EFCO Special Purpose Windows Understanding Condensation - Manual (Page 4)

General Service and Maintenance Manual
SECTION 5
CONDENSATION
5.c. FREQUENTLY ASKED QUESTIONS:
WHAT IS CONDENSATION?
Condensation is the process by which a gas changes to a liquid. As air become saturated with too much humidity, it cannot hold the
water vapor. Moisture is in the air all around us. When warm, moist air contacts a cooler surface, such as window glass, the air cools
and cannot hold as much water vapor so it condenses and collects on the cool surface.
DO WINDOWS OR DOORS CAUSE ROOMSIDE CONDENSATION?
Windows and doors do not cause condensation. Typically the first place condensation can be seen is on window and door glass. Just
like a bathroom mirror doesn’t cause condensation after a hot shower and car windows don't cause interior frost in the winter when
several passengers are in the vehicle; the cooler surface is simply where it collects.
WHY DOES ROOMSIDE CONDENSATION OCCUR?
Condensation is water appearing on the roomside of windows and doors because conditions are just right for this to happen. The
roomside glass surface temperature is at or below the dew point for the amount of moisture (humidity) in the inside air. When warmer
air, which can hold more moisture than cooler air contacts the cool surface of the glass, the air condenses the excess moisture out
onto the cool surface.
WHAT IS DEW POINT?
The temperature of air, at a given humidity level, at which it can no longer hold all of its water vapor and some of the water must
condense into liquid water.
WHAT CAUSES EXCESS HUMIDITY?
Everyday living: Showers, baths, cooking, washing dishes, laundry, pet water bowls and cleaning all add moisture to the air; as much
as 4 gallons or more per day in some living areas. People even exhale moisture into the air as they breathe. Building construction:
Modern, energy efficient, well insulated, building help hold down heating and cooling costs however, the same building techniques
that help blocks outdoor air from entering buildings also keep moisture from venting to the outdoors.
IS ROOMSIDE CONDENSATION MORE LIKELY TO OCCUR IN CERTAIN CLIMATES OF TIMES OF THE YEAR?
In areas where January temperatures average 35
ࡈ F or less, condensation is more likely to occur. In the summer and fall months,
buildings pick up moisture from the damp air. As the heating season begins and windows are closed, the indoor air will have more
moisture, so temporary condensation for the first few weeks is possible.
ARE THERE OTHER CASES WHERE WINDOW CONDENSATION IS ONLY TEMPORARY?
Building materials used in new construction or renovation such as wood, cement, dry wall, plaster and paint all contain moisture which
is gradually released into the air. This excess moisture can cause condensation but will usually disappear after the first few heating
seasons. Buildings also absorb moisture during humid summers. This moisture condenses during the first few weeks of heating until
the building dries out. Additionally, anytime there are quick and sudden drops in temperature during the heating season,
condensation may temporarily appear.
WHY DO I HAVE CONDENSATION WITH MY NEW WINDOWS WHEN MY OLD WINDOWS DID NOT?
Windows do not cause condensation; however, they are an indicator of high humidity levels. The older less efficient windows allowed
air to move across the glass by letting outdoor air inside or allowing inside air to escape outdoors, preventing the air temperature of
the glass from reaching the dew point.
WHY DO I HAVE CONDENSATION ON MY WINDOWS AND MY NEIGHBOR DOES NOT?
Indoor temperature, ventilation, air exchange, window coverings and floor plans as well as everyday life can vary from room to room.
It is not unusual for a family of four to contribute 15 to 20 pounds of moisture per day to their indoor environment depending on their
habits. The typical family of four can produce 12 pounds of moisture per day just breathing. Washing dishes for three meals a day
can produce one pound of moisture. One shower can add 1/4 pound and there are many other activities or situations where moisture
is added to the indoor air.
IN THE SAME ROOM, WHY DOES ONE WINDOW HAVE ROOM SIDE CONDENSATION AND OTHERS DO NOT?
There are many factors attributing to this phenomenon including any number of the following; Air circulation within the room or
building varying room temperatures, air register location, type of window (hung and sliding windows may be colder), window size,
glass type (Low-E versus clear), window coverings, window screens, placement of moisture sources in relation to windows (i.e.
plants), the direction the windows are facing, elevation of the windows, wind direction, direction of the sun or partial blockage of the
sun due to trees, buildings, etc.
EFCO CORPORATION 2013 PAGE 16