the U.K. are force-ventilated. The largest supplier of fans to the industry forecasts an output in 1969 of sufficient fans to ventilate 20 acres (8 hectares), and estimates that approximately 50% of fans sold are for installation in new glasshouses. It may be of interest to note that the Ministry of Agriculture, Fisheries and Food collected statistics in 1963, 1965 and 1967 which included information on the area of glass fitted with automatic ventilation equipment. In March 1967 it is estimated that approximately 200 acres (81 hectares) or 5% of the total glasshouse area was so equipped. There are no more up-to-date figures available but it may be expected that the area is now of the order of 10% or 400 acres (162 hectares) as most new glasshouses are now fitted with automatic ventilation as they are built. Thus approximately 15% (60 acres, 24 hectares) of automatically-ventilated glasshouses may be equipped with fans.
Jamieson, M. (1971). FAN VENTILATION OF GLASSHOUSES - PRACTICAL ASPECTS. Acta Hortic. 22, 86-94