I am currently looking to utilize the prescriptive method in order to calculate the amount of daylight entering the regularly occupied spaces of a student housing complex. I have calculated the floor area and window area of each individual space within each dwelling unit (bedrooms, living room, kitchen), and I am often finding that the resultant product of the VLT and the Window-to-Floor Area ratio exceeds the accepted daylight zone of 0.15 and 0.18.
My issue is that the calculations do not seem to take into account orientation of glazing. This means that via the prescriptive method, I can have north-facing window into a living room that would exceed the acceptable amount of daylight, since the number would equal that of a south-facing window. Is this correct?
Also, if I have a room that has a daylight value exceeding 0.18, does the entire room not count towards the credit? Is there a method to alter the calculation in order to get at least a portion of the room to meet the credit, which, when calculating the sum of accepted spaces would total at least 75% of the total floor area of the regularly occupied spaces within the building?
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Eddy Santosa
Director of SustainabilityDBR Engineering Consultants
376 thumbs up
November 5, 2012 - 12:03 pm
Dan,
I suggest you use the simulation to design the daylight. Typically, housing complex has modular design so it will be faster and easier to use simulation or daylight measurement. It give you a lot of advantages to have a better design and high performance building by incorporating daylight into design by using a simulation.
If your goal is only to achieve LEED point which I don't recommend actually, you may reduce your VLT of your glass to lower the number or view-preserving automated shades.
Dan Bielenin
William Rawn AssociatesNovember 5, 2012 - 12:11 pm
If we are utilizing an external louver solar shading system, what is the determining factor for adjusting the VLT?
Eddy Santosa
Director of SustainabilityDBR Engineering Consultants
376 thumbs up
November 5, 2012 - 12:26 pm
Dan, to reduce VLT, we can use darker tinted window. If you want to adjust VLT based on the external louver, my recommendation is using simulation which is almost same as the effort to run daylight simulation.additionally, I am not sure whether the approach will be accepted by the reviewer.
I use similar method to adjust SHGC for my energy simulation purpose.