The variables we consider are hour of a day, day of the week, all national holidays, bridge days, working days near a holiday, and school holidays. We expect that the effect of the holidays depends on which weekday they take place (e.g., a holiday on a Sunday has hardly any effect on the electricity infeed, while a holiday on a weekday has a significant effect). Hence national holidays, bridge days and school holidays are further distinguished according to the days of the week. We do not distinguish among the holidays, however. Although Christmas has a different effect on the infeed than Easter, no distinction is made due to the limited infeed data available for these special days. For example, the effect of a Queen’s day on a Saturday cannot be determined, since this situation did not occur between 2007 and 2010.