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U. Pont, A. Mahdavi:
"Transparent Facade Constructions: A Comparison between Conventional Insulation Glass and Vacuum Glazing";
Talk: enviBUILD2017 - Buildings and Environment - From Research to Application, TU Wien, Vienna, Austria; 2017-09-07 - 2017-09-08; in: "12th international enviBUILD conference 2017 - Buildings and Environments - From Research to Application", U. Pont, M. Schuss, A. Mahdavi (ed.); Department of Building Physics and Building Ecology, TU Wien, (2017), 23.

In recent years, contemporary architectural design has been influenced by new technical opportunities offered by the glass industry. Large glass panels and even structurally active glass elements can be found in many recent building designs. Moreover, building envelopes in many cases include large glass panels. Needless to say, the use of glass as an envelope material comes with advantages and disadvantages, and a good architectural design has to consider these aspects. Advantages, amongst others, encompass the increased solar penetration and solar gains in the cold season, the increased daylight availability, and the "clean" appearance of buildings; Disadvantages include, amongst others, the overheating risk in summer, thermal discomfort as a result of radiant temperature asymmetries, and increased heat loss. The last two aspects are directly linked to the rather high heat flow through conventional glazing systems compared to well-insulated opaque building components. There are numerous examples of buildings, where prevailing performance problems can - in one way or the other - be linked to inadequate planning of the transparent building envelope. Generally speaking, the transparent parts of building envelopes can be distinguished in elements that are operable (windows, doors), and elements, which are fixed. The former are characterized by highly complex opening mechanisms and seals and thus rather high cost. The latter regularly are less complex, but their design needs to consider other aspects (durability, structural stability, etc.). This contribution illustrates the results of a number of numeric thermal bridge simulations focusing on transparent façade constructions with fixed glazing. Thereby, the key performance indicators of different construction scenarios are derived and compared. These indicators include thermal coupling coefficient, surface temperature, and condensation risk. The scenarios are based on typically applied transparent façade constructions, which are simulated with insulation glass and, alternatively, with vacuum glazing. As transparent constructions with fixed glazing regularly have higher life-time expectancies than openable windows (given the reduced complexity), such constructions might be promising in terms of vacuum glass application and a thus improved thermal building performance. Moreover, the reduced weight of vacuum glazing panels in comparison to highly-insulating double and triple glazing might allow for more efficient building construction (structural elements, etc). The present contribution illustrates the construction principle of different elements, the simulated scenarios, and the results of the simulation runs.

(no german version) In recent years, contemporary architectural design has been influenced by new technical opportunities offered by the glass industry. Large glass panels and even structurally active glass elements can be found in many recent building designs. Moreover, building envelopes in many cases include large glass panels. Needless to say, the use of glass as an envelope material comes with advantages and disadvantages, and a good architectural design has to consider these aspects. Advantages, amongst others, encompass the increased solar penetration and solar gains in the cold season, the increased daylight availability, and the "clean" appearance of buildings; Disadvantages include, amongst others, the overheating risk in summer, thermal discomfort as a result of radiant temperature asymmetries, and increased heat loss. The last two aspects are directly linked to the rather high heat flow through conventional glazing systems compared to well-insulated opaque building components. There are numerous examples of buildings, where prevailing performance problems can - in one way or the other - be linked to inadequate planning of the transparent building envelope. Generally speaking, the transparent parts of building envelopes can be distinguished in elements that are operable (windows, doors), and elements, which are fixed. The former are characterized by highly complex opening mechanisms and seals and thus rather high cost. The latter regularly are less complex, but their design needs to consider other aspects (durability, structural stability, etc.). This contribution illustrates the results of a number of numeric thermal bridge simulations focusing on transparent façade constructions with fixed glazing. Thereby, the key performance indicators of different construction scenarios are derived and compared. These indicators include thermal coupling coefficient, surface temperature, and condensation risk. The scenarios are based on typically applied transparent façade constructions, which are simulated with insulation glass and, alternatively, with vacuum glazing. As transparent constructions with fixed glazing regularly have higher life-time expectancies than openable windows (given the reduced complexity), such constructions might be promising in terms of vacuum glass application and a thus improved thermal building performance. Moreover, the reduced weight of vacuum glazing panels in comparison to highly-insulating double and triple glazing might allow for more efficient building construction (structural elements, etc). The present contribution illustrates the construction principle of different elements, the simulated scenarios, and the results of the simulation runs.

Vacuum Glazing, Performance Comparison, Key Performance Indicators, Numeric thermal bridge simulation, Transparent facade construction

http://bpi.tuwien.ac.at/envibuild/enviBUILD2017_book_of_abstracts.pdf