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Calculating the length of an over hang for sun shade: help needed.

  • 11-03-2009 11:31am
    #1
    Carlow52
    Closed Accounts Posts: 2,389 ✭✭✭


    Anyone know how to use a sun shade calculator/have access to one please?

    The window eave height is 2.4m.

    The house is located at 53.45° North and 6.16° West.
    The back of the house faces South West,( 230°).

    Have sun shade till 1700 hrs
    Thanks


Comments

  • #2
    CJhaughey
    Registered Users Posts: 14,906 ✭✭✭✭CJhaughey


    Try using google sketchup, it has a feature that can simulate sun and shadow.


  • #3
    pauln
    Registered Users Posts: 366 ✭✭pauln


    You'd need to specify more information such as the hour of shading start and range of days of year to shade this time range. Any overhang design will only work exactly to design on two days of the year the other days it will either over or under shade.

    At the shortest day of the year the sun will be lowest in the sky at 12 noon. At the longest highest. The overhang would need to be much longer if you required shading during the shortest day of the year.

    Also at the longest day of the year the sun spends it's longest period of time above the horizon so east-west shading is more important as is when shading starts and ends as there is greater potential for rooms overheating.


  • #4
    Carlow52
    Closed Accounts Posts: 2,389 ✭✭✭Carlow52


    Pauln: thanks for the reply.
    do u per-chance have the necessary software and expertise to do the calc for say shading from march 21 to Sept 21: eg over shaded for the 6 months.

    there are trees and a house 'in the way at 250 degrees west.

    The idea is to just put the rafters in now and figure out the exact shading later.

    I can always cut them off if 2 long


  • #5
    pauln
    Registered Users Posts: 366 ✭✭pauln


    Hi,
    Is this the kind of setup you have?
    74867.jpg

    There's a bit of maths involved but nothing to bad. I'll need to know the roof pitch angle also. I have it at 18 degrees there as an example.


  • #6
    Carlow52
    Closed Accounts Posts: 2,389 ✭✭✭Carlow52


    Pauln That is the set up exactly: roof slope is 11 degrees.

    I have an overhang of 750 up at the moment and am tracing the shading on the floor between the clouds:)

    Have marked the floor at 12:20 which seems to be the peak so I now expect this point to move nearer the window until mid summer.

    I do intend getting around to the math but I need to order the rafters on Monday: I have a slot at the mill where they will cut them to the exact length as they come out of the extrusion die:)

    Thanks


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  • #7
    RKQ
    Registered Users Posts: 2,292 ✭✭✭RKQ


    Carlow52 wrote: »
    Pauln: thanks for the reply.
    do u per-chance have the necessary software and expertise to do the calc for say shading from march 21 to Sept 21: eg over shaded for the 6 months.

    Try a quick sketch on Sketchup7 as it can be used to work out angle of sun on any day anywhere in the world.
    Worth a try.


  • #8
    Carlow52
    Closed Accounts Posts: 2,389 ✭✭✭Carlow52


    RKQ wrote: »
    Try a quick sketch on Sketchup7 as it can be used to work out angle of sun on any day anywhere in the world.
    Worth a try.

    CJH had already suggested that. I was hoping someone who was proficent with it would be kind enough to do the 'quick' sketch:)


  • #9
    RKQ
    Registered Users Posts: 2,292 ✭✭✭RKQ


    Carlow52 wrote: »
    CJH had already suggested that. I was hoping someone who was proficent with it would be kind enough to do the 'quick' sketch:)

    Their is a demostration video on Youtube. Shows exactly how to do it.
    I'm a real novice at Sketchup7, still leaning via youtube and experimentation - otherwise I'd be glad to do it for you:)


  • #10
    HeatLoad
    Closed Accounts Posts: 42 ✭HeatLoad


    Hey Carlow you need to pay someboby that knows what they are doing and stop looking for free advise at this late stage> I can smell the timber from here


  • #11
    Carlow52
    Closed Accounts Posts: 2,389 ✭✭✭Carlow52


    HeatLoad wrote: »
    Hey Carlow you need to pay someboby that knows what they are doing and stop looking for free advise at this late stage> I can smell the timber from here

    I was actually looking for someone to do the calculation and certainly not looking for free advise. Tu tranceulo is ameuga

    I think this forum is full of free advice, but maybe I need someone to advise me on this.


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