A ‘nationally’ calculated energy performance value is the product of:

  • the actual building (of course)
  • “the EP METER” with which you ‘measure’ your building. This is the calculation method that consists of
    • the national definitions,
    • nationally assumed indoor and outdoor conditions, and –last but not least:
    • the calculation engine.

It’s obvious that you need the same EP METER to compare EP values. National benchmarks (reference values) that are used for information, for (national) comparison, and as basis for EP requirements are determined on the basis of the same national definitions, conditions and calculation engine. So, benchmarks and regulatory values are also EP-METER dependent.

  • That different conditions lead to different EP values is obvious.
  • Less obvious, but nevertheless very true is that different definitions also lead to different EP values. For example: the definition of useful floor area has a significant effect on the calculated EP.
  • Even less obvious, but also very true is that different calculation methods (the engines) also lead to different EP values.

Some examples:
Hourly versus monthly methods (see webinar on this subject).
A monthly method lacks the capability to detect (to name a few):

  • undersized systems,
  • thermal comfort problems,
  • the potential of ventilative cooling,
  • the dynamic interaction of heat pump performance with energy needs,
  • the surplus of on-site produced electricity
  • control strategies potential
  • generators interactions with storage.

Details of the method:

  • A significant influence may be observed from calculation procedure versus tabulated values for specific elements, e.g.:
    • Thermal bridges,
    • Heating or cooling generators,
    • Heat distribution systems,
    • Heat recovery units,
    • A different method may have incompatible parameters.
      • E.g.: not compatible with the choice between total, non-renewable, renewable primary energy….
      • E.g. not compatible with perimeter choices of the energy performance
  • A different method may have a limited range of covered technologies.
    • E.g. not all relevant parameters (input data) included
      (for instance: missing distinction between different types of heat pumps, ventilation systems, etc.)
  • The method may embed and hide relevant choices, such as exported energy evaluation

Related FAQs:

2022-02-07