Data from several experiments on the modification of the climate in a glasshouse are presented to test their influence on the possibility of using the glasshouse in a hot summer. The glasshouse is an aluminium structure glazed with light-diffusing glass and is orientated N-S. It is equipped with a cooling system consisting of two ventilators and a water-curtain with a forced-air circulation through them. Solar radiation measurements inside and outside the glasshouse show that between one half and two-thirds of the incident global radiation was transmitted through the roof and sides, the amount depending on the angle of incidence. Measurements of humidity and temperature of air and irrigation water were carried out in the glasshouse. Using the cooling system, the temperature regime in the micrometeorological layer is the same inside as outside the glasshouse. As a result of the various modifications, climatic improvements were achieved which make the use of the glasshouse possible in the heat of summer. © 1978.