Everything you need to know — from CRI and beam angles to IP ratings and control protocols — in one comprehensive reference. Written for lighting designers, architects, and electrical engineers.
Color Rendering Index (CRI) measures how accurately a light source renders colors compared to a natural reference source (daylight or incandescent). The scale runs from 0 to 100, with 100 being perfect color rendering.
CRI is calculated by measuring how 8 standard test colors (R1-R8) appear under the light source versus a reference. The average of these 8 values gives the CRI (Ra) number. Higher = more accurate color rendering.
R9 measures the rendering of saturated red. It's not included in the standard CRI calculation, but it's critically important. A light source can have CRI 90 but poor R9, making reds look dull, skin tones appear washed out, and food look unappetizing. Always check R9 values — R9 ≥ 50 is considered good for most applications, R9 ≥ 80 is excellent.
TM-30 is a newer color rendering metric developed by the IES that uses 99 color samples instead of 8, and provides two values: Rf (fidelity, similar to CRI) and Rg (gamut, how saturated colors appear). TM-30 gives a much more complete picture of color quality. Look for Rf ≥ 90 and Rg between 95-105 for natural, accurate color.
All Yakeen fixtures come with CRI 90 as standard. CRI 95+ with R9 ≥ 80 is available on all product lines for projects requiring premium color quality. We use TM-30 verified LEDs with Rf ≥ 92.
Beam angle is the angle at which light intensity drops to 50% of the maximum (the "half-peak" angle). Choosing the right beam angle is essential for achieving the desired lighting effect and uniformity.
| Beam Angle | Category | Typical Applications |
|---|---|---|
| 8° – 12° | Very Narrow Spot | Sculpture, high ceiling accent, dramatic spotlighting, vertical surfaces at distance |
| 15° – 20° | Narrow Spot | Artwork, retail displays, feature accent, museum exhibits |
| 24° – 36° | Medium Flood | Retail shelf lighting, wall washing at close range, general accent |
| 40° – 60° | Wide Flood | General ambient lighting, wall washing, low ceiling downlights |
| 60° – 90° | Very Wide | High-bay downlights, indirect lighting, cove lighting |
| 90°+ | Ultra Wide | Linear ambient systems, low-bay, surface mount general lighting |
Beam angle is the angle at which intensity is ≥ 50% of maximum. Field angle is the angle at which intensity is ≥ 10% of maximum. The field angle is always wider than the beam angle. Both matter — the beam angle determines your "hot spot," while the field angle determines how far the light spills.
As a general rule: for a given mounting height, narrower beams create more focused, dramatic light with higher contrast. Wider beams create softer, more uniform light with less shadow. For accent lighting, match the beam angle to the size of the object and the mounting height — taller ceilings need wider beams to cover the same area.
Yakeen track and spotlights offer beam angles from 8° to 60°, with interchangeable optics on many models. Our wall washers feature 2:1 uniformity optics for even wall illumination. IES photometric files are available for all products.
Correlated Color Temperature (CCT) describes the color appearance of white light, measured in Kelvin (K). Lower values are "warmer" (more yellow/amber), higher values are "cooler" (more blue/white).
| CCT | Description | Best For |
|---|---|---|
| 2200K – 2400K | Extra Warm White | Fine dining, luxury hotels, lounges, high-end residential. Very warm, amber, intimate. |
| 2700K | Warm White | Hotels, restaurants, residential, hospitality. Classic warm white — most common for hospitality. |
| 3000K | Soft Warm White | Retail, general commercial, upscale offices. Warm but not yellow — the most versatile choice. |
| 3500K | Neutral White | Offices, schools, healthcare, retail. Balanced, neither warm nor cool. |
| 4000K | Cool White | Offices, schools, hospitals, laboratories. Crisp, alert, clinical. |
| 5000K – 6500K | Daylight | Industrial, outdoor, task lighting, studios. Bright, energetic, blue-ish. |
Not all LEDs of the same color temperature are identical. MacAdam ellipses measure color variation — 1 step MacAdam is imperceptible to the human eye. 3 step MacAdam is standard for commercial lighting, meaning you might see slight color differences between fixtures. For premium projects, specify 2 step or 1 step MacAdam for perfect color consistency across all fixtures.
