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| Humidity, Dew Point, Heating and SolarVenti |
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![Humidity, Dew Point, Heating and SolarVenti]( "Humidity, Dew Point, Heating and SolarVenti") If you're having trouble understanding "dew point" and "relative humidity," you are not alone! so do most people. The text below should help you.
First, the warmer air is, the more water vapor it can "hold." As you heat the air its relative
Dew point is a measure of how much water vapor is actually in the air.
Relative humidity is a measure of the amount of water in the air compared with the amount of water the air can hold at the temperature it happens to be when you measure it.
Below is the amount of water vapor air can hold at various temperatures:
30 C: 30 grams per cubic meter of air
20 C: 17 grams per cubic meter of air
10 C: 9 grams per cubic meter of air
These numbers, which apply to air at sea level pressure, are based both on measurements over the years, and theory. They are basic scientific facts.
Now, let's see how dew point and relative humidity work.
Imagine, that at 3 p.m. you measure the air's temperature at 30 degrees and you measure its humidity at 9 grams per cubic meter of air. What would happen if this air cooled to 10 degrees with no water vapor being added or taken away?
As it cools to 10 degrees the air becomes saturated; that is, it can't hold any more water vapor than 9 grams per cubic meter. Cool the air even a tiny bit more and its water vapor will begin condensing to form clouds, fog or dew - depending on whether the air is high above the ground, just above the ground, or right at the ground.
Back at 3 p.m., when we made the measurements, we could say that the air's dew point is 10 degrees C. That is, if this particular air were cooled to 10 degrees at ground level, its humidity would begin condensing to form dew.
How about relative humidity? At 3 p.m. the air has 9 grams of water vapor per cubic meter of air. We divide 9 by 30 and multiply by 100 to get a relative humidity of 30%
In other words, the air actually has 30% of the water vapor it could hold at its current temperature.
Cool the air to 20 degrees. Now we divide 9, the vapor actually in the air, by 17, the vapor it could hold at its new temperature, and multiply by 100 to get a relative humidity of 53% (rounded off).
Finally, when the air cools to 10 degrees, we divide 9 by 9 and multiply by 100 to get a relative humidity of 100% - the air now has all the vapor it can hold at its new temperature.
Amount of water in a 3 bedroomed house at 22 degrees centigrade
1 room is say: 4 x 3.5 x 3 = 42
six rooms of that size = 252 cu m
20 grams per cu metre at 100% RH
total weight of water in air in above house = 5.040 kilos of water
at 75% humidity = 3.78 kilos
at 35% humidity = 1.26
SolarVenti saves you having to pay to heat about 2.5 kilos of water just in the air
we estimate you can double that to 5 kilos because of what is absorbed in the fabric of an air tight damp house
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| Contact us |
Telephone:
01782 791572 or on
08458 736359 (Local rate from anywhere within the UK)
Fax:
Please call and request number
eMail:
info@solarventi.co.uk
Our new address is:
Unit 14A
Moorfields Industrial Estate
Cotes Heath
Stafford
ST21 6QY |
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| Products
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There are six products in the SolarVenti range. Under ideal sunny conditions the smallest unit, the SV2 has a minimum airflow of 20m³/Hour whilst the largest, the SV30 unit has a minimum airflow of 120m³/Hour.
The newest product, the SV30H Plus, is a hybrid version of the SV30 which additionally provides Solar Water Heating. |
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