Condensation wet windows mould

duncan303

hi

Can any of the experts work out:

the volume of water contained 1 one cubic meter of air at a temperature of 2 C with a relative Humidity of 68%, @1000mb pressure.

and the volume of water contained 1 one cubic meter of air at a temperature of 18 C with a relative Humidity of 64%. @1000mb pressure


Is the simple advice to open windows always applicable?


cheers


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ariba10

It is only feasible to open the windows if the humidity outside is lower than the inside.

duncan303

The airs' capacity for water vapour increases as the temperature increases


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keystone

ariba10 wrote: »

It is only feasible to open the windows if the humidity outside is lower than the inside.

Crikey - I didn't know that humidity could exert so much pressure. J/K.

Cheers

duncan303

I am reliably informed (by an expert)

that the answer to:
the volume of water contained 1 one cubic meter of air at a temperature of 2 C with a relative Humidity of 68%, @1000mb pressure.

is that Saturation point is ~5.7gm/M^3 and the water volume is at RH 68% is ~3.8gm/M^3 and therefore the dewpoint is ~ -3.8C.

so you can only cram ~1.9gms/M^3 or 19 ml of water out the window before it visibly condenses(saturates).


So how many cubic meters are there in an standard sized house?
Ta


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duncan303

The volume of the the ubiquitous 1919 – 1964 semi is approx 200 cubic meters.

with an outside temperature of 2 deg @68% RH (today's readings)
if you opened all the windows and had the same temperature inside and outside and then after a while you closed all doors and windows and extracted all the water vapour out of the enclosed air you would end up with 38ml x 200 which equals approx 7.6 litres of water. Note that we have a dew point of -3.8degC

We mostly only know what the RH is outside because BBC and weather stations tell us but what is generally accepted to be the most comfortable RH for humans to live in ?

I have just come back from a decent walk and the air was cold but I didn't really feel it to be humid, it was very enjoyable.


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keystone

Is there a point to this thread?

Cheers

27col

Not one that I can discover.

duncan303

keystone wrote: »

Is there a point to this thread?

Cheers

Condensation in the home is almost a daily topic in here, causing £1000's damage to belongings and property and possibly serious long term health issues.

I saw a photo recently of a babies cot surrounded by severe mould on the walls and at the bridging and the possible remedy suggested was to spray bactericide.


RH is something that we cannot see with naked eye so to a lot of people it is a total mystery and possibly something mystical.

Is opening the window always applicable? OP Question asked

Is the new part H going to cause more problems or less? Are desiccants a complete waste of money? Why does condensation still occur on triple glazing?

Are you going to help guys?




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keystone

With all due respect your calculations are totally meaningless to the vast majority of peeps. All they know is they have a problem. That was my point asking what was the point.

When houses were built to breathe and there was no CH blasting out all day and no mysterious fascination with blocking up each and every possible source of a "draft" and insulating the hell out of the place just because Prescotts envirostasi said so the condensation problem didn't exist. However, your calculations would have been no different then than they are today and add very little to solving this "problem" which is largely of our own making. You then add several showers a day into the equation plus taking wet clothes out of the washer and sticking them on the radiators to "dry" and we are totally suprised that humidity builds up inside the property whch manifests itself as condensation whenever it hits a cold surface.

Therefore I'm sorry but I still can't see the point of the thread to be brutally honest.

Cheers