### Outdoor Lighting Design Calculations – Part One

In the previous article " Outdoor Lighting " in " Course Light-1: An Introduction to Lighting Design ", I classify the outdoor lighting fixtures according to usage and lamp type.

Today, I will begin explaining the outdoor lighting design by using different methods as follows.

You can review the following previous Articles related to indoor lighting design for good following:

General overview for Outdoor lighting

The outdoor lighting can be classified according to application as follows:

1. Ambient (General) lighting,
2. Accent lighting,
3. Orientation lighting,
4. Floodlighting,
6. Sports lighting.

First: Ambient (General) lighting

Ambient lighting produced by wide beam light distribution facilitates perception and orientation in the horizontal plane. It contributes to recognizing pathways and to save circulation.

Ambient lighting include two types:

1. General lighting- direct, aimed,
2. General lighting - direct, diffuse.

1- General lighting- direct, aimed

Direct and aimed general lighting produces an even illumination on the horizontal working plane.
The architecture is visible and it is possible to orientate oneself in the room.

The directed light produces good modelling and brilliance. The uniformity on the working plane increases as the mounting height increases or as the beam angle widens. Directed light enables good appreciation of form and surface texture. The visual comfort increases as the cut-off angle increases. A feature of direct illumination is its highly efficient use of energy.

Preferred luminaires for using with General lighting- direct, aimed:

1. Downlights,aimed (recessed or surface mounted),
2. Uplights, aimed.

A- Downlights,aimed (recessed or surface mounted)

Downlights have a rotationally symmetric beam that is directed vertically downwards.

They are usually mounted on the ceiling and illuminate the floor. They are offered with narrow-beam symmetric light distribution. The cut-off angle of narrow-beam downlights means they are largely free of glare. On downlights with Darklight reflector, the lamp's cut-off angle is identical to that of the luminaire. This gives a luminaire with the widest beam possible while simultaneously having an optimised light output ratio.

The use of a diffuser reduces the luminance in the luminaire and thereby improves the visual comfort and the evenness.

Criteria for Downlights:

• Choice of lamp determines light colour, functional life, efficiency, light intensity,
• Emission angle determines the beam of light and is defined by the reflector and the lamp,
• Cut-off angle limits glare and increases visual comfort,
• Light output ratio is increased by optimised reflector technology.

Applications of General lighting- direct, aimed:
• Entrance areas,
• Passages,
• Atria.

B- Uplights, aimed

Uplights feature an upwards directed beam with symmetrical light distribution. The narrow, rotationally symmetrical beam is used for highlighting objects.

Criteria for Uplight, aimed:
• Choice of lamp determines light colour, functional life, efficiency, light intensity,
• Uniformity with wallwashers: optimised reflector for even illumination of areas,
• Range of tilt for directional luminaires with high glare protection,
• Light output ratio is increased by optimised reflector technology.

2- General lighting - direct, diffuse

Direct, diffuse general lighting designates an even illumination with respect to a horizontal working plane. The architecture is visible and it is possible to orientate oneself in the room.

Direct, diffuse light produces a soft illumination with little shadow and reflection. The limited formation of shadow results in weak modelling capabilities.

Shapes and surface textures are only slightly emphasised. One feature of using fluorescent lamps for the general lighting is an efficient use of energy.

Preferred luminaires for using with General lighting- direct, diffuse:

1. Downlights, diffuse
2. Wall-mounted downlights
3. Uplight, diffuse

A- Downlights, diffuse

see paragraph " Downlight" in above.

B- Wall-mounted downlights

Wall-mounted downlights are available with narrow-beam, wide-beam, symmetrical or asymmetric light distribution.

Wall-mounted downlights have (2) types:

1- Normal

Wall-mounted downlights, with their diffuse beam in the room, provide good visual comfort. They can also be mounted on the ceiling.

2- Shielded

Wall-mounted downlights with half-shielded face offer good visual comfort and illuminate the floor area in particular.

