Hygrothermal behaviour of double-skin facades in solar irradiation - theory evaluation by means of on-location measurements
In the course of the boom in "glass architecture", double glass facades, as they are called, have been the subject of extremely controversial international discussion for more than ten years.
In addition to aesthetic aspects, the discussion also emphasises advantages in terms of energy and, particularly, noise and ventilation related benefits. The possible disadvantages, on the other hand, include increased investment and maintenance costs, potential problems in terms of building physics and, not least, considerable uncertainties regarding planning.
The aim of this research project was to evaluate transient thermal and fluid mechanical simulation models by means of on-site measurements in order to obtain information concerning the importance of the various extremely important base parameters of these very complex models of calculation. Extensive literature research revealed that, in recent years, there has been an increasing number of international research projects focussing on this subject - a fact that underlines the significance of the current research task. And yet completely documented measuring results on real, particularly small and medium-sized facades, are few and far between.
From October 2001 to September 2002, climate and flow conditions were measured on and in the glass facade of the new Federal Institute of Social Education building completed in 1998 in Baden near Vienna and analysed as to their correlation with the results of parallel numerical simulation calculations. The analysis focussed on two extreme cases of the space between two facade layers: free, solar and wind induced flow in the undisturbed gap between the primary and the mounted glass facade and the case of complex turbulent flow conditions in the double glass surface area and around the window boxes installed between the facade layers.
It was shown that the basic version of the TRYNSYS software package lends itself well to describing the thermal situation in the space between the facade layers. The findings may be taken as a base for further development of the calculation model for more complex facade structures with partially transparent outside walls (double facades).
The CFD (Computational Fluid Dynamics) calculations performed with the aid of the FLUENT software package also correlated well, in part, with the measurements, although they are more suited for scientific applications than for construction practice due to the considerable hardware requirements and duration of computing.
|Project manager:||Ao.Univ.Prof.DDr.Peter Kautsch
Institute of Building and Industrial Construction, Graz University of Technology
O.Univ.Prof.DI.Dr. Jürgen Dreyer
Ass.Prof.DI.Dr. Walter Meile
Ao.Univ.Prof. DI.Dr. Wolfgang Streicher
|Participating Company:||MSB Morocutti GmbH
Stahl-, Alu-, Fassadenbau
Graz University of Technology
Institute of Building and Industrial Construction
A 8010 Graz
Tel.: +43 316 873-6245
Fax: +43 316 873-6082
Dipl.-Ing. Herwig Hengsberger
Tel.: +43 316 873-6807
Fax: +43 316 873-4999