Why install a VMC in your bathroom?

Problems caused by poor bathroom ventilation

The bathroom is the most humid space in the house, with an ideal humidity level of between 40% and 60%. Without adequate ventilation, this rate can quickly climb and lead to several problems.

Condensation on walls and mirrors

Condensation occurs when warm, moist air comes into contact with cold surfaces. In a poorly ventilated bathroom, this phenomenon first manifests itself in foggy mirrors that remain fogged up for a long time after showering. However, it's not just an aesthetic inconvenience.

This excessive humidity also deposits on walls, ceilings and windows, creating a persistent film of water. Without an efficient bathroom ventilation system, this condensation cannot drain away properly. As a result, water gradually accumulates, forming droplets on vertical and horizontal surfaces.

Mould growth

Stagnant humidity creates an ideal environment for mold growth. These microscopic fungi usually appear as black, green or brown spots in tile joints, ceiling corners and around windows.

Beyond their unsightly appearance, these molds present serious health risks. They release spores into the air which, when inhaled, can cause respiratory problems, allergies and irritation, particularly in sensitive people or those suffering from asthma. Inadequate bathroom ventilation considerably amplifies these risks.

Degradation of materials and coatings

Prolonged exposure to humidity leads to gradual deterioration of materials. First, paint begins to blister and peel from walls. Next, wallpaper peels, tile joints become brittle and plaster crumbles.

Wooden elements, which are omnipresent in bathrooms (furniture, doors, skirting boards), are particularly vulnerable. Wood absorbs moisture, causing it to swell, warp and eventually deteriorate structurally. Even materials like metal can suffer, with rust appearing on fasteners and accessories.

What's more, water can seep into the house's structures, compromising the integrity of the building. Installing a bathroom VMC is therefore not only a question of comfort, but also of preserving your home.

Why choose a bathroom VMC?

Controlled mechanical ventilation (CMV) is the ideal solution for maintaining a healthy environment in your bathroom. Unlike natural ventilation, which depends on opening windows, CMV offers a systematic, permanent approach to indoor air management.

Constant air renewal

With VMC, the air in your bathroom is continuously renewed, even when you're not there. This system ensures a permanent exchange of air between outside and inside, eliminating unpleasant odors and pollutants. A double-flow CMV can recover up to 90% of the heat contained in the extracted air, guaranteeing not only fresh air, but also considerable energy savings.

The system operates 24 hours a day, creating a continuous flow of air that prevents stagnation, the main cause of mold growth. What's more, some models are equipped with humidity sensors that automatically adjust the extraction flow rate as needed, offering optimum efficiency.

Efficient moisture evacuation

One of the most important functions ofa bathroom VMC is moisture evacuation. Indeed, a VMC efficiently extracts the water vapor produced during showers and baths, preventing its condensation on cold surfaces. To be effective, the extraction flow must be adapted to the size of your bathroom - generally between 15 and 30 m³/hour for a standard bathroom.

In addition, the CMV creates a slight negative pressure in wet rooms, drawing air from other rooms into the bathroom before exhausting it outside. This sweeping principle ensures that air circulates throughout the home, maximizing the system's efficiency.

Reduced health risks

Installing a bathroom CMV makes a significant contribution to improving indoor air quality. It eliminates contaminants such as volatile organic compounds (VOCs), suspended particles and allergens. By maintaining humidity levels between 40% and 60%, the optimum level for good health, CMV considerably limits the development of bacteria, viruses and fungi.

In addition, models equipped with filters purify the incoming air, reducing the risk of allergies and respiratory problems, particularly beneficial for asthma and allergy sufferers. A well-maintained CMV can therefore become a real ally for your long-term health.

What type of VMC should I install in my bathroom?

Choosing the right type of VMC for your bathroom is an important decision that will directly influence your daily comfort and the durability of your space. Several options are available, each with its own specific advantages.

