ᐅ Replacing Single-Pane Wooden Windows with Double or Triple Glazing in Older Homes

Hello,

I own a 97m² (1,040 sq ft) older apartment.
The building dates from 2010.
The windows are double windows (i.e., two windows one behind the other), made of wood and single-glazed.

The thermal insulation is virtually nonexistent—in winter, placing your hand near the edges of the windows is enough to feel the cold air coming in; from an energy perspective, especially nowadays, this is a disaster.

Questions:

• As far as I know, replacing them with triple-glazed PVC windows would be eligible for subsidies (up to 20%)—is that correct?
However, this would likely carry a significantly increased risk of mold growth—is that correct?
Active ventilation would probably be difficult to implement due to the very thick exterior walls of this old building.

• Replacing them with double-glazed PVC windows is, as far as I know, not eligible for subsidies at all (which makes no sense)—is that right?
Would there still be a significantly increased risk of mold growth here, or is this risk no longer really present compared to triple glazing?

• a) A cheaper solution might be sealing, for example using self-adhesive sealing tapes.
Would there still be a significantly increased risk of mold growth in this case?

b) Any recommendations for suitable sealing tapes?

• Is it possible to roughly estimate or quantify the potential energy savings of these three options?

Any other tips on what could be done in the short term or planned for the long term?

Thank you.

Best regards,
AnNaHF79

It doesn't matter whether you use double- or triple-glazed windows. Mold occurs due to insufficient ventilation and inadequate heating. As a result, moisture in the air condenses either on the wall or on the window.

The solution is not to prevent condensation on the window, but to heat and ventilate properly. If necessary, use trickle vents in the window frame.

So you should correct the construction year again. These windows are definitely more than 11 years old (I had similar ones in my old (parents’) house; they were replaced around 1980 with double-glazed insulated glass windows).

So, you should double-check the construction year. These windows are definitely more than 11 years old (I had similar ones in my old (parents’) house; they were removed around 1980 and replaced with double-glazed insulated glass windows)

Sorry, the building is of course from the year 1910 (not 2010) 🙂

Joedreck schrieb:

It doesn’t matter whether you use double- or triple-glazed windows. Mold occurs due to insufficient ventilation and inadequate heating. As a result, moisture in the air condenses either on the wall or on the window.
The solution is not to worry about condensation on the window, but to heat and ventilate properly. If necessary, use trickle vents.

Trickle vents do not provide full ventilation, but only guarantee minimum airflow. In other words: Proper heating and ventilation cannot be replaced by these small devices.

@AnNaHF79 Good advice: Before taking any measures, read up on proper ventilation practices—it’s not complicated.
In older buildings, it’s easier to develop bad ventilation habits because constant air exchange is ensured by poor sealing. Speaking from experience...

Box sash windows can be refurbished quite well. The easiest way is to apply self-adhesive sealing tapes to the inner window only. However, only the inner window should be sealed. If the window putty is crumbling, the windows can also be reglazed.