# IECC 2015 ed. Section C402.4.2 for Minimum skylight fenestration area



## George McGerd (Mar 3, 2016)

Hello:

IECC 2015 ed. Section C402.4.2 Minimum Skylight Fenestration Area:

Working on a project where this "new" requirement will apply to a space in the building I am designing, since the space is over 2,500 sf and directly under roof (the space is a high school gymnasium).  We will use skylights and vertical fenestration to daylight the space; however, the skylight manufacturer can not provide any of the data required to run the calcs / equations listed under this section of the code.  Plus, I am not an engineer so these kind of calcs are not really my baileywick anyway.  Third thing is I honestly admit I am a bid confused about what this section of the code is actually requiring.

Having a better understanding of the definition of "Daylight Zone" would be helpful.  The Chapter 2 definition is a bit weak.  If an area is daylit by skylights is that area considered a Daylight Zone, or does this term only apply to areas daylit by vertical fenestration?

Can anyone shed some light (no pun intended) on what this section of the code is actually requiring and how to demonstrate compliance?  I apologize in advance because I do not own the code commentary for the 2015 edition of the IECC.  If someone could 'enlighten' me, it would be much appreciated.

Thanks


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## RLGA (Mar 3, 2016)

See IECC Sections C405.2.3.2 and C405.2.3.3.


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## George McGerd (Mar 3, 2016)

Thanks.  That was very helpful.  I was able to run the calcs and the total daylight zone under skylights for the space is equal to 96.8%  However, the space does not comply with Section C402.4.2 paragraphs 1 and 2, which talk about minimum skylight area and skylight effective aperture required.  This is most likely because we are proposing to use a solar collector w/ amplifier (i.e. SkyVault by Solatube) instead of a conventional "skylight".  The space does not qualify under exceptions 1-5.  Are there any other exceptions that allow for use of a solar collector, which is a much better performing piece of equipment, in lieu of a conventional skylight?


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