A wide range of exterior roller shades, screens, hinged shutters, and roller shutters can block unwanted sunlight. Roller shutters, common in Europe but uncommon in North America, can also provide security and some insulation benefit. In coastal areas, both hinged and roller shutters can protect against severe weather. All of these systems also provide privacy, though interior shades (see below) are easier to control.
Roller shades roll down from the top of a window to provide shade. They typically are made from screening material (often PVC-coated polyester) to block most solar gain while still allowing some view to the outside. Non-roller shade screens can be mounted in a rigid frame that fits into routed grooves in exterior window casings or applied with Velcro. Hinged shutters are commonly installed on houses as decorative features, but operable shutters can provide protection against storms as well as control of solar gain. They can be made of wood, vinyl, or aluminum. Roller shutters typically have tubular, rigid aluminum slats that fit into side tracks and roll up into a valance at the top of the window.
As with awnings, blocking sunlight before it gets through the windows (as these exterior window treatments do) is more effective at controlling heat gain compared to interior shading. Some products also allow partial visibility and daylight—this is denoted by the openness factor, which typically ranges from 3% to 30% with exterior window shades. Shade screens typically have higher openness factors than exterior roller shutters, which often block all light penetration (0% openness factor).
Roller products, including shades, screens, and shutters, roll up into valances at the top of the windows. Motorized options are available with most of these exterior treatments. Hinged shutters are usually made of wood or vinyl.