Common set of units
Article 13
1. Each transmission system operator shall use the common set of units defined in this Article for any data exchange and data publication related to Regulation (EC) No 715/2009. 2. For the parameters of pressure, temperature, volume, gross calorific value, energy, and Wobbe-index the transmission system operators shall use: (a) pressure: bar (b) temperature: °C (degree Celsius) (c) volume: m 3 (d) gross calorific value (GCV): kWh/m 3 (e) energy: kWh (based on GCV) (f) Wobbe-index: kWh/m 3 (based on GCV) For pressure, the transmission system operators shall indicate whether it refers to absolute pressure (bar (a)) or gauge pressure (bar (g)). The reference conditions for volume shall be 0 °C and 1,01325 bar(a). For GCV, energy and Wobbe-index the default combustion reference temperature shall be 25 °C. Whenever transmission system operators communicate data on the volume, GCV, energy and Wobbe-index, they shall specify under which reference conditions these values were calculated. 3. In cases where one Member State is connected to only one other Member State, the adjacent transmission system operators and the parties they communicate with may agree to continue to use other reference conditions for data exchange in connection with Regulation (EC) No 715/2009, subject to the approval of their national regulatory authorities.