advanced building skins 14 | 15 June 2012 - lamp.tugraz.at - Graz ...

Advanced Building Skins
Another problem was the choice of the new glass for the windows. It should reach the same high level
of quality in flatness and the surface as the original crystal plate glass. Modern insulating glass often
includes coating systems based on metal oxides to improve the energetic properties. After several tests
with different glasses from different manufacturers in test facades the designers realized that the
reflection behavior of the glasses is influenced by the different coating systems. As a result they used a
krypton-filled insulating glass with uncoated iron oxide reduced white glass. In contrast to insulating
glass with coating, which have a U-value of Ug = 1.0 W/m²K to 1.6 W/m²K, this glass has an
U-value of only Ug = 2.6 W/m²K.
Areas which are not renovated because of their status as an architectural monument have to be
investigated with a focus on building physics. As a result designers used a mineral insulating plaster in
the reveals of the atelier building. The original steel sub construction of the strip windows in the north
wing was not thermally separated. Therefore, an electrical trace heating in form of heating tapes has
been added. These two measures could not prevent the condensation of water at reveals and walls
during extreme temperature and humidity conditions. So, the users had been introduced in the proper
ventilation behavior. In some areas electronic humidity controls had been installed. These systems
emit a signal, which triggers the ventilation. Figure 4 shows the renovation of the steel sub
construction of the strip windows at the north wing.
1.4 Results
Figure 4: Bauhaus-building during renovation.
All measures on the Bauhaus-building in Dessau led to a simulation result of 39 % in energy saving at
the north wing and 66 % at the eastern facade. It is a fact that there is a low value of saved energy in
the north wing in contrast to the eastern facade due to uninsulated areas and the electrical trace heating.
All participants agreed that an architectural monument with the status as a world cultural heritage
cannot be compared to a new building in term of energy saving. So, the energetic renovation will take
second seat behind heritage protection. The designers accepted a glazing with a U-value of
Ug = 2.6 W/m²K. By comparison to the original windows with a U-value of Uw = 5.88 W/m²K, this
still means a huge improvement of the indoor climate and the quality of occupancy. During this
renovation obtained results and technical solutions represent a progress in the renovation of steel
windows for buildings of the International Style.
- 4 -