Then National Calculation Methodology (NCM) is the framework defined by the UK Government for the analysis of buildings and their systems for the purpose of analysis relating to Part L (for England, Wales and Northern Ireland), Section 6 (for Scotland), and Energy Performance Certificates (for all UK regions).
NCM analyses are governed by rules setting out the simulation methods to be used and the conditions applying in those simulations. Set-points, occupancy, DHW consumption, internal gains and minimum ventilation rates are specified for a standardised set of building types and activities. Systems are organised into categories, infiltration rates are calculated by approved methods, and rules are laid down for the calculation of energy used by fans and pumps (‘auxiliary energy’). These rules mean that conditions and methods used within the NCM framework to simulate the Actual Building (a specialised NCM term) may differ from those applicable to the real building (the building as designed, occupied and operated).
