Storm window

Storm windows are windows that are mounted outside or inside of the main glass windows of a house. Storm windows exist in North America, but are uncommon in continental Europe, where double, triple or quadruple glazing is prevalent. 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.

In the United States, the older style of this window is often referred to as a "storm sash".

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.

Energy upgrade
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.

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%, 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. Storm windows are an inexpensive add-on: 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; exterior storm windows can have a negative visual effect.

The negative visual effect can be minimized by using single line storm sashes. Condensation problems can be avoided by incorporating vent holes and a sealed fit.

Types of Storm Windows
Storm windows are used as an additional layer of insulation and protection for existing windows and are available in various materials and configurations.

Material and Design

 * Aluminum Frames: Known for their affordability and durability with minimal maintenance required. These frames typically feature standard or low-e glass panels and often have corrosion-resistant coatings.
 * Wood Frames: Offer an attractive appearance and can be painted or stained to match a home's exterior but require more maintenance and are generally more expensive.
 * Vinyl Frames: Notable for their energy efficiency and affordability. They require low maintenance but are less durable than aluminum or wood frames.

Glass Types
Storm windows come with either glass or acrylic panes. Glass panes provide better visibility and last longer, whereas acrylic panes are less breakable but can scratch more easily. Modern storm windows often feature low-e glass, which improves energy efficiency by reflecting heat.

Configurations

 * Two-Track: Featuring an outer track with a screen on the lower half and a pane of glass on the upper half, and an inside track with a half-pane of glass for ventilation.
 * Triple-Track: Consisting of two window panes and a half-screen on three separate tracks, allowing for adjustable ventilation.
 * Two-Track Sliders: Designed for horizontal opening, suitable for slider windows.
 * Basement Storm Windows: Typically a single fixed pane of glass covering the window.

Installation
Installing storm windows can be a DIY project, requiring tools like a screwdriver, caulk gun, and putty knife. Proper installation ensures their effectiveness and energy efficiency.

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.