Energy audit & EPC for your windows in 2026
In Wallonia, the prior home audit unlocks the enhanced rates of the Prime Habitation for your windows. Replacing your windows can gain you one or two EPC letters and raise your property value. Audit cost, accredited auditor, PAE report and combining windows + insulation: we explain it all and build your application.
Indicative 2026 costs. The Walloon home audit is partly reimbursed via the audit grant (up to 450 €).
Audit types for window replacement
Indicative 2026 costs for a standard single-family home (150 m²). The real amount depends on floor area, building complexity and the accredited auditor. In Wallonia, an audit grant of up to 450 € reduces what you pay out of pocket.
| Audit type | Gross cost incl. VAT, before grant | Out-of-pocket after audit grant | Validity report lifespan |
|---|---|---|---|
| Wallonia home auditmandatory for enhanced Prime Habitation window rates | 750 – 1 200 € | 300 – 750 € (audit grant deducted) | 10 years |
| Brussels Renolution auditrequired to access the full window programme | 900 – 1 400 € | 600 – 1 000 € (partly covered) | 10 years |
| EPC quick scanestimate of label gain before works, not mandatory | 150 – 300 € | 150 – 300 € (not reimbursed) | 1 year |
Indicative costs incl. VAT. In Wallonia, the audit grant (up to 450 €) can be combined with the window grants. See all window grants or request your quote for a precise calculation.
The key criteria of the energy audit tied to your windows
The audit is not just paperwork: it quantifies the real gain of your new windows, guides the glazing choice and maximises your grants. Here are the six essentials.
- When the audit is mandatory
In Wallonia, the prior home audit is mandatory to benefit from the enhanced rates of the Prime Habitation for windows (income categories I and II). In Brussels, the Renolution audit conditions access to the full grant programme, windows included.
See the window grants → - EPC gain with new windows
Replacing single glazing or old double glazing (Ug ≥ 2.5 W/m²K) with high-performance double or triple glazing (Ug ≤ 1.0 W/m²K) can move the EPC label up by one to two letters in a home built between 1970 and 1990. The auditor models this before the works.
- Property value uplift
A home that gains an EPC letter sees its sale or rental value rise. In Wallonia and Brussels, the EPC is mandatory when selling and letting: a good label is a concrete selling point. The EPC certificate updated after the works formalises the gain.
- Accredited auditor
Only an auditor accredited by the relevant region can issue a recognised audit. In Wallonia, they are certified by SPW Énergie. In Brussels, they are listed by Bruxelles-Environnement. wendows works with a network of accredited partners who factor your windows into the overall analysis.
- PAE report
The PAE report (Projet d’Acte d’Engagement) issued by the Walloon auditor lists the recommended works, including window replacement. It states the minimum Ug to reach, the expected energy savings and the available grants. Its validity is 10 years.
- Combining insulation + windows
The audit lets you plan windows and insulation within a single grant application: both items can be combined in Wallonia (Prime Habitation) and Brussels (Renolution). The EPC label gain is greatest when both works are carried out together or in stages guided by the PAE.
See window prices →
Energy audit and window grants: what each region provides
Audit obligations and grant amounts differ between Wallonia and Brussels-Capital. Here is the essential for each region in the context of window replacement.
Home audit + enhanced Prime Habitation for windows
In Wallonia, the prior home audit is mandatory to access the enhanced rates of the Prime Habitation for windows (income categories I and II). A separate audit grant (up to 450 €) partly reimburses the cost. The PAE report plans your window and insulation works over 10 years.
- Audit carried out by an SPW Énergie accredited auditor before the works begin
- Valid PAE report: target Ug, EPC label gain and available grants
- Audit grant up to 450 €, combinable with the Prime Habitation for windows
- Enhanced rates (up to 240 €/m²) accessible for income categories I and II
Renolution audit + full window grants
The Renolution programme of Brussels-Capital opens access to the full range of window grants once a Renolution audit is carried out by an auditor accredited by Bruxelles-Environnement. It is valid for 10 years and may cover windows, insulation and a heat pump within the same plan.
- Accredited auditor listed by Bruxelles-Environnement
- Audit report valid for 10 years: staged planning possible
- Access to the full Renolution programme: windows, insulation, heat pump, PV
- Application submitted within 12 months of the last window invoice
We connect you with an accredited auditor
wendows works with a network of accredited auditors in Wallonia and Brussels. We coordinate the audit, factor the window recommendations into your quote and build the grant application.
