Paper Conference

Proceedings of eSim 2008: 5th Conference of IBPSA-Canada

     

THE ASSESSMENT OF THE ACCURACY OF DIFFUSE IRRADIATION MODELS AND THEIR POTENTIAL IMPACT ON BUILDING SIMULATION

Spencer Dutton, Shao Li, Robert Clear

Abstract: A study was undertaken to verify the performance of five different models used to separate global horizontal radiation measurements into constituent diffuse and direct components. Model predictions were compared with measured data for ten locations in the UK , US and Japan. The study showed that there are significant differences in the accuracy of available diffuse/direct radiation models. Their performance has been shown to vary depending on location, time of year and the clearness of the sky. The accuracy of these models has been shown to have a significant impact on the hourly demand profile of a typical building in the UK. Pervious studies used statistical analysis of the accuracy of modeled diffuse radiation component to determine the most suitable model for a location. In this study the accuracy of each model was determined for each of three sky conditions: overcast, partially cloudy and clear. Using building simulation with both modeled and measured data, it was determined that accurate representation of clear sky conditions has the greatest impact on simulation performance. This was used as the determining factor in recommending models. This study concludes that when using diffuse ratio models for building simulation, Maxwell's model is the most accurate for sites based in the UK, Reindl's for American sites and Muneer's model for any other world location where a geographically specific model is not available.
Pages: 235 - 242
Paper:
esim2008_235_242