In some areas, installing outdoor window shades is a well-known tactic for keeping houses cooler while saving money. If you drive around the U.S. South, Southwest, Southern California or any place where the sun is relentless, you'll find an ample number of houses with outdoor window shades.
Venture beyond those areas and far fewer homes have outdoor window shades; they're practically unheard of. But in this age of climate change—and even for those sunnier times of the year—outdoor window shades are looking better all the time.
Windows Are Major Energy Losers
It's sometimes said that windows are thermal holes. What this means is that window-less walls provide the absolute best barrier against outside heat or cold.
No window—no matter the number of panes, type of interior gas, or low-e coating—can compare to the insulating effect of siding, fiberglass insulation, and interior drywall, all sandwiched together. The minute you punch a window in a wall, exterior temperatures begin to influence interior temperatures.
Windows rapidly lose whatever kind of artificial climate you are trying to create in your home, and that's why we say that windows are losers.
Anything you can do to block the sun from entering your home when you're trying to keep the home cool will help with those efforts: low-e glazing, sunscreens, interior blinds, awnings, and shutters.
Interior blinds are best for privacy but aren't best for preventing the convection effect of sun blasting inside and heating your home.
What works better is to catch the sun before it reaches your home's interior. Stopping the sun from reaching your exterior window glass is just one step, but an important step, in cooling down your house and reducing your energy bills.
Most of us don't want to live in a dark, windowless box. The second-best option is to avoid having windows on sun-facing sides. This can be incorporated into house plans upon construction. Or, if remodeling, you can remove windows, build over the gaps, and possibly reinstall the same windows in a different area.
Hood and Solid Aluminum Awnings
Hood and solid aluminum awnings are the best way to ambush the sun before it can hammer your windows. Hood awnings are like hat visors for houses, but with side protection, as well.
- Pros: Unlike motorized awnings, fixed hood awnings are DIY-friendly. Since they are fixed in place, the wind has to work that much harder to tear them from their footings.
- Cons: Functionally, awnings are great. Stylistically, awnings date your house, as these types of awnings were used in great numbers from the 1920s to the 1970s. Faded, falling-apart aluminum awnings litter the U.S. South. Even in good condition, these awnings have a ponderous visual effect on your home's exterior.
Bahama (or Bermuda) Shades
Louvered shutters that have a long piano hinge at the top and tilt upward. Side arms are then set in place to hold the shades at an approximate 30-degree angle. When the shade is up, the louvers are horizontal, permitting people in the house to look outside. Bahama shutters have two functions: keeping the sun out and protecting the glass from flying debris during hurricanes. The cost is about $300 for a self-installed Bahama shutter.
- Pros: Bahama or Bermuda shades are easy to install. Once you have the top track in place above the window, you have little else to do besides sliding the shutter in place, attaching the side arms, and screwing in the locking brackets.
- Cons: If you like lots of light, these shades cannot be flipped all the way up. Also, they do not block light coming in from the sides.
Fabric awnings are stored in a tube mounted above the window. Electrically or manually operated, these awnings unroll from the tube and extend to become a self-supporting (no vertical supports) cover for your window.
- Pros: Roller awnings retract when not needed. It's possible to purchase awnings that cover the width of two or three windows.
- Cons: Fabric will eventually degrade due to sun exposure. Flimsy shades can tear away. Even when retracted, roller awnings' storage tube remains and may be unsightly.
Exterior Rolling Shutters and Sunscreens
Shutters and sunscreens are metal gates that roll down and completely cover the window. They look much like security gates used to cover up businesses in malls or on crime-prone public streets.
- Pros: Shutters and sunscreens provide complete coverage of the window. No sunlight will enter the house.
- Cons: With shutters and sunscreens, you are preventing sunlight from entering at the expense of your view. Since these shutters rest close to the glass, heat can build up between shutters and glass. Better for preventing glass breakage in high winds than for shading windows.