Window condensation

ozner

We just moved into a new house. Last night was the first cold night and I noticed condensation this morning in this double glazed window (leaded on the outside). Condensation was in the inside of the house (ie not between the two layers of glass). 3 people slept in that room (all other rooms are being redone).

Aside from leaving the window open etc

What can I do? Can better dealing fix it? Or do I need to replace the glass (outside or inside)? 

housebuyer143

I got brand new A rated windows last month and it does this more than my last windows. It's probably because they are better at keeping the cold air out and thus more condensation is formed because the old windows were a bit leaky. Add that to hot breath and moisture and you have condensation.
You can ventilate more or get a dehumidifier but I bought a minky glass cloth and just go and wipe down the windows every morning.

CliveOfIndia

ozner said:

What can I do?

Stop breathing, that'll do the trick

Joking aside, it's simply physics (or maybe thermodynamics, not sure??).  Warm air holds more moisture than cold air.  Any moisture in the air is fine when the air is warm, it'll condense out when the air cools - e.g. when it comes into contact with a cold surface.  Just the same as you may have seen in a pub that has those steel beer dispensers, they're covered in condensation.

A dehumidifier would do the trick - but they're probably too noisy to run all night in a bedroom, and they cost money to run, and actually breathing in very dry air for a long time isn't all that good for you.

Increase ventilation - that will help to a certain degree, though it's unlikely to cure the problem completely.  Plus, if you do have the window open, the room may get quite cold overnight when winter sets in.

The simplest and most practical solution I've found is just a quick run over with a squeegee (or even an old windscreen wiper blade) when you get up in the morning, then mop up the resulting little puddle of water with a cloth.

Unless you've actually got severe damp issues, any other solution is likely to be costly and in all likelihood still not completely effective.

ThisIsWeird

Hi Ozner.

As you surmise, the solution is to ventilate that room overnight, and that means cracking the windows open to 'vent' setting.

You can demonstrate this by simply trying it. If the only bedroom ventilation you are currently relying on is 'trickle', then try a few nights with the windows open to at least 'vent' setting. Bedroom door shut. Heating off overnight (it's a waste). Thick duvets and/or leccy overnight blankets.

Yes it'll be cold if you need to get out of bed during the night, but it should be plenty warm under the sheets. I suspect the occupants will wake to a dramatically-reduced level of cond.
If it's unpleasantly cold, then have the heating set to come on at least a half hour before waking time. One of you jumps out and shuts the windows until the bedroom is vacated.
Once you're out, then crack open the windows again, and leave them like that all day - even open them wide if needed. Close the bedroom door.
Before bedtime, I will assume the windows will be dry, so shut them a half-to-one hour before bed and turn on the rad. That should be welcoming. Then, heating off just before bed, windows on vent (more than one if you can), and jump into bed. LOVE the cold nose sensation - it's GREAT.
Please at least try this, and see if it makes a difference. It could be completely transformative.

That cond currently running down your panes - that's almost all from the sleepers

ozner

Thanks all, I assumed a new window would do the trick but apparently not the case?
i should add windows in other rooms don’t do that (we only had 2 sleepers in one), but they are newer windows (no lead windows). 

im just wondering if it might be that the lead window lets some air through, which gets in contact with the inner window? Which is warmer due to it being inside, and that’s why it happens in those old windows but not in the new ones? 

ThisIsWeird

If the occupants really cannot cope with an overnight chill, then the next best thing is to simply 'manage' the issue and ensure it doesn't cause issues such as mould.

As explained by others, that will mean mopping up the cond using a wrung-out damp cloth, and finishing with a dry one - remove every trace. Then crack open all the windows to 'vent', shut the bedroom door, heating to that room off, and leave to ventilate like this all day.

That should dry the room well enough - which will almost certainly be needed, because other cold surfaces such as the walls will have higher levels of moisture in them; they might not be 'running', but they will be damp. And if that is allowed to continue, expect mould.

So, window on vent overnight if you can. If you really cannot - whimps - then dry up in the morn, and 'air' that room all day.

housebuyer143

ozner said:

Thanks all, I assumed a new window would do the trick but apparently not the case?
i should add windows in other rooms don’t do that (we only had 2 sleepers in one), but they are newer windows (no lead windows). 

im just wondering if it might be that the lead window lets some air through, which gets in contact with the inner window? Which is warmer due to it being inside, and that’s why it happens in those old windows but not in the new ones? 

It might simply be that the extra occupant pushes the moisture that much higher. We lived in a 2 bed house for years with no condensation issues, we had a baby and water would literally run down the walls and we had to get a dehumidifier. Took us a long time to work out the extra body was the cause. 

Arguably the better the window is at keeping out drafts the more condensation you will get. That's why trickle vents are a requirement now in all new windows. I'm not sure replacing the window will do anything to stop it tbh. 

casper_gutman

Condensation forms when the humidity rises in the room , in this case due to water vapour exhaled by the sleepers in the bedroom. The air next to cool surfaces like the windows drops in temperature and so can't hold as much moisture. The vapour in the air therefore turns to liquid and is deposited on the surface.
 
If you could get a window with an extremely low U-value (i.e., really well insulating) then eventually you wouldn't notice condensation forming on the windows. But almost certainly there would still be condensation somewhere - the humidity can't keep going up forever. The condensation would now be forming on whatever was now cooler than the window - probably the ceiling or wall in some secluded corner of the room. Most likely you wouldn't notice a wet surface - at least, not until black mould started forming on the paintwork!

Condensation on windows is just "one of those things" in most UK homes over the cooler part of the year. Personally I use a cheap Karcher window vac to clear it in the morning. More expensive than wiping it away with a cloth, but I can whizz round and do all the bedroom windows without having to faff about squeezing a cloth out somewhere. 

stuart45

I've still got single glazing, so the windows are often soaked in the mornings. A wife with a few J cloths is quite an efficient dehumidifier.

twopenny

New windows would make no difference.
If you have 3 people breathing out moisture in an enclosed box for 8hrs onto cold glass it's going to happen.

ThisIsWeird

twopenny said:

New windows would make no difference.
If you have 3 people breathing out moisture in an enclosed box for 8hrs onto cold glass it's going to happen.

Yes, all that vapour has to go somewhere.

You either increase the air temp to silly levels in order to keep the moisture suspended, or you simply vent it away.

If you can enjoy the feeling of a snug warm bed within a chilly room, then it's an easy choice :-)

A true delight is a gentle cold breeze running over your face whilst you are being cooked in bed. Awesome.

Until your bladder fills...