How humid is your house?

I’ve been watching the humidity reading on a couple of clock/weather stations in my house this winter and seen them plummet with the cold weather. It has made me think, are my readings typical?

House is 1930s solid wall with modern windows but well ventilated through all the airbricks still in place/unblocked, 2 wood burners run daily, extractor hood in kitchen, extractor in bathroom just an axial but straight out through the wall. At the start of winter the humidity was around 65-75%, but lighting a stove would bring it down about 5%. It’s got drier as winter as gone on and current cold spell has it down to low 40s, running stove brings it down 1-3% and this morning I saw 39%. Seems a big change over a few months and Seems quite dry, which I’m happy with so long as it doesn’t get dryer. 2 adults, 2 very young kids and all that entails to make the air moist.

Just interested to know what others have. I’m also aware the humidity reading on a cheap weather station may not be bang on, but the 2 different ones seem to agree closely so I’m inclined to think they are close.

My nest thermostat varies between 40-50%, most days about 44%, never seen it higher than 50%. No idea how accurate it is.

Similar age house, and yes ours goes down. It’s simple isn’t it, heat squeezes the moisture out of the house. Cold air outside is less humid too.

Low humidity can be as bad for you as high humidity

49% at the moment, it used to be quite a lot higher till we got a condensing tumble drier, it freaks me out every time i empty it, the sheer volume of water that we were putting into the air.

Depends which bit of the house.

The housekeeper informs me that the pantry is as dry as an old stick whilst the pool area is normally quite humid, especially if someone leaves the steam room door open.

The media room and the ball room usually fall somewhere in between.

Used to be around 60-70% lowering in winter to about 50-55. We had issues with mould growth especially in the bathroom and ran a dehumidifier most days to try to manage that.

about a month ago we fitted a decent extractor fan to the bathroom to clear the worst of the shower steam and a PIV which, although blows cold air into the house, has resulted in our humidity reducing to between 40-50%. This should have a positive impact long term not only on the house, but also on us living in it.

According to my Canary camera the living room is currently 49%, the highest it’s been the last couple of days is 60% and it was raining at the time.

Our house is old and well ventilated. Seems to sit in the low 40s

mid 50’s most of the time. low 60’s if its particularly damp outside.

before I fitted a nuair PIV unit it was regularly in the 80/90’s and had all kinds of damp problems and massive condensation on the windows.

edit: 1880’s terrace with 3ft thick solid walls and floors straight onto dirt.

After reading perchy’s post the humour rate has gone up in my living space.

Oh how the butler and I laughed.

nest says 41% not sure of its accuracy. Thats after a day of washing draped about.  I do like to open the windows daily much to the annoyance of my wife.

We’re about 50%-65%. It’s about 10% lower in the rooms that we’ve had insulated which are also a bit warmer.

The media room and the ball room usually fall somewhere in between.

Good to hear it, nothing worse than mould on constantly damp balls.

Thinking about it I’m sure it never got lower than about 55% last year and I saw it in the mid to high 70s a few times. I had just had a load of plastering done and freshly painted some rooms, I guess the moisture from that took months not a week or so to disperse.

I’m glad it’s lower this winter. Mould wasn’t a big problem before but I did have a bit in a couple of places where I had cracks in external render. I’ve fixed that now and mould hasn’t returned, but I guess it’s why I’m interested in the humidity….. You’re never quite sure you diagnose and fix damp correctly!

1930 house brick built.

nest reports it anywhere between 60 and 75%

My lounge is anywhere between 40 and 80% depending on the weather, and that’s with two large aquariums in the room.

New build airtight house with heat recovery ventilation.   Currently around 40%, from memory I think the ventilation goes to boost mode above about 60%.  I have a ‘summer override’ switch i’ve needed to use a few times that changes the parameters as if ambient humidity gets really high there’s no point boosting it continuously.

I’ve no idea about percentages, but it’s certainly more humid in summer.  I have a dehumidifier in one room, in the summer I’m emptying it every couple of weeks, whereas I think the last time I emptied it recently was before Christmas.

perchypanther wrote:

Depends which bit of the house.
The housekeeper informs me that the pantry is as dry as an old stick whilst the pool area is normally quite humid, especially if someone leaves the steam room door open.
The media room and the ball room usually fall somewhere in between.

How is the dungeon?

Dank.

As it should be.

So far in 2018 it is between 37.5 and 60%.

Between 37.5 and 47.5% today.

1970’s apartment, 12th floor with a big, sunny living room – sunny here today to the point I’ve not needed the heating on for the last 24 hours and I am sat watching tv in a t-shirt.

It was between -2 and +4 deg outside today.

About this much according to Tado. Seems to rise and fall during the day.

in my bedroom it’ currently 16.2 degrees and 51% humidity.  Drafty 1930s house.

I had a ventilation system installed last week in our shonky 1980s NZ wooden house to hopefully help during Winter. There’s hardly any gas central heating here, and you’re lucky to have double glazing.

Right now it’s around 50%, that’s with the windows open, it’s been sitting in the 40% bracket most of the time and was in the high 60s before the system was installed so it’s definitely working bringing warmer (39c!) dry air from the ceiling space into the house.