- We check whether the audit is mandatory
Region, income category and type of window works: we tell you straight away whether a prior audit is required to maximise your grant.
- We schedule the audit
We connect you with a partner accredited auditor, book the appointment and prepare the file. The audit takes place before you order your windows.
- We integrate the PAE report
The auditor’s recommendations (target Ug, window type, insulation combination) are built into your quote. The EPC label gain is estimated and the real out-of-pocket amount is shown.
- We build the full application
Audit grant + window grants: forms, technical sheets, PAE report, compliant invoices. We submit and follow the file through to payment.
Are you in Flanders? The EPC-attest (Flemish EPC certificate) may be required before certain works subsidised by the Mijn VerbouwPremie — contact us to check the conditions for your municipality.
Estimate the cost of your window audit in seconds
Select the audit type for your region to get an indicative cost range. The auditor’s quote remains the only way to get a precise amount.
Indicative estimate. The real cost depends on the floor area, the type of home and the accredited auditor. In Wallonia, the audit grant (up to 450 €) reduces your out-of-pocket amount.
Home audit + replacement of 9 windows in Namur
A concrete case: how the audit fits into a window replacement project, with the EPC label gain, the grants and the real out-of-pocket amount.
Indicative example dated 2026, income category II, Wallonia. Households in cat. I (low income) obtain even higher rates. The estimated EPC label gain is D → C on this home. Request your quote for a calculation tailored to your situation.
Dig deeper into your window project
- Window prices 2026 Costs & quotes
Ranges by material (PVC, aluminium, wood-alu) and by size, cost factors and a worked example net of grants.
See window prices → - Window grants 2026 All the support
All amounts by region (Wallonia, Brussels, Flanders), eligibility conditions and the steps to obtain your window grant without fronting any cash.
See all grants → - Window grant in Wallonia Walloon region
Detail of the amounts, technical conditions and application procedure for the Prime Habitation for exterior joinery in 2026.
See the Walloon grants →
Your questions about the energy audit and windows
Is the energy audit mandatory to obtain the window grants?
In Wallonia, the prior home audit is mandatory to access the enhanced rates of the Prime Habitation (income categories I and II), windows included. For the base amounts, it is not required. In Brussels, the Renolution audit conditions access to the full grant programme, windows included.
What EPC label gain can I expect by replacing my windows?
The gain depends on the performance of the current glazing and the new glazing fitted. In a home built between 1970 and 1990 with single glazing or old double glazing (Ug ≥ 2.5 W/m²K), switching to triple glazing (Ug ≤ 0.7 W/m²K) can move the label up by one to two letters. The accredited auditor models this precisely before the works.
How much does an energy audit cost before replacing windows?
The Walloon home audit costs between 750 and 1 200 € incl. VAT depending on the floor area and building complexity. In Wallonia, an audit grant (up to 450 €) partly reimburses this cost. The Brussels Renolution audit ranges between 900 and 1 400 €. A simple EPC quick scan costs between 150 and 300 €.
Can the audit grant and the window grant be combined?
Yes. In Wallonia, the audit grant (up to 450 €) can be fully combined with the Prime Habitation for windows. The audit also unlocks access to the enhanced per-m² rates for windows, which largely offsets its cost. The net gain is positive in almost all cases for categories I and II.
Can window and insulation grants be combined in the same application?
Yes. In Wallonia (Prime Habitation) and Brussels (Renolution), window and insulation grants can be combined in the same application. The PAE report or the Renolution audit plans both items in stages over 10 years. wendows builds the overall application to maximise the combination.
How long is the PAE report valid for windows?
The PAE report (Projet d’Acte d’Engagement) is valid for 10 years. During this period, you can carry out your window (and insulation) works in stages, relying on its recommendations. Each stage is the subject of a separate grant application.
How do I find an accredited auditor for my window project?
In Wallonia, accredited auditors are certified by SPW Énergie. In Brussels, they are listed by Bruxelles-Environnement under the Renolution programme. wendows works with a network of accredited partners: we connect you directly and coordinate the audit with your window order.
Audit planned, grants maximised, windows fitted
We check whether the audit is mandatory for your situation, connect you with an accredited auditor, integrate the PAE report into your window quote and build the entire grant application.
- Connection with a partner accredited auditor
- Window quote net of grant with the PAE report integrated
- Audit grant + window grant application built and followed