In rough payback order across all industries: eliminate standing heat losses (insulation, 2–5% of site fuel), run a steam-system programme (traps/leaks/combustion — DOE puts the economic potential at 18–20% of boiler energy), recover waste heat (20–50% of industrial energy input is lost as heat, US DOE), fix compressed-air leaks (20–30% of compressor output, DOE/Energy Star), fit VSDs on variable loads (20–50% of the drive's electricity), LED the lighting (50–60% of lighting electricity), run a water programme (10–30% of water cost), then the structural moves: heat pumps, electrification, fuel switching.
From our guide: Industrial Decarbonization Practices — full context, charts and sources there.