Criteria for wallmounted downlights:

• Choice of lamp determines light colour, functional life, efficiency, light intensity,
• Uniformity: optimised reflector for even illumination of areas,
• Cut-off angle increases visual comfort and limits glare and light pollution.

C- Uplight, diffuse

Recessed floor luminaires with diffuse light intensity distribution are used for marking paths or emphasising architectural lines.

Applications of General lighting - direct, diffuse
• Entrance areas,
• Overhanging or cantilevered roofs,
• Floor lighting on access driveways, paths and public squares.

Second: Accent lighting

Accent light emphasises vegetation, individual objects or architectural elements using narrow beams of light. Bright points in dark surroundings attract attention.

They separate the important from the unimportant, allowing individual objects to come to the fore.

Preferred luminaires for using with Accent lighting:

1. Projectors,
2. Directional downlights.
3. Directional uplights.

A- Projectors

Projectors illuminate a narrowly constrained area. The type of mounting and the orientation are variable. Projectors are offered with different beam emission angles and light distributions.

Criteria for projectors:

• Choice of lamp determines light colour, brilliance, functional life, light intensity,
• Emission angle determines the beam of light and is defined by the reflector and the lamp Cut-off angle limits glare and increases visual comfort,
• Rotatable and tiltable Projectors have narrow-beam light distribution with a rotationally symmetrical beam.

The use of accessories is also typical for projectors:
• Lenses: spread lenses or sculpture lenses,
• Filter: colour filter, UV or IR filter,
• Glare control: anti-dazzle screen.

B- Directional downlights

Accent lighting enables good appreciation of form and surface structure. The focused light produces pronounced shadows and good modelling ability, as well as brilliance. A narrow beam and a high brightness contrast to the surroundings give the object particular emphasis.

C- Directional uplights

Directional luminaires provide highlighting for individual areas or objects with a medium to narrow light distribution. The beam can be titled.

Applications of Accent lighting:

• Entrance areas,
• Park and garden complexes,
• Objects.

Third: Orientation lighting

Orientation lighting, points of light or rows of lights are used to provide orientation in the outdoor area.

Orientation lighting improves the perception by adding light points and lines, e.g. along pathways and on stairs. The light must function as a signal. Illuminating the surroundings is of secondary importance here.

Low illumination levels are sufficient for orientation purposes. Small luminaires with high luminance clearly set themselves apart form their surroundings.

Preferred luminaires for using with Orientation lighting:
1. Floor washlights,
2. Wall-mounted downlights,
3. Recessed floor luminaires,
4. Orientation luminaires,
5. Bollard Luminaires.

A- Floor washlights

Floor washlights form points of light on the wall and serves as an orientation light on the floor surface.

B- Wall-mounted downlights

see paragraph "downlight" in General Lighting in above.

C- Uplight, diffuse

see paragraph "Uplight, diffuse" in General Lighting in above.

D- Orientation luminaires

Orientation luminaires are defined first and foremost by the task of providing orientation.
This can be achieved by luminaires that function as sources of illumination or as signals.

Criteria for orientation luminaires:
• Luminance: noticability of the luminaires in their surroundings.

E- Bollard Luminaires

Bollard luminaires have a widebeam characteristic. They are offered with an asymmetric light distribution.

Pathway lighting luminaires with asymmetric light distribution provide uniform illumination on pathways. The light is spread in its width so that pathways can be evenly illuminated. Their small shape makes these luminaires suitable for lighting steps.

Criteria for luminaires for open area and pathway lighting:

• choice of lamp determines light colour, functional life, efficiency, light intensity,
• uniformity: optimised reflector for even illumination of areas,
• gradient: soft edges to beam of light,
• cut-off angle increases visual comfort and limits glare and light pollution,
• light output ratio is increased by optimised reflector technology.

Applications of Orientation lighting:
• architectural lines,
• steps and exclusion zones,
• entrances,
• routes,
• emergency exit routes.

in the next article, I will explain other types of outdoor lighting; flood lighting. Please keep following.