Humidity levels domestic

[devonwoody]

Present weather conditions over the past two months prompted me to go looking around.

http://www.telegraph.co.uk/property/pro ... -home.html

They recommend 50%

 

[RogerS]

You worry too much, dw :wink:

 

[Racers]

Its a bit more than 50% down south!


Pete

 

[bugbear]

Its a bit more than 50% down south!


Pete

Does half way up the front door count as 50%?

BugBear

 

[Sgian Dubh]

Present weather conditions over the past two months prompted me to go looking around.
They recommend 50%

A fairly typical UK residential annual RH cycle is down to as low as 35- 40% RH in the coldest part of the winter (around January/February) to somewhere in the region of perhaps 60- 70% RH in the latter part of the summer (August/September). This assumes decent climate control measures (heating and/or AC) insulation, draught proofing and the like. The reason for this is that cold air in the winter can't hold as much water vapour as warm air, and any air that comes into the house through windows and doors that are kept closed most of the time is warmed, which reduces its RH. In the summer, warmer outside air holds more water vapour and residents in houses tend to open windows to generate a breeze, etc.

The author of the article is right to point out that what we do inside our houses can have a significant effect, e.g., cooking, washing, hanging clothes up to dry, showering, etc. My wife doesn't get it, but I try to hang clothes to dry outside as much as possible even in winter when the weather may not be ideal for drying: I like to get as much water out of the clothes as possible before they're finally dried inside. Similarly, I always open the bathroom window at least a bit when taking a shower, even if it's bitterly cold outside. After showering I wait for the condensation to disappear off the bathroom mirror before closing the window. I also make sure the vents through the wall are never fully closed so that air can at least circulate a bit. Slainte.

 

[MMUK]

Its a bit more than 50% down south!


Pete

Does half way up the front door count as 50%?

BugBear

=D> :lol:

 

[Racers]

Its a bit more than 50% down south!


Pete

Does half way up the front door count as 50%?

BugBear

No, half way down!

Pete

 

[MMUK]

Its a bit more than 50% down south!


Pete

Does half way up the front door count as 50%?

BugBear

No, half way down!

Pete

There's always a pessimist :lol:

 

[Rhossydd]

Here's an example of how humidity actually varies indoors:

It shows the recoded humidity in our living room over the last year, 20% > 70%

 

[devonwoody]

I understand that last year Jan/April was colder than average so humidity would be down, this year we have not had any frost down here in our part of Devon, and you know all about the present conditions so I got a dehumidifier and our bedroom now reads around 54% from 73% a week ago.
We are a corner plot, very exposed and bedroom faces SW, emptying around 2ltrs a day.

 

[KevM]

I can't remember the exact numbers, and it doesn't really matter because there's a lot of different estimates out there depending on a host of environmental and physiological factors, but I remember a particularly angry instructor shouting at me that all the time I was busy lounging around doing nothing but stealing oxygen I'd be losing somewhere between 05-1.0 litre every 24hrs.

I never did work out why he was quite so angry...

 

[devonwoody]

OK, we have now emptied 2ltrs. a day from the bedroom for the past 3 weeks.

If we had not got that dehumidifier where would that 50/60ltrs be?

The wool 80% fitted carpet in the bedroom definitely feels drier, and I guess bed clothes must be the same.

 

[Fishandchips]

No ventilation it would have found the coldest part of the room, the windows probably.

With a window open the humidity would have equalised with outside. Which is much drier at the moment.

 

[Jacob]

OK, we have now emptied 2ltrs. a day from the bedroom for the past 3 weeks.

If we had not got that dehumidifier where would that 50/60ltrs be?

The wool 80% fitted carpet in the bedroom definitely feels drier, and I guess bed clothes must be the same.

Most of your 2 litres will be from the ambient air passing through the room. So the answer to your question is that most of the 50/60 litres would have been taken out of the room by ventilation. Without the dehumidifier there would be very little difference, except you wouldn't have to empty the water out, ventilation would take it away for you.
You would get the same effect by running a heater at the same wattage.
Or to put it another way - if you run a dehumidifier in the middle of a field it will extract several litres a day but you won't end up with a drier field.

 

[devonwoody]

But we swear the carpet feels drier.

And we are having to close the windows because it is so draughty up here, plus all our heating would escape and then normalise with the outside?

Soooooooooooooooooooooo?

Perhaps we should emigrate?

 

[MIGNAL]

You need a serious dehumidifier to have a large effect on indoor RH. I run a domestic (an Ebac) dehumidifier in my small workshop and with the door closed and the dehumidifier running at full blast the best I can obtain is a 5% reduction.
The lowest I've personally recorded is 25% RH. That was last April when we had the unusual very cold snowy weather. I've been recording RH for over 10 years.

 

[Jacob]

You need a serious dehumidifier to have a large effect on indoor RH. ...

Or seal the room. Risk of suffocation, but at least you will be dry!