8 years on average between launching the first discussions and starting the works. 90% of co-ownership buildings combine at least 3 funding sources. EUR 100–180 per month per unit in 86% of cases. The Syndic Reno Support programme (Federia) analysed 15 real renovation cases. The findings challenge several received ideas.
How long does an energy renovation actually take in a co-ownership building?
On average, 8 years separate the launch of initial discussions from the actual start of energy renovation works in a co-ownership building. This figure, drawn from the analysis of 15 concrete cases by the Syndic Reno Support programme, is striking in its scale — and it has a structural explanation: the co-ownership general meeting, which meets only once a year, mechanically slows collective decision-making.
Only 2 of the 15 co-ownership buildings studied managed to start in less than 3 years, and only thanks to substantial financial support that accelerated consensus among co-owners.
The Syndic Reno Support programme: analysis of 15 real cases
The Syndic Reno Support programme, launched in February 2024 by the professional federation Federia with the support of the Brussels and Walloon Regions, supports professional syndics in managing energy renovation projects. Its "Reno Stories 2024–2025" report documents 15 concrete cases of completed or ongoing renovations — a rare and valuable source of data for the sector.
Who carried out these renovations?
The 15 co-ownership buildings studied vary in size (from fewer than 10 flats to more than 50) and location (mainly Brussels and Wallonia). What they share: they all engaged in an energy renovation process through to completion, or to a sufficiently advanced stage to be documented. They therefore represent the "star pupils" — the co-ownership buildings where the process worked. Failures and blockages are not in the study, which means the figures presented are probably optimistic relative to the sector average.
Why energy is almost never the primary motivation
One of the most surprising findings of the study concerns the initial motivations of co-owners.
Breakdown of motivations across 15 cases
- Only 3 co-ownership buildings had improving energy performance as their main objective at the outset
- 6 co-ownership buildings initiated works primarily because of building pathologies — water infiltration, cracks, roof deterioration, acoustic insulation problems — with an energy component added later
- 6 co-ownership buildings only incorporated the energy aspect after receiving specialist advice or support (architect, engineering firm, programme such as Syndic Reno Support)
This finding has a major practical implication: syndics and property managers who wait for co-owners to spontaneously raise energy renovation at the AGM are waiting too long. The impetus most often comes from outside — from a professional who flags the opportunity to incorporate an energy component into works already planned.
The window of opportunity in mandatory works
Routine maintenance works (roof replacement, façade renovation, boiler replacement) constitute windows of opportunity to incorporate energy thinking. A trained syndic can transform a "boiler replacement" into a "partial energy renovation project" by suggesting at the right moment that a switch to a collective heat pump or simultaneous loft insulation be considered.
Without this integrated energy thinking from the start, some works block any further improvement for 15 to 20 years. Installing a new gas boiler in 2026 without thinking about the future of the installation could commit the co-ownership to keeping that system until 2041 — when regulations may impose a more demanding standard.
Financing: a complex but manageable puzzle
The 3-source minimum rule
In 90% of the cases studied, co-ownership buildings combined at least 3 distinct funding sources to close their renovation financing plan. The most common combinations:
- Co-ownership reserve fund — initial contribution, often insufficient on its own
- Collective loan — borrowed by the owners' association
- Regional energy grants — Renolution (Brussels), Habitation (Wallonia)
- Municipal grants — varying by municipality
- Green certificates — for renewable energy production installations
The complexity of this puzzle partly explains the average preparation time: identifying, checking eligibility for, and coordinating 3 to 5 funding sources takes time, especially in a collective annual decision-making structure.
The lending offer remains the weak link
The study identifies a structural bottleneck on the banking finance side: only 4 lenders are actually active in the collective lending segment for co-ownership buildings in Belgium. Their terms are often poorly suited:
- Short repayment periods (5–10 years vs. the actual amortisation of works over 20–30 years)
- Insufficient credit ceilings for large co-ownership buildings
- Difficulty establishing guarantees on a collective asset (no simple right of follow-through as with an individual property)
This co-ownership lending market remains underdeveloped compared to our European neighbours, where "on-bill" financing products (repayment integrated into service charges) are starting to emerge.
What co-owners actually pay
Despite the complexity of financing, the amounts borne per unit remain contained in the vast majority of cases:
| Monthly amount per unit | Share of cases studied |
|---|---|
| EUR 100–180 / month | 86% of cases |
| EUR 350–550 / month | 14% of cases (major pathologies) |
Cases with high monthly payments (EUR 350–550) involve co-ownership buildings that combined major building pathologies (requiring heavier works) and high-value flats (where owners can more easily bear higher charges).
For the remaining 86%, the EUR 100–180 monthly payment per unit is roughly equivalent to the energy charge savings achieved after renovation — making the project broadly neutral on co-owners' monthly budgets.
What the syndic can do to accelerate the process
The 8-year average delay is not inevitable. Several structural factors explain this figure, and some can be influenced by a proactive syndic.
1. Anticipate rather than react
A syndic who waits for a co-owner to raise energy renovation at an AGM loses several years on average. The proactive approach is to:
- Commission a preliminary energy audit in the 2 years before a major installation is due for replacement
- Put "Energy strategy" on the AGM agenda before being forced by an emergency
- Present the audit results with an estimate of the cost of inaction (energy bills at 5 and 10 years without works)
2. Rely on co-ownership specialists
The Syndic Reno Support study confirms that support from architects or engineering firms specialising in co-ownership buildings significantly accelerates decision-making. These professionals know how to present options in a way that a general meeting can understand, incorporate available grants into the financing plan, and coordinate the multiple parties involved.
3. Break decisions into stages
Rather than presenting a complete (and therefore costly and anxiety-inducing) renovation project at a single AGM, effective syndics break up the process:
- AGM 1: Vote to commission a feasibility study (limited budget, simple decision)
- AGM 2: Vote on the principle of renovation and priorities
- AGM 3: Vote on the financing plan
- AGM 4: Vote on the choice of contractors
Each stage is individually digestible. The overall process remains long, but each AGM moves it forward.
Seido for co-ownership buildings: managing an energy renovation over 8 years requires rigorous tracking. With Seido, every stage is documented — from initial quotes to AGM decisions, through to works tracking and contractor management. Co-owners have real-time access to progress, which facilitates votes and accelerates decisions. Plan your renovations with Seido →
This article is part of Property Essentials #2 — February 2026. Also read: Fibre optic in co-ownership buildings: rights and obligations of the syndic — Hidden defects in co-ownership: the Court of Cassation ruling.
Sources and references
- Reno Stories 2024–2025 Report (PDF), Federia / Syndic Reno Support, analysis of 15 Belgian co-ownership buildings
- Syndic Reno Support launch, Federia, 20/02/2024
- Syndic Reno Support programme: syndicrenosupport.immo