# Heat loss due to linear thermal bridging

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In physics, $H_TB$ is the heat loss due to linear thermal bridging when calculating the energy performance of buildings. It appears in both United Kingdom[1] and Irish[2] methodologies.

## Calculation of $H_TB$

[3]

The calculation of the heat loss due to linear thermal bridging is relatively simple, given by the formula below:

$H_TB = y \sum A_{exp}$

In the formula, $y = 0.08$ if Accredited Construction details used, and $y = 0.15$ otherwise, and $\sum A_{exp}$ is the sum of all the exposed areas of the building envelope,