Shop for solar or roller shades and one spec decides most of what the shade does: openness factor. It is the percentage of the weave that is open space. A 1% fabric is nearly solid; a 10% fabric is closer to a screen. Everything about glare, view and privacy hangs on that number.
What each range does
- 1%: maximum glare control and UV blockage, soft view, best on brutal west glass and screens-heavy rooms
- 3%: the Texas workhorse, strong glare control with a usable view through the weave
- 5%: brighter rooms and clearer views, for windows that get sun but not punishment
- 10%: view-first shading for covered or north-facing glass
Direction decides more than taste
A west-facing Texas window in July argues for 1% to 3%. A north-facing window with a view argues for 5% or more, because the sun never hits it hard enough to justify losing the view. Mixing openness by direction on the same house is not inconsistency, it is the right answer, and matching fabric colors keeps the look unified.
The dark-fabric secret
Counterintuitively, darker solar fabrics see through better than light ones at the same openness, because a dark weave swallows reflections instead of lighting up. Light fabrics reflect more heat but glow; dark fabrics preserve the view. Which matters more depends on the room, and holding samples against your own glass settles it in minutes.
How openness relates to heat
Openness controls how much light and view comes through the open part of the weave. Heat control also depends on the fabric's color: a light face reflects more of the sun's energy back out through the glass, while a dark face absorbs more of it. Two fabrics with the same openness can perform differently on a hot west window for that reason.
For the strongest heat control on the worst exposure, combine a low-openness interior shade with exterior shading, which stops the sun before it reaches the glass.
Testing samples at your own window
- Hold each sample against the glass at the time of day the sun hits that window.
- Look through it at the view you care about, and at any screen in the room.
- Check it from outside at dusk with the lights on, if privacy at night matters.
- Compare a light and a dark color at the same openness side by side.
These four checks take a few minutes, and they settle questions that a spec sheet cannot.