Replacing old windows with newer energy-efficient versions improves functionality and can boost property value. Homeowners may not see significant savings in their heating and cooling costs, however, unless the existing windows leaked severely.
As the seasons evolve and temperature changes, contractors should discuss installing storm windows with their client base. Storm windows can produce savings similar to new windows at a much lower initial cost. Although they add little to the insulating performance of an existing window (in good condition), storm windows reduce the air movement through primary windows, which leads to less expensive heating and cooling bills for clients.
What exactly are storm windows?
Storm windows, which are available for most types of windows, can be installed on the interior or exterior of primary windows. For the most part, interior storm windows offer greater convenience than exterior storm windows because they are easier to install and remove (in other words, no ladder or scaffolding necessary).
Interior storm windows also require less maintenance because they are not exposed to weather elements, and they are more effective at reducing air infiltration because they seal tighter to the primary window. All things considered, interior storm windows are often the best choice for apartments and houses with more than one floor.
Storm windows range from inexpensive plastic sheets (or films) designed for one season to triple-track glass units with low-emissivity coatings that provide many years of use. The low-e coating—an ultra-thin, virtually invisible layer of metal—reflects infrared heat back into the home, improving the window’s insulation ability.
On average, low-e storm windows can save between 12 and 33 percent on the heating and cooling bills for a typical home, which ends up being $120 to $330 in yearly savings for a residence with annual heating and cooling costs of $1,000.
Mid-priced storm windows often use glass, plastic panels or special plastic sheets that can have specific optical qualities. Windows made of polycarbonate plastic or laminated glass also offer a higher degree of resistance to breaking, especially during a severe weather event.
What are the best storm windows?
In general, plastic storm windows are the most economical choice for homeowners with small budgets or people who live in apartments. Plastics are relatively inexpensive and simple to install, though they can damage easily. Glass panes offer better visibility and last longer than plastic, but glass can be heavy and fragile.
Plastic panels such as Plexiglas are tougher and lighter than glass, although they tend to scratch more easily and may turn yellow. Some plastic films can even diminish visibility significantly and degrade over time when exposed to sunlight.
The most common frame materials—wood, aluminum and vinyl—have their advantages and disadvantages. Aluminum frames are light, strong and nearly maintenance free, but they conduct heat rapidly and, therefore, prove to be a poor insulating material. Wood frames insulate well, but they expand and contract in response to weather conditions.
Wood-frame storm windows installed during the winter, for example, might not close easily in the summer, and windows installed over the summer might fit loosely in the winter. Wood frames are often heavy and thicker than metal frames, making storage difficult and possibly reducing the amount of natural light let into a room.
Vinyl frames are usually made of polyvinyl chloride (PVC) with UV stabilizers to keep sunlight from breaking down the material; however, they may expand and warp at very high temperatures, and crack in extremely low temperatures. Also, if sunlight hits the material for many hours a day, colors other than white will likely fade over time.
What else should contractors know?
Wood frames with aluminum or vinyl cladding give clients the best of both worlds: the natural beauty of wood, which is a better insulator than aluminum and vinyl, combined with the lower maintenance requirements of the other two materials.
When installing any storm window, there is a risk of condensation developing between the new unit and the existing window, so be sure to caulk the jambs and head to ensure the existing window is air tight, and fix any missing glass, rotting wood, broken parts or water leaks that could compromise the storm window down the road.
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