ISHS Acta Horticulturae 115: Symposium on More Profitable Use of Energy in Protected Cultivation
PROGRESS IN MOVABLE BLANKET INSULATION SYSTEMS FOR GREENHOUSES |
| Authors: | W.J. Roberts, D.R. Mears, J.C. Simpkins, J.P. Cipolletti |
| Abstract:
Movable curtain insulation systems can save substantial amounts of heat energy in commercial greenhouses. Work at Rutgers over the past few years has concentrated on automatically controlled mechanical systems which draw curtains across a supporting network of polypropylene monofilaments in double-covered polyethylene greenhouses. Energy savings ranging between 22% and 58% have been obtained. It has been found that in a full scale commercial greenhouse, the energy savings depend upon the mechanism used to pull the curtain and the material used. 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. | |
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