What to put on a west-facing window

A west window takes low, direct afternoon sun that arrives almost horizontally, which is why a roof overhang does nothing about it — the sun comes in underneath. Shading at the glass is the only thing in its path. A solar-screen roller at a low openness is the first-line answer: it cuts glare and UV while keeping the view out. Add a blackout roll behind it if the room also has an evening job. And the colour choice is counter-intuitive: a light fabric reflects more heat but scatters more light into the room, while a dark fabric absorbs more heat and cuts glare hardest.

Why west windows are different

Between roughly four and sunset, the sun on a west elevation is low. It enters at a shallow angle, passes under the overhang that handles the midday sun perfectly well, and reaches deep into the room — across the floor, up the far wall, and straight into whatever screen happens to be facing it.

Glare, heat and fade are three problems

People conflate them and they have different answers.

• Glare is a comfort problem, worst on screens, and it is the one people actually complain about.
• Heat is an energy problem: the room is warmer than the rest of the house and the thermostat is somewhere else.
• Fade is a slow damage problem on floors, art, upholstery and fabric — the one nobody notices until it has already happened.

Openness: 1%, 3%, 5% or 10%

Openness describes the weave rather than the glass. A lower percentage is a tighter weave: less view out, more UV and glare stopped. The category publishes 1%, 3%, 5% and 10%, with roughly 99% of UV blocked at 1% and about 90% at 10% — the category's published range, not a specification of ours.

On a west window you will usually want a tighter weave than you would choose elsewhere. The trade is real: a 1% shade is close to a solid panel to look through, and a 10% keeps much more of the view.

The colour paradox

This is the part almost nobody explains, and it decides the specification.

A light fabric reflects more solar energy back out through the glass, so less heat gets into the room. But it also scatters more of the light that does get through, and scattered light across a whole shade can make glare on a monitor worse than a dark fabric would.

A dark fabric absorbs more of that energy — some of which re-radiates into the room — but it cuts glare hard and keeps the view out much crisper, because you are looking through a dark screen at a bright world rather than through a bright screen at it.

So: if the complaint is “this room is hot”, lean light. If it is “I cannot see my monitor at four o'clock”, lean dark. If it is both, that is a conversation at the window rather than a rule.

When you need two layers

A solar screen is the right answer at four o'clock and the wrong answer at ten at night: it was designed to keep the view, and after dark that means the room is on display. A dual roller puts a blackout roll behind the solar screen on the same bracket, so the window does the afternoon and the evening without a second treatment on the wall. Day-night dual shades.

Put it on a schedule

The best solar shade in the world does nothing while it is up. A motor on a schedule drops it before the sun arrives rather than twenty minutes after somebody notices — which on a west elevation is most of the benefit. A motor on a sun schedule.

The same problem exists at scale on a building: glare and heat on a west office facade.