ANALYSIS OF THE AIR-FLOW CHARACTERISTICS OF GREENHOUSE SCREENING MATERIALS

Experiments and analyses were conducted to examine the airflow charact eristics 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 defi ned, based on the Forchheimer equation, in terms of permeability and p orosity. Further, an analysis was made of the effect on these characte ristics of damage caused by handling of the screen materials. Experime nts 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. (C) 1997 Silsoe Research Institue.