ISO 16346:2013 sets out ways of expressing the energy performance in an energy performance certificate of a building (including the technical building systems) and ways of expressing requirements as to the energy performance. This includes an overall numerical energy performance indicator and classes against benchmarks.

ISO 16346:2013 additionally includes numerical indicators at system or component level.

ISO 16346:2013 defines the different types of rating (such as calculated, measured, design, and tailored rating) and the energy uses to take into account (such as heating, cooling, domestic hot water, ventilation, and lighting).

ISO 16346:2013 defines

a) overall indicators to express the energy performance of whole buildings, including heating, ventilation, air conditioning, domestic hot water, and lighting systems (this includes different possible indicators),

b) ways to express energy requirements for the design of new buildings or renovation of existing buildings,

c) procedures to define reference values, and

d) ways to design a procedure for building energy certification.

Furthermore, it provides a (calculation) link between delivered energy and the energy performance indicators for buildings. Since a building generally uses more than one fuel (e.g. gas and electricity), the different energy sources are collected per energyware. The overall rating is based on a weighted sum of delivered energywares. The weightings can be related to, for instance, primary energy or CO₂ emissions to provide the end result of the calculation of energy performance.

It also provides calculation procedures to assess the energy performance on the basis of measured energy use, including ways to convert the measured values to values under standardized conditions (environment, user).

Finally, it defines the system boundaries needed to make a distinction between building energy needs, technical building systems, energy supply systems on site, and distant energy supply systems.