Air changes per hour (ACH) targets vary by occupancy and activity.
Building Regulations Part F enforces minimum fresh-air rates for new and refurbished spaces.
Heat recovery ventilation (HRV) can reclaim up to 90% of extracted heat.
Ventilation
UK ventilation requirements by sector
Offices 6 ACH, retail 8, restaurants 10, gyms 12, kitchens 12+ — what Part F requires.