Tunable white fixtures allow color temperature adjustment, typically from 2700K to 6500K. Useful for spaces that need different moods at different times (e.g., offices with circadian lighting, classrooms, healthcare facilities). Controlled via DALI-2 or 0-10V dual-channel systems.
3000K is our standard color temperature. 2700K, 3500K, 4000K, and 5000K are available on all lines. Tunable white (2700K-6500K) is available on select product lines. All LEDs are binned to 3 step MacAdam minimum, with 2 step available for premium projects.
Unified Glare Rating (UGR) is the international standard for measuring discomfort glare from indoor lighting installations. The scale runs from 10 (imperceptible glare) to 28 (uncomfortable glare).
Glare reduces visual comfort, causes eye strain and headaches, and decreases productivity. In offices, excessive glare can reduce productivity by 10-15% according to some studies. Good lighting design balances sufficient light levels with comfortable glare levels.
Several strategies reduce UGR:
Deep recessed apertures — recessing the LED source deep inside the fixture hides it from normal viewing angles.
Louvers and baffles — parabolic louvers and cross-baffles block direct view of the source at high angles.
Diffusers — frosted or prismatic diffusers spread the light and soften the source appearance.
Proper spacing — following manufacturer spacing-to-height ratios ensures the right uniformity and glare performance.
Indirect lighting — bouncing light off ceilings and walls creates very low-glare, comfortable illumination.
Yakeen linear systems and select downlights achieve UGR < 19 with deep-recessed optics and precision-engineered reflectors. We provide UGR calculations for all linear lighting layouts to ensure compliance with EN 12464-1.
IP (Ingress Protection) ratings describe how well a fixture is sealed against solids and liquids. The rating consists of two digits: the first for solid particle protection (0-6), the second for liquid protection (0-9).
| Rating | Protection Against | What It Means |
|---|---|---|
| IP2X | Fingers > 12mm | Basic protection against accidental contact. Indoor dry locations. |
| IP4X | Tools > 1mm | Protection against small tools and wires. Indoor, some dust protection. |
| IP5X | Dust protected | Dust cannot enter in sufficient quantity to interfere. Protected outdoor. |
| IP6X | Dust tight | Complete dust protection. No dust can enter. Harsh environments. |
| Rating | Protection Against | Typical Application |
|---|---|---|
| IPX0 | No protection | Dry indoor only |
| IPX4 | Splashing water | Bathrooms (Zone 2), covered outdoor areas |
| IPX5 | Water jets | Wet rooms, food preparation areas |
| IPX6 | Powerful water jets | Exterior, facades, washdown areas, marine |
| IPX7 | Immersion up to 1m | Inground lights, fountains, submersion |
| IPX8 | Continuous immersion | Underwater lighting, pools, deep submersion |
IK ratings measure mechanical impact resistance. IK08 resists 5 joule impacts (equivalent to a 500g weight dropped from 1m). IK10 resists 20 joule impacts (5kg dropped from 40cm). For exterior and public space fixtures, IK10 is recommended to withstand vandalism and accidental impact.
Indoor fixtures: IP20 standard, IP54 available. Exterior fixtures: IP66 standard with IK10 impact resistance. Inground fixtures: IP67. All exterior products are salt-spray tested for coastal applications.
Lighting controls range from simple on/off switching to fully integrated building automation systems. Choosing the right control system depends on project size, complexity, budget, and required features.
| Protocol | Type | Best For | Key Features |
|---|---|---|---|
| 0-10V / 1-10V | Analog | Small projects, simple dimming | Low cost, widely compatible, simple wiring, per-zone dimming only |
| DALI / DALI-2 | Digital | Commercial, offices, hospitality | Individual addressing, scenes, sensors, emergency testing, precise dimming |
| DMX512 / RDM | Digital | Architectural color, facades, theatrical | Color changing, dynamic effects, 512 channels, RDM remote configuration |
| KNX | Building automation | Integrated buildings, Europe | Full building system, lighting + HVAC + blinds + security |
| Bluetooth Mesh | Wireless | Retrofit, smart offices, small commercial | No control wiring, app control, easy reconfiguration |
DALI (Digital Addressable Lighting Interface) is the most common control protocol in commercial lighting. DALI-2 is the updated version with improved interoperability between manufacturers. Each DALI bus can control up to 64 individually addressable fixtures. DALI-2 supports:
• Individual fixture dimming (0.1% – 100%)
• Scene recall (16 scenes per fixture)
• Occupancy and daylight sensor integration (D4i)
• Emergency lighting testing and monitoring
• Energy metering and diagnostics
• Color temperature control (DT8, tunable white)
Small retail, cafe, small office: 0-10V or Bluetooth mesh. Simple, cost-effective.
