I live in an older rented flat where the windows are lovely but single-glazed and a little drafty — the kind that steals warmth in winter and leaves condensation along the sills. I wanted a simple, low-waste fix that wouldn’t damage the frames or require landlord approval. The solution I kept coming back to was a removable insulating window panel made from thrifted fabric and recycled batting. It’s cosy, inexpensive, and pleasing to look at — and best of all, I tested it in my own living room before sharing it here.

Why make an insulating window panel?

Insulating window panels (also called thermal panels or window quilts) are a great way to reduce heat loss through glass without replacing windows. They trap a layer of air between the panel and the glass and add a layer of thermal resistance with the batting. For renters, they’re attractive because they’re reversible and non-destructive: you can take them down when you move.

I care about sustainability, so I avoid buying new technical fabrics if possible. Thrifted curtains, duvet covers, or heavy upholstery fabrics work brilliantly. For the insulating layer, recycled cotton or wool batting (from old quilts or thrift stores) is warm and breathable. In my flat I achieve a noticeable reduction in drafts and a calmer room temperature after a cold night — and my energy bills nudged down too.

Materials and approximate cost

Here’s what I typically use. Quantities depend on your window size; I’ll give guidance below on measuring.

Item Use Where to find
Thrifted fabric (curtain, quilt cover, upholstery) Visible face and backing Charity shops, Freecycle, local markets
Recycled batting (cotton/wool/poly blend) Insulating middle layer Old duvet/blanket, quilt, or specialist thrift
Velcro or magnetic tape Mounting method (non-damaging) Hardware store, Amazon, online haberdashery
Bias tape or cotton tape Edge finishing Haberdashery, reuse from old curtains
Thread, needle or sewing machine Sewing seams and hems Already at home or thrift

Cost: if you use only thrifted materials, expect to spend under £15 per panel (mostly on Velcro or magnetic tape). Buying new batting or specialist mounting hardware raises the price but still beats most professional secondary glazing options.

How to measure your window

Measure the glass area you want to cover, not the frame. I like to make the panel slightly larger than the glass — about 1–2 cm on each side — so it seals against the frame when pressed. For a snugger fit and better thermal performance, add up to 3 cm if you want the panel to sit against the frame rather than inside it.

Useful checklist:

  • Width of glass (left-to-right)
  • Height of glass (top-to-bottom)
  • Depth of the window reveal (to decide if panel sits inside or against frame)

    • Cutting and assembling the panel

    Once I have my measurements, I cut the thrifted fabric into two rectangles (front and back) matching the panel size plus a 1 cm seam allowance on all sides. Then I cut the batting to the same size but without extra seam allowance, so it sits neatly between the fabric layers.

    Step-by-step:

  • Layer with the right side of the front fabric facing down, then the batting centred, then the back fabric right side up (so the wrong sides of fabrics touch the batting).
  • Pin or clip around the edges. Leave a 15 cm gap on one short side for turning.
  • Sew around the perimeter with a 1 cm seam allowance, reinforcing the corners. Turn the panel through the gap so the right sides face out.
  • Poke out the corners carefully and press the seams flat. Close the turning gap with an invisible hand stitch or topstitch around the entire edge 5 mm from the edge for a tidy finish.
  • Add rows of quilting stitches running horizontally or vertically across the panel to keep the batting from shifting. I usually do lines 10–15 cm apart. You can do simple running stitches by hand if you don’t have a machine.

    • Finishing touches and aesthetics

    I like panels that look as carefully made as they function. If your thrifted fabric has a pattern, orient it so it reads correctly from inside the room. Add a strip of cotton tape around the edge for a neat binding, or leave raw edges if the fabric is heavy and won’t fray.

    If you enjoy a more decorative finish, stitch a thin pocket across the top edge and insert a small, lightweight wooden batten or curtain rod to create a slight bow effect when mounted. Or sew on loop tabs and hang with removable adhesive hooks (check weight limits).

    Mounting options for renters

    The mounting method depends on how permanent and airtight you want the panel to be. I use two approaches depending on the window:

  • Velcro tape (hook-and-loop): Attach the loop side to the window frame with the adhesive backing (or sew the fabric to the loop side if the adhesive won’t stick to painted wood). Attach the hook side to the panel edge. This is quick and the panel sits flush. Choose heavy-duty indoor Velcro; it’s removable and usually leaves no damage if peeled carefully.
  • Magnetic tape: If your window has a metal frame (or you can fit a very thin metal strip that isn’t damaging), magnetic strip is lovely and neat. Sew the magnetic strip into the top seam and use matching metal tape on the frame.
  • Tension rod: For windows with a deep reveal, slide the panel into place and use a small tension rod or curtain wire to hold it. This works especially well for tall panels.
  • Adhesive hooks and tabs: For lightweight panels, removable adhesive hooks around the reveal can hold loops sewn onto the back of the panel. Use Command strips rated for the weight.

    • Whichever you choose, check the manufacturer instructions of adhesive products and test a small area of paint or wood first. I usually press the Velcro on with firm pressure and leave it for 24 hours before hanging the panel.

    Performance and care

    Thermally, a well-fitted panel will reduce drafts and slow heat loss. It won’t replace double glazing, but it’s effective at evenings and overnight when you want to keep warmth in. I noticed less condensation on the glass and a cosier corner for reading after adding my first panel.

    Cleaning: most thrifted fabrics tolerate gentle machine washing; check the labels. If the fabric is delicate, spot-clean or dry-clean as needed. The batting can mat down over time, so swapping in fresh recycled batting every couple of years keeps performance high. Store panels flat or rolled in a breathable bag when not in use.

    Troubleshooting and tips I learned

  • If the panel feels floppy, add more quilting lines to secure the batting.
  • For very large windows, make two panels that meet in the middle rather than one oversized panel — it’s easier to handle and still seals well when both are pushed toward the centre.
  • Keep a small bead of foam weatherstrip around the window frame if you want to boost the seal without adhesives — it’s removable and cheap.
  • If adhesive Velcro peels paint, a gentle trick I use is to place a thin strip of painter’s masking tape under the Velcro on the paint surface to protect it (test first).

    • Making insulating window panels from thrifted fabric and recycled batting is one of those small projects that brings disproportionate joy: it’s tactile, frugal, and immediately rewarding. I hope you’ll enjoy making one for your own space — it’s a lovely way to add warmth, texture, and a little more sustainability to your home.