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Can you get condensation on windows with vacuum glazing?

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View of the main master bedroom heritage windows before installation at the Maltsters Tap in Shropshire

Can you get condensation on windows with vacuum glazing?

Reading Time: 5 Minutes
Published on: May 26th, 2022

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Do your windows have a condensation problem? In this article, we will tell you all about condensation on windows – why it happens, how you can prevent it and whether vacuum glazing is the solution.

Why do windows get condensation on them?

Windows get condensation because of the difference in air temperature between the inside and the outside of the windows.

Air contains water in its gaseous form. Warm air is very good at retaining water vapour, cold air has less energy and cannot hold the moisture as well. This means that the air inside your home is typically damper than the air outside.

When warm air hits a window that has been cooled, its temperature is lowered. This makes the air lose the energy needed to retain its airborne water content. This water then returns to its liquid form and is deposited on the glass. This moisture builds on the surface of the window until it’s covered in water – sometimes there’s so much water it literally runs off the windows.

What are the worst rooms for condensation?

Rooms that are warm and wet are particularly bad for condensation

  • Bathrooms
  • Kitchens
  • Bedrooms
  • Utility rooms

Cooking, bathing and washing and drying clothes all warm up the air and add more water content, no surprise there.

Why do bedrooms get condensation?

Bedrooms are a bit of a mystery as to why they are prone to condensation. It’s because of the moisture in our breath when we exhale. We move around from room to room during the day, but at night we generally close the bedroom door and lie (relatively) still for 7 or eight hours. The moisture build up is slower, but it has the same effect.

Why is condensation bad?

Condensation is not good for your home. It encourages mould growth on your windows and everywhere else in your room. Timber windows can suffer particularly badly because the water soaks into the wood, accelerating the rot.

How to prevent condensation

It’s easy to prevent condensation. However, it’s not easy to prevent condensation and have a comfortable home…

To prevent condensation you need to do two things:

  1. Ventilate your room, this will also achieve the second thing you need to do;
  2. Make your rooms cooler.

In short, make your home less comfortable.

There are other things you can do to prevent condensation:

  • Use and Extractor fan
  • Use a de-humidifier
  • Don’t dry laundry inside
  • Rearrange your house plants

An extractor fan will remove the warm, damp air from your rooms before it has a chance to leave condensation on your windows.

A dehumidifier will remove the excess moisture from the air to achieve the same result. They do tend to clutter your home and they aren’t very pretty.

Drying laundry outside will reduce condensation forming on your windows. UK residents may only be able to dry their clothes outside for about 3 days in the summer of course.

Move your house plants outside during the winter months to prevent condensation. This will kill them quite effectively and prevent them from causing condensation ever again.

Joking aside, what is the solution to preventing condensation from forming on your windows?

Will double glazing stop condensation?

Anyone who has ever lived in a house with single glazed windows will know what a difference having double glazing makes to the rooms. However, double glazed windows are not the perfect solution to condensation problems. This is especially true in winter when the difference in temperature between the inside and outside is greater. Basically, on cold days when you have your heating on, the problem can still occur.

There’s also the problem of condensation inside the double-glazed windows. This happens when the seal on the windows is damaged or broken – usually on older windows where the sealant decays. This can only be solved, by replacing the glazing unit.

One way to reduce the impact of internal condensation is to use vacuum glazing.

Can you get condensation on windows with vacuum glazing?

What is vacuum Glazing?

Vacuum glazing is an improvement on standard double glazing in many ways. It’s more efficient at keeping a constant room temperature, and it looks good too!

It is more efficient than standard double glazing because the cavity between the two panes of glass is a vacuum. Normally, this cavity is filled a noble gas such as Argon. These gasses are denser than air, and heat and sound can’t cross them as easily as with air.

Vacuum glass on the other hand has, as the name suggests, a vacuum chamber between the two panes of glass. As we know, heat and sound cannot cross a vacuum, which makes them much more effective at insulating your home.

They look better than standard double glazing because they are much slimmer. Vacuum units have a cavity of less than a millimetre thick.  The gap of over 25mm in standard double glazing seems like a yawning chasm by comparison.

This narrow gap means than none of the unsightly inner working of the glass unit is on show, and the windows take on the appearance of single glazing. This is especially desirable in restoration projects when planning regulations require windows to be as close to the original units as possible. In older buildings, this means single glazing. Heritage windows made with vacuum glass have a better chance of being approve for listed buildings.

So how does vacuum glazing prevent condensation?

Remember how we told you that condensation forms on windows because of the warm air in your rooms hitting a cold window?

Well, when vacuum glazing is used there is very little heat transfer across the gap from the inner to the outer window. The glass on the inside stays warm – the warm air touching it isn’t cooled as much and it has no need to lose its moisture content. This can significantly reduce condensation build up. As part of a strategy which includes better ventilation, vacuum glass can prevent internal condensation completely.

Before and after shot of window in a listed building with condensation -the problem is solved by installing heritage windows with vacuum glazing
A heritage window before and after installing vacuum glazing.

What about external condensation in vacuum glass?

Any super-efficient glass unit can suffer from external condensation, which can be seen when the external pane is cold and the air is humid. This phenomenon actually demonstrates the effectiveness of the glass unit and is explained in full in the following blog post: