Should you really renovate before selling?
In a market where interest rates reach 3.8% in 2026, the buyer of a thermal sieve (F or G) often applies a "fear discount" well above the actual works cost. This discount can reach -25% of market price in some regions (Paris, Lyon, Bordeaux), turning your property into "unsellable" or "fire-saled".
The question is therefore no longer "should I renovate?" but "does renovating earn me more than selling as-is?". In 2026, with the rental ban for EPC G (effective since 2025) and F (from 2028), this decision has become a pure financial arbitrage that can make you gain or lose €30,000 to €80,000.
🎯 The RenovMatch Tool: Thermal Sieve Arbitrage Simulator
Our Arbitrage Simulator compares in 2 minutes the 2 scenarios and tells you which maximizes your net seller price. The tool calculates:
- Scenario A: As-is sale: Market price - thermal sieve discount = Immediate net seller
- Scenario B: Renovation then sale: Renovated market price - works cost - holding = Net seller after works
- ROI comparison: Net gain of scenario B vs A, sale delay, construction risk
- Recommendation: Numbered verdict based on your situation (urgency, cash, local market)
📊 The Thermal Sieve Discount in 2026: Real Figures
Average Discount by EPC and Region
| Region | EPC G | EPC F | EPC E |
|---|---|---|---|
| Paris / Île-de-France | -20 to -25% | -12 to -18% | -5 to -8% |
| Lyon / Bordeaux / Nantes | -18 to -22% | -10 to -15% | -4 to -7% |
| Toulouse / Lille / Strasbourg | -15 to -20% | -8 to -12% | -3 to -5% |
| Medium cities | -12 to -18% | -6 to -10% | -2 to -4% |
Source: Green Value Barometer 2026 - Notaires de France
💰 Real Case 1: G House in Lyon - Renovating Wins
Property: 110m² house Lyon 7th, EPC G, renovated market price €420,000
Scenario A: As-is sale
- • Renovated market price: €420,000
- • Thermal sieve discount (-20%): -€84,000
- • As-is sale price: €336,000
- • Agency fees (5%): -€16,800
- Net seller: €319,200
Scenario B: Renovation then sale
- • Energy works (G → D): €28,000
- - Attic insulation R=7: €5,500
- - Air/water heat pump: €14,000
- - Double glazing joinery: €8,500
- • Holding 3 months (loan + charges): €3,600
- • Renovated sale price: €420,000
- • Agency fees (5%): -€21,000
- Net seller: €367,400
✅ Verdict: Renovating earns +€48,200 net (172% ROI). Delay: 3 months. Recommendation: RENOVATE
💰 Real Case 2: F Apartment in Toulouse - As-is Sale Wins
Property: 65m² apartment Toulouse Center, EPC F, renovated market price €245,000
Scenario A: As-is sale
- • Renovated market price: €245,000
- • Thermal sieve discount (-10%): -€24,500
- • As-is sale price: €220,500
- • Agency fees (5%): -€11,025
- Net seller: €209,475
Scenario B: Renovation then sale
- • Energy works (F → D): €18,500
- - Wall ITI insulation: €6,500
- - Joinery: €5,200
- - Double flow MVHR: €4,800
- - Compliant electricity: €2,000
- • Holding 2 months: €1,800
- • Renovated sale price: €245,000
- • Agency fees (5%): -€12,250
- Net seller: €212,450
⚠️ Verdict: Renovating earns +€2,975 net (16% ROI). Weak gain vs construction risk. Recommendation: SELL AS-IS (unless low sale urgency)
📋 5-Step Arbitrage Methodology
How to Make the Right Decision?
Step 1: Estimate the Real Discount
Check recent sales of similar properties in your area (DVF - Demande de Valeur Foncière). Compare EPC G/F vs D/C prices. The real discount is often different from the national average.
Step 2: Cost Works Precisely
Don't rely on "finger in the air" estimates. Use RenovMatch to get precise costing based on your photos. Energy works cost on average €250-400/m² to move from G to D.
Step 3: Calculate Holding Cost
During works (2-4 months), you pay loan + charges + insurance. Count €1,000-1,500/month for an average house. This cost reduces your net gain.
