Does reducing an LED lighting level by half also halve its electrical demand?

The short answer

Not necessarily. A dimming percentage can describe a control signal or a light-output target, rather than a proportional fraction of AC input power. Driver behavior and the luminaire's actual light output must be established. The useful decision is whether the proposed dimmed state delivers the owner's accepted illumination with a supported lower electrical input.

Identify the dimming quantity

Obtain the driver and luminaire documents, including the meaning of the external signal and supported range. MEAN WELL notes that some control-signal/output-current relationships are nonlinear. That does not provide a universal curve for another driver. Keep commanded percentage, LED output current, light output and mains input as separate quantities until their relationships are evidenced.

Compare light service and input together

Use measured or supported input at relevant accepted lighting states, with the illumination designer's service requirements. Hypothetically, a 50 percent command cannot be assumed to reduce a 100 W input to 50 W without that evidence. The figures are illustrative. Include driver overhead and any controls outside the luminaire meter, but do not count downstream LED watts again as extra mains consumption.

If a lighting controller reports only a percentage, retain that raw field. Convert it to input power only through evidence for the installed driver/luminaire configuration rather than a spreadsheet's default linear assumption.

Define supported renewable dispatch

Ask which areas and times permit dimming and what response is required when the renewable contribution changes. Avoid claiming savings by accepting inadequate task or site lighting. Supply the accepted light-state/input table to the wind integrator, with switching or smooth-dimming behavior described by the actual equipment. A controller advertised for dimming does not prove source compatibility or supported external commands. The RFQ should specify the lighting service to preserve, rather than promise that halving a command always halves demand or that MARSTON equipment includes a lighting-control interface.