Session: Architectural Challenges & Solutions
Event: GPD Finland 2023
Historic glazing in existing buildings using the example of Dresden Trachau
Glass surfaces are defining elements of facades and represent a significant contribution to the authenticity of building monuments.
Glass as a material is considered an important testimony of its time. Depending on the manufacturing process, it differs both in surface and material composition. The period of high modernism (ca. 1880-1970) overlapped with the technical developments of the industrial revolution, which led from manual production to industrial production.
The further development of the manufacturing processes as well as the dimensions and qualities of the glass thus shaped the development of the glass constructions, which had to be made increasingly slimmer over time in order to ensure a high degree of transparency. Today, historic windows are often replaced by new glazing made of float glass, which can cause the authentic character of buildings to be lost.
A team around the research project of the Technical University of Dresden and the University of Bamberg, both in Germany, has therefore set itself the goal to examine in detail the glass and its construction in the period from about 1880 to about 1970 and to define the living character of industrially manufactured glass from the time before the introduction of float glass as an authentic and style-defining feature of the time.
The present work focuses on the chronological presentation of the development of historical glass designs. In particular, the relationship between the development of the glass pane size and the frame construction is discussed.
All right our final speaker um has been working at The Institute of building design in the field of Energy Efficiency and sustainability since 2013 uh during her studies at Tu Dresden she uh traveled abroad or or worked abroad at several well-known architecture firms with a focus on design development and
Sustainability in addition to teaching uh building history and design and en energy efficient she’s also primarily involved in the research topics of historic glass structures existing facades and renewable energies please welcome Francisco Raa thank you very much thank you very much Mr chairman for the introduction words actually I’m very
Happy that I see some people I was very afraid of uh that the topic might be so boring because a lot of people just head up to another presentation so uh thanks again for having me and and um today I would like to introduce you to historical class and historical class
Constructions their characteristics and uh where they’re still installed in old houses in the next 20 minutes I would like to show you how essential old class and class constructions are for the appearance in a building and of a building and I hope I can inspire you a
Bit um that from now on you walk through all cities with total different eyes that you see old buildings with old class and you think about me by the presentation um about well it’s very important to keep them and not to replace them by float and why I’m going to tell you
Now um so uh first of all did you always see perfect class or just did you recognize also the historical ones I explained you in the past slide um you know the one with stripes the one with streaks unevenness or you even little bubbles um often that makes the building
And it is actually part of the building and it’s very important so class surfaces shape the appearance of facades and make an essential contribution to the authenticity of architectural monuments um the class itself is a testimony of the materiality of its perspective time in former times so it’s very important Unfortunately today um
Old class is being replaced most L uh for reasons of building physics sometimes also for political reasons but most mostly for physical ones and they do not meet their today’s uh standards and historical class is interpreted as a defect rather than a testimony of technical process so the visual impression of the
Buildings are lost you can see some pictures and when you see the pictures um four pictures are shown very old class with stripes with bubbles and everybody of you just thinking oh it looks so good it looks so old I’m feeling like an old city and old uh Heritage but uh once
You replace it uh the totally um appearance is just gone I can show you one example here see uh the refurbishment of a class Tru an example uh this is the of H before the refurbishment in 2008 um the building is a large production hall for iron casting it has
A transparent uh South facade made of cast iron profiles and small sized flat classes as you can see here very small class sizes and uh the picture you see here the upper picture shows the hall before the refurbishment and the picture underneath is after so during the Furbish month the structure was totally
Replaced now you see the structure made of R steel and you see the difference I’m pretty sure everyone sees um the characteristic light reflecting glass history was displaced to float glass and Float glass has totally other properties as you know that means the visual appearance of the
Facade seems to have been preserved but it looks fresh and new but in fact the authenticity has been totally lost so when we need to referb wish it mostly looks like that you might say okay it’s not a problem for it looks also nice but it’s not an
Old building anymore and we’re living in a courage in a culture that uh it’s it’s it’s very um important that we just keep those old buildings and there are other Solutions so if you want to recognize and evaluate historical class you have to know the development of the production
