Hello,
I'm trying to get IEQ C8.1 by the prescriptive option, but I'm having problems with the calculation of the visible light transmittance.
Inside of the same space I have an outer glass facade, which has, according to the data sheet, a visible light transmittance of 0.61.
Within this space, I have a glass partition, with another visible light transmittance of 0.88.
When this is the case, two differents glasses with differents visible light transmittances, in the same space... Which of these two data should I use? or How should I use these two facts?
Thank you in advance.
TODD REED
Energy Program SpecialistPA DMVA
LEEDuser Expert
890 thumbs up
July 31, 2015 - 11:36 am
Francisca,
So, my understanding of the condition based on your description is this; you have the exterior window wall with a VLT of 0.61. In that space you have an interior partition wall located some distance away from the window wall and it has a VLT of 0.88. Am I correct?
If this is the case, then you have what is know as shared daylighting scenario. That is when an enclosed interior space receives daylight that must come through the exterior glazing and then at least one interior glazing wall before entering the space. You cannot use the prescriptive method to determine the daylight compliance for the interior space(s) beyond the interior glazed partition. The prescriptive method is a simple calculation which can only use one glazing element. You cannot do a weighted average or have shared daylighting scenarios.
You will either need to use another option such as simulation or measurements or use a combination of the three. You can use the prescriptive method for the space with adjacent to the window wall. You will have to use either simulation or measurements for spaces on the other side of the interior glazed partition.
Hope this helps.