From EPC E to B: the four works that make the real difference

A dwelling rated EPC E consumes a lot, is increasingly hard to rent, and sells at a discount. Aiming for an EPC B is a realistic goal for an older house — provided you don't scatter the budget. Because not all renovations are equal: some gain a whole class, others barely improve the letter while costing a fortune. The useful question is therefore not "what can I do?" but "where do I start to gain the most classes at the best cost?"

Four items concentrate most of the result. Here they are, ranked from best to worst ratio of cost to EPC class gained.

1. Roof insulation: the best ratio, no argument

Heat rises. In an unrenovated house, a large share of the losses escape through the roof or the loft. That's why roof insulation is almost always the first item to tackle: it's the one that gains the most EPC classes per euro invested.

The works are often less heavy than people imagine — insulating an unused loft, insulating a pitched roof from the inside — and the project doesn't turn life in the home upside down. In Brussels, this item opens a Renolution grant in the region of €60 per m² insulated, capped at roughly €2,700, modulated by income and the type of works (source: renolution.brussels).

2. Wall insulation: the big structural lever

After the roof come the walls, which represent the largest surface in contact with the outside. Three approaches exist: insulation from the inside (the cheapest, but it reduces the living area), insulation from the outside (the best-performing, but more expensive and subject to planning rules), and cavity-wall filling for hollow walls, an in-between option that is often very cost-effective.

Wall insulation costs more than the roof, but on an E-rated house it is generally essential to reach class B: the roof alone isn't enough. This item also opens a Renolution insulation grant, on the same order of magnitude, and benefits from the reduced 6% VAT for a dwelling over ten years old (finances.belgium.be).

3. Glazing: real comfort, a more modest EPC gain

Replacing single or old double glazing with high-performance glazing improves comfort immediately: fewer cold surfaces, less condensation, less noise. On the other hand, the impact on the EPC class is more modest than that of roof or wall insulation, because windows represent a limited surface compared with the whole envelope.

The right reflex: change the window frames at the same time as you insulate, to deal with air-tightness in one go and avoid thermal bridges around the openings. It's also the chance to install a balanced (heat-recovery) ventilation system — an item that opens a bonus of around €500 in Brussels and that becomes useful as soon as you make a dwelling more air-tight.

4. Heating and the heat pump: the item that depends on the other three

Modernising the heating — a high-efficiency condensing boiler or, better still, a heat pump — weighs heavily on consumption and therefore on the EPC. But it's the item that obeys a strict rule of order: insulate first, heat second. Installing a heat pump in a sieve means oversizing it and paying to make up for losses you should have eliminated.

Handled at the right moment, after the envelope, high-performance heating clears the final notches towards class B and lastingly cuts the bills. The Sibelga energy grant (in the region of €450, source sibelga.be) and the heating side of Renolution come in support.

Why the deadline matters as much as the works

Improving your EPC is no longer just a matter of comfort or bills. In Brussels, renting out dwellings rated F or G will be banned by 2033: for a landlord, getting out of the red zone becomes a dated obligation. In Flanders, a renovation obligation requires the buyer of an energy-hungry dwelling to begin improvement works within a limited period after purchase. In other words, the regulatory timetable turns "someday" into "before such-and-such a date".

In that context, planning the move from E to B in advance lets you spread the items, capture grants across several scales and avoid doing everything in a rush — always more expensive.

Pricing the journey, grant by grant

The classic trap is to estimate each item "by guesswork" and discover the real cost when the quotes come in. The reliable method is the reverse: price each item on the ABEX index, then deduct the matched grants item by item, to obtain a credible amount left to finance. If the mechanics of indexation intrigue you, we explain it in detail in our article on the ABEX index.

That's exactly what a Qote report produces: your four items calibrated on the ABEX index, the Renolution, Sibelga and ventilation grants matched, the reduced VAT built in, the whole reviewed by an expert. The grants guide completes the picture region by region. In twenty minutes, remotely, you know what your climb from E to B really costs — and how much you have left to finance.