Lighting
Occupancy Sensor Savings Calculator
Calculate annual energy saved from controlled lighting power and avoided operating hours. The default values illustrate the workflow; replace them with measurements or ratings from one documented condition.
Enter values for Annual energy saved
Enter ratings or measurements that describe one scenario.
Annual energy saved: calculation method
For this worksheet, the governing relationship is savings = power × avoided hours. The formula draws on Controlled lighting power and Avoided operating hours.
Using the loaded examples gives 2,250.00 kWh. Your saved case should identify where each entry came from.
Calculate annual energy saved from controlled lighting power and avoided operating hours. A separate annual lighting cost result is available from Lighting Energy Cost Calculator.
Before entering values
Use photometric data for the actual fixture, optic, mounting height, and task plane. If operating conditions changed between readings, calculate separate cases.
Check every prefix before entry; micro, milli, kilo, and mega are not interchangeable.
- Controlled lighting power
- Default example: 2.5 kW. Enter controlled lighting power in kW.
- Avoided operating hours
- Default example: 900 h. Enter avoided operating hours in h.
Applying the result
The calculated Annual energy saved is meaningful only with its input conditions attached. Compare it with the fixture photometric file and the measured task plane.
A result without its source conditions is difficult to compare or audit.
Sensitivity check
Change Controlled lighting power from 2.5 kW to 3 kW while preserving the other measurements. The output changes from 2,250.00 kWh to 2,700.00 kWh.
The comparison demonstrates sensitivity, not a guaranteed field response.
Checks before using the answer
Measure actual schedule changes where possible.
Outside the entered variables, consider daylight variation, control behavior, depreciation, and spatial uniformity. Do not hide omitted behavior inside an unexplained correction factor.
Use photometric data for the actual fixture, optic, mounting height, and task plane.
Questions about Occupancy Sensor Savings
Which operating condition belongs in this calculation?
Measured and rated values can represent different states. Record reflectance, maintenance condition, beam definition, and measurement location.
Which assumptions matter most here?
Measure actual schedule changes where possible. A broader review should include fixture distribution, reflections, mounting, maintenance, and meter position.
Why might measured annual energy saved differ?
First confirm that the measurements match the equation. Then review driver efficiency, optical loss, surface reflectance, and beam-edge definition.
What should remain fixed in an alternate case?
Change one uncertain entry at a time and preserve the baseline. Record reflectance, maintenance condition, beam definition, and measurement location.
Does the answer include a design margin?
Use the number as one check, then review the fixture photometric file and the measured task plane.
Why does Annual energy saved show several decimals?
Keep full precision while transferring annual energy saved; round only at the final reporting or selection step.