Mid-size commercial, hotel, restaurant: DALI-2. Individual control, scenes, sensors.
Large office, school, hospital: DALI-2 with building management system integration. Full automation.
Exterior facade, color changing: DMX512/RDM. Dynamic color and effects.
Integrated smart building: KNX or DALI-2 via BACnet gateway. Whole building control.
All Yakeen fixtures are available with 0-10V, DALI-2, or TRIAC dimming. DMX512/RDM is available for color-changing and exterior products. KNX integration via gateway. D4i sensor-ready drivers available on select lines. Our team can design complete control systems for your project.
Photometric data describes how light is distributed from a fixture. It's essential for lighting design software like DIALux and Relux to calculate light levels, uniformity, and glare.
IES files (.ies format, defined by the Illuminating Engineering Society) contain standardized photometric data for a luminaire. They describe the intensity of light in all directions (the candela distribution). Lighting design software uses IES files to simulate how light will behave in a space.
DIALux Evo — The most widely used lighting design software in Europe and the Middle East. Free to use.
Relux — Popular in some European markets, similar capabilities to DIALux.
AGi32 — More common in North America. Advanced calculation capabilities.
All these programs use IES files to calculate lux levels, uniformity ratios, glare (UGR), and to generate false color renderings and iso-lux diagrams.
IES photometric files are available for all Yakeen products. Our design team provides full DIALux Evo calculations, including lux level analysis, uniformity checks, UGR calculations, and false color visualizations for all projects.
LED lifespan is heavily dependent on temperature. Good thermal design is the difference between a fixture that lasts 10 years and one that fails in 2 years.
LEDs don't burn out — they slowly dim over time. Lifespan is rated based on when the light output drops to a certain percentage of the original:
L70 — 70% of initial output remains. The standard industry benchmark. When an LED reaches L70, it's considered at the end of its useful life for most applications.
L80 — 80% of initial output. Used for applications where light level is critical.
L90 — 90% of initial output. Used for very demanding applications.
LM-80 is a testing standard that measures LED lumen depreciation over 6,000 or 10,000 hours at specific temperatures (typically 55°C, 85°C, and sometimes 105°C). This is real measured data.
TM-21 is a calculation method that takes LM-80 test data and extrapolates it to predict long-term LED life (e.g., 50,000 or 100,000 hours).
Always look for LM-80 verified LEDs with TM-21 projections. Be wary of "100,000 hour" claims without LM-80 data — they're almost always marketing, not engineering.
Every 10°C increase in LED junction temperature roughly halves the LED lifespan. Good thermal design — high-quality heat sinks, proper PCB design, good airflow — keeps LEDs cool and ensures they reach their rated lifespan.
For exterior fixtures in hot climates (Middle East, Southeast Asia), pay special attention to the rated ambient temperature. A fixture rated at 50,000 hours at 25°C might only last 25,000 hours at 55°C ambient.
All Yakeen fixtures use aircraft-grade 6063 aluminum heat sinks for optimal thermal performance. All LEDs are LM-80 verified with TM-21 projections of L70 > 50,000 hours at Ta 55°C. We design for Middle Eastern and tropical climates — our exterior fixtures are rated for 55°C ambient operation.
