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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 assed of cultural heritage";
Talk: 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 1a), 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 modernday 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 (VAMOS) focussed onto the construction implementation of vacuum glass in demonstration windows, which was accompanied by comprehensive simulation.

no german abstract:
Traditional casement windows are considered not only as aesthetically sophisticated window constructions (see Figure 1a), 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 modernday 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 (VAMOS) focussed onto the construction implementation of vacuum glass in demonstration windows, which was accompanied by comprehensive simulation.

Casement Windows, Thermal Retrofit, Vacuum Glazing Products, Built Environment, Thermal Improvement

https://www.chnt.at/wp-content/uploads/Longabstract_U.Pont_P.Schober_M.W%C3%B6lzl_M.Schuss_J.Haberl_K.Hauer_A.Mahdavi-.pdf