Openness Factor on Blinds Explained: 1% vs 3% vs 5% vs 10%

What does openness factor mean on a solar or roller shade?

Openness factor (sometimes called "open weave" or "OF") is the percentage of a woven shade fabric that is made up of open space, tiny gaps between the yarns, versus solid material. A 5% openness fabric is 5% holes and 95% solid yarn; a 1% fabric is almost fully closed. It applies mainly to solar shades and light-filtering roller blinds, not to blackout fabrics (which are effectively 0% openness).

The key trade-off is simple: the more open the weave, the more you can see out, but the more light, heat and UV pass through. The tighter the weave, the better it blocks sun, glare and heat, and the more privacy you keep, at the cost of a slightly softer, less crisp outward view.

• Lower % (1-3%) = tighter weave = more heat, UV and glare control, more privacy, softer view
• Higher % (5-10%) = more open weave = clearer outward view, more daylight, less heat and privacy control
• Applies to solar/light-filtering shades; blackout fabrics are a separate 0% category
• Openness factor affects glare and view; a separate rating (UV block %) measures sun protection

1% vs 3% vs 5% vs 10% openness compared

Think of openness as a sliding scale between maximum sun control and maximum view. Here is how the common weaves behave in a real room. Note that fabric colour also matters: darker fabrics give a sharper view-through and better glare control, while lighter fabrics reflect more heat but can look hazier.

• 1% openness: Tightest common solar weave. Excellent heat, glare and UV control; strong daytime privacy; view is present but muted. Best for west/south glare and screens/TVs.
• 3% openness: The popular all-rounder. Balances a usable outward view with solid heat and glare reduction. A safe default when you're unsure.
• 5% openness: More open and view-friendly. Good for taking in a nice view (mountains, backyard) while still cutting some heat and UV. Less daytime privacy.
• 10% openness: Very open, screen-like weave. Prioritizes view and airiness over sun control; noticeably more heat and glare pass through, and little privacy.
• Nighttime note: at night, with interior lights on, ALL open-weave solar shades allow silhouettes from outside, higher openness = more visibility. Pair with drapery, a dual/zebra shade, or a blackout layer where night privacy matters.

How to choose openness factor by window exposure

The best openness factor depends on which direction a window faces and what the room is used for. In Calgary, intense high-altitude sun and long summer daylight make heat and UV control especially valuable on sun-facing windows, while north windows can afford a more open weave.

• South & west windows (hottest, most glare): 1-3% to block heat, protect furniture from UV fading, and kill screen glare
• East windows (bright morning sun): 3-5% to soften early glare while keeping a pleasant view
• North windows (soft, indirect light): 5-10% to maximize the view and daylight; sun control is less critical
• Home office / TV room: 1-3% to protect screens from glare regardless of direction
• Rooms with a prized view: 5% is often the sweet spot, view plus meaningful heat reduction
• Bedrooms / bathrooms: openness alone won't give night privacy, choose blackout or pair a solar shade with a second layer

Openness factor vs UV block and privacy: don't confuse them

Openness factor and UV protection are related but not identical. A low openness factor generally blocks more UV, but the exact UV-block percentage depends on the fabric and colour, so always check both specs. Likewise, openness affects daytime privacy and view clarity, but never guarantees nighttime privacy on its own.

If your main goal is fading protection, ask for the fabric's UV-block rating (often 95-99% on tighter weaves). If your goal is total darkness or full privacy, openness factor is the wrong lever, you want a blackout roller, a dual zebra shade with a closed band, or a layered solution instead.