In my post above there is a link to the European Parliament proposal with some informative description of the effects of DST.
Discontinuing seasonal changes of time:
"To understand the impact of summer-time arrangements on a given territory, it is important to understand the relationship between time and daylight on the one hand, and the geographical position of a given territory (defined by its longitude and latitude) on the other. The latitude, i .e. the distance from the equator, influences the hours of daylight and explains the considerable difference in day length between Northern and Southern Europe. During the shortest day of the year, at the winter solstice, a city located in the north, such as Helsinki, would receive less than six hours of sunlight, while it would get almost 19 hours of sunlight at the summer solstice. On the other hand, in cities located closer to the equator, i.e. southern cities such as Lisbon and Athens, the day length would be more balanced, with around 15 hours of daylight at the summer solstice and approximately 9.5 hours at the winter solstice.
Another key element is the geographical longitude which defines local time.
...
This results in current summer-time arrangements changing the time when sunset and sunrise occur, but without modifying the actual length of day, or daylight hours, experienced at a specific time of the year, while the geographical longitude defines local time."
