No, a stone coated steel roof will make your home more energy efficient. The level of efficiency differs based on the attachment system. When stone coated steel is attached direct to deck, or over existing shingles, an insulated "dead-air" space is created and there is no heat gain. Much like dual-pane windows, the design actually works as an energy-saving barrier.
Energy savings are even greater when stone coated steel is attached to battens. This creates an above sheathing ventilation process where hot air rises and exits at the ridge. The result is a much cooler attic and living space in the home.