How do you install a VMC in your bathroom?

In Luxembourg, many houses still have "natural ventilation" (i.e. no ventilation at all). In this type of home, you have to open the window every time you take a shower to get rid of the excess humidity. As a result, the air is stale, and you lose a lot of heat. Here's how to install ventilation in your bathroom.

Why should damp rooms be ventilated?

In Luxembourg, relative humidity can reach 85% in winter. So bathroom ventilation is not a luxury, but an absolute necessity. Very humid air presents a number of risks:

• Mould can develop in your home (affecting the health of residents - allergies, asthma, etc.)
• Materials can deteriorate over time (including tile joints, wooden structures, etc.)
• You use a lot more energy to heat your home in winter (humid air makes you feel colder)

To remedy this, the regulations impose minimum air ventilation rates to ensure adequate ventilation of wet rooms. In general, you should allow :

• 15 m³/h for a shower room equipped only with a shower
• 30 m³/h for a bathroom with bath
• 45 m³/h for a bathroom with separate bath and shower

What are the advantages of VMC in Luxembourg?

The advantages of a Controlled Mechanical Ventilation are manifold:

• You improve the comfort of residents: No more fogged up mirrors and unpleasant wet sensations after a shower
• You protect your property investment: You protect the cladding and structure of your home - an important factor in the Luxembourg property market
• You'll make substantial energy savings: The air is drier and therefore easier to heat. As a result, you reduce your heating bills.
• Improve the quality of your indoor air: Because you eliminate odours and pollutants, ensuring a healthier environment

In conclusion, installing a VMC in your bathroom in Luxembourg is not just a recommended operation, it's essential for maintaining a healthy and comfortable home, especially in an environment that can be cold and very damp in winter.

How do you choose the right CMV system for your bathroom?

Three types of VMC dominate the bathroom ventilation market, each meeting specific needs and budgets. The final choice depends on the configuration of your home, your usage habits and your budget.

Self-adjusting single-flow ventilation: the entry-level solution

Self-adjusting single-flow ventilation is the most economical and widespread solution in Luxembourg. This system works on a simple principle: stale air is constantly extracted from your bathroom and replaced by fresh air from outside.

Main features:

• The flow rate is constant and permanent: The ventilation system operates continuously at a predefined airflow rate, generally between 15 and 30 m³/h depending on the standards adopted.
• Installation is simple: A central motor is installed in the attic and ducts are laid in the wet rooms.
• The price is particularly affordable

However, this method is becoming less widespread. The fact that it operates continuously can create significant draughts of cold air in winter.

Humidity-sensitive single-flow ventilation: the preferred solution for renovation projects

Humidity-sensitive CMV is now the preferred choice for anyone wanting to optimise their energy consumption. This intelligent system automatically adapts its flow rate according to the humidity level detected in your bathroom. When the air is too humid, the ventilation motor runs at full speed until the humidity level in the bathroom or WC is reduced to acceptable levels. Then the motor stops;

There are two versions of humidity sensitive CMV:

• Hygro A CMV : Only the extract units adapt to the humidity level, while the air inlets remain self-regulating.
• Hygro B CMV : This is a complete system in which the extract units AND air inlets adapt intelligently to the humidity level.

The advantages of humidity sensitive CMVs :

• They are energy-saving: They reduce heat loss by 15 to 25% compared with a conventional system
• They keep your home comfortable: By stopping when the humidity level is satisfactory, they prevent the creation of draughts.
• They last longer: as the engines are not subject to continuous stress, they can last for several decades (provided they are regularly maintained)
• And best of all: they're very affordable. (It's a little more expensive than self-regulating CMVs, but still within acceptable ranges). However, you will need to provide ventilation grilles above each window.

Dual-flow CMV: top-of-the-range energy efficiency

La Double flow CMV is the premium ventilation solution in Luxembourg, particularly suited to new homes and complete renovations. This system recovers heat from the exhaust air to preheat the incoming air, offering exceptional energy performance.

Dual-flow CMV offers thermal savings of 80 to 95% compared with a conventional ventilation system. But this requires ductwork in every room of the home. This is a very major project, usually undertaken as part of a major renovation or new build. A complete system costs around €20,000 or more.

Generally speaking, the humidity sensitive solution is recommended for renovation projects in Luxembourg.

In brief: a comparison of CMV systems in Luxembourg

Criteria	Self-adjusting single flow	Single flow humidity sensitive	Double flow
Purchase price	€€	€€€	€€€€€
Installation	Simple	Moderate	Complex
Energy savings	Limited	Good	Excellent
Comfort	Correct	Good	Excellent
Maintenance	Easy	Easy	Specialist
Adapted to the LU climate	Yes	Very good	Perfect

The final choice depends on your priorities: budget, energy performance, comfort and type of home. Don't hesitate to consult a Luxembourg professional for a personalised assessment of your needs.

How do you install ventilation in a bathroom?

Where to install the VMC inlet?

Would you like to install a ventilation system in your wet room? Here are a few rules you need to know to ensure that your system runs smoothly:

1. The vent must be installed on the ceiling or at the top of the wallat least 1.80 m from the ground. The warm, humid air rises naturally, and that's where you need to capture it.
2. It must be positioned above or in the immediate vicinity of the shower or bath.where water vapour is most concentrated.
3. Maintain a distance of at least 20 cm from wall/ceiling corners to avoid areas of turbulence. or condensation (which reduce extraction efficiency).
4. Ideally, you should also keep the mouth away from draughts (to avoid the mouth sucking up draughts and creating a loop, instead of sucking up the steam).

What diameter for the VMC inlet?

The sizing of the extract units is also important and must be defined according to the regulatory flow rates:

• Allow for an 80 mm diameter for a bathroom with shower (flow rate 15 m³/h)
• Choose a diameter of 100 mm for a bathroom with bath (flow rate 30 m³/h)
• Finally, choose a diameter of 125 mm for a large bathroom requiring a higher flow rate (45 m³/h)

Important information: The diameter of the outlet must correspond exactly to the diameter of the connecting duct. Incorrect sizing leads to pressure losses and reduces the efficiency of the system.

Mistakes to avoid

These common errors can compromise the efficiency of your ventilation system:

• If you place the mouth behind a piece of furniture : this would block the suction and prevent the circuit from working properly
• If you put it too close to a window : A ventilation unit too close to a window can create disruptive draughts
• If you install it in a poorly designed false ceiling : Ensure that the false ceiling allows easy access for maintenance
• If you neglect the seal around the mouth : This can lead to loss of efficiency and noise pollution.

Ideally, use the services of a renovation professional in Luxembourg. He'll know exactly how to install your VMC to ensure it works at its best.

The price of VMC for a bathroom in Luxembourg

Here's a comparison table that roughly sums up the prices for installing a VMC motor and a vent in your bathroom. Obviously, the price will be higher for each additional room to be ventilated.

Type of CMV	Hardware price only	Price including installation	Installation time
Self-adjusting single-flow CMV	£150 – £400	€450 – €850	1 day
Humidity-sensitive single-flow CMV	€300 – €650	€650 – €1,200	1 to 2 days
Double flow CMV	€1,200 – €3,500	€2,500 – €6,000	2 to 3 days