Abstract
This paper describes the energy conservation techniques for a heating greenhouse. The overall heat transfer coefficient (U-value) was measured by using a hot box model and two actual small greenhouses which were a wooden frame house and a steel frame one.
By the hot box model, two cases of covering conditions were measured, one of them consisted of a PVC film for covering and steel frames, another was a PVC film only. The U-value of the Covering with frames was 10% greater than that of the covering alone. Likewise, in comparison of effect of frame materials in the greenhouses, the wooden frame one had 11% less U-value than the steel frame one. Those differences are considered to result from a kind of frame materials and their size of contact area with a covering material.
In addition to above facts, the changes in U-value of the greenhouses were mearsured as a functioned of wind verocity
Furthermore, a simple method for estimating U-value is described for any greenhouses consisting of various materials for covering and framing.
