HVAC & Ventilation Calculators

Heating, ventilation, and air conditioning systems are fundamental to building performance and occupant comfort in the UK. Approved Document F of the Building Regulations sets minimum ventilation rates for dwellings and non-domestic buildings, while Part L governs the energy efficiency of HVAC systems. Our calculators help mechanical engineers, HVAC installers, and building services consultants design systems that meet these requirements while optimising energy performance.

Proper duct sizing is essential for system efficiency and noise control. These tools calculate duct dimensions using the equal friction method or velocity reduction method, accounting for fittings, bends, and transitions that create pressure losses in the system. For domestic installations, our extract rate calculators help you specify fans and MVHR units that achieve the minimum extract rates specified in Approved Document F — typically 13 l/s for kitchens, 8 l/s for bathrooms, and 8 l/s for utility rooms in continuous mechanical extract systems.

From commercial air handling unit selection to domestic bathroom fan sizing, these calculators support the full range of HVAC design tasks encountered by UK professionals. All tools reference CIBSE guides, British Standards (including BS EN 16798 for indoor environmental parameters), and current Building Regulations to ensure your designs meet the standards expected by Building Control and commissioning engineers.