Qu'est-ce qu'un angle de faisceau dans l'éclairage et comment le choisir ?

Beam angle is a simple metric that helps you optimize the light coverage inside your house or building. Any modern lighting work involves beam angle and light spread calculations. Beam angle is often used in lighting work, but few people know its details and uses.

So here is a detailed guide to help you understand all about beam angle in l'éclairage and choose the perfect beam angle for your needs.

What is beam angle?

Beam angle measures the dispersion of light from a light source (such as a light bulb). The larger the beam angle, the more scattered light there is, but the intensity of the light is also lower. Conversely, the narrower the beam angle, the less scattered light there is, but the intensity of the light is higher.

This light intensity is usually measured in lumens. Lumens per square meter are called “lux” and lumens per square foot are called “foot candles.” The total lumens needed to light a room will vary depending on the type of light and the size of the room.

Examples:

1. What does 120 beam angle mean?

120 refers to the angle of the fixture. A 120° angle is a wide beam angle for a bulb that can cover an entire room if the ceiling is high enough.

2. What does narrow beam angle mean?

Narrow beam angle refers to bulbs with a beam angle less than 30°. However, there are more detailed categories of beam angle, such as spot angle or narrower beam angle.

3. Common beam angles

There are two ways to refer to beam angle. One uses degrees, such as 10°, 60°, 120°, etc. The other uses terms, such as narrow beam angle, spot angle, wide, wider angle, etc.

The terms and standards for beam angle are not universal, but the NEMA classification is the most commonly used. NEMA is the National Electrical Manufacturers Association, the largest association of electrical equipment manufacturers.

Why is beam angle so important?

Beam angle helps determine light coverage; the larger the angle, the greater the coverage, and vice versa. To fully cover the floor of a 40×40 square foot room, you would need one 60° lamp centered on a 34-foot-high ceiling, or two 60° lamps 10 feet from the center of a 17-foot-high ceiling.

Proper light spread calculations allow you to achieve a fully illuminated room using the fewest fixtures.

Low or narrow beam angle lighting can also be a stylistic choice for accent or mood lighting.

How to measure beam angle?

Here is a simple trigonometric formula to calculate beam angle (beam spread).

Angle = 2* Tan-1 [Beam Spread / Light Distance]

Beam spread here is 50% of the total light output; any light outside the concentrated center is called “spill light” or “beam field.”

The beam angle of a bulb is calculated using precise instruments in a controlled environment. The average consumer does not need to calculate the angle; they can check the bulb’s packaging or the manufacturer’s website. This section is only for informational purposes to help you better understand the correct beam angle.

Beam Angle Selection Criteria

Now that you understand the importance of beams and the difference between narrow and wide beam angles, we can move on to selection criteria. To choose the best beam angle for your building, consider five factors.

1. Building Type

There are two key building types when considering beam angle:

• Residential Buildings
• Commercial Buildings

Residential buildings focus on even lighting in every room. Therefore, a wide beam angle light in the center of the room is usually sufficient.

However, commercial buildings such as restaurants or factories will focus on effectively lighting large areas of floor. They need medium to narrow angle lights distributed over large areas of ceiling. Restaurants are particularly focused on mood and accent lighting.

2. Light Fixtures

Light fixtures are the next most important factor in beam angle selection. A light fixture is the base of the lamp, which is usually mounted on the wall or ceiling. It can also have a light source (bulb or LED).

Light fixtures can change the beam angle of a bulb. Pendant lights usually reduce the angle, while recessed fixtures may increase the angle.

3. Lighting Types

The lighting type may vary depending on who you ask, but traditionally, there are three types of lighting.

• Ambient Lighting – Diffuse lighting is used to illuminate an entire room.
• Accent Lighting – Focused and indirect lighting is usually directed toward a wall.
• Task Lighting – Focused and direct lighting highlights work areas, such as desks.

Ambient lighting requires wide beam angles, while task and accent lighting require narrower light angles.

4. Ceiling Height

The farther away from the light source, the lower the light intensity; the higher the ceiling, the weaker the lighting at floor level.

