C
System C is mechanical extraction with natural supply via window grilles. Affordable and suited to many renovations; with sensors (C+) it becomes more efficient and comfortable.
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Ventilation guide for Flanders
Ventilation system C: natural in, mechanical out
A healthy indoor climate without complicated technology. System C lets fresh air in naturally and removes used air mechanically. Discover whether this is the right system for your home or business.
- Local installers throughout Flanders
- Clear advice without technical jargon
- Always a tailored quote
Quick answer
What is a ventilation system C?
Ventilation system C is a mechanical ventilation system where fresh air is supplied naturally through grilles in windows or walls, while used air is mechanically extracted by a central fan in wet rooms. It combines the comfort of controlled exhaust with the quiet, energy-efficient principle of natural supply.
Unlike system D, where both supply and exhaust are mechanical, system C lets nature lend a hand. Window sections with built-in ventilation grilles provide the supply; the mechanical exhaust creates a slight negative pressure that distributes fresh air evenly throughout the home. This makes it an affordable and low-maintenance choice for many Flemish houses and commercial buildings.
How ventilation system C works in your building
The supply: natural and silent
Fresh outside air flows in through self-regulating or manually adjustable ventilation grilles in windows or facades. These grilles are designed to cause no nuisance even in wind and rain. The air spreads through dry rooms such as the living room and bedrooms, and is further transported to wet rooms via grilles in internal doors.
The exhaust: mechanical and effective
A central ventilation unit, usually in the attic or a storage room, extracts the used air through ducts in the kitchen, bathroom, and toilet. This unit contains an energy-efficient DC fan that is infinitely adjustable. With a remote control or app, you adjust the extraction level when cooking, showering, or when there are extra people.
Ventilation system C+ with humidity sensors
More and more often, a C+ variant is chosen. Here, the supply grilles are equipped with sensors that respond to humidity or CO2. This way, air only flows in when needed, which reduces energy consumption for heating in winter. Together with a mechanical exhaust with a humidity sensor in wet rooms, this creates a demand-driven system that smartly responds to the actual occupancy of the building.
The difference with ventilation system D
With system D, both supply and exhaust are mechanically controlled, with a heat recovery unit that extracts heat from the exhaust air to preheat the incoming air. System C does not have this recovery, but is quieter, simpler, and cheaper to install. Because most heat loss through ventilation occurs via drafts and gaps that are not insulated, the absence of heat recovery in a well-insulated home does not always outweigh the higher investment of system D. Curious which system suits you best? Read our comparison between ventilation systems C and D.
Why Flanders chooses us
No complicated air studies, just breathing room tailored to you
As the only ventilation specialist with such strong local roots, we understand that every home and business breathes differently. We translate complex systems into understandable solutions.
Regional experts in your area
Our installers know the typical homes in Flanders through and through: from terraced houses in Antwerp to detached villas in Limburg.
Clear advice without doubt
You get honest explanations of the pros and cons for your specific situation. So you choose with 100% confidence.
Craftsmanship you can rely on
Our installers are certified and work according to the latest ventilation standards. After installation, we test everything thoroughly and go over the operation together.
A system C does not fit equally well everywhere
In which buildings does system C feel at home?
Not every space has the same ventilation needs. Discover where system C performs best.
Existing homes you are renovating
During a thorough renovation, installing ventilation grilles and exhaust ducts is easy to combine. System C delivers fresh air without costing a fortune.
New builds up to moderate size
In compact, well-insulated homes, system C works great. For larger projects or passive houses, system D is often more logical to limit heat loss.
Apartments with sufficient facade openings
Also perfect on the third floor: the central fan can be hidden in a storage room or ceiling. Do pay attention to sufficient distance between supply grilles and noisy streets.
Offices and small retail businesses
For a fresh working climate without complex air handling, system C is ideal. The mechanical exhaust switches on when the CO₂ level rises, and the natural supply never feels chilly or drafty.
What investment can you expect?
The price of a ventilation system C in Flanders
The total cost depends on the size of the building, the type of vents chosen, the fan, and the complexity of the ductwork. A system C for an average family home typically costs between €1,500 and €3,000, including installation. For larger projects or upgrades to C+ with sensors, the guide price can rise to €4,500. Be sure to also check whether you qualify for <a href="#">Flemish renovation grants</a> or a reduced VAT rate.
