# U-value

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## U-value

[′yü ‚väl·yü]
(engineering)
A measure of heat transmission through a building part or a given thickness of insulating material, expressed as the number of British thermal units that will flow in 1 hour through 1 square foot of the structure or material from air to air with a temperature differential of 1°F.

## U-value

A measure of the amount of heat that flows in or out of a substance under constant conditions when there is a 1-degree difference between the air within and outside a building. U-values are used in determining the performance of a glazing system or window assembly.

## thermal transmittance, U-value

The time rate of heat flow per unit area under steady conditions from the fluid on the warm side of a barrier to the fluid on the cold side, per unit temperature difference between the two fluids.
References in periodicals archive ?
U-value is calculated according to the following formula:
Indeed, using the best windows solutions, the glass U-value will be always 5-8 times higher than a modern standard brick insulated walls and much more solar radiation can enter into the building.
The new solution will help in reducing production and estimation time by 50 per cent as well as preparing structural and u-value calculations, it said.
The perimeter walls are 8-inch pre-cast concrete with Integral Insulation and achieve a U-value that Is 5% higher than required by code.
Note that the R-value and U-value are reciprocals of each other but are typically presented with different units, and the U-value also contains the surface resistance.
These might include the U-value of a wall in an existing building.
Ask a carpet retailer for underlay with a low u-value - the lower the u-value, the better the insulation qualities.
An 8-inch-thick concrete wall has the U-value of a single piece of glass.
Jewers says its Esavian doors comply with the latest Part L building regulations for air leakage and are clad with composite panels with a nominal heat loss U-value of 0.

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