Methods um in our research project we are investigating a period time from 8080 to 1970 why 1970 1970 the float class production was invented and was running from this very uh very uh fast and at the time class was basically produced according to the four methods by casting pressing blowing and at least
By drawing and uh um the path to today’s float L process um can be traced by exactly two ways you can see here so the left uh race is um it’s coming up from Mirror class and um it’s very important in the miror class industry and on the
Right hand side you see the uh window P pain development um what you see here the first raw is it’s manual that means um at the end both developments combined the properties from manual up to Mechanical uh to the float class process properties and you can see in the scheme too that the
Production changed um from manual to Mechanical very quickly and that’s because of the industrialization and ends up in today’s float class process so the whole um the whole um properties are just end up in our float class process which which which we are still using
Today so I will keep you up updated a bit um about the manual manufacturing process here in Germany um in the past 200 years there has been more than 2,500 patents for class production but not all of them were ready for the market 2005 100 that’s a lot but only just five
Class production processes has been developed at the end especially in England in France and in Belgium um there were the first patents and uh licenses for it and to Germany all these glass production methods came always 10 years later uh the zylinder sleeve process was running for quite a long time see
Here it’s one of the oldest ones it was a process where you need your lungs to form a long cylinder and then you cut it off you fold it up and then you have glass panels you see in there there are still um uh a company is still
Working like this um but only one in Germany um the thickness of this class panes were about 0.9 M by 1.8 m and it was a maximum of 4 mm thick um and and the features are very parallel orientation of bubbles so what you keep in mind is the cylinder with your lungs
You produce Bubbles and on the upper ra here you can see the cost class process what happens there uh you have like um um a claive harbor which is filled with melted class and after it reach a certain temperature it was pour out on a rolling table to cool out and the
Thickness about there is 11 Me millim by what is it uh up to 30 mm um when I was at shot in March this year um I saw the C Class process and it was like about 50 minutes and it’s all done but to heat this uh to to reach the
Temperature was about two days it tookes two days and after 50 minutes it’s all done so um I told you because of the industrialization the manual facturing process in Germany changed into the mechanical ones and one very famous process is the Fuko uh process where melted class went through a construction to cool
Down so we were at shot and uh we just had a look into the oven and but it wasn’t allowed to take pictures usually I wanted to show them pictures but it wasn’t allowed to so you have the melted class up there and it goes through upwards a huge
Tower so um we went up the tower and there was a guide who said who was cutting off the glass paints and put it on a table and it was running and running and running all the time and uh I told him since when the machine runs
And he said since 100 years so only just uh they had issues about twice twice times um so for about 100 years it is running and running and running and running and so on and from now on larger quantities with this f um and certain thicknesses could be produced and
Thicker class of course um can have larger sizes so the red mark Market time period what you can see here um was kind of a turning point in the class production um they were used in industrial constructions as well as in residential constructions so now for you it’s very
Important how does it look like I tell you everything about the class production and but for you it’s important when you go through the city how does it look like on the left hand side you see um a house in the opposite of a street with no class if you’re not allowed to
Wear glasses or it’s not possible to wear glasses usually there’s no Stripes no bubbles everything is fine in the middle is the see through cylindric sleeve process and you see like a very uh common picture underneath like with a big bubble and the third one is um when you
The see through uh the drawn cylinder process that means it’s a bit w and a bit curvy at least so this you have to take in account what’s also very important is um where are all these factories actually so um we did a lot of research work on
Um to find out where all these companies are located we had a few uh Moments Funny Moments in the libraries out there and archives um and uh we just found out that a lot of uh companies are in the ru area in zarand in the la la
It’s in the eastern part of Germany and also in salesia salesia that’s because was a part of Germany that’s why we take it in account or took it in account so in this areas there are many raw materials like wood or coal for the heating sand and so on and what’s also
Very important is the way of trans uh the way of transportation so when you see it here it’s always located on very very important rivers in Germany then the industrialization games and what happens in the 20s you can see already the mentioned significant decline of factories I told
