How to use this result
Use measured or documented input wattage, actual operating hours and an installed project cost. Keep rebates outside the base comparison so the economics remain transparent.
Energy calculation
Fixture quantity, wattage, hours and electricity rate create the annual operating comparison.
Simple payback
Installed cost is divided by annual energy and maintenance savings; financing and tax effects are excluded.
Important: A lower-watt fixture is not automatically an acceptable lighting design. Verify photometrics, glare, controls and electrical work.