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How do we calculate skylight placement?

catherinetilton | Posted in General Questions on

We are building a new house in DeRidder,Louisiana. Our walls are 8 inch cement block(featherlite rock face), 8 ft, 9 inch to top of block. Roof is 8 in 12. Kitchen faces directly south. Kitchen island runs from 6 feet inside block wall to 13 ft and is 4 ft wide. We want to install a velux skylight( GGL P10 3073 ) in the roof running long way with the kitchen island. We want the sun angles average north peremeter(probably noon, September 21) to stop at the north end of the 3 foot tall counter with perhaps soapstone on top of it. There should be a not too complicated formula or program to help us figure the placement of the skylight in the roof. Thanks for any help or direction! Cathy Tilton

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  1. wjrobinson | | #1

    Catherine, any science teacher at a nearby school could sketch this for you. If you have someone near you to run this in Sketchup, you could play with all your ideas and really fine tune. Your plans were drawn by? You have a bulder? Sketchup is free too.

    Idea #2 On September 21, just before noon, have your installer move your skylight into the position you desire with a mockup of your island in place. When you are happy, you yell, NAIL IT.

  2. wjrobinson | | #2

    70634-Zip Code longitude lattitude
    central time and yes for daylight savings time-time zone daylight savings time
    203'-altitude of location
    September 21 2012, noon

    55.74-altitude angle .36-declination
    -30.26-azimuth angle .12-equation of time
    12PM-clock time 6:59AM-time of sunrise
    10:54AM-solar time 7:11PM-time of sunset

    You can use a protactor with this info a draw out your options.

    Velux skylights, has software to do daylight checking.

  3. wjrobinson | | #3


    Top of skylight finished interior opening is, drum roll please...

    90 5/64" up ceiling from top of wall

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