Natural ventilation in your home: clear explanation and practical tips

A natural ventilation system works with two fixed air streams: supply of fresh outside air in dry rooms (living room, bedrooms, office) and exhaust of stale air through wet rooms (bathroom, kitchen, toilet). These streams are driven by natural forces: temperature differences (thermal buoyancy) and wind pressure. Because warm air is lighter than cold air, it rises through vertical ducts to the roof. Wind creates positive pressure on one side of the house and negative pressure on the other, which boosts the airflow.

This system works completely passively, without fans or electricity. The key to a well-functioning natural ventilation is a well-thought-out design with sufficient openings for air supply and exhaust in the right places. In Flanders, the ventilation standard NBN D 50-001 prescribes how much fresh air must enter and be exhausted per room at minimum. That depends on the room size and usage.

In a standard Flemish terraced house, you often see ventilation grilles above windows in the living room and bedrooms, and exhaust ducts in the kitchen, bathroom, and toilet. These ducts terminate on the roof via a wind-driven cowl or via a central exhaust shaft. The gap under interior doors is at least 1.5 cm high, so that air can flow unhindered from the dry to the wet rooms. In new-build homes, system A is often used: fully natural ventilation, but with self-regulating grilles that respond to wind pressure and humidity. Want to know more about ventilation system A?

Traditional ventilation grilles are opened and closed by hand. Self-regulating grilles, on the other hand, automatically adjust the air passage based on wind pressure or humidity. During strong wind, they partially close to prevent drafts and energy loss. When indoor humidity rises, they open further to provide extra ventilation. This makes them particularly suitable for the Flemish climate, with its often changeable weather.

In practice, you see that many homeowners in Flanders have their old ventilation grilles replaced with self-regulating models. This can be done per room or for the whole house. The investment pays for itself through less heat loss and a more stable indoor climate. Request a no-obligation consultation to discover if your home is suitable for self-regulating grilles.

Below we've listed what you can expect:

Advantages

• No electricity consumption: The system runs on natural driving forces and therefore uses no power. That saves on your energy bill and is better for the environment.
• Silent: No humming fans. Only the soft rustle of the wind.
• Low maintenance: No filters to replace quarterly. Occasional cleaning of the grilles and inspection of the ducts suffices.
• Constant air quality: The system works continuously, 24/7. You don't have to think about it.
• Affordable: Lower installation costs than mechanical systems and almost no operating costs.

Disadvantages

• Dependent on weather and wind: On calm, warm days, air exchange can decrease. Then extra ventilation by opening windows is recommended.
• Less precisely controllable: You cannot regulate the amount of fresh air down to the cubic meter like with balanced ventilation with heat recovery (system D).
• No heat recovery: In winter, heat escapes through the exhaust. This can be partly remedied with self-regulating grilles.
• Susceptible to blockage: If gaps and grilles are sealed shut (for example, by insulation work), the system can malfunction, and a thorough check is needed.

Doubting whether natural ventilation still suits your home? Schedule a no-obligation ventilation check at your home.