[Back]

U. Pont, P. Schober, M. Wölzl, M. Schuss, J. Haberl, K. Hauer, A. Mahdavi:
"The eyes of the city: Historic casement windows as a threatened asset of cultural heritage. Improvement of casement windows with vacuum glazing.";
Poster: Conference on Cultural Heritage and New Technologies CHNT26, Wien / Rathaus; 2021-11-02 - 2021-11-04; in: "Proceedings for CHNT26", ICOMOS Austria (ed.); Eigenverlag ICOMOS, (2021).

Traditional
casement windows are considered not only as aesthetically sophisticated window constructions (see Figure 1 a, 1 b and 1 c), but also as those window construction that
have been subjected to century long optimization processes Rough estimates state that there is a large number of these windows still to be found in the building stock of
European cities, e g Vienna However, the number is in constant decline, as casement windows often are considered to be expensive in maintenance and dissatisfactory in their
thermal performance and fulfilment of current comfort desires of building occupants, and thus are often demolished and replaced by new windows Moreover, many building
retrofit subsidy projects do not consider the restoration of windows as a feasible measure and only subsides window exchange Needless to say, the replacement of casement
windows with modern day single layer multi pane windows in historic facades is often a fundamental distortion in the corresponding façade appearance and thus a threat to the
built cultural heritage of cities The Austrian monuments office thus states in their guideline onto energy performance of building stock that a replacement of exiting historic
window constructions is regularly a no go in building conservation (BDA 2011 However, the necessity to severely reduce building related energy consumption requires also
technologies for improvement of existing buildings Windows are considered one of the building construction elements that are "weak spots" in the envelope, and thus is their
improvement considered a leverage improvement As such, new approaches are required that encompass both the improvement of the thermal performance of the windows and
ensure the upkeep of the appearance of buildings and preservation of the historic casement windows The research unit of Building Physics and Building Ecology of the TU Wien,
Vienna Austria, started together with the Austrian Forest Products Research Society Holzforschung Austria) in 2014 R&D efforts toward implementation of vacuum glass in existing
window constructions with the goal of significantly increased thermal performance at little to no aesthetical impact onto the windows The implementation of vacuum glass in
existing window constructions brings up a set of questions, such as thermal performance improvement of the window, thermal bridge effects in the glass/frame/Wall joints, and
constructive integration possibilities A project started in 2019 ( focussed onto the construction implementation of vacuum glass in demonstration windows, which was
accompanied by comprehensive simulation efforts

Traditional
casement windows are considered not only as aesthetically sophisticated window constructions (see Figure 1 a, 1 b and 1 c), but also as those window construction that
have been subjected to century long optimization processes Rough estimates state that there is a large number of these windows still to be found in the building stock of
European cities, e g Vienna However, the number is in constant decline, as casement windows often are considered to be expensive in maintenance and dissatisfactory in their
thermal performance and fulfilment of current comfort desires of building occupants, and thus are often demolished and replaced by new windows Moreover, many building
retrofit subsidy projects do not consider the restoration of windows as a feasible measure and only subsides window exchange Needless to say, the replacement of casement
windows with modern day single layer multi pane windows in historic facades is often a fundamental distortion in the corresponding façade appearance and thus a threat to the
built cultural heritage of cities The Austrian monuments office thus states in their guideline onto energy performance of building stock that a replacement of exiting historic
window constructions is regularly a no go in building conservation (BDA 2011 However, the necessity to severely reduce building related energy consumption requires also
technologies for improvement of existing buildings Windows are considered one of the building construction elements that are "weak spots" in the envelope, and thus is their
improvement considered a leverage improvement As such, new approaches are required that encompass both the improvement of the thermal performance of the windows and
ensure the upkeep of the appearance of buildings and preservation of the historic casement windows The research unit of Building Physics and Building Ecology of the TU Wien,
Vienna Austria, started together with the Austrian Forest Products Research Society Holzforschung Austria) in 2014 R&D efforts toward implementation of vacuum glass in existing
window constructions with the goal of significantly increased thermal performance at little to no aesthetical impact onto the windows The implementation of vacuum glass in
existing window constructions brings up a set of questions, such as thermal performance improvement of the window, thermal bridge effects in the glass/frame/Wall joints, and
constructive integration possibilities A project started in 2019 ( focussed onto the construction implementation of vacuum glass in demonstration windows, which was
accompanied by comprehensive simulation efforts