Step 4: Evaluate Your Personal Situation
- • Sale urgency: Relocation, divorce, inheritance → Sell as-is
- • Cash: No funds for works → Sell as-is
- • Local market: High demand → Renovating can take months
- • ROI: If net gain < €15,000 → Sell as-is (construction risk too high)
Step 5: Make the Decision
Simple rule: If ROI > 150% AND acceptable delay → Renovate. Otherwise → Sell as-is with certified works report (to limit discount).
🔑 The 3 Levers to Limit Discount (If As-is Sale)
- 1. Provide a certified works report: Show the real works cost (ex: €25,000) to avoid buyer imagining €50,000. This limits discount to 70-80% of real cost vs 100-120% without report.
- 2. Target investors: Property merchants and investors seek thermal sieves for property tax deficit. They accept a lower discount as they value potential.
- 3. Offer facilitated works financing: Indicate in the listing that you provide a complete banking file (RenovMatch report + quotes) to facilitate the buyer's integrated works loan.
⚠️ The 3 Fatal Errors to Avoid
Error 1: Renovating without precise costing
You estimate €20,000 of works, construction costs €35,000. Your ROI collapses, you lose money. Always cost BEFORE deciding.
Error 2: Selling as-is without works report
Without report, buyer overestimates works by 40-60%. You suffer a -25% discount instead of -15%. You lose €20,000-40,000.
Error 3: Renovating for ROI < 100%
If you invest €30,000 to gain €25,000 in value, you lose €5,000 + construction stress. Absurd. Sell as-is.
FAQ Thermal Sieve: Sell vs Renovate
What is the value jump between an EPC G and an EPC D?
In Lyon or Paris, the difference can reach 15 to 20% of net seller price. Example: €400,000 house in EPC D is worth €320,000 in EPC G (-€80,000). Doing works often allows capturing this "green value" everyone talks about in 2026. However, if works cost €50,000, your net gain is only €30,000 (€80,000 - €50,000), i.e. 60% ROI. Therefore, works cost must be < 50% of discount for it to be profitable.
How much do works cost to move from G to D?
On average €250-400/m² for a house, €200-350/m² for an apartment. Example: 100m² house = €25,000-40,000. Main posts: attic insulation (€4,000-6,000), heat pump (€12,000-16,000), double glazing joinery (€6,000-10,000). Warning: these prices exclude MaPrimeRénov' aids (which only apply if you occupy the property 3 years, so not in case of immediate sale).
Can I benefit from MaPrimeRénov' aids if I sell after works?
No, unless you occupy the property 3 years after works. MaPrimeRénov' imposes a 3-year occupation clause. If you sell before, you must repay the aids. Exception: some local aids (metropolises, regions) don't have this clause. Check with RenovMatch. Conclusion: in most cases, you must cost works excluding aids for sale arbitrage.
How long to sell a thermal sieve in 2026?
Average delay: 6-12 months for an EPC G, 4-8 months for an EPC F (vs 2-4 months for an EPC D). The worse the EPC, the longer the delay. Reason: 73% of buyers filter by EPC on real estate portals. Your property doesn't even appear in their searches. Solution: either renovate to sell quickly, or accept long delay + significant discount.
Should I do an EPC after works before selling?
Yes, mandatory. The EPC is valid for 10 years. If you do energy works, you MUST redo an EPC to display the new class (D instead of G). Cost: €150-250. This new EPC is your best sales argument: it proves works were effective and the property is now "rentable" and "financeable" by banks.
Can you sell a thermal sieve to an investor?
Yes, this is the best strategy. Investors (property merchants, LMNP, tax deficit) actively seek thermal sieves to benefit from works tax deduction. They accept a lower discount (10-15% vs 20-25% for first-time buyers) as they value potential. Tip: mention "Ideal tax deficit investor" in the listing + provide a certified works report to facilitate their analysis.
What minimum ROI for renovating to be profitable?
Empirical rule: ROI > 150% for it to be interesting. Example: if you invest €30,000 in works, you must gain at least €45,000 in value (150% of €30,000). Why? Because you must compensate construction risk (budget overrun, delays), holding cost (3-6 months), and stress. If ROI < 150%, sell as-is with a works report to limit discount.
🔥 Arbitrate Your Thermal Sieve
Compare as-is sale vs renovation. Discover which scenario maximizes your net seller price in 2 minutes.
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