In several countries both new buildings and renovations are traditionally built using massive wall constructions with interior insulation. This solution allows the walls to be insulated when the facade cannot be changed. 
Internal insulation of a massive wall - 1
Internal insulation of a massive wall - 2
Internal insulation of a massive wall - 3
For constructions utilizing interior insulation, the airtight layer is placed on the heated side of the building fabric. Combining this with a professional airtight treatment of the details (e.g. window frame to wall junctions, penetrations for cables and pipes), it protects the construction from damages and provides a high level of comfort for the residents.
 

Overview of solutions for massive walls with internal insulation

France
Ireland
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