Impact on the U-value Due to Airflows Behind Insulation Modules Attached to Façades of Old Buildings

AbstractThe paper analyses the impact of air flow between an existing construction and an attached thermal insulation module. The paper presents general and handy formulas which can be used to determine the degradation of the U-value due to forced and natural induced air flows. The presented formulas accounts for varying insulation degree of the existing wall and the insulating modules, as well as the air flow rates. The estimations of the changed U-value can be used to balance moisture safety of the new construction and the energy performance