Our 1800’s terrace with 2ft thick stone walls sits around 50% in winter when the hearings on and sits higher about 65% in summer.

The dryer in our utility room is vented to outside but seams to be kicking some damp air into the room.  Must find that leak!

I live in Colorado, so we have the opposite problems to when we were in the UK. In the winter the humidity can drop dangerously low, to the point where you get static shocks off everything. We have a wood burner and normally keep a pot of water boiling on the top to get the humidity up slightly.

Lowest I’ve seen outside was 8% here in Boulder. Lowest in the house this year has been about 22%

Our house (60’s bungalow) normally sits around 65% according to Nest, which I know is high. Do have a few mildew issues.

Our bathroom and kitchen open straight onto the hallway but we try to keep doors closed and have extractors in both rooms, we rarely dry ‘wet’ washing in the house, it normally just needs a couple of hours after a jump start in the dryer or on the line.

Just bought a 2nd hand dehumidifier, it will fill it’s 7 litre tank within 24 hours. After running it for about 36 hours over the last week humidity is down to 55%, I left it on auto last night and it stayed on boost mode all night and sucked 4 litres. This morning the house is back at 60%.

I wonder if I wasn’t so tight with the heating, would the humidity be lower? I assumed the air could just hold more moisture which would reduce condensation/mildew….until the heating turned off for the 12hrs we are out of the house each day…

What are these humidity readings? Are they absolute or relative humidity?

Humidity is normally displayed as relative (RH), which is the amount of water in the air divided by the maximum possible at that temperature. As the maximum varies with temperature, so does the RH value.

40%RH at 15 deg C is not the same amount of water in the air as 40%RH at 25 deg C, because hot air can hold more water than cold air.

Most humidity sensors include a temperature sensor so I guess are displaying RH.

^ exactly what I was going to say. Part of the drop in humidity when a wood burner is lit is due to the temperature rise. If it is particularly damp the extra airflow may move out very damp air but a lot of it will be due to the warmer air being able to hold more water vapour.

You can see how a small increase in hemp allows a lot more vapour to be held here

http://www.engineeringtoolbox.com/water-vapor-air-d_854.html

Does it matter? Unless it’s really low, like @mtbcoach indicates or really high then it’s pretty much what it is. Unused/unheated rooms will feel damp but even a slight input of heat will sort that out.

which is how the PIV units work. outside air say 10deg, 90% humidity, once warmed to 18 degree is only 60% humidity. and dry air costs less to heat. I have a cold-ish draft on the landing but overall its made a massive difference to the house.

the other key if you have mould problems is understanding the relationship between dew point and humidity. if you want to stop condensation forming you either need to drop the RH or up the surface temperatures.

My kid has an old weather station in his room .. it’s way older than him so sensor’s might not be great… it was showing 27% in his room which is the new part of the house and just moved it into my office and its showing 36% but the heating has been on.

I remember being in Aviemore when the temperature dropped to minus 24c, it was so dry that we were getting static belts off everything including the car after wading through deep dry powdery snow.

Our house is built on a concrete platform so the walls and foundations are extremely dry. We also have an Aga, which sucks lots of air up the flue and we run the stove in the lounge in the evenings so it’s a pretty dry house although I’ve never measured it. Must check out the weather station thingy.

Most people here seem to get it, the warmer air can hold more moisture so RH of a body of air drops as temp rises. The reason stoves dry the air is, besides just the warming, they act like a heat powered extractor and push a lot of warm moist air out the flue to be replaced by cold and drier air from outside. Over time the fresh drier air warms up and picks up moisture from the house, slightly lowering the RH.

The reason it matters is condensation, RH is tightly linked to dew point. With 8 inch solid brick walls the inside face of them is fairly cool in my house. Room temp can be 19 or 20C but inside face of walls can be 13 or 14C according to my ir thermometer. Doing the calcs (or rather plugging numbers into an online calculator) I was surprised to see how close the house often is to having those walls at the dew point and suffering condensation. for example at 20C if the RH is 64% the dew point is 13C. Autumn heading in to early winter, those sort of conditions probably existed, or close to, quite often. This mornings 19C and 42RH downstairs, 19C and 55RH in the bedroom give much lower dew points so I’m well away from condensation.

I wish external wall insulation wasn’t so expensive. In the meantime i’ll keep running the stove to dry the house out I guess, and it shows how important the bathroom and kitchen extractor fans are.

bigG – My Tado report for January is identical to yours – every single stat!
Coincidence or is it all a lie?

Apogies for not reading the whole thread.someone may have already said this.

Running the wood stove is unlikely to reduce the humidity, just the relative humidity (by making it warmer)

A lot less than it used to be. Fitted a humidistat inline extract in the bathroom a few months ago. Gone from averaging 70% on a good day to 45-50% now. Had used a dehumidifier that past few winters. Didn’t need to this year.

…in the short term ie 3 hours after you switch it on.  Obviously it will make the house drier over days/weeks

@nellnevil – a very rough dew point approximation (doesn’t work for extreme values) is:

Dew point = Actual temp – ((100 – RH) / 5)

So in your case 20 – (36 / 5) = 13C