Smart Urban Lighting: Lecture 7

Question 1

Name the three functions of public lighting

Answer 1

1. Light supports adequate human functioning during dark hours providing visibility
2. Light as a crime deterrent (evidence is mixed)
3. Light to create an esthetically pleasing nighttime environment

Question 2

Why do some people say that lighting does not improve crime rates?

Answer 2

Multiple studies show that there was no significant change in crime following street lighting improvements. –> light is unlikely to suppress crime

Question 3

Results of study of Atkins 1991

Answer 3

Crime reduced at night
But also during the day
No statistical difference between day and night
Conclusion: No effect of street lighting on crime

Question 4

Criticism by Marchant

Answer 4

Ending low can be a regression towards the mean
Also if crime is very low, regresses towards the mean and thus becomes higher

Trend in crime reduction started before the introduction of brighter light?

Question 5

How to detect real effect of lighting according to Marchant? Ultimate test:

Answer 5

Randomized half of streets with brighter light (experimental), other group not. Do pre-test and test.
Then swap the experimental and control group and do post test

Question 6

What are possible direct or indirect mechanisms of light’s effects on crime?

Answer 6

Enhanced visibility scares criminals away because more easily identified

Enhanced visibility changes odds in favor of pedestrians

Better lighting increases activity on the street and thus informal surveillance

Improving lighting may affect community pride and bonding, thus leading to increases informal surveillance during day and night

Better lighting may improve the appearance of poorly maintained streets and thus decreasing the ‘broken window effect’

Better lighting at night may reduce littering due to reduced nocturnal incivility

Question 7

What is the broken window effect?

Answer 7

An academic theory proposed by James Q. Wilson and George Kelling in 1982 that used broken windows as a metaphor for disorder within neighbourhoods. Their theory links disorder and incivility within a community to subsequent occurrences of serious crime.

Question 8

What is the prospect refuge theory for perceived safety in lighting (3 parts)?

Answer 8

1. Prospect: good lighting allows for overview
2. Concealment: good lighting may remove dark spots in which criminals may hide
3. Escape: good lighting reveals possibilities for escaping dangerous situations

Question 9

What are two societal challenges regarding lighting?

Answer 9

1. energy consumption

2. lighting polution

Question 10

Some consequences of light pollution on humans

Answer 10

Nuisance to astronomers
Disturbs circadian rhythm
Affects the quality of sleep
(Causes cancer?)

Question 11

Benefits of solid state lighting:

Answer 11

High energy efficiency
Long lifetime
Easy to steer with lenses
Fast of and on switching
Flexible (OLEDS)
Connect to sensors

Question 12

What is the result of luminaire reflector technology?

Answer 12

No emission into sky

Higher energy efficiency

Question 13

What is the rebound effect?

Answer 13

Energy efficiency improved with LEDs, however because they were energy efficient, more people started to buy/use them, leading to large increase in usage

700 times more efficient
7000 times higher usage

Question 14

Example of conventional lighting

Answer 14

Perhaps fixed dimming schedule for times of lower traffic

Question 15

Example adaptive lighting

Answer 15

Lights turn on as someone passes

Question 16

Example light on demand

Answer 16

Light turns on when user takes control over it