Most of the energy used for heating is not created by burning firewood but by solar collectors on the roof and a large winter garden which stretches all along the south side of the home. The extra cost for insulation and solar panels were absorbed by leaving out the usual bay windows and balconies which are so common in this area.
Dr. Thoma guarantees his Holz100 houses for 50 years against moisture and mold. He has already built over 1000 houses in 33 countries, from the tropics to the Arctic Circle and, so far, has not received a single complaint.
Lower Saxony's research has revealed recently that 80% of all homes equipped with styrofoam thermal insulation have developed mildew between the wall and the styrofoam. Mold is one of the worst poisons of all that can toxicate residential buildings.
Moisture is yet another problem in construction. Water vapor and condensation is such a difficult issue that no company in the world can guarantee construction materials free of condensation and mold growth for more than 5 years.
The test room was at a room temperature without heating, and the outside temperature was -10 degrees C'. The test measured the time, in which the internal wall would reach 0 degrees C'. To reach 0 C', It took 2 days for the prefab wall, the insulated brick wall took 10 days, and finally the solid wood wall (holz100) required over a month of time.
Over time, both the Frauenhofer and the Graz Technical University confirmed the results and issued relevant certificates. The U value does not tell us everything, however; it turns out to be a poor manipulation created to favor thermal insulation manufacturers.
As such, a 36 cm thick Holz100 wall would provide a similar insulation to a 75 cm thick, solid, glue-laminated wooden wall (CLT) or a 10 m thick reinforced concrete wall. Leaving out chemicals and toxins in the processing of Holz100 surprisingly led it to break the world record in thermal insulation for building materials. The results were so unbelievable that initially the Frauenhofer Institute in Stuttgart denied to issue a certificate.
Absence of glue between layers create microscopic air gaps. There are additional air channels between some layers, allowing for improved thermal insulation. In this field, it has been so far assumed that the highest heat transfer coefficient (U-value) that wood can achieve is 0.14. However, this is true for glue laminated wood. Unglued and mechanically linked walls of Dr. Thoma have achieved a result twice as efficient; a U-value of 0.078.