PROGRESS IN MOVABLE BLANKET INSULATION SYSTEMS FOR GREENHOUSES
It is important that the system enable all edges to be closed tightly to prevent warm air leakage past the curtain. In tightly closed systems, the energy savings depend upon the geometry of the curtain closure and the material used. The curtain area should be minimized, therefore, in gutter-connected houses, the curtain should be drawn horizontally. The completely porous materials tested provided the least heat savings but were easy to handle mechanically and had the potential to also serve as summer shade. Thermally opaque, air tight materials provided more heat savings and the best thermal insulation was provided by materials aluminized on their upper surfaces.
In some cases, condensation dripping from the greenhouse onto the curtain can cause mechanical problems. If the curtain geometry does not allow this moisture to drain off, a material which allows water to pass through should be used or the curtain should be perforated. It is desirable for a curtain to be strong and also to be capable of compacting into a small bundle for daytime storage to minimize shading.