West windows and sunrooms: heat, glare and fading in summer 2027

Updated October 22, 2026

The short version: west windows and sunrooms get the low, hot afternoon sun. Inside shutters with the louvers closed cut the glare and keep direct sun off you and the floor, which slows fading. They do less for heat than shading on the outside of the glass, because the sun has already come through by the time it reaches them. Use both if you can; use the shutters well if you can’t.

Why 2027 is a good year to think about this

Summers have been getting hotter. NOAA reported that “Annual temperatures across the contiguous U.S. (CONUS) averaged 54.6°F in 2025”, which “ranked as the fourth-warmest year in the 131-year record”^[1]. A warm year doesn’t predict next summer, but the long run of hot ones is why more homeowners are asking what to do about their sunniest rooms.

Cooling is already a large part of what homes pay for. The US Energy Information Administration puts air conditioning at 19% of residential electricity use in 2020, measured at the home^[2]. In a house with a big west window or a glassed-in sunroom, that room is often the one the air conditioning is fighting.

Why west windows are the hard ones

This section is our reasoning, not a measured result.

East windows get sun in the morning, when the house is cool. West windows get it in the late afternoon, after the house has been warming all day and when the outdoor temperature is near its peak. The sun is also low in the sky by then, so it comes in nearly level and reaches deep into the room, across the floor and onto the sofa, the desk or the TV. Roof overhangs and porches that shade a south window at noon do little against it.

A sunroom has the same problem on three sides, often with a glass roof or skylights too. It can be the best room in the house in April and the worst in July, and it often swings between cold and hot, and between dry and humid, more than the rooms around it.

What the research says inside coverings can do

The clearest public summary comes from Pacific Northwest National Laboratory’s Building America Solution Center. Its guidance on window attachments is honest about the limit: interior coverings “can be less effective at reducing heat gain than comparable exterior shading systems” because “they do not block direct sunlight until after it has already passed through the window”^[3].

That’s the plain truth about any interior shutter, including ours. When the sun hits a closed louver, the louver warms and so does the air between it and the glass, and that heat is inside the house. Some of the sunlight bounces back out through the glass; the rest stays. Shading on the outside never lets that heat in.

The same guidance gives the most useful operating advice we’ve found: “The optimal strategy for operating window attachments for cooling energy savings is to simply close them during the day”^[3]. For a west window, that means close the louvers before the sun comes round, not when you notice the room is hot.

Fading: what the sun does to floors and furniture

Fading is mostly about direct sun. The Skin Cancer Foundation notes that “UVA rays can pass through window glass and reach you indoors, at home and on the road,” and that “sunlight can fade home furnishings and flooring over time”^[4]. Visible light and heat play a part too, which is why a floor fades in a shape that matches the patch of sun that crosses it every afternoon.

Closed louvers keep that patch off the floor. They slow fading; they don’t stop it, because light comes through the gaps and the room is still bright when they’re open. We don’t give a UV-blocking figure for our shutters because there’s no tested one to give. If fading of a valuable floor or rug is the main worry, UV-blocking window film on the glass is the product made for that job, and it works with shutters rather than against them.

One honest note on our own product: wood shutters fade too. The louver faces toward the glass get the most sun. Painted finishes hide it well, because you see the paint, not the wood. Stained finishes show it more, slowly and evenly, as the wood’s colour changes. If you want a dark stain on a west window, know that it will look a little different in five years.

Your options, side by side

How to use shutters on a west window

This section is our reasoning, not a measured result.

• Morning: louvers open. There’s no direct sun on a west window, and you get the view and the daylight.
• Early afternoon: tilt the louvers so the room-side edge points up. Direct sun is deflected toward the ceiling instead of the floor, and the room stays bright.
• Late afternoon: close them, before the sun comes round. This is the PNNL advice in practice.
• Evening: once the sun is down, open them again for the view, or keep them closed for privacy.

A divider rail makes this easier. The top and bottom louvers tilt separately, so you can close the bottom half against the level sun and leave the top half open for sky. On a sliding door into a sunroom or onto a west deck, see our patio door shutters.

Choosing the build for a sunny room

This section is our reasoning, not a measured result.

• Colour. A white or light painted finish is the safest choice on a west window. It shows the least change as it ages in the sun, and it reflects more of the light that reaches it back toward the glass than a dark finish does. If you love a dark stain, consider it for the rooms that get less afternoon sun.
• Louver size. On a big sunroom window, wider louvers give the clearest view when open, which is the point of the room. 4½ in louvers give the fewest louvers and the widest view, but the window needs more depth for them. On smaller windows, 3½ in is the usual choice.
• Tilt. You’ll adjust a west window every afternoon. A tilt rod set near the left or right stile is easy to reach and keeps the middle of the view clear. Hidden tilt has no rod at all: move any louver and the rest follow.
• Layout. A divider rail lets the top and bottom louvers tilt separately, which suits the low afternoon sun. On a run of sunroom windows, use the same louver size and layout on each, so the room reads as one wall.

Before you spend money on any covering, look at the glass. A sunroom with old single glazing or failed double-glazed units will be hot in summer and cold in winter whatever you hang inside it, and fixing the glass comes first.

Sunrooms and the 2027 aluminum line

Sunrooms are harder on a shutter than an ordinary room. They see more sun, and many swing between cold and hot, and humid and dry, more than the rest of the house, especially a three-season room that isn’t heated or cooled with it. Wood moves with moisture, and a finish in strong sun works harder. Our poplar shutters are built for ordinary living rooms; if your sunroom isn’t heated and cooled with the house, tell us about it before you order.

For rooms like these, our aluminum interior shutters are coming in 2027. They’re movable-louver interior shutters with a wood finish, in moulding levels 1, 2, 3. What’s different about them:

• An aluminum frame and louvers in place of solid wood.
• A finish chosen to stand up to sun and humidity, on a shutter designed for the inside.
• Aluminum doesn’t rust the way steel does. A thin oxide film forms on its surface and reseals itself if it’s scratched.

They’re interior shutters, fitted inside the window like our wood ones. There’s no price yet; people on the waitlist hear first. You can join it on our aluminum shutters page.

A worked example, with today’s prices

Take a small sunroom with four windows, each 36 in wide by 60 in high, inside mounted. In our wood line’s basic build (flat moulding, paint stage 1, 3½ in louvers), one window costs $400 – $500 in the US and $580 – $710 CAD in Canada. All four come to $1,620 – $1,980 in the US and $2,320 – $2,840 CAD in Canada.

These ranges come straight from our live price list. A divider rail, a different louver size or a higher moulding level can change them, and the designer shows the effect of each choice before you order. The aluminum line isn’t in these figures because it isn’t priced yet. For more window sizes, see what shutters cost.

What we won’t claim

• No percentage energy saving. There’s no tested rating for louvered interior shutters to base one on.
• No UV-blocking figure, for the same reason.
• No promise that shutters will keep a sunroom cool in July. Exterior shading and the glass itself do more.

What shutters will do in a west room is give you control: daylight in the morning, the direct sun off the floor in the afternoon, privacy at night, all from one covering. Our energy guide goes deeper into what the research has and hasn’t measured.