Abstract: A method for bringing a plurality of steel slabs to rolling temperature uses a furnace having a controllable energy supply. To accommodate variation of slab temperature at entry, especially mixing of cold and hot slabs, at least one virtual slab corresponding to a group of the steel slabs is determined, and the energy supply is adjusted in dependence on the desired mean temperature at exit from the furnace of the virtual slab. Suitably the furnace has at least two zones each with an individually controllable energy supply, and virtual slabs are determined for the slabs in each zone. Then the energy supply in each zone is adjusted in dependence on the desired mean temperature at exit from the furnace of the virtual slab of that zone and preceding zones.