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Heating Ventilating and Air Conditioning

Why do windows ice up inside?

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Wiki User
February 01, 2009 1:47PM

The air inside contains more moisture and "condenses" on the surfaces. If below 32deg.F it forms ice. This will occur usually where the insulating quality of the surface is poorest. This may be the product of air "infiltration". Consider caulking the inside perimeter of the windows when the ice is gone and the surface is dry. If these are single pane, consider upgrading to double or tripple pane windows. If retrofitting is not an option, consider the addition of storm windows or as a cheap seasonal fix, get the shrink wrap clear window kits at the hardware store. If this is a very "tight" house, consider the adition of an air to air heat exchanger system. These will help exaust the moisture and pollutant laden air, replacing it with fresh air, etc. The two air streams do not communicate with eachother, but much of the energy from the exaust air stream is transferred to the fresh air via a heat exchanger, keeping your heating costs in check. lc