- Basic installation: on average €1,800 to €2,500
- C+ upgrade with humidity sensors: +€500 to €800
- Low maintenance: annual cleaning of vents and fan is sufficient
- Energy consumption comparable to an LED bulb, thanks to efficient DC motors
Specialist installation in your region
Our ventilation experts work throughout Flanders
From our local bases, we serve all Flemish provinces. Choose your region and we'll connect you with an installer who knows your neighbourhood inside out.
- Antwerp
- Limburg
- East Flanders
- Flemish Brabant
- West Flanders
Frequently asked questions about ventilation system C
What is the difference between ventilation systems C and D?
With system C, fresh air enters naturally through window vents and is extracted by a mechanical fan. System D mechanically controls both supply and extract, and recovers heat via a heat exchanger. System C is cheaper to buy and maintain, while system D can be more energy-efficient in very well-insulated homes.How much does a ventilation system C cost on average?
For a complete installation in an average home, expect to pay between €1,500 and €3,000. The price rises for larger areas, extra sensors, or hard-to-reach ductwork. Always request a tailored quote, as every project is different.Can I install a ventilation system C myself?
Installing a ventilation system C yourself is not recommended. Laying extract ducts, positioning vents, and correctly balancing the fan require professional expertise. A poor installation leads to noise, draughts, or mould. Leave it to a certified specialist.How often should I maintain a ventilation system C?
Clean the supply vents and the inside of the fan at least once a year. Clean the vents with a vacuum cleaner and a damp cloth. Have the ducts professionally cleaned every three to five years to prevent fire hazards and unpleasant odours.What is ventilation system C+?
C+ is a smarter version of system C. The supply vents measure humidity or CO₂ and only open when there is demand for fresh air. This means you ventilate exactly when needed, saving energy and improving comfort without cold draughts in winter.Which ventilation system C brands are good?
Well-known brands in Flanders include Duco and Renson. These manufacturers offer reliable fans and vents that meet EPB requirements. Choose an installer who works with multiple brands so they can objectively advise what best suits your home.Is ventilation system C suitable for every home?
System C fits most homes, but it is not ideal everywhere. In homes with only one façade or without window openings in every dry room, natural supply is difficult to achieve. In very noise-sensitive areas, open vents can also be disruptive. Our expert will assess your situation on site.How much noise does a ventilation system C make?
A correctly installed system C is barely audible. The fan is usually in the attic and the supply vents are sound-dampened. At the highest extract setting, there may be a soft airflow sound, similar to a cooker hood on low.
Your questions about our approach
From quote to perfect installation: how we work
- Do you only work in Flanders?
- Yes, our installers are active throughout Flanders. From Antwerp to West Flanders: we make sure an expert is always available in your area.
- How does the installation of a ventilation system C proceed?
- First, an advisor visits you to measure the situation and discuss your requirements. Within a week, you receive a clear quote. After your approval, we schedule an installation day. Our team installs the vents, fan, and ducts, tests everything, and walks you through how it works.
- Do you also offer maintenance contracts?
- Certainly. In addition to installation, you can take out an annual maintenance subscription with us. This keeps your system working optimally and ensures you meet the manufacturer's warranty conditions.
- Can I get a tailored quote without obligations?
- Absolutely. You can request your quote without obligation, and we will create a proposal that fits your home or business exactly. Only when you are satisfied do we get to work.
- Is system C suitable for my old home?
- In most older homes, system C can be installed perfectly well, as long as there are sufficient natural supply options. During the site visit, we look at windows, existing chimneys, and insulation to determine what is feasible.
- What warranty do I get on my ventilation system?
- We provide a three-year full warranty on all materials and installation. The mechanical fan carries the manufacturer's warranty, typically five years. We repair any defects free of charge.
Ready for a healthy indoor climate?
Every home breathes differently. Let us assess your situation and discover exactly which system C fits best. Request your free quote now.
Related pages
Ventilation for Homes: Clear Guide for Your Ideal System
Ventilation selection guide: which system suits your home?
Ventilation system maintenance: your guide to fresh air at home and at work
Custom ventilation plan: guide, rules & local approach
Office ventilation system: healthy air, productive employees
Ventilation for businesses: breathing space for your company