Basics of Condensation

Product Knowledge Course
Introductory Level
THE BASICS OF CONDENSATION

This course covers the basic principals of
condensation as they relate to windows
and doors.
Condensation can be contributed to many
factors. Understanding them and taking the
appropriate measures to keep them
regulated will assure a comfortable and
healthy living space.
Objectives
______________________________
At the end of this course, you will
understand:
1. What is Condensation?
2. The two active elements
3. How to control condensation
4. Summary
The Basics of Condensation

Basic Principal
For condensation to form on window glass,
two elements are necessary:
COLD HUMIDITY
What is Condensation?

1st Element: The Cold
In winter, temperatures drop well
below the freezing point. The sealed
glass unit has an overall thickness of
between 19mm and 23mm which
separates the outside and the inside.
Two glass panes separated by an air
space ranging from 10mm to 16mm
forms the barrier between the cold
outside and the interior of the home.
The glass pane on the inside cools
rapidly and reaches temperatures
similar to those on the outside.
The Two Active Elements

It is, therefore, quite normal that the surface of
the glass becomes cold.
One of the ways to decrease, or rather slow
down the transfer of cold to the interior, is the
use of a gas in the air space, such as argon.
This gas has insulating properties higher than
that of normal air. The interior side of the glass
sealed unit will take more time to cool.

2nd Element: Humidity
The second essential element for the
formation of condensation is humidity. The
question that must then be asked is:
Where did the humidity come from?
In general, moisture in the home is produced
from bathing, cooking and is also released by
the human body. This humidity is carried by
the ambient air, and is found in the form of
vapour, invisible to the eye in this state.

The water is suspended in the air as a vapour. What you need to know, as a
basic, is that air is a gas which may contain a certain amount of water. The
warmer the air is, the more water it is capable of carrying.
The air, as all gases, reacts to changes in temperature in the same way. A hot
gas takes more space than a gas that is cold. When a gas is cooled, it shrinks
or contracts, and when it is heated, it expands.

Here are two examples that demonstrate that
phenomena:
When you store bikes away in the fall in the
garage, the tires are always properly inflated.
In the spring, when the time comes for the first
ride, why do you need to re-inflate your tires?
It is because the air of the tires has cooled down.
Take a balloon and blow it up. Once properly
inflated, put it in the freezer for 15 minutes.
After 15 minutes, open the freezer and retrieve
your balloon. What has happened? The balloon is
softer. It is not yet completely deflated. The air that
was inside has cooled and now takes up less
space.

Therefore, the air contracts or expands depending
on its temperature.
But what actually happens when a gas contracts?
Let’s compare air to a sponge. A sponge can
hold a certain amount of water before it is
saturated. If we halfway soak the sponge
in a basin of water, we can lift the sponge and the
water will not drain. It will retain it.
If we shake the sponge a little, water will always
remain on the inside. Now if we squeeze the
sponge, water will be released. The air is
the same way. Ambient air contains a certain
amount of water according to its temperature. If the
air is cooled, it contracts, and the water is then
expelled.

In the summer, when we are talking about the dew
point; it is the same phenomenon that we encounter in
homes in the winter.
The warm air in the month of August is responsible for
moisture. It is 30 degrees Celsius. When we look at the
weather, it tells us that the Dew point is 13 degrees
Celsius.
What does this mean?
It means that if the temperature drops to around 13
degrees, dew will then deposit on the ground. In other
words, that the air, which is now at 30 degrees,
contains a certain amount of water, and that it can
keep this water as long as its temperature does not
drop below 13 degrees.

The air occupies a certain space
according to its temperature and
water content When the air shrinks, its
molecules of water compress
If the air contracts too much, the
surplus of water must be
expelled

When hot air comes in contact with the cold surface of window glass, it cools and
expels its water, creating condensation.
The area of the glass most conducive to forming condensation is the perimeter,
where the glass spacer is found. It acts as a conductor and transmitter of the
temperature differences.

What’s important to remember:
The water that is found on the glass DOES NOT COME FROM OUTSIDE.
If humidity levels are controlled, the chances of condensation are reduced.
The cold alone cannot produce condensation.

Dealing with cold weather:
If the glass surfaces are kept at a high temperature, the
condensation will be limited.
The best example to illustrate this is the fog that forms on
the inside of the cars. To remove this mist, hot air must be
directed to the inside windshield. It is, therefore, the same
principal as windows.
It is necessary to allow the heat to circulate and reach the
windows:
-Remove window screens in winter
-Open the curtains and blinds during the day
-Leave the blinds and curtains halfway open during the
night
-Increase the home’s temperature
How to Control Condensation

Dealing with condensation:
Work to reduce the amount of humidity in the air:
-Do not dry clothes indoors on lines
-Run exhaust fans during showers or baths
-Run exhaust fans when cooking
-Limit the number of plants
-Shake boots, hats and mittens well before entering the home
-Do not keep wood used for heating inside
-Check the condition of the dryer vent
-Do not leave standing water in sinks

Another source of humidity in the air comes from
respiration. Depending on the number of occupants in a
home, the air must be filtered more often.
Upon exhalation, the human body expels moisture. We
can see this phenomenon in the winter in the form of
vapour.
It is important to take these factors into account, and
ensure that the ambient air is constantly changing.
-Obtain an air heat exchanger
-Leave the doors of rooms open at night
-Open the windows

Relative to external temperatures, this table indicates what the rate of
humidity should be in order to avoid the formation of condensation.
Attention, this data is given to show how to avoid condensation. Some
levels of humidity can be harmful to one’s health.
Outside
Temperature
Relative Humidity
Inside
-7° Celsius 35%
-12° Celsius 30%
-19° Celsius 25%
-23° Celsius 20%
-29° Celsius 15%

It is a physical science!!!
Condensation is the transfer of water from a gaseous state to a liquid state, caused
by a decrease in temperature. Therefore, we have no control over this, just as we do
not control the fact that water boils at 100 degrees Celsius.
However, we can control the factors that come into play by changing the habits of
occupants or by installing devices to control the rate of moisture and the movement
of air.

Windows should not be seen as a source of
moisture, but as an indicator of the level of humidity
in the home.
If a condensation problem occurs on windows, there
is a strong chance that the same problem is present
behind the interior walls, and on the cold walls of the
building envelope.
If the phenomenon was not present on old windows,
it is likely that air was escaping through them along
with moisture.
In Summary

-Windows should not be seen as a source of
moisture, but as an indicator of the level of
humidity in the home.
-If a condensation problem occurs on windows,
there is a strong chance that the same problem
is present behind the interior walls, and on the
cold walls of the building envelope.
-If the phenomenon was not present on old
windows, it is likely that air was escaping
through them along with moisture.
For other explanations, consult these sites…
http://www.apchq.com/quebec/fr/conseils-
apchq.html_periodes-de-grand-froid-et-
condensation-l-apchq-rappelle-quelques-
trucs-pour-eviter-le-probleme22-01-201.html
http://www.cmhc-
schl.gc.ca/odpub/pdf/61033.pdf?fr=14395642
19363
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