Question:
On BAU 2003, the company group Hueck/Hartmann introduced the innovative concept of a transom/transom facade. Here, mullion and transom have the same profile geometry. The results are manifest, multi-stage rationalization effects from production, tool costs and inventory management to assembly. In addition, the efficiency concerning the fabricator is optimized by a maximum length yield per rod. What do you think about this development?
Dr. Küffner:
From my point of view, this development leads back to the beginnings of facade technique where transom/transom constructions were common. Only the wish for the glazing of horizontal and inclined surfaces required the mullion-transom constructions, that are common now and which, in my opinion, can be left out on vertical facades. The felicitous new construction of the transom/transom facade is interesting not only according to cost aspects and, as there are no disadvantages, can be appreciated.
Question:
Rationalization certainly is an important topic on building. Practicability is another one. From your point of view, how does the new development come off concerning this point?
Dr. Küffner:
I think the new transom/transom facade is an interesting, practical solution - definitely in the vertical line. I could imagine a useful solution for slants and horizontal areas if it is posssible to realize an according drainage. In any case, I think the new transom/transom solution is an interesting starting point, combining low costs and a felicitous technical problem solution.
Question:
Air permeability, water tightness and resistance to windload play important parts on elemented curtain walls. How do you evaluate the new facade and its connecting technique concerning this?
Dr. Küffner:
There are no deficits concerning air permeability, water tightness and resistance to windload. Possible leakage water should be brought out properly via the venting profiles arranged by fields.
Question:
Could you say something about the solution of the vapour pressure equalization?
Dr. Küffner:
The areas are efficiently ventilated. There is a circulating air layer between glass and insulating profile.
Question:
How would you evaluate the thermal qualities of the new transom/transom facade?
Dr. Küffner:
Good! As is generally known, all facade systems suffer from the fact that the screws through the profiles bring out a certain thermal bridge. This could be minimized by avoiding the metallic contact of screws and profiles with an insulating washer which is possibly provided with a short bush to also avoid a lateral metallic contact of bolt and profile. In other respects, I think this solution is convincing. The lateral insulation of the screws has been solved properly on the variant with foamed spacer profile - this can also be seen in the tests of the Uf-value.
Question:
Regarding the technical and optical features, how would you evaluate the new facade?
Dr. Küffner:
The transom/transom facade is an interesting further development of the common mullion-transom technique and presents itself as coherent system solution, convincing not only by an enclosing, reasoned documentation. This provides the planning architect as well as the fabricator with all information necessary for a perfect planning and realization of standard- and special solutions. Especially worth mentioning are the good format and comprehensibility of the technical documentation. I think the transom/transom facade can count on the interest of the fabricators and that it will find its market. At the same time, this felicitous development proves that progressive solutions are not only found in major enterprises but that medium-sized companies are still able to make a contribution to efficiency and variety of ideas.
Erich H. Heimann
The Interview partners:
Dr.-Ing. Peter Küffner is head of the institute for building and construction physics and facade technology in Düssseldorf and is working as a consultant in many major projects. He is also expert for facades, windows, doors and gates made of metal, officially appointed and sworn by the chamber of commerce and industry Düsseldorf. Furthermore, Dr. Küffner is associate lecturer at the technical college Hildesheim and member in several trade organizations.
Erich H. Heimann is free journalist with focus on building technique and architecture and he is carrying on his own press agency in Düsseldorf for more than thirty years now.
