Eco radiator foil, 2.25 square metres for EUR 17.99: on uninsulated brick it repays inside one heating season

Before the heating season starts, the most overlooked surface in a Dutch home is the wall behind the radiator. This Eco radiator foil is 500 by 45 cm, which is 2.25 square metres, costs €17.99, and is rated 4.6 from 113 reviews. It goes behind the radiator and blocks the share of the heat that disappears into the wall. It is cheap and takes minutes to fit, but whether it is worth buying turns entirely on something the listing never mentions: whether that wall is insulated.

The official figures are given per square metre. Milieu Centraal states that on an uninsulated solid brick wall each square metre of foil saves 11 cubic metres of gas a year, which is €15 at €1.37 per cubic metre; on an uninsulated cavity wall it is 7 cubic metres, or €10. If the wall is already insulated, or if the radiator hangs on an internal partition, the saving is close to nothing. That is not a fault in the product; there is simply no escaping heat left to catch.

• Specification: 500 by 45 cm, which works out at 2.25 square metres, fitted behind the radiator, and described by the seller as suitable for all radiator types. (source 1)
• Listing data: €17.99, rated 4.6 from 113 reviews. The same seller lists a 400 cm version with 20 magnets at a different price; both share one review pool. (source 1)
• Official saving, solid brick: on an uninsulated solid brick wall, each square metre of radiator foil saves 11 cubic metres of gas a year, equal to €15. (source 2)
• Official saving, cavity wall: on an uninsulated cavity wall the same square metre saves 7 cubic metres a year, equal to €10. (source 2)
• The price assumption: both euro figures use €1.37 per cubic metre, the official long-term average for 2026 to 2040, not the rate on your current contract. (source 2)

The sum has two steps and both use your own wall and your own gas price. First measure the area: radiator width times height is the square metres you need to cover. A common 120 by 60 cm radiator has roughly 0.72 square metres behind it, so this 2.25 square metre roll covers about three of them. Then convert to money: square metres times 11 for solid brick, or times 7 for a cavity wall, is the cubic metres of gas saved a year, multiplied by the rate on your own bill.

Put the two together for this roll. If all three radiators sit on uninsulated solid brick, 2.25 times 11 is 24.75 cubic metres, which at the official €1.37 comes to €33.91 a year, and €17.99 divided by €33.91 is about 0.53 of a year, so it pays for itself inside one heating season. If those walls are uninsulated cavity walls instead, 2.25 times 7 is 15.75 cubic metres and €21.58, and the payback runs to 0.83 of a year, roughly ten months. Both land inside a year, but the gap is nearly double, so working out which wall you have matters far more than comparing prices.

How to tell. If the radiator hangs under an exterior wall, the house predates 1975, and that wall feels noticeably colder in winter than the other walls in the room, it very likely belongs to the uninsulated category the official figures describe, and the foil is worth fitting. If instead the radiator sits on a partition between two rooms, the heat it reflects only travels back from the room next door and your bill will not notice. If you rent, ask the landlord one extra question: fitting foil behind a radiator is reversible, but whether you use adhesive or magnets decides whether it leaves marks when you move out.

The bol link on this page is an affiliate link. If you order through it the price is still €17.99, and Hokimi may receive a small commission.

Price

€17.99; no struck-through list price shown

Rating

4.6 stars across 113 buyer reviews

Specs

500 by 45 cm, 2.25 square metres - fitted behind the radiator - stated to suit all radiator types

Platform

bol.com, EAN 8720865011042

Checked

Listing and the official saving page read on 8 September 2026