Save Money and Energy with Window Film Save Money and Energy with Window Film

New windows have lots of great energy saving feature - double and triple glazing, air gaps in the frames and low E argon gas between the panes of glass.  But what if you can't afford to replace your existing windows, does that mean there are no ways you can save money and energy? Fortunately there is a relatively low cost, easy to install window energy saver - window film. Installing window film on your old windows won't make them totally energy efficient , but it will allow you to save some money and energy without the cost of replacing your existing windows. Here's a quick primer of window films

Are window films really effective?

  • Window films can be very effective, some blocking out 70 - 80 % of the solar heat that would pass though a clear glass window as well as blocking out as much as 99% of the UV radiation.

How do window films work?

  • Sunlight is composed of three parts - the light we can see as well as infrared and ultraviolet rays we can't see but definitely can feel.
  • Window film acts as a barrier or a sunscreen to block UV rays and limit the amount of heat that can pass through the glass.The result is less harmful light and heat can get through the window glass so less energy is required to cool your home in the heat of the summer.
  • Primarily composed of thin plastic or polyester there are essentially two types of window film - non reflective (colored/tinted films) that basically absorb heat and reflective (metallic) films that have a thin coating of metallic particles to both reject heat and reflect ultraviolet and infrared light while allowing natural daylight to come through.

Choosing window film

  • When choosing window film there are two measurements you need to understand
  • Visible Transmittance (VT) is a measure of the amount of light passing through a window expressed as a number between 0 and 1. A higher VT indicates a film that allows light to pass through while blocking out unwanted heat gains.
  • Solar Heat Gain Coefficient (SHGC) is the other indicator (also a number between 0 and 1) and is a measure of heat admitted through a window. A low SHGC indicates less solar heat entering and more darkening or shading.
  • In general, colder climates benefit from products with a high SHGC (more heat allowed in), while hotter climates are better suited to low SHGC window films.

DoItYourself or have the pros do it?

  • Depending on the characteristics of the film chosen, you can expect to pay between $3 and $12 pre square foot while installation costs can range from $1 to $5 per square foot. Warranties on the film are commonly in the five year range but some has a lifetime warranty. The downside is often the longer warranty requires professional installation for the warranty to be effective.
  • Installing window film isn't overly complicated and can be done by a DIY'er willing to take the proper time and care to do the job right.

Murray Anderson is an experienced freelance writer whose work has appeared on numerous web sites, as well as in newspapers and books in both the US and Canada. He is often cited as an expert on home related topics.

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