Is mechanical ventilation mandatory for a small renovation?

In small renovations, such as a bathroom renovation, mechanical ventilation is not legally required. However, you must ensure sufficient air exchange. A mechanical extraction system is often the simplest way to comply with building regulations and prevent mold.

When do you need a ventilation report?

A ventilation report is mandatory for a major energy renovation (IER) and for new construction. For other renovations, it is not always necessary, but we still recommend it to guarantee a correct installation and to meet the EPB requirements.

What is the best ventilation system for an old home?

In an old home, system C is often the most practical choice: mechanical extraction via wet rooms and natural supply via window vents. It requires less invasive duct work than system D and provides good air quality.

How do you ventilate a bedroom after renovation?

Always ensure fresh air supply via a window vent, a decentralized unit or an opening in the door. A quiet, self-regulating vent or a decentralized fan with heat recovery keeps the bedroom comfortable and healthy, without drafts.

Can I install ventilation grilles in windows myself?

Technically possible, but to guarantee proper functioning and appearance, it is best to have them integrated by the window manufacturer or a professional. This way they are neatly installed and meet the required flow capacity.

Are there premiums for ventilation during renovation in Flanders?

Yes, through Fluvius you can sometimes receive a premium for certain energy-efficient ventilation systems, for example in combination with a heat pump. Our advisors help you find out if your project qualifies.

Local ventilation specialist in Flanders

Ventilation during renovation: your complete guide to a healthy home

From regulations to practical systems, we translate complex ventilation into understandable advice, so you can confidently make the right choice for your renovation.

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A worker in blue overalls installs a ventilation grille in a renovated living room overlooking a green garden, while dust particles dance in a sunbeam.

Why ventilation is essential for every renovation

You insulate your home, replace windows or renovate the attic, all interventions that increase airtightness. But without thoughtful ventilation, moisture, CO2 and fine dust can accumulate. The result? Mold, musty smells and even health problems. Ventilation replaces polluted indoor air with fresh outdoor air and ensures a healthy and comfortable indoor climate.

During a renovation, you immediately seize the opportunity to integrate the ventilation system into the home. That is more efficient than making interventions afterwards. Whether you choose a simple system C or a full system D balanced ventilation, we help you clearly see the possibilities.

Is ventilation mandatory during renovation? The Flemish rules clearly explained

In Flanders, the EPB regulation (Energy Performance and Indoor Climate) applies to new construction and major energy renovations. But what if you only replace your windows or renovate the bathroom?

When is ventilation mandatory?

In the case of a major energy renovation (IER), where you insulate at least 75% of the building envelope and also address the installations, you must meet the ventilation requirements. You must have a ventilation preliminary design and report drawn up by an EPB reporter. For smaller renovations, such as replacing windows or a bathroom, a full ventilation report is not mandatory, but minimum requirements do apply: you must guarantee supply of fresh air in dry rooms and extraction in wet rooms.

Check the exact requirements on Vlaanderen.be or ask our advice. We know the rules and ensure that your project meets the standards, without paperwork stress.

Which ventilation system do you choose for a renovation?

Not every system suits every home. We look at the options and their suitability for renovation.

Ventilation system C: mechanical extraction, natural supply

In existing homes, system C is often the most affordable and simplest upgrade. A central fan extracts air via kitchen, bathroom and toilet. Fresh air enters through window vents. Ideal for renovation because no extensive duct network is needed, often an extraction duct to the roof suffices. Price indication: from €2,500 to €4,000, installation included (depending on the situation).

Balanced ventilation system D: mechanical supply and extraction with heat recovery

System D offers the highest comfort and is interesting if you renovate thoroughly and create an airtight envelope. It simultaneously supplies fresh air and extracts polluted air, with heat recovery up to 90%. This saves on heating. Ducts are required throughout the home, which requires more planning during the renovation. Price: count on €6,000 to €10,000 for a complete installation.

Decentralized ventilation: ventilating per room

Decentralized units are placed in the outer wall of a specific room, such as the bedroom. They extract or supply air with heat recovery. Handy if you only tackle one room or cannot lay central ducts. Price per unit: €500 to €1,500, depending on the type.

Ventilation grilles in windows: the basics

Are your windows being replaced? Then immediately have ventilation grilles integrated. They are unobtrusive and provide the necessary air supply. Price: €50 to €150 per grille, including installation during window production.

Practical ventilation tips per renovation project

Each intervention requires a specific approach. These are the main points of attention.

Replacing windows or glazing

New windows are often much more airtight than old ones. Without ventilation grilles, insufficient air exchange occurs. Have the window manufacturer install grilles or opt for self-regulating grilles that respond to moisture or CO2. This meets the minimum supply requirements.

