Effect of Latent Heat Phenomena on Thermal Insulation and Inside Climate of Greenhouses

By means of a dynamic greenhouse climate model, it was shown that condensation highly alters the thermal insulation properties (from +25% to -17%) of greenhouse cladding materials, depending on the far-infrared radiation transmittance of the dry material. Neglect of condensation and evaporation gave rise to an overestimation of the yearly mean inside air relative humidity of about 10% for most materials and to overestimates or underestimates of the vegetation temperature, according to the cladding's far-infrared radiation transmittance. The relative contri bution of condensation to the nighttime water vapor removal from the inside air was found to range from 79 to 89%.