Lighting in Design Q2 2021

Sidewalk placement : In addition to the technical criterion of the lights themselves, the distribution of lightposts along the street can have a dramatic effect on the nature of the street and its secondary uses. • Staggered arrangement: Staggering lightposts across the street from each other allows for an arrangement that is less formal, and can potentially use fewer lights, since there will be some overlap illumination. • Opposite arrangement: Light fixtures that are aligned directly across the street from each other set up a more formal condition. Opposite arrangement allows for spanning the street with banners or holiday lights. • Sensitivity to existing conditions: Although a standard distance between street lights might be specified, make allowances to respond to existing or recommended circumstances, such as a street café, compatibility or conflict with existing traffic signals, benches, bus stops, and telephones. • More closely spaced lightposts create a stronger edge along the sidewalk, reinforcing the sidewalk itself as an exterior habitable space. • Using more numerous and closely spaced light fixtures is one way of lowering the wattage, and therefore potential glare, of each fixture. Street scale is an important factor in determining the appropriate configuration of street light fixtures. Broad avenues require fixtures of a different scale from narrow side streets, because the arc of light created by a source varies with its height from the ground. Very wide streets may also require that the light source be extended further over the roadbed. Getting light back onto the sidewalk, on the other hand, requires a pedestrian fixture at a

that results in poor colour rendition; it compromises visual clarity and detracts enormously from the overall quality of the night-time urban environment. By contrast, metal halide as a light source produces a soft, white glow that renders colour accurately; it offers better visual clarity, improves reaction time for vehicles, and requires less wattage for the same perceived visibility. LED lighting, however, is becoming the standard today. Quality of light is also influenced by quantity of light – or more specifically, by the relationship between the brightness of a light and one’s distance from it. Light becomes more diffuse farther away from the source, so for a given brightness, there is a range of heights within which the source should be located to create the desired quality of light. Height of the luminaire: Although luminaire mounting heights have typically increased over the past few decades as lamp technology has allowed for higher and brighter road lights, the result is often lighting designed for the car or the parking lot, not for the person walking on the side of the street. Reducing the luminaires’ height, and adjusting it to the scale of the person on the sidewalk, calls for more fixtures, which in turn means that the luminaires, the poles, and their placement can have an impact on the streetscape. Type and wattage : However, as a luminaire’s height is lowered, the lamp’s brightness must be adjusted so that is does not create excessive glare for pedestrians. At the same time, the wattage must also be capable of adequately lighting the road. For instance, 2,5-3 m luminaires might be augmented with overhead lights because, depending on the street width, the wattage needed to light the street would create a blinding glare for the pedestrian.

In addition to the technical criterion of the lights them- selves, the distri- bution of lightposts along the street can have a dramatic effect on the nature of the street and its secondary uses.

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LiD Q2 - 2021