Ventilation of dwellings is governed by Part F of the building regulations. A new house must have adequate means of ventilation for its occupants, which in practice means background ventilation, extract ventilation from kitchens, bathrooms and utility rooms, and purge ventilation, or an equivalent mechanical system.
Part F requires adequate ventilation for people in a building. Technical Guidance Document F describes acceptable approaches, including natural ventilation with background ventilators and intermittent extract fans, continuous mechanical extract ventilation, and mechanical ventilation with heat recovery.
Ventilation has become more important as houses have become more airtight. Where leakage paths have been sealed to meet Part L, the designed ventilation system is the only reliable source of fresh air and moisture removal, so its specification, installation and commissioning must be correct.