A cheat sheet for common lighting specification requirements across different project types.
| Application | CRI | CCT | Beam Angle | IP Rating | UGR | Control |
|---|---|---|---|---|---|---|
| Office | 90 | 3500-4000K | 60-90° | IP20 | < 19 | DALI-2 |
| Retail (Fashion) | 90-95 | 3000K | 15-36° | IP20 | < 22 | DALI-2 |
| Hotel Lobby | 90+ | 2700-3000K | Mixed | IP20 | < 22 | DALI-2 |
| Restaurant | 90+ | 2700K | 24-36° | IP20 | < 22 | 0-10V / DALI |
| Museum / Gallery | 95+ | 3000K | 8-24° | IP20 | < 19 | DALI-2 |
| Exterior Facade | 80-90 | 3000K | 10-60° | IP66 | N/A | DMX / DALI |
| Warehouse | 80 | 5000K | 60-90° | IP65 | < 25 | 0-10V |
| Healthcare | 90 | 3500-4000K | 60° | IP54 | < 19 | DALI-2 |
Answers to the most common questions lighting specifiers ask.
For retail lighting, specify CRI 90 as a minimum. For high-end retail, fashion, cosmetics, and jewelry, specify CRI 95 or higher with R9 ≥ 50 (ideally ≥ 80). Higher CRI renders colors more accurately, making products appear more vibrant and true-to-life, which directly impacts purchasing decisions and perceived product value.
0-10V is a simple analog dimming protocol using a 0-10V control signal — it's low cost, widely compatible, but limited to per-zone dimming with no individual fixture addressing or feedback. DALI is a digital protocol that enables individual fixture addressing, precise dimming down to 0.1%, scene control, occupancy sensing integration, and system diagnostics. For small projects with simple needs, 0-10V works fine. For commercial projects with multiple zones, scenes, or sensor integration, DALI-2 is recommended.
Choose beam angle based on mounting height and what you're illuminating. For accent lighting on artwork or features at typical ceiling heights (2.8-4m), use narrow beams (8-15°). For retail shelves and general accent lighting, use medium beams (24-36°). For wall washing and ambient lighting, use wide beams (60°+). As a rule of thumb: narrower beams = more focused light, higher contrast, more dramatic. Wider beams = more uniform light, softer shadows, more ambient. Always verify with photometric calculations.
For bathrooms, IP rating requirements depend on the zone. Zone 0 (inside the bath or shower, where fixtures can be submerged): IP67 minimum. Zone 1 (above the bath or shower enclosure, up to 2.25m): IP45 minimum. Zone 2 (0.6m outside Zone 1, up to 2.25m): IP44 minimum. Outside Zones 0, 1, and 2: IP20 is acceptable. Always check local electrical codes — requirements vary by country.
UGR (Unified Glare Rating) measures the discomfort glare from a lighting installation. The scale runs from 10 (imperceptible) to 28 (uncomfortable). For offices, EN 12464-1 specifies UGR < 19 for general office work and detailed tasks. High glare causes visual fatigue, reduces productivity, and can cause headaches. Achieve low UGR with deep recessed fixtures, louvers, diffusers, and proper fixture spacing-to-mounting height ratios.
For hotels, 2700K (warm white) is the standard for guest rooms, lobbies, restaurants, lounges, and spa areas — it creates a warm, inviting, luxurious atmosphere. For back-of-house, kitchens, and functional areas, 3000K or 3500K may be more appropriate. Consistency across the property is important — stick to one color temperature per space type, and ensure all fixtures (downlights, track, wall washers) use the same CCT to avoid color mismatch.
LM-80 is a testing standard that measures LED lumen depreciation over 6,000 or 10,000 hours at specific temperatures. It's actual measured data in a lab. TM-21 is a calculation method that takes LM-80 test data and extrapolates it to predict long-term LED life (e.g., L70 at 50,000 hours). LM-80 is the test, TM-21 is the projection. Always look for LM-80 verified LEDs with TM-21 projections for accurate lifespan claims. Be skeptical of "100,000 hour" claims without LM-80 data.
Yes, we provide full DIALux Evo lighting calculations and visualizations for projects. Our in-house design team can produce complete lighting layouts, lux level calculations, uniformity analysis, false color renderings, UGR calculations, and daylight simulations. We provide IES photometric files for all our products, which can also be used in Relux, AGi32, and other lighting design software.
Our technical team can help with product selection, photometric calculations, specification writing, and control system design. Free, no obligation.