Bathroom or kitchen renovation

These are wet rooms where extraction is crucial. Provide powerful mechanical extraction, for example via a fan that you can connect to a presence detector or humidity sensor. Combine this with a non-return valve to keep cold air out.

Converting the attic into a living space

An extra bedroom or office in the attic requires supply of fresh air. Provide a roof window with a ventilation grille or install a decentralized unit. Also think about transfer openings in the door or a grille to the hallway.

Post-insulation of walls or roof

Insulation makes your home more airtight. Check whether the existing ventilation still suffices. Often it is wise to immediately install a system C or D, because the home otherwise becomes too humid. Request a ventilation audit to assess the risk.

Removing a chimney

An old chimney sometimes served as natural ventilation. Upon demolition, that ventilation disappears. Replace this with a mechanical extraction system in the relevant room.

What does ventilation cost during a renovation? Clear price insights

The price depends on the type of system, the size of the home and the complexity of the installation. Below a realistic overview, based on average project costs in Flanders (indicative, for an exact price it is best to request a tailor-made quote).

System C (mechanical extraction): €2,500 - €4,500
System D (balanced ventilation): €6,000 - €12,000
Decentralized unit per piece: €500 - €1,500 (excl. installation)
Ventilation grilles per window: €50 - €200

Moreover, you can receive a premium for certain interventions via Fluvius. Ask our advisors about the current premium conditions.

Our approach

Personal advice tailored to your renovation

Every home breathes differently. That's why we first listen to your plans and inspect the home on site. Only then do we propose a system that works optimally, nothing more, nothing less.

Local experts across Flanders

Our installers know the Flemish building styles and regulations. Wherever you live, we come by for a site visit and take care of the complete installation.

No hidden costs

Our quotes are transparent and detailed. You know exactly what you pay and why, without surprises afterwards.

Certified quality

We work with recognized materials and trained professionals. After installation, you receive a completion report for the EPB administration.

Always a specialist in your area

Active across Flanders

From Antwerp to Limburg, from the coast to the Flemish Ardennes: our ventilation specialists come to your home for advice and installation. We know the local nuances and rules, from city centers to rural villas.

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Frequently asked questions about ventilation during renovations

Is mechanical ventilation mandatory for a small renovation?
In small renovations, such as a bathroom renovation, mechanical ventilation is not legally required. However, you must ensure sufficient air exchange. A mechanical extraction system is often the simplest way to comply with building regulations and prevent mold.
When do you need a ventilation report?
A ventilation report is mandatory for a major energy renovation (IER) and for new construction. For other renovations, it is not always necessary, but we still recommend it to guarantee a correct installation and to meet the EPB requirements.
What is the best ventilation system for an old home?
In an old home, system C is often the most practical choice: mechanical extraction via wet rooms and natural supply via window vents. It requires less invasive duct work than system D and provides good air quality.
How do you ventilate a bedroom after renovation?
Always ensure fresh air supply via a window vent, a decentralized unit or an opening in the door. A quiet, self-regulating vent or a decentralized fan with heat recovery keeps the bedroom comfortable and healthy, without drafts.
Can I install ventilation grilles in windows myself?
Technically possible, but to guarantee proper functioning and appearance, it is best to have them integrated by the window manufacturer or a professional. This way they are neatly installed and meet the required flow capacity.
Are there premiums for ventilation during renovation in Flanders?
Yes, through Fluvius you can sometimes receive a premium for certain energy-efficient ventilation systems, for example in combination with a heat pump. Our advisors help you find out if your project qualifies.

Your ventilation quote

How does it work? Practical questions about our service

How can I request a tailor-made quote for my renovation?

Click "Request your quote now", fill in the form and we will quickly contact you for a free site visit. During that visit, we discuss your plans and give an exact price.

Do you also work in my municipality?

We are active across Flanders, so also in your area. Our local installers know the region and the specific building characteristics.

How quickly can you start the installation?

After the site visit and quote confirmation, we can usually start within 2 to 4 weeks, depending on the schedule. We align the timing with your renovation schedule.

Do you also provide the necessary documents for the EPB regulations?

Yes, after installation you receive a completion report and ventilation performance document that you can use for your EPB declaration. We ensure everything is in order.

Can I combine a ventilation system with a heat pump?

Certainly, a balanced ventilation system D with heat recovery works perfectly together with a heat pump. Our experts advise you on the optimal combination for your energy-efficient home.

Do you also give advice if I'm not yet sure which system is best?

Absolutely. Our specialists listen to your wishes, analyze the home and clearly explain the pros and cons of each system. This way you can make a choice with confidence.

Ready for a healthy indoor climate in your renovated home?

Request your personal quote today and benefit from clear tailored advice. Our local specialists are ready for you.