Ventilation selection guide: which system suits your home?

Why is good ventilation crucial for your home?

A healthy indoor climate starts with fresh air. Without ventilation, moisture, CO₂ and harmful substances build up. This leads to mould, health problems and a stuffy feeling. In Flanders, ventilation is also legally required for new builds and major renovations, according to EPB regulations. A good system not only ensures a comfortable home, but also increases the value of your property.

The four basic types of ventilation systems at a glance

Ventilation systems are divided into types A, B, C and D. The main difference lies in how air is supplied and extracted, and whether there is a mechanical component. Below you will discover each system in detail.

System A: natural ventilation

With system A, air enters through grilles in the facade and leaves the building via vertical ducts. Everything works on natural draught, no fans. It is the simplest and cheapest option, but performance depends on the weather. In older homes without insulation, system A may suffice, but in modern airtight houses it is often insufficient. Maintenance comes down to cleaning the grilles.

System B: mechanical supply, natural exhaust

Here, a fan pushes fresh air into the home, while stale air escapes naturally. System B is rarely used, as it is more complex than A but does not offer the benefits of C or D. It requires a well-adjusted installation and the supply fan can produce noise. For most homes, there are better alternatives.

System C: natural supply, mechanical exhaust

This is the most popular system in Flanders: air enters through window grilles and is centrally extracted by a ventilation box (usually in the kitchen, bathroom and toilet). The exhaust fan runs at a low continuous power and can switch to a higher setting on demand. System C is easy to install, also in renovation projects, and consumes little energy. Many brands such as DUCO and Renson offer extensive controls and designer grilles. The supply of fresh air does depend on open grilles, so occupants must open them themselves.

System D: balanced ventilation with heat recovery

System D, also known as balanced ventilation, works fully mechanically: a unit draws in both fresh air and extracts stale air. A heat exchanger recovers up to 90% of the heat from the extract air and transfers it to the supply flow, a significant energy saving. No window grilles are needed, which reduces noise nuisance and draughts. System D is ideal for airtight new-build homes, but the installation is more complex and requires well-adjusted ductwork. Combine it with passive cooling for extra comfort in summer. Since the system runs continuously, regular filter maintenance is a must.

Which system suits your situation?

The choice depends strongly on the type of home and your budget. For an existing house with moderate insulation, system C is often the practical solution, while a new build or a major energy renovation calls for system D. Our local specialists are happy to look at your situation with you. They take into account the layout of your home, the ventilation flow rate, and your wishes regarding comfort and noise.

What does a ventilation system cost in Flanders?

Prices vary greatly. System A: from €500 in materials, but the low performance often makes it not recommended. System C: count on €1,500 to €3,000 including installation, depending on the number of grilles and the ventilation box. System D: here costs start around €5,000 for a simple setup, but for larger homes or extra ductwork this can rise to €10,000 or more. Request a tailor-made quote to get a realistic picture for your project.

Premiums and subsidies for ventilation in Flanders

The Flemish government encourages energy-efficient ventilation. For new builds, system D is often the standard to meet EPB requirements. For renovation, there are premiums from Fluvius and the grid operator, depending on the energy label. Moreover, ventilation can count towards obtaining an EPC certificate. Our selection guide automatically takes into account current premiums in your municipality.

Maintenance and lifespan of your ventilation system

Every system requires regular maintenance. With system C, cleaning the grilles and vacuuming the exhaust vents annually suffices. System D requires new filters every 3 to 6 months. The ventilation box lasts an average of 15 to 20 years. Good maintenance keeps efficiency high and prevents costly repairs. Many installers offer a maintenance contract.

Decentralised ventilation: an alternative for renovation

In major renovations where central ductwork is not feasible, decentralised ventilation provides a solution. Small units per room provide demand-controlled ventilation, often with heat recovery. Brands like Renson Endura Delta or DUCO Box offer compact solutions that work locally and are easy to integrate.