How to calculate solar heat load on a roof?
How to calculate solar heat load on a roof?
(OP)
I am determining the amount of air required to cool a outdoor space with only fans, so the indoor and ambient temperatures will be very similar. For my purposes the roof load from the sun will be the only heat conducted to the space.
The only method I have found to determine solar load is the CLTD (Cooling Load Temperature Difference) method with Q = U * A * CLTD, although I am not sure it is appropriate for ONLY solar loads. Is there another method to determine solar loads suitable for manual calculations?
The only method I have found to determine solar load is the CLTD (Cooling Load Temperature Difference) method with Q = U * A * CLTD, although I am not sure it is appropriate for ONLY solar loads. Is there another method to determine solar loads suitable for manual calculations?





RE: How to calculate solar heat load on a roof?
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RE: How to calculate solar heat load on a roof?
Is it only an area? Is there a canopy or other shade?
If you have no walls and the room under the roof is cooler than outside you have no conduction.
RE: How to calculate solar heat load on a roof?
MintJulep: It is a single story building with only one room and no windows. A standard construction of four walls and a roof with no shading.
RE: How to calculate solar heat load on a roof?
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RE: How to calculate solar heat load on a roof?
RE: How to calculate solar heat load on a roof?
RE: How to calculate solar heat load on a roof?
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RE: How to calculate solar heat load on a roof?
I hope this clears up any confusion I've caused. If it helps the building in question is a simple maintenance garage for vehicles with a flat built up roof.
RE: How to calculate solar heat load on a roof?
1120W/m^2 in * absorptivity = passive convection up + radiation up + conduction down.
The interior surface then has:
conduction down = forced convection + radiation down
Given the boundary conditions, there will be a T.rooftop and T.ceiling that balances all the heat flows.
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RE: How to calculate solar heat load on a roof?
The CLTD calculation has some values for indoor and outdoor temperature assumed into it.
You can correct for non standard conditions such as yours. See here:
http://
RE: How to calculate solar heat load on a roof?
MintJulep: Yes, that would just be ridiculous then! Also, thank you for the confirmation that the CLTD calculation is appropriate. I am using the 1997 ASHRAE Fundamentals (which was the last year CLTD tables were produced in ASHRAE) for guidance but I will also check out your link. I'm assuming you're not aware of any other method for this calculation (beside the one IRstuff has posted)?
RE: How to calculate solar heat load on a roof?
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