Feedback: EPC renovation to keep indexation rights
Nathalie, owner of a 1960s flat in Ixelles, shares her EPC renovation from F to C: works, costs, grants and impact on rent indexation.
- 01 The context
- 02 The EPC diagnosis
- 03 The works
- 04 The grants
- 05 The building site
- 06 The result
- 07 Financial review
The context: a 1960s flat and a letter from the Region
I inherited this flat in Ixelles in 2015. A 2-bedroom, 75 m2 unit on the 3rd floor of a 1962 building: solid parquet flooring, high ceilings, lovely natural light. I have been renting it since 2016 for 850 EUR per month to a tenant I have never had to chase even once. The ideal tenant.
In September 2023, I received the new mandatory EPC certificate upon renewal of the lease: label F, 478 kWh/m2/year. A cold shower. With an EPC F rating, I lost the right to index the rent in Brussels. Concretely, this meant my rent would remain frozen at 850 EUR for years, while inflation was eroding my profitability.
I did the maths: without indexation, I was losing approximately 480 EUR per year, and this would only increase over time. I had to act.
The diagnosis: understanding what drags down the EPC
Before requesting quotes, I called in an energy auditor accredited by Brussels Environment (cost: 450 EUR). Their report identified the main areas of heat loss:
| Area of heat loss | Impact on EPC | Priority |
|---|---|---|
| Uninsulated roof (access via loft) | Very high | 1 |
| Single-glazed windows (6 windows) | High | 2 |
| Atmospheric gas boiler from 2001 | Medium-high | 3 |
| Uninsulated walls (rear facade) | Medium | 4 (not treated) |
The auditor explained that roof insulation alone could improve the EPC by 2 labels. It is the item with the best cost/impact ratio. Without this audit, I would have started with the windows — more visible but less effective per euro invested.
With items 1, 2 and 3, the auditor estimated a move from F to C, or even C+. Wall insulation (item 4) would have achieved B, but at an additional cost of 12,000 EUR. I decided to aim for C, sufficient to regain full indexation.
The works: 28,400 EUR for 3 items
I requested 3 quotes per item and selected the following offers:
| Works | Selected quote | Duration |
|---|---|---|
| Interior roof insulation (rock wool, 18 cm) | 6,200 EUR | 3 days |
| Replacement of 6 single-glazed windows with HR double glazing | 12,800 EUR | 4 days |
| Replacement of gas boiler with condensing boiler | 8,400 EUR | 2 days |
| Initial EPC audit + final certificate | 1,000 EUR | - |
| Total | 28,400 EUR | ~3 weeks |
The choice of a condensing boiler rather than a heat pump was pragmatic: the building has no space for an outdoor unit, and switching to a heat pump would have required a complete overhaul of the heating system (low-temperature radiators). Estimated cost: 18,000 EUR instead of 8,400 EUR, for a similar EPC improvement.
The grants: 8,200 EUR recovered
In Brussels, the Renolution programme offers grants for energy renovations. I submitted my applications before the start of works (a mandatory condition for certain categories).
| Grant | Amount |
|---|---|
| Roof insulation (income category II) | 3,200 EUR |
| HR double-glazed windows (6 units) | 2,400 EUR |
| Condensing boiler | 1,800 EUR |
| ”Combined works” bonus | 800 EUR |
| Total grants | 8,200 EUR |
Renolution grants are paid after receipt of the final invoices and proof of payment. In my case, I received the transfer 4 months after submitting the complete file. Budget the cash flow to finance the works in the meantime.
Net cost after grants: 20,200 EUR. I financed this amount from my savings, without a loan. For those who do not have this cash available, some banks offer “green” renovation loans at preferential rates (2 to 3% in 2024).
The building site: 3 weeks with a tenant in place
My tenant, informed 3 months in advance, agreed to stay during the works. We agreed on a 50% rent reduction during the 3 weeks of works (a shortfall of 425 EUR for me).
The schedule was tight:
- Week 1: roof insulation (works in the loft, little disturbance in the flat)
- Week 2: window replacement (2 days without windows in the living room — the tenant took leave)
- Week 3: boiler replacement (1 day without heating or hot water, in April)
I hired a site coordinator (1,500 EUR included in the quotes) to synchronise the 3 tradespeople. It is a luxury, but it saved me from taking 3 weeks off to supervise. For a project of this scale in an occupied property, I strongly recommend it.
