i live in a Victorian house which has a humidity problem indoor humidity 65% at 18c I have been advised to reopen the air vents in the bay window and one at the back of the house to allow air flow the ground floor is a solid floor. The only issue i have with this idea is outdoor humidity is usually about 85% so would ventilation work?
condensation damp
- Thread starter paul161201
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How does the house stay warmer when this colder air is let in?
What happens to the 20% extra moisture that the OP lets in?
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Central heating is usually the way, that's why ventilation doesn't work with sheds and garages that are unheated.
And it's 20%extra relative humidity (to the temperature) and warmer air can hold a lot more water.
Read about "dew point" if you're interested.
And it's 20%extra relative humidity (to the temperature) and warmer air can hold a lot more water.
Read about "dew point" if you're interested.
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Is 65% really a problem?
See the table at
http://www.engineeringtoolbox.com/relative-humidity-air-d_687.html
Saturation vapour pressure @ 18C = 21 mb, so 65% = 13.65 mb.
If the outside temperature were 10C, then saturation = 12.3 mb so 85% = 10.46 mb.
So the outside air is drier, and opening windows would reduce the inside humidity - BUT ONLY IF the inside temperature does not fall much, i.e. you have enough heating inside to warm the new outside air.
http://www.engineeringtoolbox.com/relative-humidity-air-d_687.html
Saturation vapour pressure @ 18C = 21 mb, so 65% = 13.65 mb.
If the outside temperature were 10C, then saturation = 12.3 mb so 85% = 10.46 mb.
So the outside air is drier, and opening windows would reduce the inside humidity - BUT ONLY IF the inside temperature does not fall much, i.e. you have enough heating inside to warm the new outside air.
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NotSoSure
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N
NotSoSure
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That's very long. I wonder if anybody will read it all. Where did you copy it from?
Now here's a thing:
So when you walk into a house and measure the RH, what do you think you are measuring, other than the air?
Now here's a thing:
So when you walk into a house and measure the RH, what do you think you are measuring, other than the air?
N
NotSoSure
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Why don't you just synthesize all of that into something that is actually readable and understandable by people who are likely to be here on a diy forum, rather than plagarising someone elses stuff?
i.e. what are you on about?
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NotSoSure
Kind words, woody, I won't bother again.
One suggests no-one will bother reading it and another accuses me of plagiarism and unintelligible comments.
One suggests no-one will bother reading it and another accuses me of plagiarism and unintelligible comments.
They could do.
But in all my years of visiting some right mouldy homes, ventilation on its own never works.
"Open the windows/vents" is the standard advice of clueless surveyors and home inspectors. And it is never the correct advice.
The actual cause needs to be determined and dealt with. That cause could be the OP, the building or both.
I'm curious to know if the poster actually has a problem other than seeing a meter reading of 65% and reading on the internet that 65% is "high". it's true that it is probably higher than ideal, but it's not ridiculously moist. What's the whole story?
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