In the competitive world of outdoor lighting tenders, a polished brochure and an attractive unit price are rarely enough to win a government or EPC contract. Procurement officers, municipal engineers, and lighting consultants increasingly demand something far more rigorous: a photometric simulation report that proves, before a single pole is installed, that the proposed lighting scheme will actually deliver the required illuminance, uniformity, and glare control on the real road surface.
Industry field audits consistently show that up to 40% of solar street lighting installations in emerging markets fail to meet their design illuminance targets after installation. The causes range from oversized spacing assumptions and incorrect optical selection to missing maintenance factors and unverified IES files. For contractors, these failures mean rejected handovers, costly re-lamping, and reputational damage. For municipalities, they mean dark stretches of road, elevated accident risk, and wasted capital.
A DIALux simulation report is the universal language that designers, specifiers, and tender evaluators use to compare bids on an apples-to-apples basis. This article explains what a DIALux report contains, how to read its key metrics, how it supports bidding, why simulation and on-site results can differ, and how CHZ Lighting helps clients bridge that gap with verified photometric data and real-world project validation.
What is DIALux?
DIALux is the world's most widely used free lighting planning software, developed by DIAL GmbH in Germany. It has become the de facto industry standard for professional lighting design across architectural, indoor, and outdoor applications, used by designers in more than 190 countries.
The software's strength lies in its open, manufacturer-neutral platform hosting over 2.5 million luminaires from more than 400 manufacturers, each described by a standardized photometric file (IES or EULUMDAT format). A designer can select a specific CHZ street light model, import its verified IES file, and calculate its performance on any road geometry with confidence.
For roadway applications, DIALux supports all major international standards: EN 13201 (European road lighting standard covering M, C, and P classes), IESNA RP-8 (American standard), and CIE 115 (international recommendations). Designers model the complete site - road width, lanes, sidewalks, medians, pole positions, mounting heights, arm lengths, and tilt angles - then calculate illuminance and luminance distribution on the road surface. The software produces both numerical results and visual outputs, enabling engineers to evaluate uniformity, glare, and standard compliance before construction begins.
For CHZ Lighting, DIALux is also a quality assurance instrument: every IES file is derived from measurements in its TUV-witnessed laboratory, ensuring the digital luminaire in the simulation accurately represents the physical product shipped to site. This traceability from lab measurement through simulation to field installation is what separates credible bids from speculative ones.
What a DIALux Simulation Report Contains
A professional DIALux report is a structured document of 10-30 pages that tells a complete story: what is being lit, what equipment is used, what assumptions were made, what results were obtained, and whether they meet the specified standard.
2.1 Project Information & Site Geometry
The report opens with a description of the site: road name, classification, number and width of lanes, sidewalks, medians, and surrounding features. It states the target lighting class - for example, M3 for a medium-traffic arterial or P4 for a pedestrian walkway. A 2D site plan shows the road cross-section and proposed pole layout.
2.2 Luminaire Schedule
This is one of the most scrutinized sections in tender review. It lists for every position: manufacturer and model number, rated wattage and luminous flux, optical distribution type, IES/EULUMDAT file reference and date, mounting height, arm length and tilt, and pole spacing/arrangement (single-sided, staggered, opposite, or twin-bracket).
This schedule allows evaluators to cross-reference the simulation against the bill of quantities (BOQ). If the report models 80 poles at 30-meter spacing but the BOQ lists 60, the discrepancy is immediately visible.
2.3 Calculation Parameters
Every calculation depends on assumptions, and a credible report declares them:
- Maintenance factor (MF): Accounts for lumen depreciation, soiling, and surface aging. For LED outdoor installations, 0.80 is standard; harsher environments may justify 0.67-0.75.
- Grid resolution: The density of calculation points on the road surface, aligned with lane markings.
- Surface reflectance: Road surface reflectivity (CIE R-class), which directly affects luminance calculations.
- Surrounding surface reflectances: For sidewalks, medians, and adjacent ground.
Transparency matters: a bidder using MF 0.95 will produce more favorable numbers than one using 0.80, but the latter is far more realistic over a 5-7 year operating period.
2.4 Results Summary
The core numerical outputs include: average illuminance (Eav/lux) and minimum (Emin); average road surface luminance (Lav/cd/m²); overall uniformity (Uo) and longitudinal uniformity (Ul); threshold increment (TI/%) representing disability glare; and surround ratio (SR). Each value is shown alongside the target class requirement with a pass/fail indicator.
