LED-Street-Lighting-East-Hampton-2021-07-13_RPI

LED Street Lighting Maximizing the Benefits Jean Paul Freyssinier Lighting Research Center, Rensselaer Polytechnic Institute Presented to the Town of East Hampton, NY July 13, 2021... •

LED Street Lighting

Maximizing the Benefits

Jean Paul Freyssinier

Lighting Research Center, Rensselaer Polytechnic Institute Presented to the Town of East Hampton, NY

July 13, 2021

• Background

• Purpose of street lighting and characteristics

• Guidelines for selecting appropriate retrofit lighting

• Services offered by this program

• Questions and answers

Background

Why do we light?

• Visual performance

• Speed and accuracy of high visual acuity tasks

• Safety – crash avoidance

• Vehicle-to-vehicle – on-axis judgement

• Vehicle-to-pedestrian – off-axis detection

Value – beyond energy savings

• Value can be increased by reducing costs, including environmental costs, and/or

by increasing benefits to humanity

Value

Benefits

Costs

=

Appearance Visual System PerformanceVisual

Performance

Alerting Effects Non-Visual Systems Phase Shift

Amount Spectrum Distribution Timing Duration

Timing Spectrum Duration Amount Distribution

Lighting affects two systems

Visual + non-visual

Main properties of electric light sources

• Parametric failure (lumen depreciation)

• Warm up and restrike time

• Operating costs

Boyce 2014

Boyce 2014

~200 1800–6500 ~100

Comparison among different light sources

Luminaire System Application Efficacy (LSAE)

LSAE has a good correlation with a parking lot’s lighting power density.

10:1

Uniformity of illumination

• Commonly, LED luminaires are built to match beam

distributions of traditional HID luminaires

– To maintain similar light levels and distribution

• Small source size allows LED luminaires direct light

to where it is needed

– Highly uniform illuminance on parking lot surface.

Narendran, N., J.P Freyssinier, and Y Zhu 2016 Energy and user acceptability benefits from improved illuminance uniformity of parking lot illumination Lighting Research and Technology, 48(7): 789–809 Sponsor: NYSERDA, ASSIST, GE product donation

75% less light needed!

Purpose and

Characteristics of

“Good” Street

Lighting

What Factors Contribute to Good Street

Lighting?

Street lighting contributes to:

Light level

• Depends upon specific situation

Uniformity

• Avoid contrast between light and dark

regions of the street and sidewalks

What Factors Contribute to Good Street

Lighting?

Aesthetics and appearance

• Luminaires (light fixtures) should fit the

character of an area

Cost

What Factors Contribute to Good Street

Lighting (cont’d.)?

Glare control

• Avoid light fixtures that do not shield view of

the light source

• Low mounting heights can be problematic

Light pollution control

• Sky glow

• Light trespass (shielded or properly located)

Guidelines for

Identifying

Appropriate

Retrofits

LED Streetlights and Application Efficiency

• Even when matched for lumen output, LED streetlights produce higher illuminances on the roadway compared to HPS

Equivalent LED Lumen Output for Equal Illuminance as HPS

• Because LEDs produce more short-wavelength (“blue”) output, LED lumen output can be reduced to achieve equivalent brightness perception

– 4000 K CCT: Factor = 1.46, 3000 K CCT: Factor = 1.21

LED Lumen Output Ranges for Equivalent Visual Perception

• LED lumen output is used rather than LED wattage because LED luminous efficacies continue to increase

• Use the lowest lumen output that is at least within the specified range

LED Streetlights and Uniformity

• In general, LED streetlights produce more uniform illumination than HPS, but when spacing is very long (~300 ft),

lighting will always be non-uniform.

Conclusions and Caveats

• Selection of LED luminaires based on the

previous table will achieve energy savings of

~70%

– Lower illuminances and increased application

efficiency of LEDs can lead to corresponding decreases in light pollution and light trespass – Increased application efficiency for roadway

illumination could result in proportionally lower light levels on sidewalks, if present

– If sidewalk appearance is critical, consider

increasing LED lumen output by 10%

Services Offered

by This Program

Technical Assistance is Available

NYSERDA offers limited technical

assistance to municipalities looking to

convert street lighting to LED technology

• Assistance with product selection

• Technical analysis of light levels/distributions

• Evaluation of existing/replacement lighting

Contact your Clean Energy Communities

coordinator to get started

Thank You!

Questions &

Answers