Ventilation for Homes: Choose the System that Fits Your Home

Why is good ventilation in the home essential?

Every day we produce moisture, CO₂, and particulate matter in our homes. Without sufficient fresh air, it accumulates, with possible consequences such as mold, allergies, or headaches. Ventilating is literally letting your home's lungs breathe.

But how do you do that smartly? Opening windows helps, but a well-thought-out ventilation system continuously ensures a healthy indoor climate without you having to think about it. Especially in well-insulated homes, it is important to balance air quality and energy efficiency.

The 4 Types of Ventilation Systems: A, B, C, and D

In the construction world, we speak of four basic systems, each with a different combination of natural or mechanical supply and exhaust. Below, I explain them clearly so you know what to look for.

• System A, Natural Supply and Exhaust: Fresh air enters through grilles in windows or walls, stale air disappears via natural draft in small ducts. Simple, but dependent on weather conditions. Often insufficient in winter or during calm wind.
• System B, Mechanical Supply, Natural Exhaust: Fans push filtered air inside, exhaust happens as in A. Rarely used in homes because the overpressure can cause windows to draft.
• System C, Natural Supply, Mechanical Exhaust: The most popular solution in Flemish homes. Grilles (mostly self-regulating) let fresh air in, a central extraction box removes humid air via kitchen, bathroom, and toilet. Energy-efficient and relatively affordable. More about system C.
• System D, Balanced Ventilation with Heat Recovery: Both supply and exhaust are mechanically controlled. A heat exchanger extracts heat from the exhaust air and transfers it to the supply air. This way you hardly lose heat. Ideal for well-insulated homes and new construction, or renovation with attention to air ducts. Discover the advantages of system D.

What does a ventilation system for a home cost?

The price strongly depends on the chosen system, the size of your home, and ease of installation. A simple system C with self-regulating grilles and a central box starts around 2,500 to 4,000 euros (incl. installation). System D with heat recovery is more expensive: count on 7,000 to 12,000 euros or more, depending on the ductwork. For a precise estimate, request our free valuation.

Extra costs may arise in an existing home if breaking work is needed for the ducts. Fortunately, there are now also decentralized system D solutions, where you install small units per room, limiting the intervention.

Ventilation in an existing home: what should you pay attention to?

Installing a ventilation system in an existing home often requires creativity. System C is popular because it can be done with simple adjustments: replace old grilles, install an extraction box, and pull ducts through existing shafts. System D requires more work, but with decentralized balanced ventilation, it becomes easier. In Flanders, it is mandatory during major renovations to comply with the ventilation standard.

Also a mechanical ventilation system in an old house is possible, provided you take into account noise standards and airtightness. Get good advice beforehand.

How do you ventilate efficiently in winter?

In cold months, we don't want to throw away heat. System D with heat recovery then scores best: you retain up to 90% of the heat. With system C, self-regulating grilles ensure that no more air enters than necessary. Don't forget to properly maintain your device and replace filters annually.

Grants and regulations in Flanders

The Flemish government encourages energy-efficient ventilation. For system D with heat recovery, you can apply for a grant via Fluvius (up to a few hundred euros). Also, new-build homes must meet the EPB requirements, which prescribe a minimum ventilation flow rate. Always check the current regulations, which may differ by construction year and municipality.