Building thermal regulations enforce different insulation levels all over Europe according to the severity of the climate. There is nevertheless a tendency towards more stringent levels in particular due to the EPBD in action and its expected second version.

Good insulation of walls and roof limits the heat losses in winter and increases the interior surface temperatures, minimizing the risk of interstitial condensations and improving thermal comfort of the occupants. During hot periods in summer, insulation may be beneficial at reducing the heat flow from the outside to the inside in particular due to solar radiation incident on the surface and high external temperatures. Conversely, high levels of insulation are disadvantageous at dissipating internal gains, and other passive cooling strategies, such as ventilation, may be advised.

Heat transfer in the walls and roof is generally higher than via the ground due to a higher temperature difference between the space and the outside, whereas the ground temperature is milder. Insulation levels are therefore much more important at surfaces in contact with the exterior. Interior walls (in contact with other spaces not heated/cooled) require less insulation.

3.4 Thermal bridges

On highly insulated buildings the effect of thermal bridges may be aggravated when the insulating layer is interrupted. A special concern is made in the Passivhaus to avoid significant heterogeneities on the envelope that can result in thermal bridges. Those usually occur in corners, edges and joints. External insulation can minimize thermal bridges by creating a continuous layer.

It also enables the building to maintain its inertia on the construction walls and ceilings.