What is the relationship between MVHR and thermal bridge management?

Managing thermal bridges with insulation systems helps eliminate cold spots and heat loss, but it can also make buildings increasingly airtight, compromising ventilation in indoor spaces. Introducing MVHR with heat recovery ensures correct air renewal in thermally insulated buildings without undermining investments in energy efficiency.

A thermal bridge is a localised area of the building envelope where a discontinuity causes heat flow between the interior and exterior to differ from and be more intense than in surrounding areas. This creates cold spots that can lead to condensation and mould growth.

It is the designer’s responsibility to carry out a careful analysis of the hygrothermal behaviour of every heat-dispersing surface. In particular, for work involving the envelopes of new buildings and in all cases covered by Ecobonus and Superbonus schemes, the designer must verify, in accordance with current technical standards, the absence of interstitial condensation and the risk of mould formation, with particular attention to thermal bridges.

In simplified terms, managing a thermal bridge requires adding a thermal insulation material to the wall build-up, installed externally – as in an external thermal insulation system – or internally – such as internal insulation or insulated roller shutter boxes – in order to eliminate cold spots and reduce heat loss. However, the high level of insulation that makes the building more airtight also requires particular attention to ventilation, so that the minimum air renewal rates needed for health, comfort and humidity control can be guaranteed.

This is where controlled mechanical ventilation inevitably comes into play, both as a valuable benefit for occupants and as a form of protection for the designer. In energy-efficient homes with high levels of airtightness, MVHR becomes essential for managing continuous and automatic air renewal without wasting valuable energy by opening the windows.