Radiator Reflector Panels: Do They Work? (UK Guide)

The Short Answer

Yes, they work — but only behind radiators on uninsulated external walls. If your radiator sits on a wall that faces outside and that wall doesn't have cavity or internal insulation, a reflector panel genuinely reduces heat loss by reflecting warmth back into the room instead of letting it soak through the wall. Expect to save £5–£15 per radiator per year. At £7–£10 per radiator, they pay for themselves within a year.

If your walls are already insulated, reflector panels make almost no difference. Don't bother.

How They Work

When a radiator heats up, roughly half its heat goes forward into the room (useful) and half goes backward into the wall behind it (wasted, if that wall faces outside). A reflector panel — basically a sheet of foil-faced foam — sits in the gap between the radiator and the wall and bounces that backward heat back into the room.

It's simple physics and it genuinely works. The Building Research Establishment (BRE) has tested this and found that reflective panels behind radiators on uninsulated walls can reduce heat loss through that wall by 30–45%. For an average radiator on an uninsulated external wall, that translates to a saving of roughly 50–100 watts — enough to notice on your energy bill.

When They're Worth It

• Solid-walled Victorian/Edwardian houses — these have no cavity to fill and external wall insulation is expensive. Reflector panels are the cheapest way to reduce heat loss through the wall behind the radiator.
• Homes with unfilled cavity walls — if you haven't had cavity wall insulation done yet (or can't for some reason), reflectors are a stopgap that costs almost nothing.
• Rented properties — if you can't modify the building, reflector panels are one of the few things you can do. They peel off without damage when you move out.

When They're NOT Worth It

• Insulated cavity walls — if your walls already have cavity fill, the insulation is doing the job. A reflector panel on top adds negligible benefit.
• Internal walls — if the radiator is on a wall between two heated rooms, heat going into the wall isn't wasted — it's heating the next room. No point reflecting it.
• Modern homes built after 2000 — these are built to insulation standards that make reflectors unnecessary.

What to Buy

The Radflek brand is the best-known option and the one most commonly tested in energy studies. A 3-pack costs about £20–£30 and covers three average-sized radiators. The material is a multi-layer reflective foil that's easy to cut to size with scissors.

You can also buy generic radiator reflector foil from builders' merchants for a bit less, but Radflek's adhesive tabs make installation easier — you stick it to the wall behind the radiator without having to remove the radiator from the wall.

Avoid the ultra-cheap silver foil sheets that are essentially just kitchen foil. They crinkle, fall down, and don't have the insulating foam layer that makes proper reflectors effective.

How to Fit Them

1. Measure the width and height of each radiator
2. Cut the reflector panel to size (slightly smaller than the radiator so it's hidden behind it)
3. Slide it behind the radiator, reflective side facing into the room
4. Attach with the adhesive tabs to the wall (or use Blu Tack if you're renting)

It takes about 5 minutes per radiator. You don't need to remove the radiator or drain anything.

Realistic Savings

Scenario	Radiators Fitted	Cost	Annual Saving
3-bed solid wall terrace	5–6	£35–£60	£25–£75
Semi with unfilled cavities	4–5	£28–£50	£20–£50
Modern insulated home	Don't bother	—	Negligible

These aren't life-changing sums, but for a product that costs less than a takeaway and takes 5 minutes to fit, the return is excellent — especially in solid-walled homes where every bit of help counts.

For more on reducing heat loss, see our insulation costs guide. If you're considering a heat pump, our insulate-first guide covers the priority order for upgrades.