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# Hi CARRIER HAP load calculatio

## Hi CARRIER HAP load calculatio

(OP)

Hi
CARRIER HAP load calculation shows different heat load for a same roof/wall with same U value but different thickness. Logically more the thickness greater the heat/cooling load
but by the equation of heat transfer for wall/roofs it only depends on the area, U and temp.difference

could anybody explain why?

### RE: Hi CARRIER HAP load calculatio

The thicker the wall, the more it slows down heat transfer.

### RE: Hi CARRIER HAP load calculatio

This U value is the thermal transmittance, it depends on the thickness and the thermal condutivity. If the software is only showing you the U value, it is already taking the material and thickness into account.

U = t/lambda t: thickness; lambda: thermal condutivity

Q=U*A*deltaT

"CARRIER HAP load calculation shows different heat load for a same roof/wall with same U value but different thickness."
I don't quite understood what you meant whit "same roof/wall".
I'm going to guess that they have the same area, but have different materials.

### RE: Hi CARRIER HAP load calculatio

When thichness Change same time u value also changing. how u value is constant when change the thickness of building wall.

### RE: Hi CARRIER HAP load calculatio

The u-value can stay the same with the thickness changing if lambda is also changing.
Is the material the same in both cases?

### RE: Hi CARRIER HAP load calculatio

robertogrramos: what you mean 'lambda', the OP says that value varying on same materials.

### RE: Hi CARRIER HAP load calculatio

moideen: I mean "thermal condutivity".
Is it the same material? I don't know, that's why I said:
I don't quite understood what you meant whit "same roof/wall".
I'm going to guess that they have the same area, but have different materials.

If they have the same material, makes no sense to change the thickness and U-value stays the same.

### RE: Hi CARRIER HAP load calculatio

robertogrramos : i also meant like you.[2thumbsup] But OP does not response what he means.

### RE: Hi CARRIER HAP load calculatio

(OP)
Thanks Guys

Robertogrrmos, you must be right, though the heat transfer equation shows only the area, the U value should depend on the thickness.
I meant same wall that the same area and orientation.

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