Strategy Solar Insulation (GAP)

The heating costs of a 50 unit apartment building built in 1957 Linz AT were reduced by 88 %. The comprehensive renovation included an innovative solar insulation system of prefabricated panels (figure 4). Sunlight passes through a glass layer and is trapped in the air gaps of corrugated cardboard (with a fire suppressant). The resulting warm air buffer reduces heat losses by the facade. The static U-value is 0.15 but the dynamic U-value over the heating season approaches zero. To reduce thermal bridges, the balconies were glazed and at the same time enlarged. Conventional insulation was added to the roof and the ground floor (U = 0.16 and 0.20 W/m2K). New windows were installed (Uw =

0.86 W/m2K) with louvered blinds within the glazing unit for sun shading. Finally, through- wall ventilation units provide good room air quality with 70% heat recovery. As a result of this package of measures, heating demand was reduced from 150 to 20 kWh/m2a [5].