Operational Energy Calculations (TM54)


Operational Energy Calculations project the energy performance of buildings at the design stage. Non-TM54 energy usage calculations have historically been inaccurate at predicting energy usage of buildings, leading to higher than budgeted for energy costs and a growing concern surround how much of an impact ‘low energy’ buildings are really having.

The TM54 method is a clear guidance for the creation of Operational Energy Calculations that can be used to accurately estimate a buildings energy requirement. This is achieved by taking into account a wider range of energy drawing factors within a building once operational.

GreenBuild utilizes this methodology to clearly provide information to designers on where actual and estimated energy use may differ. By doing so, GreenBuild is then able to aid in problem-solving these issues.

Some – but not all – of what TM54 takes into account compared to traditional energy calculations are:

  • Lifts and escalators
  • Catering requirements
  • Server rooms
  • Office equipment

This more thorough methodology reduces the performance gap between the estimated and actual leading to more impactful environmental solutions to energy inefficiency in buildings.


Ingram House, London

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