Test and measurement of solar visible radiation transmittance of greenhouse glazing

Solar visible transmittance is crucial for greenhouse glazing. Different test methods for solar visible transmittance of glazing induce different results. The present paper described test and calculating methods for solar transmittance of glazing. Three typical glazing materials, namely, polyethylene(PE) film, float glass and double polycarbonate(PC) sheet, were measured and calculated under different International Commission on Illumination(CIE) standard sources(A, C and D65), within the visible and photosynthetic active radiation(PAR) spectra, using four response coefficients to solar radiation. Results show that PE film is not affected and float glass differs 2%, the difference of double polycarbonate sheets is up to 2%～3.7%.