As could be expected, the majority of houses are extremely well insulated and have high quality windows.

The graph Fig. 9 includes U-values for walls from 0.06 — 0.25 W/m2K. The impressively low U-value of 0.06 W/m2K comes from a very new construction type "space frame”. The "space house” walls are 60 cm think and consist of a wooden space truss filled with cellulose (Fig. 11). The high value of 0.25 W/m2K comes from a project which was a renovation of a historic building and the insulation thickness was limited. The U-value of our projects averages 0.14 W/m2K. This is even below the target value of 0.15 W/m2K the Passivhaus Standard recommends not to exceed.

Also, the weighted U-value of the windows (Fig. 10) at 0.81 W/m2K corresponds very well to the passivhaus standard recommendation of 0.8 W/m2K. The very low U-value of the windows in the space frame project of 0.31 W/m2K was easily possible because of the thick wall construction, which allowed a double window construction with very good glass and frames (Fig. 11)

The window area to facade area lies between 15 and 40 percent, with the majority of houses having approximately a 25% window to wall ratio. The exceptions are the projects with special facade constructions, i. e. “Lucido” or transparent insulation (Fig. 12).

Air tightness, on the other hand is very important to high performance, with the majority of projects having a measured tightness between 0.3 and 0.9 [1/h] at 50 Pa over and under pressure. The average lies at 0.6 [1/h], which fulfils exactly the passivhaus and Minergie-P standard target. The exceptions are again projects with special facades and understandably, the retrofitted existing building project. For four of the twenty projects no air tightness data is available(F/g. 13).