Division (b): Solar water heaters: - Commission Delegated Regulation (EU) No 812/2013 of 18 February 2013 supplementing Directive 2010/30/EU of the European Parliament and of the Council with regard to the energy labelling of water heaters, hot water storage tanks and packages of water heater and solar device (Text with EEA relevance)

The water heating energy efficiency is calculated as follows:

η_{wh} = \frac{0,6 \times 366 \times Q_{ref}}{Q_{tota}}

Where:

Q_{tota} = \frac{Q_{nonsol}}{1,1 \times η_{wh,nonsol} - 0,1} + Q_{aux} \times CC

Division (b) Solar water heaters: