ISHS Acta Horticulturae 170: Greenhouse Construction and Covering Materials
OPTIMISATION OF THE DESIGN OF A SOLAR HEATED GREENHOUSE |
| Authors: | L.A. Bellamy, G.T. Ward |
| Abstract:
Traditionally, greenhouse engineers have designed structures to maximise light transmittance. Since 1973 energy considerations have dominated research with subsequent development of twin-skinned claddings, thermal screens and other energy conserving components. Overseas designs may well need to be adapted to suit New Zealand's sunny, temperate climate. In 1982 a project was begun to assess the potential of new designs, with the aim of producing working drawings of a commercial greenhouse optimised for local conditions. Rate of return on capital was chosen as the variable to be maximised. Consideration of the effects of each parameter should result in a well-balanced design, even if the nature of the latter precludes the precise determination of these effects. To calculate rate of return the following information is required over the investment's economic life:
As well as being cost effective, the design should be able to accommodate a range of crops, and be technically simple to promote acceptance by industry. This paper briefly outlines the method of analysis and presents preliminary results. As it was not feasible to apply optimisation theory to this problem owing to the complex relationships between the design factors and the rate of return a decision was made to select 50 different designs for intercomparison. As is shown in Figure 1 a set of models with design variables as inputs is required so that the yield and heating/cooling bill can be determined. Rate of return indicates the investment potential of a greenhouse. Theoretical analysis enables the optimal design factors to be fixed whereas sound engineering judgement will ensure the design's success. | |
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