By 1pm, a west-facing HDB bedroom is already heating up. By 4pm the sun is direct on the glass, and any curtain that lets light through is letting heat through too. After 17 years of measuring HDB blocks across Bukit Batok, Jurong, Choa Chu Kang, and Clementi, the question we hear most often from west-facing owners is the same: why is it still hot in here.
What “West-Facing” Actually Means in Singapore
Singapore sits 1.3 degrees north of the equator. The sun tracks high overhead from late morning to mid-afternoon, then drops west between 4pm and 7pm. A “west-facing” room is a room where the bedroom or living-room window directly catches that 4pm to 7pm beam, often through unobstructed glass on the upper floors of older HDB blocks. The temperature inside the room can run 3 to 5 degrees Celsius above the rest of the unit by 5pm, even with the fan on.
The window is not the only variable. The wall material, the floor (tile reflects, parquet absorbs), and whether the unit above and below have their aircon running all change the temperature. Curtains are one part of the answer. Sometimes they’re the right part. Sometimes the answer is on the outside of the window.
The Three Things That Decide a West-Facing Curtain
1. Fabric Weight and Weave
Standard day curtains run 150 to 200 g/m². They’re for privacy and softening light, not for heat. For a west-facing window, you want either a heavier blackout fabric (280 to 340 g/m² standard, 380 to 420 g/m² premium triple-weave with thermal backing) or a layered setup with a sheer day curtain in front of a heavier night curtain.
Premium triple-weave is the only fabric category that meaningfully reduces heat transfer through the cloth. You can feel the difference when you put your hand near the glass at 5pm: with standard blackout, the fabric is warm to the touch. With thermal-backed, it’s noticeably cooler. The price difference is around 30%. For a master bedroom you sleep in every night, it earns its cost in the first dry season.
2. Track Length and Side Returns
This is where most west-facing curtains fall down. Light coming in at 5pm enters at an angle, not straight on. If the track stops at the window frame, the angled beam slips around the side of the curtain and lands on the wall behind. The room stays bright. We extend the track 15 to 20 cm past each side of the frame, and the curtain wraps back toward the wall. That seal is what makes a curtain dark, not the fabric.
3. Mounting Height
HDB ceiling-to-window-top distance is usually 30 to 60 cm. Mounting the track at the ceiling rather than just above the frame means the curtain falls in a longer, straighter line and seals the top gap. The top gap is the second-biggest source of light leak after the side gap. Ceiling-mount is almost always the right call in HDB; the only exceptions are recessed false ceilings and rooms with low feature lights right above the window.
The fabric is the easy part. The track and the install are what make the room dark and cool.
When a Curtain Is Not Enough
If the window faces directly west, has no balcony, no awning, and no neighbouring block to shade it, no indoor curtain will fully solve the heat problem. The heat is on the outside of the glass before any curtain sees it. For these rooms, an outdoor zip blind or exterior roller shade does what no indoor curtain can: it stops the sun before it hits the glass.
Zip blinds run on a track recessed into the side of the window opening, and seal flush. They cut radiant heat by 60 to 80% depending on the fabric, and they’re the single most effective heat fix for a west-facing HDB unit. Cost is higher (you’re paying for an outdoor-rated motor or crank, weather-resistant fabric, and a more complex install), and they need ground-floor or balcony access for the install team. Worth it for landed homes and condo balconies with constant exposure. For a 4-room HDB master bedroom on the 12th floor with no balcony, ceiling-mount premium blackout is usually the better answer.
What We Recommend by Room
Master Bedroom
Premium blackout, ceiling-mounted, with a 15 to 20 cm side return. Sleep is non-negotiable, and the heat reduction is enough to drop aircon load by one or two degrees. If you nap during the day, this single change gives you the room back.
Living Room
A layered setup: sheer day curtain in front, dim-out or blackout night curtain behind. The sheer softens the afternoon light during family time. The night curtain pulls across in the late afternoon when you want the heat blocked. Two-track ceiling-mount is the build.
Children’s Room or Study
Dim-out (not full blackout) is usually right. Children doing homework in the late afternoon need the room dim enough to read a screen without glare, but not pitch dark. Dim-out also lets through enough ambient light that the room doesn’t feel cave-like.
The Three Mistakes We See Most
Buying off-the-shelf curtains sized for “average” windows. The fabric is fine; the dimensions defeat it. Side gaps and short drops let the angled light past. Custom is non-negotiable for west-facing, full stop.
Choosing a darker face fabric to “block more light.” The face colour does not determine heat reduction. The backing weight and the install seal do. A cream blackout with thermal backing performs identically to a navy blackout with thermal backing.
Trying to add blackout to an existing day-curtain track. The day-curtain track was sized for 200 g fabric. Adding 380 g blackout overloads the brackets, and the track sags within six months. We’ve replaced more “retrofit blackout” jobs than successfully retrofitted one.
A Short Answer to “How Much”
For a typical 4-room HDB master bedroom (window approximately 2.4 m wide), ceiling-mount premium blackout with side returns runs in the SGD 800 to 1,400 range, installation included. Standard blackout is 30% less. Layered day-plus-night with two tracks runs SGD 1,200 to 2,000. Outdoor zip blind, where applicable, is a different conversation, usually SGD 2,500 and up per opening.
The free in-home measurement is what tells us which option is right for your unit. Different blocks, different orientations, different sun paths. We don’t quote west-facing the same way we quote east-facing, and we don’t quote a 12th-floor unit the same as a 3rd-floor one with a tree outside.
If your bedroom is hot at 5pm right now, book a measurement and we’ll come out within the week.