Moisture and glass
Fogging and condensation on the inside of windows occurs when warm (and humid) air hits the cold surface of the pane. Condensation must not stay on the inside of the window for long, as it can cause rot and fungus.
What can be done to minimise condensation?
You can reduce condensation by changing two typical causes
• Reduce the humidity in the room by airing it out.
• Choose windows that do not get so cold.
Ventilation is particularly important in rooms that produce the most moisture. These are typically the kitchen and bathroom, garage and laundry room, where clothes are dried.
People also produce heat and moisture, which is particularly evident when many people are gathered in a room. But rooms and bedrooms, where we spend many hours and the air can get a little stagnant, also need ventilation.
A family of two adults and two children produces about 12 litres of fluid a day. About half of this water loss occurs through the skin and exhaled air. This is why ventilation is very important.
The "advantage" of old windows is that the frame can be slightly leaky and thereby contribute a great deal of ventilation. However, ideally you control the ventilation. That is, you have the option to increase or decrease it. This might be through ventilation grills in the outer wall, ventilation slots on the top or side of the window or electric ventilation (venting). It is very common to get more condensation on your panes after you replace the windows. This is because the house has become more dense and therefore needs to be vented more. It is important that it be vented 3 times a day. Leaving a window ajar for a while is not the best way to vent.