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radiation method was described. Some in situ experimental results of an outdoor
venetian blind transmittance were presented and compared with numerical results.
Results showed a fairly good agreement for total solar transmittance when both direct
and diffuse radiation were present whereas some differences have occurred for diffuse
solar transmittance. Moreover, a venetian blind control strategy, which avoid direct solar
radiation but enhance daylight, is also implemented.
The model can be used for different sun profile angles, venetian blind geometries, slat
properties and rotation angles. Therefore, it is suitable for comparing different venetian
blinds solutions and optimizing blind control strategies. A proper blind control strategy
should minimize HVAC and artificial lighting energy consumption while maximizing
daylight and view to the outdoor. Hence, a balance should be found between
daylighting/views and glare/solar gains. A venetian blind control strategy, based on the
profile angle of sun and the cut-off angle of slats to avoid direct solar radiation indoors
but enhance daylight, was implemented. The knowledge of the venetian blinds optical
properties is crucial in identifying the most effective strategies to improve the fenestration
system performance, regarding building energy consumption and indoor comfort issues.
The model can be used for different venetian blind configurations and control strategies
and is suitable for integration into building energy simulation tools.
Acknowledgement
The authors would like to acknowledge the financial support given by the Portuguese
Foundation for Science and Technology - FCT (SFRH/BD/27366/2006).
References
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