WHAT IS A THERMAL BRIDGE?

Thermal bridges are points or surfaces of the envelope where strong changes in heat flow from the interior to the external environment are observed.

These are the points where structural elements show significant thermal losses compared to other surfaces due to their reduced thermal resistance.

This is due either to the discontinuity of the thermal insulation layer, or to the differentiation of the material along the length of the structural element, or to the change in the geometry of the cross-section.

Depending on the cause, thermal bridges can be distinguished into structural, geometrical and a combination of two. Constructional thermal exists when there is no continuous layer of thermal insulation. Geometric thermal bridge exists when there is a schematic differentiation of structural element.

Based on the shape of the cross-section, thermal bridges are divided into linear and point thermal bridges. Linear thermal bridges occur along a surface where several structural elements are joined (floor-wall joint, beam-wall joint). In contrast, point thermal bridges occur locally at one point and there is no homogeneous heat flow along a direction, as in linear thermal bridges.

From the floor plan of a building, potential vertical thermal bridges can be identified at external corners of the design, at internal corners and at the joints of building elements (concrete with concrete masonry).

Except vertical thermal bridges located on the floor plans, there are also horizontal thermal bridges located in the building sections and are developed along the structural elements such as roof or attic thermal bridges in overhangs, and floor thermal bridges in recesses or overhangs and thermal bridges above a canopy.

Lastly, thermal bridges are observed in the frame areas (both in the frame and in the top and bottom of the frame) and have the same length as the dimensions of the openings.