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Estimation of hourly averaged solar irradiation: evaluation of models.

Tham, Yieng Wei; Muneer, Tariq; Davison, Brian


Yieng Wei Tham


Hourly solar radiation data are required in many building services applications. These are also reported in the Chartered Institution of Building Services Engineers Guides A & J. Data from 16 locations in the UK were used to evaluate the so called Liu and Jordan model1 for monthly averaged hourly solar irradiation. Individual data sets spanned periods from 12 to 26 years between 1968 and 1994, and overall, provided data from practically the full range of latitude of the UK (50.22°N—58.13°N). For hourly estimation, the model only slightly underestimated both global and diffuse radiation before noon and overestimated, again only slightly, after noon. In addition, a discrepancy was observed between the measured data and the model’s predictions at low sunset angles. Following earlier research work, an attempt was made to further improve the Liu and Jordan model. However, it was found that at least for the UK data set, any such attempts were futile. This behaviour was attributed to the highly random nature of UK’s solar climate.

Practical applications: Most meteorological stations report solar radiation data on a daily averaged basis. However, most building energy simulation software requires hourly radiation. Research studies have confirmed that the well-known Liu and Jordan model, which enables the above conversion, performs well for locations in the US. This paper evaluates the above model for locations in the UK and compares it with previously studied Indian locations. According to the evaluation, the average accuracy of the model to estimate hourly radiation from its daily counterpart is 85%.


Tham, Y. W., Muneer, T., & Davison, B. (2010). Estimation of hourly averaged solar irradiation: evaluation of models. Building Services Engineering Research and Technology, 31, 9-25.

Journal Article Type Article
Publication Date 2010-02
Deposit Date Mar 18, 2011
Publicly Available Date Mar 18, 2011
Journal Building Services Engineering Research and Technology
Print ISSN 0143-6244
Publisher SAGE Publications
Peer Reviewed Peer Reviewed
Volume 31
Pages 9-25
Keywords Solar radiation; building services applications; global; diffuse; measured data;
Public URL
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