Greenhouse insect screening can prevent many unwanted insects. Insect screens also limit the airflow. There is a relationship between screen opening and the physical size of the unwanted insect for the screen to be effective. This relationship must be balanced while keeping in mind practical aspects of proper airflow and cooling.

Typically screen material is graded by mesh size. The mesh size refers to the number of threads per inch in each direction. The diameter of each thread must also be considered. A 30 mesh screen has 30 threads running in each direction perpendicular to each other.

Screen size greatly affects airflow, cooling effectiveness, humidity levels, and light transmission. Proper sizing of screen is critical apart from of the method of cooling. Airflow, cooling, and fan performance are affected by any size screen, more so with finer mesh. Dust and debris buildup on screens also affects their efficiency. As the mesh size increases, so does the requirement to clean the screens.

Exclusion of all insects with screens can be prohibitively impractical. A level of acceptance must be understood and a cost-effective compromise be reached.