secondary glazing for reduction of condensation ?

[malakoffee]

The big bay window in my bungalow faces north-east.

The double glazed units ( fitted 2002 ) are sound but probably below modern standards.

The condensation on the inside panes is significant. Window vacuum action is essential - almost daily this winter !

I'm tempted by the idea of upgrading to triple glazing, but I'm very wary of :-
- exaggerated claims about performance improvement ( of the 3G glazing units )
- the components of the frames need to be well insulated too.
- the two different companies who have fitted newer 2G windows, here, ignored good fitting practice ( e.g air-tightness around the frames ). Leaving me to correct post-install.

As a short-term, proto-typing exercise I was thinking of DIYing some plastic glazing over the existing units to see how it performs. . . . thinking about 3G in the medium-term.

Has anyone experience of acrylic/polycarbonate secondary glazing ??

[Meatyfool]

Mal,

You asked one question and I am going to answer another - sorry!

Are you certain your home is sufficiently ventilated? I have installed a PIV (see Nuaire Drimaster Eco). It hasn't made a massive difference in my home yet, but I made a huge effort a few years ago to fill in unintended air leaks (circuiting boards, electrical sockets) so created my condensation problem myself. I now need to effectively undo some of this to enable the requisite airflow.

Meatyfool..

[Itsallaguess]

[Mal] asked one question and I am going to answer another - sorry!

Well I'll chirp in to ask another question - where's all the water/humidity coming from?

If there's large amounts of condensation on a daily basis then it sounds like tackling the source of the dampness in the air might be something to consider first, perhaps?

Cheers,

Itsallaguess

[ReformedCharacter]

I have a similar problem and have found a dehumidifier on a timer to be very helpful, I use one of these:

https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1

A small desiccant dehumidifier, 2 hours a day is sufficient, also one benefit is that it produces a small amount of heat.

RC

[malakoffee]

Well you did ask . . . . . . . .

1930's built bungalow - that used to be coal-fired and inherently leaky. i.e vast amounts of outside air dragged through the interior by coal fires.

Damp proofing restricted to cavity walls with damp-proof course. That's it.

* The rough oversite concrete under the suspended floor used to develop visible damp patches whenever the water table raised after heavy rain, This underfloor is now highly ventilated with multiple periscope vents. The floor is now insulated between the joists.

** I dug French drains around three sides of the house - slightly below the top of the foundations.

*** Wall cavities cleaned out as well as could be achieved, but still significant rubble bridging in places that I couldn't get to. Further complications with cavity insulation which should have gone no lower than DPC, but had slumped down.

In general :
I try to manage the moisture/humidity very carefully. It's the usual balance of keeping-the-flow versus keeping-the-heat.
PS. Internal temperature this winter is 13 degrees C. My choice due to climate destruction.

[sg31]

The first problem is the big bay window facing north east. I know theres not much you can do about the direction but if you are trying to keep fuel usage to the minimum this is the wrong direction.

Many years ago I renovated a C16 cottage in Lincolnshire, there were no windows whatsoever on the north side, that is where the cold north wind hits the property and where and window will natrurally become cold spots and in the old days, drafts would occur. There were windows (few and small) on the east side but these were later additions. All the original windows were on the south side where they would benefit from solar gain. They knew a thing or two back then. There was also evidence that farm animals were kept in part of the structure but let's not go there.

It is possible to get condensation on old double glazed windows. By modern standards the panes were very close together and not that efficient. By 2002 though they were reasonably good which suggests the humidity in your property is very high.

Triple glazing with modern units will help keep the windows condensation free. The problem is that moisture in the air will always condense on the coldest surface when the temperature drops and the air can no longer hold the moisture. If it's not the windows you can be assured it will be somewhere else.

You really need to research this problem much more thoroughly. You have the choice of reducing the moisture content of the air by some means, not creating the moisture in the first place, ventilation or removing the moisture with humidifiers.

You chose to keep your internal property temperature at 13 degrees. Personally I think that is too low for the health of the property but the choice is obviously yours and you have taken it for enviromental reasons. Some time ago I did come across research which suggested that 17 degrees was the minimum recommended. I can't remember when or where I saw this but maybe other posters may be able to correct me if I'm wrong.

I'm not for a moment saying you shouldn't make the choice you have, that's entirly up to you.

[AsleepInYorkshire]

The big bay window in my bungalow faces north-east.

The double glazed units ( fitted 2002 ) are sound but probably below modern standards.

The condensation on the inside panes is significant. Window vacuum action is essential - almost daily this winter !

I'm tempted by the idea of upgrading to triple glazing, but I'm very wary of :-
- exaggerated claims about performance improvement ( of the 3G glazing units )
- the components of the frames need to be well insulated too.
- the two different companies who have fitted newer 2G windows, here, ignored good fitting practice ( e.g air-tightness around the frames ). Leaving me to correct post-install.

As a short-term, proto-typing exercise I was thinking of DIYing some plastic glazing over the existing units to see how it performs. . . . thinking about 3G in the medium-term.

Has anyone experience of acrylic/polycarbonate secondary glazing ??

