Does blow drying windows cause more condensation

Will blow drying windows solve the condensation problem on my windows? At first I tried wiping them down with a hand towel but it leaves smears and doesn’t get all the moisture off. So I’ve been blow drying my windows instead. Will that help or does it only reduce the condensation temporarily?

Answer from Green Energy Efficient Homes

Blow drying your windows will remove the condensation from those windows for a short period. But the two issues contributing to the condensation haven’t been tackled at all. Those two issues are high humidity in your house, and poor insulation value of the window glazing. Typically if you have really bad condensation on your windows you have both problems. If the condensation is mild to moderate then it could be one or the other, or still both. Let’s explore each of them.

High humidity in your house: you’ll get a lot of condensation on windows if a lot of moisture is produced inside your home, or if there’s no way for humidity to escape. Common sources of humidity are things that breathe and emit moisture in the process of breathing (humans, pets, plants), exposed water surfaces such as sinks with a dripping tap that keeps the sink surface wet, sinks left full, open toilet bowls, taking showers or baths, cooking without using an outdoor venting range hood, or drying clothes on an indoor clothesline or clothes rack.

The most common reason humidity can’t escape is if the house is very well sealed. This typically only happens in very well insulated homes (because good sealing is part of what makes the home energy efficient), and since a well insulated home typically has high quality efficient windows, the condensation isn’t normally that big of a problem unless it’s very cold outside (or the windows have broken seals that mean they are no longer energy efficient). If you can think of any moisture sources that can be minimized (for instance, putting your toilet seat down, taking colder showers, fixing a dripping tap), tackle those problems first. If humidity is still a problem, you can get an energy efficient dehumidifier for under $400 which will cut the humidity enough to minimize condensation on your windows.

Poor window insulation is the other main cause of condensation on windows. Poor insulation value of the glazing is typical in older windows, or cheaper new windows that were not manufacturered to high standards of energy efficiency such as the ENERGY STAR window specification or the new, more stringent ENERGY STAR Most Efficient window specification. You can also get poor insulation value in double-glazed windows where the seal between the two panes has broken, and the inert gas used between the panes has escaped. This gas, usually argon or sometimes krypton, has a high insulation value and helps keep the outdoor cold away from the inside glass pane. If the gas leaks out, you have only a thin layer of air as an insulator. If you find that some of your windows have more condensation than others, it’s quite possible that the ones with more condensation have broken seals and the inert gas has escaped. A crack in the glass of one pane, or humidity build-up between the inner and outer panes, are both sure signs that you’ve lost the better insulation value of the gas filler.

Now, to answer your specific question: blow drying windows will remove the condensation from your windows temporarily but it won’t solve the problem. Blow drying windows will remove the condensation in the short term because:

  • Airflow causes the condensation to evaporate
  • Heat from the blow dryer warms the glass temporarily, delaying further condensation.

However, the moisture that evaporated is now in the air inside your home, available for future condensation. And once the heat from blow drying windows has dissipated (or even escaped through the glass to the out of doors), condensation can begin anew.

The main effect of blow drying windows is therefore to give you the satisfaction of seeing the moisture go away for a short time. The same applies if you use hand towels to dry off the condensation, especially if you dry the towels on a line indoors. (If you dry them out of doors or in a clothes dryer, most of the moisture does leave the house.)

For a longer term solution, first minimize the sources of moisture, perhaps using a dehumidifier to remove moisture if you can’t find an easy source to eliminate, then improve the insulation value of your windows. You can get replacement house windows that are highly efficient if you have a big budget; the improved insulation of these windows should minimize the condensation problems. If you’re on a shoestring budget and only want to spend a few dollars, consider buying plastic window insulation kits.

These kits let you seal a window off for about $5 by taping a plastic sheet around them and using your blow dryer to shrink the plastic until it’s taut and almost invisible. That’s really the only way I can think of using a blow dryer to reduce window condensation – but here the blow dryer is just helping you apply the plastic. When you put the plastic on, by the way, be sure to first remove the condensation from the windows, otherwise you’ll seal that moisture between the glass and the plastic and have to look at the condensation even after you’ve tackled sources of humidity inside your home!

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