Division (b): Solar water heaters - Commission Regulation (EU) No 814/2013 of 2 August 2013 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for water heaters and hot water storage tanks (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