Dialux Lighting Design Support for Commercial Projects — What to Prepare

The request usually arrives as a one-line email: “Please send a lighting design for our hotel lobby.” No floor plan, no ceiling heights, no reflectance values, no control intent. The manufacturer’s engineering team then spends a week extracting information by email ping-pong, the simulation is built on guesses, and when the numbers finally come back, half the assumptions are wrong — so the design is redone, and the project schedule absorbs the delay.

A Dialux calculation is only as good as its inputs. The simulation itself takes hours; assembling correct inputs is where projects lose weeks. This article lists exactly what a lighting manufacturer or design-support team needs before they can return a photometric proposal you can actually build from — and what you should expect back.

Why Input Quality Decides the Whole Design

Dialux (and Dialux evo) computes illuminance, uniformity, and glare from three input groups: geometry (room dimensions and surfaces), reflectances (how those surfaces bounce light), and photometric data (the .ldt/.ies files of the proposed fixtures). Get any group wrong and the output is confidently incorrect:

• A lobby modeled at 3 m instead of 6 m ceiling will pass uniformity checks that fail in the real atrium.

• A 30% wall reflectance assumption on what is actually dark walnut paneling can overestimate task-plane lux by 20–30%.

• Simulating a fixture from an old .ldt file, when the supplier changed LED platforms since, invalidates every number downstream.

The industry’s real divide is not between projects with simulations and projects without — it is between simulations built on verified inputs and simulations built on defaults. Engineering teams that have done this at scale treat input collection as a formal stage; at Youklight, the fixture manufacturer in Guzhen, Zhongshan with 20 years of project experience, the process runs the same way each time: a standard input checklist, then Dialux calculation, then CAD installation drawings, then control-scheme confirmation (including DMX512 for dynamic atrium features) — whether the buyer is a consultant, a contractor, or an OEM/ODM client specifying to their own brand.

The Essential Package: Six Items

Before requesting a Dialux design, assemble these. Anything missing becomes an assumption — and every assumption is a risk transferred to your site.

1. Architectural drawings (CAD or dimensioned PDF). Floor plan, reflected ceiling plan, and at least one section showing ceiling heights. For atriums and stair voids, the section is non-negotiable: it is the only document that defines the volume the chandelier must fill. Mark obstructions — beams, ducts, sprinkler lines — because they decide fixture mounting positions.

2. Surface finishes and target reflectances. Wall, floor, and ceiling materials, ideally with the designer’s finish schedule. If actual reflectance values are unknown, standard assumptions are floor 20%, walls 50%, ceiling 70% — but say explicitly that these are assumptions, so a dark-stone lobby gets flagged rather than silently over-lit.

3. The lux and quality targets. Which standard governs the project — EN 12464-1 in Europe, or the client’s own brief — and the maintained illuminance per zone: 200–300 lx lobby floor, 300–500 lx reception desk, 150–200 lx corridor, plus uniformity (U₀ ≥ 0.4 for general areas is a common threshold) and glare limits (UGR ≤ 22 for reception work, lower for lounge seating). CCT and CRI ≥ 90 belong here too — they shape fixture selection more than any dial in the software.

4. Fixture scope and mounting constraints. Which fixture families are candidates (or must be matched), pendant drop ranges, and the structural facts above the ceiling: slab type, load ratings, and lifting-point positions for heavy chandeliers. A 400 kg fixture simulated at the perfect position does not survive contact with a slab rated for 150 kg.

5. Control intent. Dimming protocol per zone — DALI, 1–10 V, or DMX512 for dynamic features — and the scene schedule the operator expects. The simulation should validate the night scene at 30% output, not just full output, or the design passes at noon and fails at 11 p.m.

6. Obstruction and furniture reality. In restaurants and offices, table layouts and partitions define task planes; in lobbies, seating clusters and the reception island define where uniformity actually matters. A design computed over an empty floor plate is a design for a room that will never exist.

What You Should Get Back: The Deliverable Checklist

Input discipline is your job; output discipline is the supplier’s. A complete photometric proposal returns:

• Per-zone results: maintained illuminance (Em), uniformity (U₀), and glare (UGR where applicable) for each area, against the targets you set.

• A fixture schedule: model references, lumen packages, CCT, CRI, beam angles, and counts per zone — priced or priceable without further clarification.

• The calculation file: the Dialux project itself, so your consultant can audit assumptions and rerun variants. A supplier that shares the file invites verification; one that sends only a PDF summary invites trust.

• Visualizations at the working planes, not just false-color ceilings — reception desk height, seating eye level, and the night scene at dimmed output.

• The bridge to installation: CAD drawings with fixture positions, mounting details, and for feature fixtures, the wiring and control schedule consistent with the Dialux layout. The most common failure at handover is a photometric design and an installation drawing that reference different fixture positions.

The Sequencing Rule That Saves Projects

Run the loop in this order and errors stay cheap: drawings → targets → Dialux → fixture selection → sample → order. Each stage validates the previous one at a fraction of the cost of the next. The expensive sequence — fixture chosen first (because it looked right), then a simulation reverse-engineered to justify it, then a sample that cannot hit the numbers — is still the most common one in the industry.

The 48 hours spent assembling the six-item package above typically saves two to four weeks of redesign cycles, and produces a proposal precise enough to order from on the first pass.

If you have a commercial project coming up — lobby, restaurant, atrium, or full hotel floor — send your floor plans, section drawings, and target lux levels to flora@youklight.com. Youklight’s engineering team will run the Dialux calculation, confirm fixture selection and control compatibility, and return the photometric package with CAD installation drawings for your review.

FAQ

Q1: What file formats do I need to send for a Dialux design? Floor plan, reflected ceiling plan, and a section showing ceiling heights — CAD (DWG/DXF) or dimensioned PDF. Add the finish schedule if available; otherwise state that standard reflectances (floor 20%, walls 50%, ceiling 70%) should be used as declared assumptions.

Q2: How long does a Dialux calculation take? With a complete input package, a single-zone calculation takes days, not weeks. Multi-zone hotel floors with feature chandeliers and night scenes typically run 1–2 weeks. The delay in most projects is not the calculation — it is the week spent requesting missing drawings and clarifying targets.

Q3: What lux levels should I specify for a hotel? Common maintained targets: 200–300 lx lobby floor, 300–500 lx reception desk, 150–200 lx corridors, 100–150 lx guest-room general. Add uniformity (U₀ ≥ 0.4) and glare limits (UGR ≤ 22 at work positions), plus CCT and CRI ≥ 90 — the latter two shape fixture selection more than the lux numbers.

Q4: Should I get the Dialux file itself, or just the report? The file. A shared Dialux project lets your consultant audit reflectances and mounting heights, and rerun variants after layout changes. A PDF summary alone cannot be verified — and a supplier unwilling to share the calculation is asking you to trust, rather than check, the numbers you will build from.