EPC guide Wallonia
How can you improve your PEB score?
Direct answer
To improve a PEB score, work in this order: insulate the roof, then the walls and floors, replace the window frames, modernise the heating and hot water production, and finally generate energy (solar panels). Providing evidence of works already carried out is the quickest and cheapest gain.
- Priority 1
- roof insulation
- Typical roof gain
- 1 to 2 label letters
- Typical window frame gain
- 0.5 to 1 letter
- Modern heating gain
- 1 letter
- Documentary gain (evidence)
- up to 2 letters, at no cost
- Support
- Housing energy audit required for Walloon grants
1. Document before renovating
The PEB method imposes default values, deliberately pessimistic, whenever a feature is not documented. An insulated but undocumented wall is recorded as uninsulated. Finding invoices for insulation, window frames, the boiler or solar panels is therefore the most cost-effective lever: it costs nothing and can gain one to two letters.
- Detailed insulation invoices and quotes (with thicknesses and material type).
- Technical data sheets for window frames and glazing.
- Invoice and data sheet for the boiler or heat pump.
- Solar panel certificate stating installed capacity.
- Plans, building permits and any PEB declaration.
2. The technical order of works
The building envelope comes before the systems: insulating first avoids oversizing a new heating system. The roof accounts for the biggest heat loss and is the cheapest to treat, which makes it almost always the first step.
- Roof or loft floor: best gain-to-cost ratio.
- Walls: from the outside if aesthetics allow, otherwise from the inside.
- Floors and cellars: more limited gain but a real one for comfort.
- Window frames and glazing: to be done after or alongside insulation, with suitable ventilation.
- Heating and domestic hot water: condensing boiler or heat pump.
- Solar panels: last, once needs have been reduced.
3. Go through a housing energy audit for grants
Walloon renovation grants require a housing energy audit carried out by a certified auditor before the works. The audit sets out the order of interventions, the expected gain at each stage and the amounts available. A PEB certificate alone does not give access to grants.
Concrete example
Frequently asked questions
Which works improve a PEB label the fastest?
Roof or loft floor insulation: it is the biggest source of heat loss and the cheapest to treat. A gain of one to two letters is common.
Do solar panels improve the PEB score?
Yes, they reduce the primary energy consumption taken into account, provided the installed capacity is documented. They are, however, more effective once needs have been reduced through insulation.
Does the PEB certificate need to be redone after works?
It is not mandatory, but it is the only way to officially confirm the new label, which is useful for a sale, a rental and financing.
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