EFCO Special Purpose Windows Understanding Condensation - Manual (Page 5)

General Service and Maintenance Manual
SECTION 5
CONDENSATION
5.c. FREQUENTLY ASKED QUESTIONS:
DO WINDOW COVERINGS OR DRAPES CAUSE ROOMSIDE CONDENSATION ON WINDOWS OR DOORS?
Drapes and other window coverings do not cause condensation; however they can contribute to the problem by restricting the flow of
air over the glass surface. Therefore, condensation is more likely to occur when drapes are closed and shades are pulled down.
HOW DOES AIR CIRCULATION IMPACT ROOMSIDE CONDENSATION?
Air circulation affects the supply of fresh air to all areas of the room. Poor air circulation within the room will keep the air next to your
windows cooler. When air movement is restricted next to a cool surface the air will cool down sooner than well circulated air. As room
are temperature decreases, its ability to hold the water vapor decreases. Using the same principle as a defroster in an automobile,
supplying fresh air to the window areas slows down the cooling process and reduces condensation.
DOES THE AMOUNT OF ROOMSIDE CONDENSATION DEPEND ON WINDOW TYPES?
Sometimes hung and sliding windows may experience more condensation than other window styles. The window depth must be split
between the two sashes because the glass is oriented in different planes, therefore those sashes are sometimes not as deep as other
window type making them generally have less condensation resistance. Hung and sliding windows could be a few degrees cooler in
temperature than other window types in the same room.
WHY DOES A STRIP OF CONDENSATION SOMETIMES FORM ALL THE WAY AROUND THE ROOMSIDE OF THE WINDOW?
The center of the glass stays warmer than the glass close to the edge. The strip of condensation is NOT an indication the window is
leaking air or not functioning correctly.
HOW CAN EXCESS HUMIDITY CAUSE PROBLEMS?
Excess humidity can create problems; some are just nuisances like condensation on the windows, musty smell, others can be serious
such as blistering of peeling paint, damage to insulation, stains on walls and ceilings or structural damage to the building.
WILL ROOMSIDE CONDENSATION RUIN MY WINDOWS?
If condensation issues are not addressed, window problems may appear over time.
WHY DO I STILL HAVE ROOMSIDE CONDENSATION EVEN THOUGH I AM RUNING A DEHUMIDIFIER?
The humidity is likely still too high. There are a variety of reasons condensation may still be appearing including but not limited to;
varying air temperature in the home, air circulation, window coverings and other sources of water placing more moisture in the air than
the humidifier can remove.
WHAT CAN I DO TO CONTROL ROOMSIDE CONDENSATION?
Reduce humidity. See table on page 15 for specific examples.
DO WINDOWS OR DOORS CAUSE EXTERIOR CONDENSATION?
No, windows and doors do not cause condensation. Exterior condensation is dew; the same condensation you see on cars and lawns
on some mornings. Dew on windows is a natural atmospheric phenomenon, and it doesn't mean your windows are leaking air or
malfunctioning in any way. Actually, exterior condensation is a sign of energy efficiency, indicating the outside pane is thoroughly
insulated from the heat indoors.
WHY DOES EXTERIOR CONDENSATION OCCUR?
Exterior condensation happens when the exterior surface temperature of the window falls below the dew point of the air. This type of
condensation is more likely to occur when outside humidity levels are higher. It typically occurs in the spring and fall when cool nights
follow warm days.
HOW CAN I CONTROL EXTERIOR CONDENSATION?
Open the drapes or shades at night, increase the interior temperature a few degrees at night or shield the windows or doors from
direct line of sight to the sky using trees, awnings, etc.
WHAT DOES CONDENSATION BETWEEN THE GLASS MEAN?
Condensation between the sealed panes of an insulated glass unit is an indication if seal failure and the insulated glass unit will need
to be replaced.
EFCO CORPORATION 2013 PAGE 17