Dehumidifier

• A dehumidifier is the most powerful weapon against mold on a window because it prevents and reverses the process that causes window mildew in the first place. You can find portable dehumidifiers in home supply stores. They work by drawing in local moisture through a filtration system and extracting it from the air to promote a drier atmosphere. Just turn on your dehumidifier until the window becomes completely dry.
  
  

Why It Works

• Mildew forms on surfaces with standing moisture, and standing moisture occurs on windows as a result of excess vapor from humidity in the air. Other household surfaces can attract mildew due to water damage, but glass windows are not subject to water damage, and therefore can only promote mildew growth due to collected moisture from the air. If you deny mildew spores this source of moisture, they become completely neutralized.
  
  

Supplementary Methods

• While a dehumidifier can neutralize mildew, you will need additional tools to fully eliminate the problem. Remove any spores resting on the surface of the window using a hand-held vacuum cleaner or vacuum hose. Remove bacteria by spraying your window with an ammonia-based glass cleaner; ammonia is a powerful anti-mold cleaning agent. If mildew has also affected the window sill, spray it with undiluted vinegar, rinse after 15 minutes and wipe it dry.
  
  

Preventative Maintenance

• If you want to prevent mold from returning, just keep the surrounding area dry. Wipe down any frost appearing on the window each morning, and turn on your dehumidifier any time the humidity in the room becomes excessive. You can measure humidity levels by placing a relative humidity sensor in your home. Try to keep your indoor relative humidity below 50 percent.