The biggest unexpected issue: replacing the last window (bathroom) revealed a crack in the lintel. Additional repair: 600 EUR unbudgeted. Always allow 10 to 15% contingency for surprises in an older building.
The result: from F to C in one month
The new EPC certificate, issued 2 weeks after completion of the works, showed 148 kWh/m2/year — label C. Mission accomplished.
Before/after comparison:
| Indicator | Before | After |
|---|---|---|
| EPC label | F | C |
| Theoretical consumption | 478 kWh/m2/year | 148 kWh/m2/year |
| Indexation right | Blocked (0%) | Full (100%) |
| Estimated annual heating cost for tenant | ~2,100 EUR | ~950 EUR |
The tenant immediately noticed the difference: “The flat retains heat, I no longer have to heat on full.” Their gas bills dropped by approximately 1,100 EUR per year. A strong argument if I ever need to find a new tenant.
I was able to apply indexation at the next lease anniversary date. The rent went from 850 EUR to 888 EUR, an increase of 38 EUR/month (456 EUR/year).
Financial review: an investment that pays for itself in 7-8 years
Let us be honest: EPC renovation to retain indexation is not a brilliant short-term financial move. Here is the full calculation:
| Item | Amount |
|---|---|
| Net cost of works (after grants) | 20,200 EUR |
| Rent reduction during works | 425 EUR |
| Unforeseen (lintel) | 600 EUR |
| Total investment | 21,225 EUR |
| Indexation recovered (year 1) | +456 EUR |
| Estimated cumulative indexation (over 10 years, 2%/year average) | +5,200 EUR |
| Estimated added value of property (F to C upgrade) | +15,000 to 20,000 EUR |
The return on investment through indexation alone takes approximately 7 to 8 years. But if you factor in the added value of the property (a label C flat sells for 10 to 15% more than a label F in Ixelles), the operation is profitable from the point of resale.
And above all, from 2033, the Brussels Region will impose a minimum EPC of E for all rental properties, then C by 2040. Better to renovate now, with grants, than to wait until you are forced to do it without assistance.
Key takeaways:
- The EPC audit is the most important step — it directs spending towards the most effective items
- Grants cover 20 to 40% of the cost — but they must be applied for before the works
- Renovation protects the value of the property as much as it preserves indexation
For landlords with a property in rental management rated E, F or G: do not wait. Obligations will tighten, grants will decrease, and every year without indexation is a year of lost income.
- “**Have an EPC audit carried out before requesting quotes.** The auditor identifies the items with the greatest impact on the score. In my case, roof insulation alone moved the EPC from F to D. Without a prior audit, I would have started with the windows, which cost more for less impact.
- “**Apply for grants BEFORE starting the works.** In Brussels (Renolution), some grants must be applied for before the start of the works. I nearly lost 3,000 EUR in grants because I had signed the quote too early. Check with your Region.
- “**Negotiate with your tenant for works in an occupied property.** My tenant accepted a 50% rent reduction during the 3 weeks of works in exchange for staying in the flat. It was simpler than a temporary move and less costly than a vacancy.
Frequently asked questions
-
In Brussels, since October 2022, properties rated F and G on the EPC certificate can no longer benefit from full rent indexation. Properties rated E can index at 50%. Only properties rated A, B, C or D retain the right to 100% indexation. This measure aims to encourage landlords to renovate energy-inefficient properties.
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The cost varies enormously depending on the property configuration. For a flat of 70 to 90 m2 dating from the 1960s, count between 20,000 and 40,000 EUR to go from F to C, including insulation (roof/walls), window replacement and heating system upgrade. Regional grants can cover 20 to 40% of the amount depending on your income.
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In Belgium, energy renovation works are not directly deductible from rental income tax (which is calculated on the basis of the indexed cadastral income). However, you can benefit from regional grants (Renolution in Brussels, Mebar+ in Wallonia) and a reduced VAT rate of 6% if the property is more than 10 years old.
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It is possible for some works (roof insulation, window replacement) but not for all (complete overhaul of the heating system). The landlord must inform the tenant in writing and agree on an arrangement: rent reduction during the works, temporary rehousing, or agreement on working hours. The tenant cannot refuse urgent works or works necessary for the preservation of the property.
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