Little bedroom's ceiling is infested with moulds

noseall said:
Wrong about what exactly?
All I know is that when I put my specs on to trim my beard they steam up. If I open the window they clear.
Now get off your high horse and explain please. And stop being so arsey.
Click to expand...

Wrong about what? Really? Wrong about offering advice to open windows to deal with condensation! You really are a hypocrite. You bring this thread down by calling me a jumped up extractor fan salesman and then have the audacity to call me arsey. Your question is so unsophisticated it is laughable. If the internal temperature of a building is 21 degrees centigrade then the internal building fabric temperature is related to that ambient temperature. If you then open a window and let in cool air at say 5 degrees centigrade then the internal ambient temperature reduces and causes two significant issues.
1. The air immediately has to give up moisture in the form of condensation because warm air holds more moisture than cool air. (This moisture has no time to escape from an open window, the effect is immediate and I'll say it one more time for your benefit... Transient condensation!
2. Because the internal ambient temperature is reduced by the cooler incoming and uncontrolled air flow then the building fabric temperature is also reduced by the cooler air.

This is quite a simple concept that I don't really think needs explaining but lets explore your knowledge now by getting you to answer my earlier question that you conveniently ignored. How do you know when a room is 'full of condensation?'
 
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You really are getting irate. You still haven't explained how opening the window works better than the fan.

How long does it take to cool the fabric of a house in any case? Can tonnes of masonry suddenly be cooled by opening a window for a few minutes?

Joe Malone said:
[How do you know when a room is 'full of condensation?'
Click to expand...
When my glasses steam up
 
noseall said:
You really are getting irate. You still haven't explained how opening the window works better than the fan.

How long does it take to cool the fabric of a house in any case? Can tonnes of masonry suddenly be cooled by opening a window for a few minutes?

Joe Malone said:
[How do you know when a room is 'full of condensation?'
Click to expand...
When my glasses steam up
Click to expand...

You don't appear to even know the difference between humidity and condensation, both very different things. You think that when your glasses steam up a room is full of condensation? Is this the benchmark for how you offer advice to your clients. You tell them if their glasses steam up they need to open a window?
Your passive aggressive approach won't fool anyone Noseall. This is an online discussion thread and I don't get irate whether online or offline. It is simply another immature attempt to divert attention from the fact that you're wrong.
Wow, you're really asking if tonnes of masonry can suddenly be cooled? At surface yes, the effect is immediate and it is only the surface temperature that we are interested in. Plus, it may not be a masonry wall that is affected. Some of the worst cases of condensation damp I see are related to rooms in roof spaces, particularly the ceiling fillets that are poorly insulated, there is no masonry! Your other question is unanswerable without knowing U-values and temperatures. In any case it's irrelevant to the issue being discussed. if cooler air hits an internal wall it will have an immediate effect on the surface temperature thereby reducing dew point temperature, thereby increasing the risk for condensation damp.
 
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As long as the differences of temperature are taken up by the internal getting system, then opening a window is fine.
Keep calm and open a window.
 
I'l now explain how an extractor fans works better than an open window, which doesn't actually work at all.

When I advise clients to install extractor fans, I advise then to install silent and continuous running fans. The reason for this is that air changes are managed over a 24 hour period so there is no immediate and drastic reduction in internal ambient temperatures, which is what we get by opening windows. Boost speed would be linked to a bathroom lighting circuit or to a pull cord for the kitchen fan. Running with controlled, rather than uncontrolled ventilation cuts out the drastic acute heat losses experienced with open windows. It helps maintain reasonable internal ambient temperatures and maintains building fabric temperatures so that dew point temperatures are improved.
 
noseall said:
As long as the differences of temperature are taken up by the internal getting system, then opening a window us fine.
Keep calm and open a window.
Click to expand...

More brilliant advice... I guess it was only a matter of time before you also advised residents to turn up their heating to compensate for the drastic heat loss from the open windows. I love this advice, open your windows and turn up the heating (Which will only be lost via the open window anyway) , excellent. Thankfully most people reading this thread will have a little more common sense than you appear to have.
 
This is like the argument I have with the wife about her opening the window next to the fan. She says that as she has to clean any mould in the bathroom she's leaving the window open, whatever I say.
 
@Joe - can you explain why when I open a window (during the past few months, i.e. summer/autumn) I see a drop in relative humidity within the room without seeing any significant drop in temperature in the room (i.e. small drop in room temperature, big drop in relative humidity).

EDIT: OK, probably a daft question, but what I really mean is whether there is a cut-off point for the outside temperature, in terms of when opening a window is a perfectly fine approach vs when opening a window causes the humidity to just condense and give the impression of lowering humidity level
 
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In the warmer months the opening of a window shouldn't be a problem, as allowing warm dry air inside and damp air out could help.
Preventing condensation problems is getting the right balance of ventilation without allowing surfaces to drop below dew point temperature.
When you open a window it also depends on the external pressure in that area as to whether more air is coming in than out.
 
stuart45 said:
When you open a window it also depends on the external pressure in that area as to whether more air is coming in than out.
Click to expand...
Open two windows then get everyone to breathe out simultaneously.
 
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