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Storm windows are windows that are mounted outside or inside of the main glass windows of a house. Storm windows can be made of glass, rigid plastic panels, or flexible plastic sheets; and may be permanently or temporarily mounted. They function similarly to insulated glazing. The term may also refer to a small openable flap found in the side window on light aircraft.
On modern houses they serve on existing windows in order to improve their thermal insulation and soundproofing. Aside from insulation, storm windows provide an additional measure of protection for homes against damages to costly glass panes during inclement weather such as hail. On older houses, storm windows were installed in autumn when window screens were removed. Later units combined the storm and screen pieces. Similarly, storm doors (also called "screen doors") allow similar energy savings with less efficient primary doors – and allow a screen for summer ventilation.
Modern storm windows are a typical energy upgrade solution for cold climates. They are mostly intended to improve the insulation value (R-value) of existing windows, especially single-glazed units.
Storm windows do not make sense in buildings with energy efficient windows with integrated screens, or in hot or moderate climates; they only make sense in buildings where windows are a major cause of heat loss and lack of thermal comfort.
Advantages and disadvantages
Storm windows can be very cost-effective, in cold climates. They are inexpensive, and can reduce heat loss by up to 50% or so, increasing the building's comfort and reducing the heating costs, which is difficult to achieve with inexpensive replacement windows.
They can also reduce exterior air infiltration significantly, and are inexpensive: even the best storm windows - three track exterior windows, with low-E glass – will cost a small fraction of the price of standard replacement windows.
Interior storm windows can produce problems of condensation and be visually obstructive, while exterior storm windows can have a negative visual impact.
The negative visual effect can be minimized by using single line storm sashes, while possible problems of condensation can also be avoided by incorporating vent holes and a sealed fit.
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A plastic PVC interior storm panel is particularly inexpensive and easy to install but these panels lose quality over time and may get broken quite easily. Storm windows with Low-E glass and metal frames are a more durable choice, and can provide better insulation.
Manufacturing process and applications
There are several laminated glass manufacturing processes:
The first method utilizes two or more pieces of glass bonded between one or more pieces of plasticized polyvinyl butyric resin using heat and pressure.
The second method uses two or more pieces of glass and poly-carbonate, bonded together with aliphatic urethane inter-layer under heat and pressure.
The third type of laminated glass is interlaid with a cured resin.
Each manufacturing process may include glass layers of equal or unequal thickness.
- Home Energy Projects: An Energy Conservation Guide for Do-it-yourselfers. DIANE Publishing. 1996. p. 62. ISBN 0-7881-3373-X.
- Oliver R. Williamson, Sarah Cory Rippey (1906). The Complete Home. Original from the University of California: D. Appleton and company. p. 51.
- "Storm Windows"; Energy.gov
- "Testing the energy performance of wood windows in cold climates"; PDF, A Report to The State of Vermont Division for Historic Preservation