2.5 Visual Outputs
DIALux produces visual outputs that make results intuitive: false-color renderings color-code the surface from blue (low) to red (high), revealing dark spots instantly; isolux curves connect points of equal illuminance to assess coverage overlap; value charts show numerical results at each grid point; and 3D visualizations help non-technical stakeholders envision the outcome.
2.6 Compliance Verification
The report concludes with a compliance matrix mapping every calculated parameter against the selected class. If any value falls short - say Uo is 0.33 when 0.40 is required - the report flags it, and the designer can adjust spacing, optics, mounting height, or luminaire output. This iterative design-verify-optimize loop solves problems on screen, not on site.
Key Lighting Metrics Explained
For project managers and procurement officers who are not lighting engineers, here is a plain-language guide to the metrics that matter most.
- Eav and Emin (Illuminance): Average maintained horizontal illuminance (Eav) is the average light falling on the road surface in lux. "Maintained" means it already accounts for the maintenance factor - it is the expected level at end of maintenance cycle, not day one. Emin is the lowest single-point value in the grid. For context, a C2 urban collector road requires Eav of 20 lux.
- Lav (Luminance): Average road surface luminance measures light reflected off the road toward the driver's eye (cd/m²). It is considered a better predictor of driver visual performance than raw illuminance because it accounts for actual surface reflectivity. EN 13201 M classes use luminance; C and P classes use illuminance. A wet or polished road surface will reflect light differently than a rough, matte one, which is why specifying the correct surface class matters for accurate luminance predictions.
- Uo (Overall Uniformity): Uo = Emin / Eav, measuring how evenly light is distributed across the road. Standards require at least 0.35-0.40 depending on class. Poor Uo means dark patches that impede obstacle detection.
- Ul (Longitudinal Uniformity): Measures uniformity along each lane's center line - the brightness variation a driver experiences traveling down the road. Standards require 0.40-0.70. Low Ul produces a fatiguing "bright-dark-bright" zebra effect.
- TI (Threshold Increment / Glare): Quantifies disability glare as a percentage. Lower is better. EN 13201 sets maximum TI from 10% (M1) to 15-20% (lower classes). High TI often results from excessive tilt, inappropriate optics, or poor backlight control.
- SR (Surround Ratio): Compares illuminance on strips adjacent to the carriageway with road-edge strips. A minimum SR of 0.5 ensures pedestrians and obstacles at the roadside are visible.
- Maintenance Factor (MF): The single most important assumption, accounting for LED lumen depreciation, dust/dirt accumulation on optics, and road surface darkening. For modern LED street lights, 0.80 is the standard; desert or coastal environments may use 0.67-0.75 with more frequent cleaning. Any report using MF above 0.85 without justification should be treated with caution.
EN 13201 Lighting Classes at a Glance
A compliance statement is only meaningful if the reader understands the target class. The tables below summarize the principal EN 13201 classes for roadway, conflict-area, and pedestrian applications.
4.1 M Classes - Motorized Traffic Roads (Luminance)
| Class | Lav (cd/m²) | Uo (min) | Ul (min) | TI (max) |
|---|---|---|---|---|
| M1 | 2.00 | 0.40 | 0.70 | 10% |
| M2 | 1.50 | 0.40 | 0.70 | 10% |
| M3 | 1.00 | 0.40 | 0.60 | 10% |
| M4 | 0.75 | 0.40 | 0.60 | 15% |
| M5 | 0.50 | 0.35 | 0.40 | 15% |
| M6 | 0.30 | 0.35 | 0.40 | 15% |
4.2 C Classes - Conflict Areas (Illuminance)
| Class | Eav (lux) | Uo (min) | TI (max) |
|---|---|---|---|
| C0 | 50 | 0.40 | 15% |
| C1 | 30 | 0.40 | 15% |
| C2 | 20 | 0.40 | 15% |
| C3 | 15 | 0.40 | 20% |
| C4 | 10 | 0.40 | 20% |
| C5 | 7.5 | 0.40 | 20% |
4.3 P Classes - Pedestrian and Cycle Areas (Illuminance)
| Class | Eav (lux) | Emin (lux) |
|---|---|---|
| P1 | 15.0 | 3.0 |
| P2 | 10.0 | 2.0 |
| P3 | 7.5 | 1.5 |
| P4 | 5.0 | 1.0 |
| P5 | 3.0 | 0.6 |
| P6 | 2.0 | 0.4 |
The appropriate class is selected based on traffic volume, speed, road-user composition, ambient brightness, and crash risk. A reputable supplier asks about these conditions before running the simulation.
