Paper Conference

Proceedings of BauSim Conference 2006: 1st Conference of IBPSA-Germany and Austria


Kurzwellige Sonnenstrahlung als Klimarandbedingung für die hygrothermische Bauteilsimulation

C. Finkenstein, H. Petzold, P. Häupl

Abstract: For a successful simulation of the transient hygrothermic behaviour of a construction or a building it is necessary to include a well-rounded physical concept of transport and storage processes as well as suitable material functions or proper climatic boundary conditions. The calculation of the heat flux density on arbitrarily oriented and tilted surfaces is based on separate data of direct and diffuse shortwave solar radiation. However, measurement of shortwave solar radiation is very often done for total radiation only. The paper presents several methods in order to calculate a separation of measured total radiation into its direct and diffuse parts. The correlation algorithms, that are taken from literature ( Loutzenhiser et al. 2006 , Perez et al. 1990, Reindl et al. 1989, Wong/Chow 2001) are presented and compared. They are based on statistical exploitation of measured radiation data. The separation of total radiation into direct and diffuse radiation depends hereby on the ratio of measured total radiation and extraterrestrial solar radiation on the horizontal surface. The study is part of the EU-funded research project CLIMON, being realised by the Institute of Building Climatology of TU Dresden (D), Department of Building Physics of CU Leuven (B), Department of Civil Engineering of IIT New Delhi (IN), Department of Civil Engineering of MNIT Jaipur (IN) and the Indian Council of Architecture. Research subject is hereby the climatological investigation of the Humayun´s Tomb in New Delhi, a very popular Mughal, built in the 16th century. There are measured all important climatic parameters as well as several state variables at the south facade such as surface temperature, relative humidity and temperature at different locations inside the construction. At the end of the paper, there is presented the application of the best correlation mentioned above on the measured data on the south facade of the Humayun´s Tomb. The measured total radiation data on the horizontal surface, being a climatic parameter, are separated into direct and diffuse parts by the correlation. Afterwards, the radiation heat flux density on the chosen south facade of the Humayun´s Tomb is calculated and compared with the measured data. The paper shows how to generate acceptable data of shortwave radiation on an arbitrarily oriented and tilted surface for the usage in hygrothermal building part or building simulation - even in a difficult starting data situation.
Pages: 34 - 35