We keep personal data only for a period that is necessary, depending on the data type and their purpose. Storage periods may vary depending on their classification. As a general rule, personal data are stored for the duration of the customer relationship and ten years after it ended. Personal data relating to metering information (such as data concerning energy usage and production) is kept for ten years from the date the metering data was obtained. Helen regularly resets and reassesses the storage periods for the personal data of different data types in its possession.  When personal data are no longer required, Helen deletes them of renders them unidentifiable as soon as possible.