How do we guarantee the start and stop times in our heating cost allocators?

In our device we always have the clock on winter time. This means that the set start time is suitable in winter, but one hour too late in summer.
Therefore, the start time for the whole year is set one hour earlier. On the other hand, the device transmits one hour longer in summer with the stop time set for winter.
Throughout the year we guarantee the start and stop times expected by the meter-reader, whereby one hour earlier in winter and one hour longer in summer.

Then there are the start and stop times and the reserves for watch tolerance of one hour each.
This ensures that the device clock does not deviate from the real time by more than one hour in 10 years.
By adding this tolerance to start and stop time, it is ensured that the devices transmit within the specified time window between start and stop time, even after 10 years.