Residential buildings, such as houses or apartments, have low ceilings, usually 10 feet or less. Therefore, such buildings require wide-angle lights to cover the entire room.

Commercial or industrial buildings, such as factories and warehouses, have high ceilings, usually over 25 feet. These buildings require powerful, narrow beam angles and multiple fixtures to cover the entire area.

5. Light Bulb Type

We’ve already talked about light fixtures, but light bulbs can vary greatly, too. The most common light bulb that everyone knows is the pear-shaped A-type bulb; this is the bulb that appears above your head when you have an idea.

Type A bulbs have no direction, so we put reflectors on them to give them direction. Modern light bulbs, primarily LED ones, come on PAR, BR, and MR reflector casings.

What is the difference between PAR, BR and MR type bulbs?

• BR (Convex Reflector) = Beam Angle > 90°
• PAR (Parabolic Aluminized Reflector) = Beam Angle > 45°
• MR (Multifaceted Reflector) = Beam Angle 15° – 45°

Which beam angle should you choose?

Finally, we have covered all the basics of beam angles in lighting and now we can start making choices.

Your choice of beam angle depends on the application de l'éclairage. The two most common classifications of lighting styles, and therefore choices of beam angles, are residential and commercial buildings.

1. Beam Angles for Residential Buildings

As mentioned before, residential buildings have lower ceilings and smaller areas. We can use the same beam angle for both houses and apartments because both are very similar from a lighting perspective.

In most houses, a medium beam angle (between 40° and 60°) is sufficient to illuminate a room. However, the actual beam angle may vary slightly depending on the five factors mentioned above.

Living rooms are larger than most other rooms in the house and often have a kitchen or dining area. A wider beam angle (greater than 60°) is recommended to cover the living room. Living rooms also don’t need as much light, so fewer fixtures can be used.

You’ll want to use narrower light angles in other areas of the house, such as stairways or walk-in closets; 25° is a standard angle for 9-10 foot ceilings.

Often, homes and apartments use a variety of lighting styles. Using a variety of lighting fixtures with different beam angles can create visual appeal. Mixing and matching can also achieve accent and task lighting.

2. Beam Angles for Commercial Buildings

Commercial buildings are very different from residential buildings. After all, there is more than one type of commercial building. So, for ease of understanding, we’ve broken down commercial buildings into the following categories.

Retail Stores

Retail stores have one goal for lighting: to show their products in the most flattering light. Ideal flattering light requires minimal shadows and glare. This requires strong ambient lighting that covers the entire store, so narrow beam angles and multiple bulbs are best used.

For example, bijouteries use narrow beam angles of less than 10° in display cases. Whereas clothing store lighting uses 30° or wider beam angles for mannequins.

Restaurants

Restaurants are an outlier among commercial spaces because they focus on aesthetics and mood lighting. Since many restaurants are only open in the evening to late night, they avoid bright environments.

A standard restaurant lighting setup uses a 25° beam angle for the dining table.

Offices

Office spaces have multiple employees spread out, and poor lighting can result in some employees facing harsh glare while others are confined to the shadows. Additionally, employees working at computer screens may experience eye strain if ambient light is too low.

Therefore, office spaces are best served with a wide flood beam angle, typically around 60°, with narrower beam angles used only for task lighting.

Warehouses

Because warehouses have high ceilings, narrower beam angles are needed to maintain their intensity as they reach the floor. The exact numbers vary depending on ceiling height.

Practical examples of beam angles

The table below describes appropriate practical scenarios for different beam angles.

Conclusion

This is a complete, detailed guide to lighting beam angles. Hopefully, this article will give you an understanding of the basics and will allow you to use the information in this article when choosing lighting for your building.

Beam angle can be a daunting metric, but once you understand it, it is a simple concept. Use a wide beam angle when you need a space to be well lit, and a narrow beam angle when you need to emphasize an area. Of course, don’t be afraid to use a combination of beam angles to achieve your ideal lighting environment.

However, if you find the beam angle selection process too tedious, you can count on the experts at RC Lighting to guide you. We offer a wide range of indoor and outdoor solutions d'éclairage for residential and commercial buildings.