Ventilation Requirements for Windowless Bathrooms in Italy

General Guidelines

A windowless bathroom lacks windows, making natural ventilation impossible. Therefore, Italian regulations mandate the installation of a mechanical ventilation system to ensure proper air exchange and to prevent mold and excess humidity. These fundamental requirements are outlined in the Italian Ministry of Health Decree from July 5, 1975, as well as local building regulations, which may differ depending on the region or municipality.

Is a Bathroom Without Ventilation Legal?

No, in Italy, a windowless bathroom without a mechanical ventilation system violates sanitary regulations. Without windows, natural air circulation is not possible, so mechanical ventilation is required to maintain a healthy environment.

Bathroom Regulatory Standards

According to the Ministry of Health Decree dated July 5, 1975, the following elements are mandatory in a bathroom:
- Washbasin;
- Bathtub or shower;
- Toilet;
- Bidet.

The size of a bathroom is not regulated nationally, but local building codes may set minimum dimensions. For instance, since 2014, Milan mandates that a bathroom must be large enough to fit all of the mentioned elements, with one wall at least **1.2 meters** high. Other areas may have different specific size requirements.

Ventilation System Requirements in a Windowless Bathroom

To ensure effective air exchange in a windowless bathroom, a mechanical ventilation system (MVS) must be installed, fulfilling the following conditions:

1. Air Exchange Volume Calculation
The required ventilation capacity depends on the room's size and usage frequency. According to the standard **UNI EN 16798-1**, the system must achieve:
- 6 air changes per hour for constant extraction;
- 12 air changes per hour for forced ventilation with automatic control.

This calculation considers the room's volume (length × width × height) and the needed air renewal rate. Fresh air intake should also be provided through specific openings or channels.

2. System Component Selection
- Fan Type: Centrifugal fans or decentralized VMC systems are options.
- Duct Size: Proper sizing minimizes pressure loss and ensures consistent airflow.
- Placement of Vent Openings: Exhaust and intake grilles should be placed to allow even air distribution in the room.

3. Noise Reduction
The ventilation system should be as quiet as possible. This can be achieved using:
- Sound-insulated ducts;
- Noise suppressors;
- Anti-vibration components.

This is crucial for resident comfort, ensuring the fan operation does not cause disturbance.

Types of Ventilation Systems for Windowless Bathrooms

1. Mechanically Controlled Ventilation (MCV)
VMC systems effectively extract moist and polluted air, replacing it with fresh, filtered air from outside. Two types of VMC exist:
- Single-flow VMC: Removes stale air and supplies fresh air through dedicated openings in other areas. It's simple and affordable but may cause heat loss due to temperature differences.
- Dual-flow VMC: Extracts stale air and delivers fresh, preheated or cooled air via a heat exchanger, offering higher comfort and energy efficiency.

2. Exhaust Fans
Exhaust fans provide a straightforward solution for removing moist air and are available as:
- Wall-mounted: Installed on an exterior wall for external air discharge.
- Ceiling: Positioned on the ceiling and linked to air ducts exiting outside.
- Timer-equipped: Activates with bathroom lighting.
- Humidity sensor: Automatically starts when humidity exceeds a set level.

Where to Install an Exhaust Fan?

For optimal efficiency, an exhaust fan in a windowless bathroom should be placed:
- Near moisture sources (like a bath or shower) to quickly remove steam and prevent condensation and mold.
- On the ceiling or upper wall, as warm, moist air rises.
- Connected to an external duct to vent exhaust air outside, avoiding stagnation in other rooms or spaces.

When selecting a fan, consider its power to match the bathroom's size and ensure adequate air exchange. Installation must meet safety standards, including proper distance from water sources and appropriate mounting height.

Conclusion

In Italy, a windowless bathroom must have a mechanical ventilation system compliant with health and building standards. This is not only a legal requirement but also a guarantee of a healthy environment in the room. When designing a ventilation system, consider the room's volume, equipment type and power, and ensure soundproofing and proper component placement.