When an oil boiler fails in the middle of winter in Brussels, the instinct to reorder the same model no longer works. Since June 1, 2025, the Region has banned the installation of new oil boilers. Existing devices are still allowed as long as they are functioning and maintained, but any replacement requires a change in technology. For condominiums as well as individual houses, this constraint reshuffles the cards of residential heating in Brussels.
PEB Control of Existing Boilers: The Schedule That Few Owners Understand
There is a lot of talk about the ban on installing oil, but less about what happens to installations still in service. Oil boilers that are still running must undergo an annual PEB control, carried out by a certified technician from Brussels Environment.
For gas boilers, the frequency changes to a control every two years. The control certificate must be kept for five years. In the case of sale or rental, this document may be required.
In practice, an owner who forgets an annual control on their oil boiler is exposed to a fine. Those considering the new rules for boilers in Brussels often discover this control aspect at the same time as the installation ban, even though it conditions the legal maintenance of their current installation.
The cost of annual maintenance with a PEB certificate represents a recurring item to integrate into the budget. As long as the oil boiler is functioning properly and passes the control, it can be kept. The day it breaks down irreparably, identical replacement is no longer an option.
Condensing Gas Boiler in Brussels: The Most Common Transition Solution
On the ground, most replacements post-ban are moving towards condensing gas. The reason is pragmatic: in a home already connected to the gas network, the work remains limited. The oil tank is removed, the hydraulic circuit is adapted, and the new boiler is connected.
Gas remains allowed for installation in 2025 and 2026, but Brussels regulations foresee a gradual tightening. The ban on gas for new installations is scheduled for the long term. Investing in a gas boiler today is buying time, not a definitive solution.
Specific Constraint for Apartment Buildings
In condominiums with a collective oil boiler room, switching to gas requires a connection to a network that may not exist in the street. Feedback varies on this point: some neighborhoods have a well-sized gas network, while others require roadworks that extend the timeline by several months.
For condominiums, the decision is made in a general assembly, which adds a layer of administrative complexity to the technical project.
Heat Pump and Hybrid System: How Building Insulation Changes Things
The air-water heat pump is the alternative promoted by public authorities. On paper, it ticks all the boxes: no fossil fuel, compatibility with long-term PEB objectives, reduction of emissions. In practice, its efficiency depends heavily on the insulation of the home.
A heat pump in a poorly insulated building consumes a lot of electricity to maintain a comfortable temperature. In pre-war Brussels homes, with uninsulated solid walls and old frames, installing a heat pump without first renovating the envelope amounts to heating the street.
- Well-insulated housing (PEB label A or B): the air-water heat pump operates autonomously and meets heating needs even in extreme cold.
- Moderately insulated housing (PEB label C or D): a hybrid system combining a heat pump and a supplementary gas boiler helps smooth out electricity consumption during peak periods.
- Poorly insulated housing (PEB label E to G): priority is given to insulation before any consideration of the heat generator, under penalty of electricity bills exceeding the former oil budget.
This link between envelope performance and heating system choice is the point we most often see underestimated. Choosing a boiler without knowing its PEB label is like buying tires without knowing the size of the rims.
PEB Objectives and Sanctions: Why Keeping an Old Boiler Becomes a Financial Risk
Brussels regulations are not limited to banning oil. They gradually impose energy performance objectives for housing, accompanied by sanctions. Keeping an outdated boiler (oil or gas) no longer only poses a comfort or bill problem: it can affect the property’s value and its regulatory compliance during a sale or rental.
A property rated F or G on the PEB certificate will become increasingly difficult to rent without renovations. Replacing the boiler with a high-performance system improves the PEB score, but is not enough if the building itself remains a thermal sieve.
Renolution Grants: The Current Situation
Renolution grants, which financed part of the energy renovation work in Brussels, have been suspended since January 2025. This suspension complicates the financial calculation for households considering a boiler replacement combined with insulation.
Without grants, the out-of-pocket cost for installing an air-water heat pump far exceeds that of a condensing gas boiler. This is a concrete barrier that explains why many Brussels residents still opt for gas, even knowing that this technology will also be banned in the long term.
Mandatory Maintenance After Replacement: What Changes Depending on the Chosen Technology
The type of system installed determines future maintenance obligations. Here’s how it works in practice:
- Condensing gas boiler: PEB control every two years by a certified technician, certificate to be kept for five years. Regular maintenance extends the lifespan and maintains efficiency.
- Heat pump: no strict PEB control, but annual maintenance is recommended (checking the refrigerant, cleaning the outdoor unit). Obligations vary depending on the power of the device.
- Hybrid system: a combination of both obligations, as it combines a gas boiler and a heat pump. It is the most maintenance-intensive system, but also the most versatile for moderately insulated buildings.
Anticipating these recurring costs is part of the initial choice. A system that is cheaper to purchase but more expensive to maintain can turn out to be more costly over ten years.
Replacing an oil boiler in Brussels is no longer a simple plumbing operation. It is a decision that commits the owner to the overall energy performance of their home, their annual maintenance budget, and the regulatory compliance of their property for the years to come.
