This is the Sankey diagram for a typical LED lamp: From the diagram, you can see that much less electrical energy is transferred, or 'wasted', as heat energy from the energy-saving lamp.

Sankey diagrams illustrate flows through training programs. Among 353,590 physicians who graduated during the period 2001–15, 11.8 percent pursued initial training in family medicine ...

Sankey diagrams show that the total energy transferred into a system is equal to the useful energy transferred plus the energy dissipated or 'wasted'. This confirms that energy is conserved.