How DIALux Reports Support Bidding & Tendering
For government municipalities, EPC contractors, and utility companies, a DIALux report is now a core evaluation criterion, not an optional attachment. Public procurement demands transparency and value for money. When ten bidders propose different wattages, optics, and spacings, there is no fair comparison without a common benchmark. A DIALux report run on the same geometry and target class answers: Does this bid actually deliver the required performance on this specific road?
- IES file traceability - the #1 tender failure point: The most common cause of technical disqualification is unverified or missing IES files. An IES file is the digital photometric fingerprint of a luminaire. If a bidder cannot provide a current, laboratory-measured file for the exact model proposed, the simulation cannot be trusted. CHZ maintains IES files for every model, all measured in its TUV-witnessed laboratory, so the luminaire in the DIALux model is the same one that arrives on site.
- BOQ auditability: The report lists every luminaire and pole position, enabling evaluators to map report quantities directly to the BOQ. Inconsistencies, such as the report modeling 120 units while the BOQ quotes 100, are immediately visible, protecting both purchaser and honest bidder.
- Maintained vs. initial performance: Evaluators look for the word "maintained." An initial (day-one) calculation ignores lumen depreciation and soiling and will always look better. CHZ reports always present maintained values with the MF explicitly stated.
- Solar-specific assumptions: For solar projects, the report must address the energy balance: autonomy days (consecutive cloudy days supported), depth of discharge (DoD, typically 50-80% to preserve cycle life), PV panel orientation and tilt, and local solar irradiance data. A scheme that looks perfect optically but cannot recharge after three overcast days will fail in service. CHZ integrates both photometric and energy-yield simulations into solar proposals.
RFQ clause example: Purchasers can level the playing field with clauses such as: "The bidder shall submit a DIALux report for each road type using verified IES files, demonstrating compliance with the specified EN 13201 class using a maintenance factor no greater than 0.80. IES files shall be dated within 24 months and traceable to an accredited laboratory." For solar projects, an additional clause can require: "An energy balance calculation showing minimum three (3) days autonomy at the specified lighting profile, using project-location solar irradiance data." Such requirements reward bidders who invest in genuine engineering and discourage those who rely on optimistic estimates.
From Simulation to On-site Reality
A DIALux report is a prediction, not a guarantee. Even careful simulations can differ from field measurements. The most common reasons are: (1) road surface aging - real asphalt reflectance may differ from the CIE R-class modeled; (2) pole placement deviations - utilities or boundaries can shift poles by 1-2 meters, affecting edge uniformity; (3) soiling - dust, salt, and insect residue reduce output faster than assumed in harsh environments; (4) voltage drop - long cable runs, especially in solar systems, can lower LED drive current; (5) construction tolerances in mounting height, arm angle, and tilt; and (6) ambient spill light from adjacent properties affecting lux readings.
How to verify on-site: Use a calibrated lux meter (illuminance) or imaging luminance meter (luminance). Establish a measurement grid matching the DIALux grid, take readings at each point after a 30-minute LED warm-up under negligible ambient light, then compare field averages and uniformity against the report's maintained values. Investigate deviations exceeding +/-10% - checking first for correct model/driver setting, actual mounting height and tilt, optic cleanliness, and supply voltage.
Real-world example - CHZ Dominican Republic: CHZ deployed 43,436 units of the CHZ-ST29 solar street light across roadways in the Dominican Republic. Post-installation testing confirmed 25.8 lux average illuminance on the center line and 25.0 lux along the rail, exceeding the SIE (Superintendencia de Electricidad) standard. The close match between simulation and field results was achieved through verified IES files, accurate road geometry, a realistic maintenance factor, and precise pole placement coordinated between CHZ engineers and the local contractor.
Optimization strategies when simulation falls short: Reduce pole spacing (improves Eav and uniformity but increases cost); change the optic (e.g., Type II to Type III or a custom CHZ lens); adjust mounting height; modify tilt and arm length; increase wattage; or switch from single-sided to staggered/opposite arrangement on wider roads. CHZ's in-house optical design team can develop custom lens distributions for unusual geometries, ensuring compliance with optimal energy efficiency.
