This paper provides an overview of how Building Information Modelling (BIM) software has been used for the design and build of the new Type 31 (T31) Frigate. With BIM software traditionally used in the building services industry, a bespoke approach has been undertaken to ensure it is appropriately utilised for marine applications. Due to the complex nature and the tight timescales of the T31 Frigate programme, traditional spreadsheet and hand calculation methods were inadequate. It was, therefore, necessary to identify and develop a new approach for the design of the platforms Heating Ventilation and Air Conditioning (HVAC) system. The BIM software packages were adapted to be capable of meeting marine design standards which enabled the complete ductwork system to be modelled in 3D. This allowed for dynamic design calculations and simulations of the ship?s HVAC system to be undertaken from concept to detailed design stages. This was conducted for both normal operating and CBRN configurations which is a vital capability in advancing the design of Naval vessels. The complex ductwork model has been developed by using three software packages; Autodesk REVIT, MagiCAD Ventilation and Integrated Environmental Solutions (IES). This paper covers the ductwork model and focuses on AutoDesk Revit and MagiCAD, with inputs from an IES thermal model. A semi-automated process has been established between the three software packages to allow for design development and maturity to easily be embodied into the ship?s model at any stage of the Concept, Assessment, Demonstration, Manufacture and In-Service (CADMID) cycle. This new approach provides the capability to undertake multiple detailed calculations and dynamic simulations of the entire system. Examples include: - Detailed ductwork sizing calculations with parameters configured to the equipment manufacturer?s requirements, specific to the marine environment. - Original Equipment Manufacturer (OEM) components, from cabin units and nozzles to flow balancing and fire dampers integrated into the 3D model. - Pressure drop calculations for high and low pressure ductwork systems, including inline components such as fire dampers, balancing dampers and non-return valves. The results of which feed into the fan sizing calculations. - Critical path identification on all systems to aid both the design and commissioning stages. - Ability to conduct system balancing simulations during the early design stages. This has the benefit of firstly, identifying areas of high noise induced by throttling the air, providing an opportunity to modify the design. Secondly, providing a baseline for the flow control damper adjustment settings to aid the commissioning process. - Calculate initial sound levels for each compartment to ensure compliance with Lloyds Register Crew and Embarked Personnel Accommodation Comfort (LR CEPAC) regulations. The paper will expand on the approach and methodology discussed and how it supports the design life cycle of the T31 HVAC System, giving examples of how it has been incorporated.