Photometric approval freezes a configuration—not the entire project forever
An approved photometric design represents a specific combination of field geometry, pole locations, mounting heights, luminaire models, optics, output settings, fixture positions, aiming directions, maintenance assumptions and acceptance criteria.
Projects still change after approval. The correct objective is not to prohibit every change; it is to identify which changes are administrative, which need technical screening and which invalidate the approved calculation.
Use four review categories instead of “minor” and “major”
Administrative change
Does not alter the product configuration, geometry, operating state, calculation method or acceptance basis. Update records and traceability.
Technical screening required
May affect interfaces or margins but may not require a full recalculation. A qualified reviewer documents the impact decision.
Recalculation or redesign required
Changes a photometric input, product distribution, output, position, orientation, target or measurement basis.
Project reapproval required
Changes scope, venue use, governing criteria, structural/electrical concept or responsibility allocation beyond the original approval.
These labels are a practical project-control framework. They are not universal standard classifications. The project team should define the approval authority for each category before changes occur.
What can change—and what normally happens next?
| Proposed change | Typical category | Photometric response | Other affected reviews |
|---|---|---|---|
| Correct spelling, tag or non-technical document reference | A | Update records | Document control only |
| Packaging, shipment split or delivery sequence | A / B | No recalculation if configuration remains identical | Logistics, identification and site storage |
| Bracket detail changes without moving optical center or limiting aiming | B | Screen geometry impact | Structure, installation and interface approval |
| Driver brand or model changes with same declared output | B / C | Confirm output assumptions | Flicker, controls, electrical, thermal and warranty |
| Fixture wattage or dimming setpoint changes | C | Recalculate affected operating scenes | Power, controls and acceptance |
| Optic, lens, reflector or visor changes | C | Recalculate distribution, glare and spill | Product schedule and aiming |
| Fixture position, pole coordinate, mounting height or crossarm elevation changes | C | Recalculate geometry and aiming | Structure, installation and drawings |
| Fixture quantity changes | C | Recalculate all relevant metrics | Structure, power, controls and cost |
| Playing level, broadcast use or required operating mode changes | D | Revise design basis and recalculate | Owner approval, controls, power and acceptance |
| Measurement grid, maintenance factor or acceptance method changes | C / D | Reissue calculation or comparison basis | Consultant, owner and handover plan |
Process every proposed change through five steps
The change request should include the reason, urgency, original configuration, proposed configuration, supporting files, affected project stage, cost and programme effect, reviewer comments and final status.
A design-freeze package makes change impact visible
Without a frozen baseline, the project team cannot distinguish a genuine change from a correction to uncontrolled information. Version control is therefore part of engineering accuracy, not administrative housekeeping.
The same change becomes more expensive later
Explore alternatives freely
Different optics, outputs, quantities and layouts can be compared while the solution is still flexible.
Control the technical baseline
Changes require documented impact review and may alter the commercial offer or approval schedule.
Protect manufacture and traceability
Changes may affect production, packaging, labels, delivery and contractual responsibility.
Use as-built evidence
Corrections may require re-aiming, hardware changes, control programming, remeasurement or formal deviation acceptance.
Six examples of correct change treatment
| Situation | Correct response |
|---|---|
| A visor is added to reduce a new residential concern. | Use the visor-specific photometric file or validated optical data, recalculate affected results and update the product/aiming schedule. |
| A fixture moves along the same crossarm to clear a bracket. | Screen optical-center movement and aiming clearance; recalculate when the coordinate change can affect coverage or glare. |
| The driver changes because of supply availability. | Verify output state, dimming, flicker, controls, inrush, protection, thermal and warranty effects; recalculate if delivered output changes. |
| A pole height differs from the approved survey. | Update the geometry and rerun the affected aiming and photometric design before accepting the installation. |
| Training mode output is reduced after commissioning. | Calculate or verify the revised scene, document the setpoints and decide whether it remains within the intended training criteria. |
| The owner requests broadcast use after procurement. | Treat as a revised project brief; reassess vertical illuminance, flicker, colour, power, controls, camera positions and acceptance. |
Key takeaways
2. Classify changes by impact, not by apparent physical size.
3. Optic, output, quantity, position, aiming and criteria changes normally require recalculation.
4. Photometrically neutral changes may still need structural, electrical or controls approval.
5. Approved changes must propagate into procurement, installation, commissioning and as-built records.
Frequently asked questions
Can the fixture brand change after photometric approval?
Yes, but this is normally a product-substitution review. The replacement photometric file, configuration, structure, electrical interfaces, controls and documentation must be assessed and the affected design reapproved.
Can aiming angles be adjusted on site without revising the design?
Commissioning normally includes controlled adjustment, but the allowed range and approval authority should be defined. Material deviations from the approved aiming schedule should be recorded and may require recalculation or remeasurement.
Does changing a visor always require a new simulation?
Usually yes when the visor changes the photometric distribution. Use the correct file or validated data for the accessory rather than assuming it only removes unwanted light.
What if the change improves the calculated result?
Improvement in one metric does not remove the need for review. The change may affect glare, spill, vertical planes, structure, power, controls or acceptance elsewhere.
Who maintains the final change log?
The project manager or document-control function usually maintains it, but each technical discipline must approve its own affected work. The final as-built package should contain the approved change history.
Screen every proposed change against the approved design baseline.
Share the approved calculation, configuration register, proposed change, reason, affected fixture IDs, structural and electrical interfaces, programme impact and approval authority. ZC Lighting can help identify whether the change is administrative, requires technical screening, needs recalculation or requires project reapproval.
Sources and professional guidance
- Illuminating Engineering Society, ANSI/IES RP-6-24: Recommended Practice—Lighting Sports and Recreational Areas.
- UEFA, UEFA Stadium Lighting Guide 2023.
- CIBSE / Society of Light and Lighting, LG4 Sports Lighting (2023).
- DarkSky International, Outdoor Sports Lighting Guidelines.
The change-control categories in this article are practical ZC Lighting editorial tools. The approved project baseline, contract, design authority, affected specialists and local requirements determine the actual review and reapproval route.