In the UK, ventilation requirements in domestic settings are governed by Building Regulations and associated standards, primarily:

Key Legislation and Standards

• Building Regulations Part F (Ventilation): Sets the minimum standards for ventilation to ensure good indoor air quality and prevent moisture buildup.
• Approved Document F (2010, with updates): Provides guidance on compliance with Part F, detailing practical methods to achieve adequate ventilation.

Main Requirements:

Ventilation for Habitable Rooms (Living rooms, Bedrooms):

• Require continuous background ventilation, such as trickle vents.
• Mechanical or natural ventilation must be sufficient to remove moisture, odors, and pollutants.

Kitchens and Bathrooms (Wet Rooms):

• Need extract ventilation (either mechanical fans or passive extract vents).
• Mechanical extract fans should provide at least 30 L/s for bathrooms and 60 L/s for kitchens.
• Fans must be effective, controllable, and maintained.

Natural Ventilation:

• Adequate openings such as windows, vents, or airbricks.
• Openings should be positioned to promote effective cross-flow ventilation.

Moisture Control:

• Proper ventilation reduces risk of condensation, mold, and damp.
• Use of vapor control layers and proper insulation is also advised.

Compliance and Implementation:

• New developments should meet the standards outlined in Approved Document F.
• Retrofitting may require upgrades to existing ventilation systems.

Additional Guidance:

• Ventilation should be balanced to avoid drafts and heat loss.
• Adequate ventilation planning is essential during the design and construction process.

Summary:

The UK law mandates that domestic buildings must have adequate ventilation to ensure healthy indoor air quality, control moisture, and meet energy efficiency standards as per Building Regulations Part F and the associated guidance in Approved Document F.

You can find the full regulations here: https://assets.publishing.service.gov.uk/media/61deba42d3bf7f054fcc243d/ADF1.pdf