2919 -- A Comparitive Evaluation of the ASHRAE and WON Solar Radiation Models PDF

Hourly values of the global and diffuse solar radiations inident on a horizontal surface, calculated with the ASHRAE and WON models at four locatinos in eastern Canada, are compared to the corresponding measured values. The comparison is carried out monthly for the period 1973 through 1976. The agreement is good for the summer months, but large discrepancies are observed during the last four months of the year. The seasonal performance of the WON model is more uniform than that of the ASHRAE model. The latter can be improved by adjusting the valued of the clearness number. Optimum monthly values of the clearness number are presented for Montreal.