Do you have trickle vents fitted?

AiYn'U

[anon155742]

A good way to start would be to get some temperature and humidity meters. Place them around various parts of your house and follow the moisture.

[stewamax]

Well you did ask . . . . . . . . 1930's built bungalow - that used to be coal-fired

Is the chimney now blocked off? If it is it may be worth unblocking it.
At 13degC, you don't need much moisture in the air for it to condense.

Some Victorian/Edwardian house ground-floor rooms even had an additional flue covered by a grating built alongside the chimney flue but vented into the loft space.

[PrincessB]

The double glazed units ( fitted 2002 ) are sound but probably below modern standards.

They shouldn't be terrible. If I recall the standard around that time was 3mm glass, 20mm air gap, 3mm glass - Seem to recall the U value was in the region of 2. Even if they were fitted by 'idiot & bodger' window company, the problems would be likely to manifest themselves in draughts and around the frames, not on the glass itself.

A quick list, bearing in mind that with U values, lower is better.

Single pane of glass - 6
Old double glazing - 2
New double glazing - 1.3
Triple glazing (normal spec) - 1
The best you can get using all the tricks - 0.7

Well I'll chirp in to ask another question - where's all the water/humidity coming from?

Well worth considering that.

Two main causes sources of moisture build up are from cooking and bathing/showering - Have you got proper extraction in the kitchen and bathroom? Unvented tumble dryers are even worse, but while eveyone has a kitchen and bathroom, an unvented dryer is less common. Will note that washer dryers or the expensive (but rather good) heat pump dryers do not cause any problems.

In general :
I try to manage the moisture/humidity very carefully. It's the usual balance of keeping-the-flow versus keeping-the-heat.
PS. Internal temperature this winter is 13 degrees C. My choice due to climate destruction.

What sort of readings are you getting?

My 1874 Victorian Cottage (solid brick wall now fitted with internal insulation) does as well energy wise as a property built to 1980's building specifications. Rather pleased to match the requirements of properties built a century later.

Humidity at about 40%, air temperature in the back with some solar gain 25ºC and in the North facing front of house the single 1kw (equivalent) radiator is not having a problem maintaining 22ºC.

If you don't have decent extraction, look at a dehumidifiers - The compressor based ones use less power per litre of water extracted and range in price from the £100 units you'll find at DIY superstores to the several hundred quid you'll spend on EBAC who consider themselves to be the best. Even the cheapy ones work well enough and you'll be amazed at how much water they extract.

A good way to start would be to get some temperature and humidity meters. Place them around various parts of your house and follow the moisture.

A simple infra red thermometer is a great thing to own, not only can you look for cold spots in the structure of the house, you can also see how hot your radiators are and they are really useful for cooking, as you can see how hot the oil in a pan is before you add the food.

It also appears that thermal imaging cameras are now relatively affordable - You're going to pay over £150 for even the most basic device, but they used to be really expensive. You can do the house from the inside and from the outside and you'll know at a glance where all of the heat is going.

In terms of draughts, a packet of smoke matches can be used to idenfity whether you've got a problem and they only cost a few quid. If you smoke, you won't need these.

Regards,

B.

[Laughton]

What is that room used for?

When you say temperature kept to 13 degrees, do you mean just in that room or throughout the bugalow?

Where is the kitchen and bathroom in relation to that room?

[stewamax]

Jeff Howell, the former Sunday Telegraph columnist, made the intriguing point that keeping rooms cool could be counterproductive unless humidity could also be kept low and the walls themselves (particularly the inner skin of a cavity wall) dry and free of condensation. If a room and inner exterior wall drop below dew point, the resulting condensation increases the wall’s thermal conductivity (i.e. ‘wet walls lose heat’). This in turn cools the room further – which for a given humidity increases condensation.
Whether this effect is significant I don’t know!

[malakoffee]

Thanks everyone so far for your questions and suggestions. It is useful for me to review every aspect of the situation in order to progress.

Humidity meters – I think the time has come to get a couple of these and start some systematic recording.

Dehumidifier – I used a borrowed one of these when I was doing the major corrective works (2012). It was a condenser type and always managed to suck a lot of moisture out of the air – despite the low temperatures inside the house. [ Condenser type not so good at low temps. ]
I would prefer not to use a dehumidifier, in the long-term, as it fails to tackle the cause. . . . and uses lots of energy. . . . . . .
However, I haven't ruled out a MVHR ( mechanical ventilation with heat recovery ) system as a longer term part of a solution.

Behind the bay window . . . .
are the guest bedroom/store . . . and the other one used as the main bedroom ( with a woodburner and a flue up the chimney ). The woodburner gives a non-trivial improvement on the condensation on the window in that room, but it still gets condensation.

Kitchen & bathroom . . . . .
Are in the middle section of the long rectangular footprint of the house.
Both have powerful inline extractor fans – which I use diligently.
I do some cooking in a microwave oven & breadmaker in the garage ( to keep the water vapour out of the house ).

