by Perry525 »
Sun Dec 23, 2007 5:30 pm
HI,
I am sorry I didn't finish my blog yesterday. I was called away to dinner.
I said the condensation was your fault and that was perhaps a trifle unkind as your situation has more to do with bad design and bad building than just leaving the kettle boiling in the kitchen.
Let me try and explain what I think is happening.
The traditional way of dealing with condensation was to open a window or door to the outside. That works most of the time, except that on some days the outside humidity is 99%. And it doesn't work. (Where I live we've had eight days of 24 hours a day 99% humidity this year.) There is also the problem of humidity coming in (water vapour abhors a vacuum) and other pollutants.
With the first oil crisis thirty years ago, came increased heating costs and people started to look at ways of saving money, they started by blocking all the ventilation holes, getting rid of drafts and then moved to increased insulation.
The result, there are millions of homes in over thirteen states in America suffering from damp due to bad practices, and millions more in this country.
The problems due to blocking ventilation are compounded by encouragement to save on heating costs by turning off the heating when going to work or bed.
The unfortunate by product of lowering temperatures by more than two degrees C is that cold air cannot hold the same amount of water vapour, so the excess water condenses on the nearest cold surface.
At 30 degrees C air holds 30 grams of water per kilo of air. (A kilo of air is about 833,333 cubic centimetres)
At 20 17
At 10 9
At Zero 5
If you pour 30 grams of water onto your kitchen floor it makes a fine mess.
If you work out the volume of your house multiply that by 30 grams and pour that on the floor - don't bother!
This water vapour is a invisible gas with a tiny molecular structure, that finds it way into your clothes, carpets, plaster walls and ceilings everything that is not totally waterproof.
The average person creates two and a half litres of water vapour each per 24 hours.
If there are two of you asleep in the same small room for eight hours that’s a lot of water vapour for the air to absorb.
You probably start off with the room at 18 to 22 degrees, then you close the blinds/curtains, then the heating goes off and the temperature drops.
At first, if you have double glazing, the temperature in the centre of the room is around 18-22. With the heating turned off and the natural daytime circulation of air stopped by the blinds/curtains the temperature in the space between the curtains/blinds and glass drops dramatically!
The water vapour condenses onto the glass and surrounding plaster, the water vapour in the surrounding air moves into the space and onto the glass and walls as the temperature of the room drops.
Once the walls and the contents of your home are damp, the spores that are in all parts of the home and outside, settle and start to grow.
This growth generates more spores that you breath in, these can make you ill.
New Zealand has one of the highest humidity rates in the world, a 80% average, they also like carpets and cats.
Damp carpets make ideal homes for Dust Mites. Dust Mites are blind little spiders that live on damp, skin particles and flour from dropped bread and biscuit crumbs. The faecal pellets (toilet) that these mites produce, four each a day, are the things that make people ill.
Each time you dust or vacuum these are stirred up and take about 30 minutes to settle again.
The mites that live on cat dander (skin flakes) produce toilet pellets that are much lighter. These float in the air for up to 75 days after a good dust and vacuum.
Beat the dust mites by showering just before going to bed.
Scandinavian countries forgo the carpets and dust mite allergies are almost unknown.
Cutting off the air supply to save heating cost is OK. provided you have enough fresh air to keep fit and well. Our homes are considered to be the most polluted places most of us use.
Fresh Air is 78% Nitrogen, 21% Oxygen, 0.04% Carbon dioxide, 1 to 4% water and a number of other gases.
We breath out 78% Nitrogen, 15 to 18% Oxygen, 4 to 5% Carbon dioxide, various other gases and our breath is saturated with water vapour.
One important product of high humidity is heating costs go up as it costs more to heat all that water vapour.
You should consider buying a good indoor/outdoor temperature gauge that has a remote outside sensor for temperature and relative humidity, use it to see what’s going on outside and inside.
Consider buying a de-humidifier, with an adjustable humidistat, one that can extract at least 10 litres per 24 hours, use it, (with a tank so you can see how much water has been harvested, and a pipe to the outside, so that once your problems have gone away, you can leave it to work and forget it.) leave it on 24 hours a day, don’t turn it off at night because it makes a noise, after a few weeks the place will dry out and thereafter it will hardly come on at all.
Finally, dust mites will grow in humidity above 45%, they will thrive and multiply like mad when the humidity rises above 60%.
