Analysis of airflow characteristics of greenhouse screens

Abstract

New experiments and analyses were conducted to examine the airflow characteristics of some currently employed greenhouse screens and the ability to predict airflow through them. Nine different thermal, shading and insect screens were tested and their airflow characteristics were defined, based on the Forchheimer equation, in terms of permeability and porosity. Further, an analysis was made of the effect on these characteristics of damage caused by handling of the screen materials. Experiments demonstrated that thermal screens have permeabilities close to 10-11 m^2 and some thermal screens, mainly woven sheet screens, can be damaged by handling, whereby the permeability is increased up to 3·5 times.