"We often get calls from homeowners who are concerned that their windows are 'sweating' or leaking either inside or outside the home because they see moisture on the glass," said Christopher Burk, technical product manager at US window maker Simonton Windows.

That's simply not the case. "While condensation may collect on the interior or exterior of energy-efficient windows, the units are really doing their job by helping serve as a barrier in the home," he said.

Windows don't cause condensation. They just prevent the moisture in the home from escaping to the outside.

"If the inside glass surface on double- or triple-glazed windows shows excessive moisture, you can be reasonably sure that the moisture is also collecting on your walls and ceilings," Burk said. "This means you should take steps to reduce the humidity level in your home by using exhaust fans and dehumidifiers."

A lot of the water vapor is created by the inhabitants. A family of four can add 250 mililiters of water vapor every hour to the home just through normal breathing and perspiration. And if you take a five-minute shower you produce another 250ml of water vapor.

Even the simple act of cooking dinner on a gas stove can produce 1.2 liters of water vapor.

Water vapor is part of our lives and our homes. To help control the amount of condensation in the home, experts at Simonton Windows recommend the following tips:

Use kitchen and bathroom exhaust fans.

If you have a humidifier, set it to the correct outside temperature.

If your home is overly humid, use a dehumidifier.

Properly vent clothes dryers, gas appliances and stoves.

Open a window in the bathroom.

Open curtains and blinds to allow more air circulation around your windows.

Homeowners with the most cause for concern are those with older, less efficient windows.

"Windows are just like any other major part of the home," Burk said. "They wear out over time and need to be replaced. If your windows have air leaks, don't close properly, or are failing to act as a solid barrier to the environment, then it's time to consider replacing them with energy-efficient windows."

He also recommends knowing the difference between condensation on the glass and between the glass panes of the window. "If you see moisture, fogging or cloudiness between the panes of glass in your window, this indicates that the seal of your window has failed and it's time to get a new window," he said.

"Failed seals lack the energy efficiency and features necessary to help you keep energy bills low and enjoy comfortable living in your home."

While condensation on the interior or exterior of the glass is manageable, moisture between the glass needs swift attention, according to Burk.

THE PHILADELPHIA INQUIRER (MCT)