These bay window units do NOT have trickle vents. However, the (small) top-hung vent windows are always ajar – equivalent to trickle vents.
However, they represent a small fraction of the glazed area of the bay window.

More later . . . . .

[PrincessB]

As you've identified, a humidistat in every room will give some data to work with.

The analogue units cost pennies from well known online retailers, I would also recommend one of these:

https://www.amazon.co.uk/Wetterladen-We ... 891&sr=8-3

Not only do you get indoor and outdoor temperatures, you've got a humidistat and the pictoral icon of the girl adds and removes clothes as the weather changes through the year. Highly recommended, I've one next to the bed and it is useful to glance at for the outdoor temperature and know whether you'll need those extra few minutes to defrost the car.

Another exercise you might wish to consider would be to work out your houses overall energy performance. It's pretty easy and there's stuff in the Lemonfool archive to give an indication on how some other board members did.

All you need to do is:

Calculate the floor area of your dwelling - We are not looking for that much accuracy, so you can do internal or external measurements, essentially you just need to know how many square feet or square metres of house you've got.

You then calculate how much power you use over the course of a year and divide one into the other to give your energy footprint for each sqaure metre.

My calculations are rather easy as the two sources of power are either gas or electric, no solar PV, heat pumps or solar thermal hot water, no log burner either!

My house has an internal footprint of (in imperial) of 1200 square feet and uses 10,000kWh (equivalent) of gas and 2,000kWh of electric which works neatly into 100kWh per square metre per year.

A PassiveHaus should in theory, be able to maintain itself using 10% of that. You can cheat by adding a stack of PV panels or for those of us with a lot of money, an underground water loop which uses the undersoil a couple of metres down both as a radiator to take the edge off the winter cooling load and a cooler to remove the need to
buy a heat pump system.

Architect Charlie Luxton has detailed his house build on Youtube, it's pretty easy to search for as well as being really interesting.

Regards,

B.

[Laughton]

Often surprises people just how much moisture we give out when breathing. This could the the main cause in the bedrooms. That breath is leaving your body at 36 degrees C and, even if your windows are slightly ajar, all that moisture is going to condense when it hits panes of glass which are 13 degrees or lower.

[staffordian]

As a matter of interest, and hopefully of use to the OP, what do others consider a reasonable humidity level?

I have a weather station in the bedroom, similar to the one PrincessB linked to, (except it shows clouds or sun icons rather than undressing girls ) and a second dial type one we move around from room to room occasionally. We never get below low 50s relative humidity, and often it is low to mid 60s. We don't sleep with a bedroom window open but do open the toplight for a few hours each morning and do likewise with other rooms to freshen the air.

We also have bathroom and kitchen extractors, diligently used, and we have a compressor type dehumidifier which we run after showers if the weather is wet and opening windows isn't ideal.

We too suffer from condensation on new double glazed windows, though it tends to be worse in autumn rather than winter, presumably because the outside air tends to be dryer in winter, even if colder.

We don't live in the same spartan manner as the OP, tending to keep the rooms at around 21C, and have the stat set to provide heat overnight if the internal temperature falls below 15C which it never does.

I'd be interested to hear of others experiences regarding any humidity measurements as trying to google ideal levels produces as many opinions as there are humidity levels

[Dod101]

Someone said that maintaining the internal temperature at 13C is not good for the fabric of the house but it would not be good for many people either. I am surprised that the OP needs a guest bedroom.

I would think that the internal temperature has a great deal to do with the high level of humidity. I must say I never have any and nor do I open my bathroom window very much but I do have a good extractor fan when using the shower. The internal temperature in my house is usually at least 21C. It is now 3.15 pm on a rather cold Sunday afternoon so I will now go and light my logburner.

Dod

[malakoffee]

This bungalow == 33kWh/m2 [ i.e. per sq. metre ] - according to the cals . . . . that was fun.

Not many "guests" over winter . . . I wonder why

Where can I buy a PassivHaus ??

[PrincessB]

As a matter of interest, and hopefully of use to the OP, what do others consider a reasonable humidity level?

I have a weather station in the bedroom, similar to the one PrincessB linked to, (except it shows clouds or sun icons rather than undressing girls ) and a second dial type one we move around from room to room occasionally. We never get below low 50s relative humidity, and often it is low to mid 60s. We don't sleep with a bedroom window open but do open the toplight for a few hours each morning and do likewise with other rooms to freshen the air.

This is something that confuses me.

Relative humidity inside never goes above 45% - It's 40% at present. I don't understand how it can be raining outside for weeks and it's still all fine indoors.

We have a lot of extraction, the cooker hood is rated at about 1hp (or 750watts) and on full blast, doors close by themselves. Bathroom is more gentle, and we run that for a few hours a day.

Apart from power extract, I haven't opened a window for months.

B.

[Dod101]

I am one for fresh air. I always have at least one bedroom window open 24 hours. Then I do open windows in my living area for a couple of hours most days unless it is extremely cold. Extractor fan in the kitchen and in each of three bathrooms. I never have condensation but I would not like to know my carbon footprint as I keep the house quite warm (obviously not when the windows are open)

Dod