You suddenly you have less factories but more mechanical class production methods when you go back you see only just two but hundreds hundred of factories and now they’re all gone and we have like mechanical sleeve process but different sleeve process um but um it was not just because of the
Change of the production methods um many companies had to join cartels and could not afford to do so because it was very expensive to be in such a cartel and pents itself were also very expensive so many companies got United in this time to larger
Ones so one of our goals um in our research project was to investigate how many glass paints from different manufacturing methods were still installed in the old buildings so what we’ve done first is um we did a lot of research work in class and class constructions of the high age and modernism
And uh second we asked also the monument reservation office and received information about the building ages and the stat if the building is a monument if the building is a monument you get a lot of archiving stuff a lot of um books about it um
So it’s a part of uh is a district of Tron was recommend to us then we investigate the area we record the data we enter it into the database and then we analyzed it um and then we looked also for possible reason for the removal um in addition to structural
Physical ones it often had political ones especially in Tron Germany was divided in two parts so Tron is the part of the eastern part and uh the political ones was um very also important um so we head off to the city district Tron TR
And we went there by bike um and as we know from the monument preservation office um 33% of all houses were built before the first world war and also 38% of the houses were built uh were built between the first and the second world war so at least we are very happy that
We can find old buildings at a percentage of 81% in TR so we had off and went by bike there and here you can see uh TR it’s it’s the red marked one so you can see a lot of houses and what you see also is uh it’s different
Colored um it’s different colored because every color means a different type of time and um we analyzed all the buildings by age and what construction and class at least we will find and at least we said okay we just focused on this red mark on the left hand side um
It’s a bit uh bigger bigger scaled um because most of the houses of this street are built almost uh 1980 up to 1930 so we were very happy and we yeah distinguish that we can find most um most uh um um um windows that are very old and they’re
Still alive so we recorded a total of 2,178 Windows it sounds a lot and it was a lot actually so what we’ve done um we just walked around and we parked our bike of course and then we walked around the houses and sometimes it was not so easy
Because it wasn’t allowed to go in the backyard but we need to do research on the whole Windows of the um complete house so um this picture shows a typical house we found and I want to um introduce you I want to show you and here you can see what we’ve done
Um for each building um the class the class struction the frames the material the whole geometry if you have smaller ones if you have bigger sizes of glass panels of class construction as well were documented in detail with the help of a recording sheet and it looks like
This so um but important for you is to see the details on class of course so at least we recorded 2178 classes and class constructions and 170 were still historical ones and 38 8 no 83 out of these um 100 and 17 were original ones they were
Built at the time the building was built so when I say original ones that means the ones who are really original and the historical ones that means that you have classes who were just um replaced after maybe 30 years and out of all buildings we have found
Out that uh 34 windows are cled with drawn cylinder class 79 with cylindric sleeve class and uh four windows were made of cast class so the result is that you have 8.4% of all recorded windows were historical ones that includes the historical original and of course the
Original that’s not so much and and um we assume that the reasons for replacing are most caused by physical ones and 88.4% it’s not so much but when you take in account it’s just one city H it’s just one street and one district and one city and in one
Country um it seems a bit lot and um our future research work is focused on that for the first time and um the second one is we want to do um a lot of those um Shadow sh uh Shadow work let me say shadow work here um so what we want to
Do is the image the historical glass paints on the wall um by using a light source and the goal is to recognize the individual waves and Stripes furthermore we want to find existing buildings in which there is still old historical class and there more um a method must be developed to
Examine these classes in inventory so as you can see um there are some interesting things coming up please have a look on our homepage if you want and the very important sentence is um that in terms of sustainability and the way to grow from the presentation yesterday
It is a question of whether these old windows can be preserved and whether there are already solutions that can be solved the question of building physics so you as researchers and class companies you are asked to take the existing buildings into consideration and support the future in the sustain sustainable
Way thank you very much to you and also to all supporters thank [Applause] you