What Is Light Distribution Type I, Type II, Type III, Type IV, and Type V?

When designing a lighting plan for a commercial space, outdoor area, or public facility, one of the most overlooked, and yet most important, factors is light distribution. Choosing the correct light distribution type ensures optimal visibility, improved energy efficiency, and a safer, more aesthetically pleasing environment.

Whether you’re an interior designer, architect, contractor, or facility manager, understanding these light distribution patterns will help you make better decisions for your project. In this guide, we break down the five commonly used light distribution types; Type I, Type II, Type III, Type IV, and Type V, and explain where and why each should be used.

What Is Light Distribution?

Light distribution refers to the pattern in which light is dispersed from a fixture onto a surface. It determines:

1. how far the light reaches,

2. how wide it spreads, and

3. the shape of its coverage

Choosing the wrong light distribution can lead to uneven illumination, wasted energy, and poor visibility, as each type is designed for specific applications and coverage needs. Thus, in order to understand each different distribution type better, the Illuminating Engineering Society (IES) has classified them into standard types, commonly labeled as Type I through Type V.

Type I – Ideal for Walkways & Narrow Paths

Pattern Shape: Long and narrow

Typical Beam Spread: Symmetrical along a central axis

Best For:

• Walkways and Sidewalks

• Narrow pathways

• Bike trails

• One-way driveways

Type I lighting casts light in a rectangular pattern, making it ideal for walkways or narrow areas where the fixture is centered along the path. With its two-way lateral spread, it ensures consistent light coverage without spilling over into unwanted areas, ensuring efficiency of illuminating places.

Type II – Ideal for Wider Walkways & Residential Streets

Pattern Shape: Slightly wider rectangle

Typical Beam Spread: Reaches about 1.75 times the mounting height forward

Best For:

• Wider walkways

• Residential streets

• Smaller parking lots

• Campus pathways

Type II lighting provides wider coverage than Type I, making it a great choice for residential areas and spaces that require broader illumination without excessive glare. Type II is most ideal when the width of the area to be illuminated is no bigger than 1.75 times the mounting height of the luminaire.

Type III – Great for Parking Lots & Roadways

Pattern Shape: Wider, “oblong” shape

Typical Beam Spread: Extends 2.75 times the mounting height forward

Best For:

• Roadways

• Parking lots

• Perimeter lighting

• Commercial outdoor spaces

Type III lighting is commonly used for large outdoor areas, and is one of the most versatile choice for most applications. It provides forward and lateral illumination, making it perfect for spaces where fixtures are mounted along the perimeter rather than in the center. It is most suitable for medium-width roadways or areas, where the width of the area does not exceed 2.75 times the mounting height of the luminaire.

Type IV – Best for Perimeter & Building Facades

Pattern Shape: Semi-circular

Typical Beam Spread: Focused forward throw

Best For:

• Perimeter of parking lots

• Building facades

• Sports grounds edges

Type IV lighting provides a forward-focused light that covers a large area without wasting illumination behind the fixture. It is often used for security purposes to illuminate the outside edge of properties, thus delivering high visibility to specific targeted zones. It is suitable for areas where the width of the area does not exceed 3.7 times the mounting height of the luminaire.

Type V – Uniform 360° Illumination

Pattern Shape: Circular (symmetrical in all directions)

Typical Beam Spread: Even light in a full 360° radius

Best For:

• Large open areas

• Center of parking lots

• Courtyards

• Plazas

Type V lighting delivers equal intensity in all directions, ensuring uniform coverage around the light fixture in a circle. With a balanced distribution of light, the overall visibility is improved and the possibility of blind spots in larger areas is significantly reduced, thus translating to lower energy waste and safer environments. It’s a go-to choice for spaces where light fixtures are mounted centrally in locations such as parking lots and public plazas.

Why Choosing the Right Light Distribution Matters

For designers, architects, and facility managers, selecting the right light distribution type isn’t just about brightness; it’s also about efficiency, safety, and visual comfort. When planning your next project, consider:

• The shape and size of the area

• The mounting location and height of fixtures

• The desired light coverage and intensity

• Local light pollution regulations

Upgrade to Smarter Lighting Solutions ✅💡

At Brite, we provide commercial and architectural lighting solutions designed for optimal performance. Whether you’re illuminating a golf course, an office complex, or a public walkway, our team can recommend the perfect light distribution type to match your project’s needs.

Get in touch with us today to speak with our lighting consultants and let's Brite-n up your space together.

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