Single-flow CMV: economical and easy to install

Single-flow CMV is currently the most widely used ventilation system. Its principle is simple: it extracts stale air from damp rooms (bathroom, kitchen, toilet) and exhausts it to the outside. Fresh air enters naturally through ventilation grilles in living areas.

Two variants exist: autoregulatory CMV which maintains a constant airflow, and hygroregulatory CMV which adjusts the extraction rate according to the humidity level in the room. The latter offers better air quality while being more energy-efficient.

Double-flow CMV: ideal for well-insulated homes

For homes with good thermal insulation, double-flow CMV is a first-choice option. Unlike the single-flow system, it recovers up to 90% of the heat contained in extracted air to preheat incoming air.

This system requires the installation of two separate duct networks: one for extracting stale air, the other for blowing in fresh air. These are linked by a heat exchanger. Although the initial cost is higher, the heating savings gradually compensate for this investment.

Automatic bathroom ventilation: effortless comfort

Automatic VMC systems represent a significant advance in comfort. Equipped with humidity, CO2 or volatile organic compound (VOC) sensors, they constantly analyze the air quality in your bathroom.

Some models monitor air quality 24 hours a day and automatically adjust ventilation levels using sensors integrated into the control modules. They even offer control via a mobile application, enabling you to view the air quality history.

Ceiling-mounted VMC: discretion and efficiency

For bathrooms with limited space, ceiling-mounted VMC offers a discreet, efficient solution. Installed in the ceiling or a false ceiling, it blends in perfectly with your decor.

There are two main types: axial (or helical) extractors for installations directly towards the façade, and the more powerful centrifugal extractors for longer ducts. For safety reasons, these fans should not be installed above the shower, unless the distance from the floor is greater than 2.25 meters.

Tips for successful bathroom VMC installation

The installation of a VMC in the bathroom requires careful attention to several technical criteria to guarantee its efficiency and compliance with current standards. A properly installed system ensures healthy air and effectively prevents humidity problems.

Compliance with extraction flow standards

The extraction flow rate is a fundamental element in the efficiency of your VMC. Regulations stipulate minimum flow rates depending on the type of room: for a bathroom, the flow rate must be at least 15 m³/h if it is shared with a toilet, and can rise to 30 m³/h depending on the number of main rooms in the dwelling. These standards guarantee efficient moisture evacuation while maintaining reasonable energy consumption.

Choosing the optimum location

The location of the VMC has a direct influence on its performance. For maximum efficiency, place your fan about 30 cm from the shower and between it and the door. This position will :

• Maximize moisture extraction at source
• Create a flow of air through the room
• Avoid dead zones where air stagnates

Avoid installing the fan directly above the shower, as this will make it feel colder during use. Likewise, don't place the fan too close to the air inlet, as this could create an air short-circuit.

Check insulation and air inlets

Good duct insulation is essential, especially in unheated spaces such as attics. Choose insulated ducts with a minimum thickness of 25 mm for heated spaces and 50 mm for unheated volumes. Check that all connections are watertight, to avoid loss of flow and noise pollution.

VMC for your bathroom to avoid unpleasant surprises

Installing a VMC in your bathroom is much more than just an additional piece of equipment. Above all, it's an essential investment in your family's health and the preservation of your home.

Several options are available to us depending on our needs and budget. Single-flow CMV remains an economical and efficient solution for the majority of homes. Nevertheless, dual-flow systems are emerging as the ideal choice for well-insulated homes, despite a more substantial initial investment. The energy savings generated gradually offset this cost.

Automatic models, on the other hand, offer optimum comfort thanks to their intelligent sensors, which adjust the flow rate according to actual needs. This technology ensures optimum air quality while limiting energy consumption.

It's important to remember that the efficiency of a CMV depends largely on its installation. Compliance with flow rate standards, strategic positioning and good duct insulation guarantee optimum performance. 

Ultimately, a correctly installed VMC transforms your bathroom into a truly healthy space. It effectively prevents humidity problems, preserves your floor coverings and materials, and contributes to the quality of the air you breathe every day. Your comfort and health certainly deserve this sound, long-lasting investment.