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====== Improving the glazing? ======
===== Classification: What is meant by good quality glazing? =====

Is it worth improving the glazing? Doesn't the glazing industry already do its best possible? Quick link: download the [[https://passipedia.de/_media/baulich/diy-anleitung-fensterfolie.pdf|Instructions for window films (German only) ]].


The straightforward answer is: yes and no.  It depends on the type of glazing that currently exists in the relevant window. Quite often, the glazing is old, from the days when building components were by far not as good as those available today. At this point one could argue that wouldn't it be better to replace the glazing or even better to renew the entire window?  Yes, in terms of energy efficiency that is always the best solution, provided that really good components are actually chosen: those are **always only** the ones with

  - **triple low-e glazing **
  - **thermally separated spacers ((that is the web at the edge, which connects both panes)) and **
  - **a certified Passive House window frame ((which are available today in all types of designs and materials)).**

All other window designs need to be improved - and unfortunately that's still most of them. But if I had just renewed my windows 5 or even 20 years ago, then an earlier-than-planned renewal((if not already being replaced for some reason 
 generally would not be very expedient from the economic as well as ecological point of view. For these cases, of which)) there are still a great many, we have conceived a "retrofit". It is presumed that such a measure, and therefore the old window, will continue to be used for another 5 years at least. 

===== The alternatives: (1) window replacement, (2) substitution of glazing  =====

This is what the priorities actually look like if something has to be considered: 

  - Whenever a window replacement is already pending in the next few years, the best advice would be to do this as soon as possible. This will possibly depend only on the availability of the crafts, and as already mentioned above, and only triple low-e glazing (or vacuum glazing), a thermally separated edge bond, and Passive House certified frames constitute a future-proof solution. Anything else will only help to prolong dependence on fossil fuels by another few decades - that's how long it will take until an unnecessarily poor quality window will have to be replaced again.
  - If the frames are still in good condition and will last at least another twenty (!) years then there is the option of renewing only the glazing; this is faster and there is less disruption involved - some manufacturers even offer this specifically with vacuum glazing. This may also be worthwhile. 
  - If the old window including the glazing won't last so long, or waiting for a window fitter is getting on your nerves, then the solutions described further below may help temporarily. You can do everything yourself and the materials for this are also inexpensive. 

If the glazing is already triple low-e glazing - that is the only case in which we do not recommend any of the measures described here as they will bring almost no benefit. How do I find out whether there are three glass panes? By looking for two edge bond seals at the glazing edge. You can see whether the panes also have a low-e coating by using the lighter or torch reflection method, see [[https://passipedia.de/_media/baulich/diy-anleitung-fensterfolie.pdf|Instructions for window films. ( German only)]]


===== How to apply window film  =====

Quick link: download the instructions [[https://passipedia.de/_media/baulich/diy-anleitung-fensterfolie.pdf|Instructions for window films. (German only)]]

First, measure the size of the film to be applied: always measure about 1 cm further than the glazing bead.

Then there is the information based on which you can purchase/order the material: it is called "insulating film/foil" ((even though this quite a badly chosen designation in terms of physics. Nothing is being isolated here; rather, an additional layer of "standing air" is created here for the purpose of thermal insulation. Be that as it may, this is the name under which you can find it.
)). There are a number of different manufacturers, it is worth comparing the prices (including delivery costs).

It is better to clean the window thoroughly before applying the film (using tape), and to wait until everything has really dried (we don't want a lot of water vapour in the air layer as otherwise it will lead to condensation). 

|The double-sided tape strips belonging to the set are stuck to the frame outside of the glazing bead. In this way any remaining gaps towards the outside in the area of the glass rebate are sealed. This has several advantages (among others: the new additional intermediate space is ventilated a little towards the outside; this helps avoid condensation because the outside air contains significantly less water vapour).|{{:picopen:improving_the_glazing_01.jpg?400|}}|
|The film can now be attached; it is best to start at the top, otherwise the manufacturer's instructions should be followed. There shouldn't be any creases in the film near the adhesive tape; creases in the inner part of the film are not problematic as this will be remedied in the next step. You can't see much in the picture - and that's how it's supposed to be, after all, the film should not be noticeable.  It is much easier if two persons work together, because then it will be easier to ensure that the film is applied tautly.|{{:picopen:improving_the_glazing_02.jpg?400|}}|
|The last step is quite fun - the film is blow-dried so that it becomes taut and the entire thing looks good. In this way we can create an air layer in front of the existing glazing which acts as a thermally insulating layer. |{{:picopen:improving_the_glazing_03.jpg?400|}}|

===== How will this help? =====

Depending on the kind of existing old glazing, this will always help a little to different degrees. It is also possible to estimate the economic efficiency. We did not take the hours of work into account initially - anyone can do that for themselves because this also depends on how much time is required and how it is assessed. But even if the net wage of a skilled worker is assumed, this will usually pay off. The material costs are already very small. 

^ Old glazing ^ Benifit? ^ Amortisation period ^
^:::^ Saved losses glazing^in months ^
| Newer douple-paned insulated glazing | 22% |13|
| Double-paned insulated before 2005| 27% |8|
| Old double glazing | 40% |3|
| Very old single-glazing | 57% |1| 

This "pays off" surprisingly well even if we include the hours of work. In addition, the inside of the room will become more comfortable because the inner side of the window is now less cold, and in the event that heating energy becomes scarce, one can not only save on this but also the room temperature will stay bearable even if heating is not possible in the worst case. 
Coming back to the beginning, everything will be even better if a really good quality new window with triple low-e glazing is installed in place of the old window. Keep that in mind when the time comes! 

[[efficiency_now:building_envelope|Back to the overview of "structural measures"]]