ISHS Acta Horticulturae 245: Engineering and Economic Aspects of Energy Saving in Protected Cultivation
LIGHT TRANSMISSION INTO GREENHOUSES |
| Author: | D.L. Critten |
| Abstract:
Theoretical advances leading to an understanding of light transmission processes and hence improved evaluation and design are presented. The results of analysing skylight into harmonic components are first presented, and energy transmission coefficients linking incident with transmitted harmonics are developed. Irradiance as the amplitude of the first 'odd-series' harmonic is demonstrated. The extended light integral, whereby the transmission characteristics of single sheets of cladding can, to a first order, be related to average multispan transmission is also described and various consequential results of this relationship are developed. A further approximation, that the light reflected per unit reflecting surface area is independent of angle of incidence, leads to great simplification in calculating reflected light losses. Finally, simple ways to calculate losses due to absorption by regularly spaced structural members in multispans are given, based on representing these components by circular cylinders. | |
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