Stubborn condensation on windows

[houseonahill]

Long story short, we have:

1950s house
Double glazing, only about 10 years old, good condition. No condensation between the panes.
Trickle vents OR openers that we leave open a crack during the night
Two adults in the house, no pets
High outdoor humidity (it was 91% RH last night!) and humidity monitors inside, they were sitting at about 67% last night. As mentioned, very humid outdoors where we live so difficult to control this
No MVHR
Type 22 rads in every room, gas boiler, smart thermostat controlled, doesn't let the temperature drop excessively overnight. Boiler flow temp currently at 45C, only needs to run occasionally as the house is well insulated: 400mm loft insulation (rockwool), 60mm anthracite bead cavity wall insulation, 100mm rigid board insulation beneath screeded floor on ground floor. PLUS a recently installed highly insulated composite front door.

This morning, when outdoor tempeatures dipped to 3C, there was quite a bit of condensation on the room-side of the inner panes of our windows, along the bottom of the unit, mostly. Not in every room, but in most - and there was enough moisture to require wiping away to prevent mould.

My question = is there a way of drastically reducing condensation in terms of adjustments to the current fabric of the building, or is it really just unavoidable in our case. No, I'm not going to stop breathing!

I am aware I could try a dehumidifier but I'm a little reluctant to rely on that. I'd rather deal with the source of moisture / problematic cold spots if possible.

Any thoughts gratefully received...

 

[freddiemercurystwin]

You could consider a PIV system they're supposed to be quite effective, you can get DIY kits.

 

[Murdochcat]

How do you dry your washing and does your bathroom have an extractor fan?

It would be useful to understand why you have so much humidity

 

[Harry Bloomfield]

I consider my home normal, to good, for moisture, but last night and this morning there was a trace of condensation at the bottoms of my DG glass. I think it's unavoidable, with the warmth we have had recently, followed by last night's cold snap.

My indoor humidity was similar to yours. Below is my record, for the past 24 hours, blue outdoor, green indoor. Note the slight increase in indoor humidity, just before the second vertical line, which was at 6pm yesterday - that was when the cooking of dinner began. The second kick up, two hours later, was due to a bath being drawn, followed by a gradual reduction, until this morning's activity. I think it's unavoidable, that the humidity should sometimes increase.

We still not had any central heating on, since the summer, though we have turned the living room gas fire on a couple of evenings.

 

[houseonahill]

Thanks @Harry Bloomfield that's interesting! Yes, to be fair, there was some washing drying inside (in a room with a slightly open window) yesterday but I think we would still have had condensation without that. The house is reasonably well sealed and it's tough to keep the air dry when one is simply living in it.

Thanks @freddiemercurystwin, a PIV is a decent suggestion though like mentioned I'm trying to think about how to deal with it passively as much as possible.

We have a Soler * Palau TD Silent 350 in the bathroom, it's excellent - stays on for about 15 minutes after the light goes off.

 

[ronniecabers]

PiV is fairly passive to be fair once it's installed.
I think part of the issue is that the amount of moisture you are producing is greater than the amount trickle vents and night vents can remove , especially if outside humidity is already high. Window panes will never have the same level of insulation as a wall , so by that nature they will be the colder spot in a well insulated house.

 

[^woody^]

there was quite a bit of condensation on the room-side of the inner panes of our windows, along the bottom of the unit, mostly. Not in every room, but in most - and there was enough moisture to require wiping away to prevent mould.

That's a thermal bridge from the spacer bar in the units.

As such, its not a condensation issue, but a localised issue relating to a single extreme temperature differences and dew points. Apart from changing the units, it will be difficult stop other than trial and error as it may well be that everything else is in equilibrium and performing as it should.

 

[ronniecabers]

That'll depend Woody, I'd be surprised if 10 year old windows had the old Ali spacer bar in them, I would expect warm edge spacer which does away with thermal bridging. Obviously a picture of the spacer bar would make it obvious which one it is