by James Dulley
Engineering ConsultantRolling shutters improve the energy efficiency and security of your windowsQ: My windows are not the most efficient, but they are still in good condition. To improve efficiency and provide more security and safety from storms, I might install rolling shutters. What features should I look for?A: Having windows that are still in good condition but are not the most energy efficient is common. If good-quality windows were installed within the past decade, they should last a very long time with little maintenance. This is particularly true for windows with vinyl or thermally broken aluminum frames. Windows with pultruded fiberglass should practically last a lifetime.
Although rolling window shutters offer many advantages in addition to energy efficiency, there are other lower-cost options to also consider. Installing magnetically attached acrylic interior storm windows is a relatively low-cost option to improve efficiency.
Some of the new low-emissivity permanent window films save energy year-round. They are nearly clear and you can install them yourself. Both of these options also block much of the sun’s fading UV (ultraviolet) rays. Installing insulating window shades or curtains is also effective.
Adding rolling shutters on the exterior of your windows improves efficiency and also offers security and storm protection. These shutters are commonly used in coastal hurricane zones.
The actual energy savings from installing rolling shutters depends on the type of window glass you have and, to a lesser extent, the types of slat in the shutter. If your house has double-pane windows, adding the shutters will about double the insulation value of the windows. With single-pane windows, the efficiency increase will be even greater.
You can get an additional energy savings during summer because the rolling shutters also block the direct heat from the sun’s rays through the windows. The shutters can be lowered to any position to allow in only as much light (and heat) as you desire. When completely lowered over the window, they block nearly all of the light.
Rolling shutters are extremely strong and secure because they operate similarly to a rolltop desk. Narrow slats roll up into a box housing above the window. The ends of each slat slide in vertical tracks on each side of the window, making them very secure and relatively airtight when fully closed. The slat itself provides insulation, as does the dead air space created between the shutter and the window glass. In cold climates, this also reduces indoor window condensation problems.
If you want security and privacy but also light and ventilation, slightly raise the rolling shutter. The bottom of the shutter will not rise, but the slats will separate slightly exposing the interlocking flanges between them. Many of the shutters are designed with narrow slots in the flanges, which allow some light and fresh air to filter in.
Roll-formed metal, plastic or extruded aluminum are used to make the slats. All are suitable for most areas. The extruded aluminum slats are the strongest and most expensive and are often used on shutters for large windows. The roll-formed metal slats can be filled with foam insulation for higher efficiency and rigidity. Check your local building codes for required materials and strength.
An important feature to consider is how the rolling shutter is opened and closed – usually with a pull strap, a crank handle or an electric motor. Keep in mind, if your shutters are inconvenient to use, you will not close them as often as you should.
For most small- to average-sized windows, a pull strap is easy to use and inexpensive. Large shutters or ones made from heavy gauge aluminum may be easier to operate with an hand crank. Electric motor operators are most convenient, but also more expensive.
If the pull strap or crank is indoors, there will have to be a hole in the wall connecting it to the outdoor housing. This will allow a slight amount of air leakage. An electric motor operator will eliminate the need for a hole.
James Dulley is a nationally syndicated engineering consultant based in Cincinnati.
If you have a question about energy use or energy-efficient products, send it to: James Dulley, Electric Consumer, 6906 Royalgreen Drive, Cincinnati, OH 45244; or visit www.dulley.com.For more informationThe following companies offer rolling window shutters:
• AC Shutters, 800-745-5261,
www.acshutters.com;
• Roll-A-Way, 800-683-9505,
www.roll-a-way.com;
• Rollac Shutters, 888-276-5522,
www.rollac.com;
• Wheatbelt, 800-264-5171,
www.rollupshutter.com.