[Radiance-general] Higher surface reflectance simulation in buildings

[Jiangtao Du]

Dear All,
 
I am doing Radiance simulations in atrium well with higher surface reflectances ( 0.6 ~ 0.8 ~ 1, diffuse surface). 
But according to   "Aizlewood M, Butt J, Isaac K & Littlefair P. Daylight in atria: a comparison of measurement, theory and simulation:  Proceedings Lux Europa. Amsterdam, 1997."   and    "Littlefair P. Daylight prediction in atrium buildings. Solar Energy, 2002; 73: 105-109.",    Radiance underestimated the reflected light (Internal reflected component) in atria with high reflectance (some measurements in the paper used a reflectance 0.85 and got the biggest discrepancy in IRC was 4.87). My some simulations  got the similar results: simulations underestimated the measurement with reflectance 0.6 and 0.8 and  the higher of surface reflectance the bigger is the discrepancy. All the studies used overcast sky model and set a higher ambient parameter setting.
 
Could you help me explain the divergence from high reflectance simulation using Radiance. Also, if these demonstrate Radiance simulation could bring some bigger errors to the dayligthing simulation in high reflectance environment?
 
BTW, I will appreciate it very much if you could share some experience or knowledge  and give some suggestion about higher reflectance simulations.
 
Cheers
 
Jiangtao
 
PhD student in University of Sheffield


      
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