How to Request a DIALux Report from CHZ
Requesting a report is straightforward. Clients provide: road dimensions (width, lanes, sidewalks, medians); pole layout constraints (positions, mounting heights, setback, arrangement); target lighting class (e.g., M3 per EN 13201 or specified lux/uniformity); environmental conditions (temperature range, solar irradiance for solar projects, dust/corrosion levels); and a preferred product family if one exists.
CHZ capabilities: Shanghai CHZ Lighting Co., Ltd., founded in 2013 and headquartered in Jiading, Shanghai, operates three production bases (Shanghai, Hangzhou, Ningbo) totaling 18,000 m² with five standard assembly lines. The company holds ISO 9001, 14001, 45001, and 50001 certifications, and its products carry ENEC+, ENEC (Class I & II), CE, CB, ETL, TUV Mark, ROHS, and SAA certifications. CHZ's TUV-witnessed laboratory and joint laboratory with Fudan University (established 2015 under Prof. Chen Dahua) ensure every photometric measurement is accurate and traceable. With seven overseas offices (Spain, USA, Nigeria, Argentina, Burkina Faso, Romania, Ghana) and exports to 100+ countries across 1,600+ projects, CHZ combines global reach with local support. Annual capacity is 1 million sets with a 99.2% delivery rate. OEM/ODM cooperation requires no MOQ; samples ship in 5-7 working days and bulk orders in 20-25 working days. A 5-7 year warranty is standard, with 0.2% spare parts provided for projects exceeding 5,000 units.
Turnaround: For standard roadway projects, CHZ delivers a complete DIALux report - including luminaire schedule, calculation parameters, results, false-color visuals, and compliance verification - within 24-48 hours of receiving complete project information.
Conclusion
A DIALux simulation report is far more than a tender attachment. It is a comprehensive engineering document bridging the gap between a product datasheet and a real-world lighting installation - defining the site, specifying equipment, declaring assumptions, calculating performance, and verifying compliance with standards such as EN 13201. For procurers, it is essential for comparing bids fairly and avoiding the failures affecting up to 40% of solar street lighting installations in emerging markets. For contractors, it solves problems on screen before they become costly field rework.
The difference between a mediocre report and a credible one lies in verified IES files from an accredited laboratory, realistic maintenance factors, transparent parameters, and the ability to correlate predictions with field measurements. CHZ Lighting's TUV-witnessed laboratory, complete IES file library, in-house optical design, and proven results - such as the 43,436-unit Dominican Republic project exceeding SIE standards - demonstrate that a well-executed DIALux report is a genuine predictor of project success.
Ready to Light Your Next Project with Confidence?
Whether you are preparing a government tender, designing an EPC roadway package, or evaluating solar street light proposals, CHZ Lighting provides DIALux simulation reports within 24-48 hours, backed by IES files measured in our TUV-witnessed laboratory and available for every model in our range. Our engineers work with your road geometry, target lighting class, and environmental conditions to deliver a compliant, optimized, and field-verifiable design.
Contact Jolina at Sales@chz-lighting.com or WhatsApp +86 159 2122 3752 to request your free DIALux simulation report and discover why clients in over 100 countries trust CHZ Lighting to deliver outdoor lighting that performs - on paper and on the road.
About Shanghai CHZ Lighting Co., Ltd.
Shanghai CHZ Lighting Co., Ltd. was founded in 2013 and is headquartered in Jiading District, Shanghai. The company operates three manufacturing facilities (Shanghai, Hangzhou, Ningbo) totalling 18,000 m², with five dedicated LED street-light assembly lines and a nameplate annual capacity of one million luminaires. CHZ's on-time-delivery rate is 99.2% across recent multi-year windows. The product range carries ENEC+, CE, CB, ETL, TUV Mark, ROHS, and SAA certifications and is manufactured under a four-system ISO backbone (ISO 9001 / 14001 / 45001 / 50001) with an on-site TUV witness laboratory and a joint laboratory with Fudan University under Prof. Chen Dahua.
CHZ exports to more than 100 countries and has delivered over 1,600 commercial projects across seven overseas subsidiaries (Spain, USA, Nigeria, Argentina, Burkina Faso, Romania, Ghana). The company offers both OEM and ODM services with no minimum order quantity, supporting municipal buyers, contractors, and ESCOs who need custom photometric, certification, or branding adaptations on small initial runs. With more than 13 years in the LED lighting industry, CHZ is structured for long-cycle infrastructure programmes - the kind of multi-year roll-outs where a single vendor must stand behind tens of thousands of luminaires in the field.
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