Recently, I made a test on the 5.5 version and 5.6 version for the daylight calculation. I just create a simple box with a window opening. The average daylight factor I got from 5.5 version is 6.5%. However, I just open exactly the same model in 5.6 version( the weather data, location, reflectance factor, Calculation method, grid point, all stay the same). I got the result is only 1.6%.
That's the huge difference. It made a big impact for us to design the glazing area and daylight. Which version's result should we rely on? or Both of them are not reliable. Right now, we are doing some daylight calculation for a school to analysis whether 80% of school area achieve 2% DF for BREEAM Rating, however, the difference of two versions could make complete different conclusion. Could anyone explain this? It's quite urgent. And we really need to get a good explanation to the client.
Many thanks.
Hi I would use radiance if
Hi
I would use radiance if I were you. If you want me to have a look at it drop me a line at
-> Daylight factor calculation 5.5ver VS 5.6 ver?
Hi to all,
i'm having a similar problem with the daylight factor calculations.
i've made several tests with the both versions 5.5 and 5.6 and exported them to radiance, and the results are very very strange....
for the version 5.6, wen i run the calculation using the ecotect algorithms i get 3.69 % of DF and when the same model is exported toe radiance the DF is 7.69 %
for the 5.5 version it's the opposite, using the ecotect algorithms i get 8.25 and with radiance 3.81 %
i just cannot get it ????? and another question
i was looking for a more basic methods to calculate the daylight factor and they request the reflection of the materials
how it is possible to specify it in ecotect and in radiance ?
thanks for the fast repluys !!!!
best
svetlin
PS the file is attached under
Window transmissivity
Hello,
I don't know about the change when using Ecotect to calculate DF, but I am pretty sure about one thing: when exporting to Radiance, Ecotect 5.5 was not converting the window's properties right, passing from transmittance to transmissivity*. That has changed in version 5.6, which may explain why you get higher results for your daylight factors when you export to Radiance with the new Ecotect version.
* if TN transmittance and tn: transmissivity
tn = (sqrt(.8402528435+.0072522239*TN*TN)-.9166530661)/.0036261119/TN)
Alice