Should a DIALux warehouse calculation compare empty and loaded racking?
Compare credible empty and loaded warehouse-rack states in DIALux without changing the lighting test or claiming that one model predicts every future pallet arrangement.
The short answer: compare credible operating states when the load can change the decision
A DIALux warehouse calculation should compare a representative empty or lightly loaded rack state with a representative loaded state when pallets, cartons or solid shelving can materially change aisle shadows, rack-face visibility or reflected light. The purpose is not to predict every future stock position. It is to test whether the proposed high-bay arrangement remains usable across the operating conditions the project team considers credible.
Keep the building, racks, luminaire positions, exact photometry, maintenance basis, calculation surfaces and result scales coordinated between scenarios. Change only the rack loading assumptions being tested, then compare the controlling floor, aisle-end and vertical rack-face results. The client, consultant and relevant authority must define the applicable criteria and accept which load states are representative.
1. Define what empty and loaded mean for this warehouse
An empty scenario might mean bare rack frames, installed shelves with no stock, or the commissioning condition before operations begin. A loaded scenario could mean full pallets at selected bays, continuous cartons on solid shelving or a conservative pattern concentrated at the heights most likely to block light. These are not interchangeable assumptions, so name and illustrate each scenario before calculation.
Ask operations for the rack type, bay spacing, shelf or beam levels, pallet dimensions, typical load height, packaging reflectance, seasonal peaks and any bays that normally remain open. Use a small set of credible states that can affect a lighting decision. Do not fill every void merely to manufacture a worst case, and do not present an unrealistically empty aisle as the permanent operating condition.
2. Build one coordinated geometry baseline
Start from the latest building and racking drawings. Fix aisle widths, row lengths, rack heights, uprights, shelves, cross-aisles, end frames, luminaires, columns and other permanent obstructions. Then create clearly named alternatives for the movable or variable stored loads. If the permanent geometry also changes between files, the team cannot tell whether a result moved because of the load state or an unrelated model revision.
DIALux supports furniture, objects, materials and custom calculation objects, but its calculation settings can also exclude furniture or use simplified calculations. Confirm which objects participate in each final calculation. A fast calculation without furniture may help early layout work; it cannot prove the shadowing effect of racks or pallets that the calculation deliberately omitted.
3. Approximate stored goods without claiming false precision
Model the blocking mass and relevant surfaces of stored goods at a level suited to the decision. Simple boxes or grouped volumes can represent pallets and cartons more reliably than decorative product models with thousands of unnecessary details. Record dimensions, positions and material assumptions, and distinguish open wire shelving from solid decks or dense pallet loads when that difference affects light paths.
Surface properties matter because a pale carton, dark shrink wrap and metallic shelf do not reflect light identically. Use supportable material values where available and test a reasonable sensitivity range when the finish is uncertain. The model remains an engineering approximation: changing labels, mixed stock, gaps and temporary staging will create local conditions that one static scene cannot reproduce exactly.
4. Keep the lighting test unchanged between scenarios
Use the same exact IES, LDT, ULD or GLDF file, lumen package, optic, mounting height, orientation, output level, maintenance factor and active lighting scene in every scenario intended for direct comparison. Preserve the calculation surfaces, grid settings and display scales as well. Otherwise a better result could come from a different luminaire or a coarser grid rather than the changed rack loading.
Calculate the base state first, duplicate the coordinated model or scenario in a controlled way, add the agreed load representation and recalculate every affected result. If the loaded case fails, diagnose the shadow or weak overlap before increasing all output. A revised optic, aisle-centred row, shorter spacing, cross-aisle treatment or local task light may solve the actual problem with less glare and energy than a uniform increase.
5. Check the surfaces people use, not only one floor average
A warehouse review may need named aisle-floor areas, cross-aisles, picking positions, packing or dispatch zones and representative vertical rack-face surfaces at agreed heights. Long averages can hide a weak aisle end or a shadow beside a loaded bay. Use result tables, minimum locations, value charts, isolines and consistent false colours to show where the loaded state changes the pattern.
Review the quantities required by the brief: maintained illuminance, minimum values and the applicable form of uniformity, plus vertical illuminance, glare, emergency conditions or other metrics only where they genuinely apply. Do not invent a universal vertical target or assume that floor performance proves label visibility. The calculation surface and criterion must correspond to the actual visual task.
6. Turn the comparison into a practical warehouse decision
The most robust option is not automatically the brightest or the one with the largest empty-rack margin. Compare performance across the named load states together with installed power, controls, glare, rack-clearance limits, sprinkler and service coordination, access for maintenance and the feasibility of keeping luminaires aligned with future aisles.
If the loaded state creates only a narrow local weakness, a targeted response may be preferable to redesigning the entire hall. If several credible loads move the controlling minimum or make vertical visibility unreliable, the layout needs more fundamental review. State the sensitivity clearly so procurement and operations understand which rack or storage changes would trigger recalculation.
7. Issue a report that another reviewer can reproduce
Identify the building and rack drawing revisions, clear height, luminaire mounting and coordinates, exact photometric files, maintenance basis, calculation settings, materials, load-state dimensions, active scenes, calculation objects, grids and governing criteria. Include plan or 3D views that make each stored-load assumption visible and label every result table by scenario.
State limitations such as provisional racking, unknown packaging reflectance, variable pallet height, unmodelled temporary staging or a future warehouse-management pattern. A DIALux calculation can support option selection, coordination, procurement or a submission, but it cannot guarantee every future stock configuration or grant client, consultant or authority acceptance.
Warehouse load-scenario decision checklist
Before modelling, confirm: (1) current building and rack drawings; (2) rack type, shelf levels and aisle widths; (3) typical and critical pallet or carton dimensions; (4) exact luminaires and photometric files; (5) named floor, task and vertical surfaces; and (6) the project criteria and representative operating states agreed by the responsible team.
Before issue, verify: (1) permanent geometry is identical between comparison states; (2) only the agreed load assumptions change; (3) furniture and objects are included in the final calculation as intended; (4) result grids and scales remain consistent; (5) controlling minima and shadows are traceable; and (6) assumptions, triggers for recalculation and acceptance responsibility are explicit.
Authoritative references used for this guide
DIAL's current indoor-lighting documentation explains that DIALux evo can add furniture, objects and textures, calculate with different detail levels, compare lighting scenes, monitor calculation-surface results and visualise them with isolines, value charts and false colours. Its calculation training also documents rectangular and polygonal calculation objects, measuring grids, height offsets and settings that include or exclude furniture.
DIALux evo 14 documentation describes room-by-room calculation, retained and outdated-result status, and targeted recalculation of rooms or spaces. Use the current software workflow, licensed standards, applicable national adoption and project brief for the actual calculation; this article does not reproduce or replace them.
Frequently asked questions
Does every warehouse need both empty and fully loaded DIALux models?
No. Compare additional load states when stored goods or shelving can materially affect the decision. Choose representative conditions with the project team; a fully loaded model is not automatically the only conservative or realistic case.
Can I compare two warehouse scenarios if one was calculated without furniture?
Not as a direct rack-loading comparison. If one calculation excludes the relevant racks or stored-load objects, the difference mixes calculation settings with the load change. Use coordinated geometry and settings, then change only the agreed load representation.