Energy efficiency is a huge concern to homeowners as 40% of the heat that escapes from your home leaves through the windows. And 50% of the solar heat that enters a room comes in through–you guessed it–the windows. Obviously, energy efficient treatments can translate into considerable utility bill savings, especially if your windows are on a cold south exposure in the winter or a sun-saturated west wall in the summer. The degree to which products will meet your energy efficiency needs will depend on the fabrics and product features you choose and whether your window coverings remain open, closed, raised or lowered.
Poorly positioned or unprotected windows could cost the average home over $500 extra in heating and cooling bills each year.
There are many ways you can prevent winter heat loss in your home, such as using curtains, internal blinds and insulated shutters.
Closely woven curtains are an effective way to protect windows from heat loss at night. They also provide extra summer protection, especially with reflective linings, and of course provide privacy.
A snug fit on both sides of the window and at the top of the curtain stops warm air from moving down behind the curtain and cooling. Boxed pelmets or solid strips above the curtain rail are essential.
Curtain tracks which provide a return of curtain to the wall to give a seal achieve even better results. If yours don't, consider attaching the drapes to the window frames using pins, hooks or Velcro tape.
With internal blinds, tightly fitting Holland or Roman type blinds using closely woven fabrics are also suitable for reducing heat loss through windows. Blinds must be tightly fitted against the window surrounds.
Insulated shutters can be installed on the inside or outside of the window, and should fit tightly against the window frame forming a sealed air space. PVC, polystyrene and solid timber shutters can be used if they shut tightly and are not louvered.
There are however window treatments which have little or no effect in reducing winter heat loss. These include louvre, venetian and vertical type blinds which are not good insulators. They allow heated air to pass through the gaps between the slats and contact the cool glass. Reflective films and tinted glass also have a limited effect in reducing winter heat losses and can, if very dark, reduce internal light levels all year round.
To prevent summer heat gain it is best to stop the sun's heat from reaching the glass, rather than deal with the problem once the heat has entered your home. So in summer, external shading is much more effective at keeping your home cool than internal blinds or curtains. Using both external and internal window coverings will, however, provide maximum protection. The most appropriate method of shading your windows depends on which direction they face.
North facing windows should be shaded during summer. However, it is important that the shading devices do not reduce the amount of sun entering the house in winter. There are a number of suitable shading options such as blinds or opaque fabric mounted on pergola frames, which are inexpensive alternatives for providing shading when desired, while on cooler sunny days they can be retracted or rolled back to allow the sun through. Also removable or adjustable vertical shading such as blinds, awnings and shutters allow you to enjoy pleasant morning and afternoon sun in winter or on cooler summer days. Screen-type fabrics can provide significant heat reflection in summer without drastically reducing the amount of light that enters your home. They provide the best of both worlds – heat reflection and natural light.