The following example demonstrates the simulation of a classical thermal bridge. The plan shows a wooden construction forming an overhanging roof parapet. In the first plan a lateral thermal insulation of the ceiling was not included. Using HTflux it can easily be shown that this setup would lead to a massive thermal bridge. By using the HTflux heat flux measuring tool the thermal loss can also be quantified. The present example has been calculated using an interior temperature of +20°C and an ambient temperature of -10°C. Under these circumstances a relatively thin thermal insulation (see Alternative I) results in a heat loss reduction of more than 10 watts (per meter). Applying additional insulation on the wooden construction (see Alternative II) leads to further improvement, but only of 0.5 watts.
The expected minimum and maximum values of the surface temperature are also determined by the software. These can also be useful to evaluate the detail. In this example the outside temperature of -10°C would result in interior surface temperature ranging below 6°C. These extremely low temperatures would lead to condensation and subsequent formation of mold around the window connection.
Furthermore the simulation demonstrates very well that the insulation around the parapet only serves an aesthetic function as ambient temperature is reached throughout the entire roof overhang. Attachment of insulation is therefore unnecessary from a thermal point of view.

I) Massive thermal bridge – unresolved

 

 

 

 

II) Alternative construction – lateral insulation

 

 

 

 

III) Alternative II – extended insulation

 

 

 

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