Photometric Reporting for Facade Lighting in Dubai: Simulation & Documentation Guide
Photometric reporting translates the lighting design concept into quantified engineering documentation — proving through simulation that the proposed fixture selection, positioning, and aiming achieves the target illuminance levels, uniformity ratios, and light pollution compliance required by Dubai Municipality, Al Sa'fat, and adjacent property considerations. No facade lighting project in Dubai can proceed past design stage without photometric documentation that demonstrates compliance with these quantitative requirements.
What photometric simulation software is used?
Three software platforms dominate facade lighting photometric design: DIALux evo (free, industry-standard for MEP consultants), AGi32 (premium, preferred for complex architectural lighting), and Relux (free, strong European manufacturer integration) — each importing manufacturer IES/LDT photometric data files to calculate illuminance, luminance, and light distribution on 3D facade models.
| Software | Cost | Strengths | Dubai Use |
|---|---|---|---|
| DIALux evo | Free | Industry standard, extensive fixture library | Most common — MEP consultants |
| AGi32 | Licensed (≈AED 15,000) | Complex surfaces, accurate facade simulation | Specialist lighting designers |
| Relux | Free | European brand integration, energy calcs | Growing adoption |
| VIVALDI (iGuzzini) | Free (brand-specific) | Real-time visualization | iGuzzini projects only |
What are IES and LDT photometric data files?
IES (Illuminating Engineering Society, .ies format) and EULUMDAT (.ldt format) files contain the measured light distribution of a specific fixture — intensity values at every angle in a 3D sphere, measured in an accredited photometric laboratory — enabling simulation software to accurately predict how each fixture illuminates the facade surface.
- IES format. ANSI/IES LM-63 standard. The global standard, used by most North American and international manufacturers. Contains luminous intensity data in candela at angular intervals (typically 2.5° or 5° spacing).
- EULUMDAT format. European standard (.ldt files). Used by many European manufacturers. Contains the same photometric information in a different file structure.
- Verification. Always request photometric data from an independent accredited lab (not the manufacturer's internal lab). Look for LM-79 (LED luminaire photometric testing standard) test reports alongside the IES file. This ensures the simulation is based on independently verified data, not manufacturer claims.
How are facade illuminance calculations performed?
Facade illuminance calculations model the facade surface as a vertical calculation grid (typically 0.5m × 0.5m resolution), position each fixture with its IES photometric data file, and calculate the illuminance contribution from every fixture to every grid point — producing a false-color illuminance map showing achieved values in lux, uniformity ratios (Emin/Emax and Emin/Eavg), and identification of hot spots and dark zones.
- Calculation grid. The facade surface is divided into a grid of calculation points. Grid spacing of 0.5m provides sufficient resolution for most facade lighting — finer grids (0.25m) are used for detailed feature elements where precision is critical.
- Target values. Typical facade illuminance targets: general wall wash 75-150 lux, feature accent 200-500 lux, texture grazing 50-100 lux (grazing angle, measuring the perpendicular component), entrance/canopy 100-300 lux. Higher values for darker facade materials.
- Uniformity. Uniformity ratio Emin/Eavg ≥0.3 for general facade wash (acceptable variation), ≥0.5 for feature elements (tight control), ≥0.7 for signage or media surfaces (high uniformity).
What compliance documentation does Dubai Municipality require?
The photometric compliance package for Dubai Municipality includes: site plan with fixture positions and aiming angles, 3D simulation renders (day and night), false-color illuminance maps for each facade elevation, spill light analysis at property boundaries (≤10 lux at residential windows), upward light ratio calculation (Al Sa'fat compliance), fixture schedule with ECAS registration numbers, and control system schedule showing scheduling and dimming capability.
| Document | Content | Purpose |
|---|---|---|
| Site plan | Fixture positions, aiming, cable routes | Installation coordination |
| 3D renders | Photorealistic nighttime visualization | Design intent communication |
| False-color maps | Illuminance levels per elevation | Performance verification |
| Spill light analysis | Light trespass at boundaries | Neighbor compliance |
| ULR calculation | Upward light ratio percentage | Al Sa'fat light pollution compliance |
| Fixture schedule | Type, wattage, ECAS number | Regulatory product approval |
| Energy summary | Total connected load, LPD | Al Sa'fat energy density |
How does the maintenance factor affect photometric calculations?
The maintenance factor (MF) — typically 0.7-0.8 for facade lighting in Dubai — reduces the calculated initial illuminance to predict the real-world performance after years of operation, accounting for LED lumen depreciation (LLD, typically 0.85 at L70 life), luminaire dirt depreciation (LDD, 0.80-0.90 for Dubai's dusty environment), and room surface depreciation (not applicable for facades).
- Dubai MF calculation. MF = LLD × LDD = 0.85 × 0.85 = 0.72 (typical for Dubai with quarterly cleaning). Using 0.70 provides a conservative design that maintains target illuminance levels throughout the fixture lifespan.
- Design implication. The initial installed lighting must deliver 1/MF (1.43×) the target illuminance, so that when dirt and depreciation reduce output, the maintained illuminance still meets the design target. This means specifying approximately 40% more initial light output than the eventual desired level.
- Sandstorm impact. Dubai's frequent dust events make the LDD component more aggressive than European calculations assume. Using European MF values (typically 0.80) for Dubai projects results in under-designed lighting that falls below targets sooner than expected.