Case 1 - I had modelled a small building surrounded by high-rise building and tried to find out the daylight factor of the small building at 750 mm above the floor level, I got average values of daylight factor.
Case 2 - I tried to move the small building little away from the neighbour building and run the model to find the daylight factor of the small building at same level (750mm) and I got the average values of daylight factor which is not seems to be correct.
1. In the first case when the small building is surrounded by high rise building the daylight factor should be lower as the small building is affected by obstructed high-rise building surrounded by it.
2. In the second case when the small building is moved little away at a certain distance the daylight factor should be higher because the neighbour building is not obstructed.
Whereas in my output the results where the other way.
Can anyone help me out?
Thanks in advance.
Often with Ecotect simulation you can get high reflectance off other objects internal or external. Perhaps try reducing the reflectance value of the surrounding buildings.
A better option, if you can, is to export into Radiance to get more accurate and reliable DF calculations.
Here is the excerpt from the Help file (Known bugs and issues, some sort of):
"Limitations to Daylight Factor Calculations
The BRE daylight factor method is not appropriate to all lighting situations, especially where predominantly indirect daylighting is used. This is because it does not consider inter-reflections between surfaces other than through a simple formula based on reflection coefficients and the ratio of surface-to-window areas. For indirect lighting, use RADIANCE as it is free, very easy to invoke from within Ecotect and is eminently suitable for any complex lighting situation."