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Stefan Dickerson
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LED Lighting for
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Public Spaces Thesis Project Carleton University
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Welcome Thank you for taking some time to review my
LED Lighting for Public Spaces
A flexible system
thesis project.
for public lighting The context of this project is Ecoville, an alternative present-day (or near-future) civilization that
that leverages
enables its citizens to live sustainably.
LED technology, Carleton University’s class of 2009 expressed our interpretations of Ecoville through a diverse set of
enabling targeted
eco-friendly projects.
illumination and At first we had no “model” of Ecoville. However as the projects materialized they formed a clearer picture, like pieces of a puzzle. I am grateful for this unique experience: I learned about sustainability from my peers’ projects as well as my own. For a quick read, I condensed my project in this booklet. More in-depth information is available. Here’s my piece of the puzzle.
eco-efficiency.
Inside this por tfolio:
4
10
16
Why LED?
Early Concepts
User Testing
6
12
18
Environmental Impacts
Preliminary Main Concept
Design Consultation
8
14
20
Going Forward: Applications
LCA (LifeCycle Analysis)
Finished Product
Why LED? Efficiency, Light Quality Improving
Verrazano-Narrows Bridge, New York â–ź Photo courtesy Rick Elkins
Tough and Long Lasting Durability is important when changing bulbs is difficult and expensive. LEDS are tough (no fragile filaments or glass). The typical lifespan of LEDs is 50 to 100 thousand hours (over 10 years).
â—„ Efficiency of various light technologies (Lumens per Watt) over time â–ź Applications of lighting, quality comparison
What This Means Widespread adoption of LED technology
Obsolescence, not just LED life cycles,
is coming. While others are flat, LED
could motivate servicing. A lighting
efficiency and light quality gains are
system should be easy to upgrade, by
rapid.
replacing just the LED component.
This trend will likely continue.
Environmental Impacts Why Focus on Lighting? An estimated 12 to 15% of worldwide electricity generation is used for lighting (Zissis and Rouffet 2005). Thus lighting is an excellent focal point for energy conservation efforts. A technological approach is to make the same amount of light with less electricity. A design approach is to reduce the amount of light required to begin with, i.e. “task lighting“ for the outdoors.
Light Pollution Public
lighting
first
Awareness of light pollution and its
Industrial
adverse effects on life is growing. Ideally
Revolution for public safety, and to
we would have full control over artificial
attract people downtown.
The idea
light emissions, putting light exactly
persists that more light is better, but
where and when it is needed, and
this is being increasingly challenged.
nowhere else.
developed
systems
during
the
were
Obstacle to Lowering Impact Public lighting has become a largely
A simple LED substitution will do nothing
mature industry. It evolved in the absence
to curb light pollution. Compounding
of light pollution awareness.
this issue is legislation, which often prescribes minimum levels of lighting.
As a result of its maturity, we expect public lighting to appear as it did in the
Exceptions can be found in “Dark Sky”
gaslight era: as centralized bright light
communities like Flagstaff Arizona, in
sources on poles.
the United States. Where light pollution informs policy, and maximum, rather
Unfortunately, LED technology is under
than minimum light levels are prescribed,
pressure to mimic existing lighting. This
conventional lighting may fail to satisfy
is a common rite of passage for new
both
technologies.
requirements.
legislative
and
public
safety
▼ LEDs adapting to current light systems
Opportunity The “Dark Sky” movement creates a market for targeted, distributed and possibly switchable lighting systems. LEDs offer these possibilities with their small size, solid-state toughness and high cycle tolerance.
Going Forward: Applications Recommendations
Concepts of Application
The following recommendations are
Targeted lighting solves the problem of
based on what was found so far:
unwanted shadows and bathing large areas in light. ▼
○ Consider light pollution and Dark Sky clients. Put light exactly where it is needed. ○ Develop a distributed lighting system. As such, it should be scalable and flexible. ○ There are many LED retrofit solutions already. Make a departure from the past. It’s been done. ○ Leverage LED technology’s strengths. Be sensitive to LEDs’ requirements. ○ Make it serviceable. Also, demarcate the LED itself from the system to minimize waste from replacement & upgrades. ○ Because it is a public product, address vandalism & tampering concerns.
By exploring possible applications (below and facing page), additional requirements were uncovered, such as physical size, and the need to get power to the fixtures.
◄ The
fixtures’
small
profiles are concealed in the storefront’s features. The desired effect is light, without the visual clutter of lighting. ◄ Area, rather than point sources are easier on the eyes.
A
resort
is
an
ideal
setting for a large-scale deployment. Long-wave (reddish) light attracts fewer bugs and helps preserve night vision. ►
Early Concepts Lots of Small Bulbs and Breadboards ▼ Breadboard connector, + LED
The use of many small bulbs and breadboard technology was applied to serviceable wall-mount lighting and portable lighting stands. ▼ ►
▼ Proposed breadboard-inspired LED circuit
Fewer High-Output Bulbs The use of high-output LEDs was ultimately more promising. They require heat sinking, but are more efficient. Engineering consultations revealed problems with highly parallel LED configurations, as proposed on the facing page. The project proceeded with highoutput LEDs mounted on extruded or sheet metal bases. â–ź Ideation sketches of LED connectors
â–ź Extrusion profiles and their applications
Preliminary Main Concept Top View of Lighting Assembly
▲ Strings of six LEDs in series are connected in parallel to power lines, which are driven by a regulated power supply. For long runs, multiple power supplies can be spliced into the lines.
LED Clip Two posts on the LED clip pass through circular cutouts on the LED’s integrated heat sink, and then snap-fit into holes in the heat sink plate. LED clips help manage supply lines and secure the jumpers to the LED contacts without solder. ►
Connecting to Power Lines A supply tap links a jumper to a supply line by clasping both wires and piercing their insulation with a single metal insert. ►
â–ź Exploded view of assembly, and application of this concept to a handrail (bottom)
Life Cycle Analysis (LCA) Based on Okala Impact Factors This form of analysis measures the impact of a product by considering the ecological costs of the following: ○ Acquisition of materials (ex. mining) including energy inputs
○ Eco-toxicity of materials (assumed to be eventually released to the environment)
○ Processing of materials (including supply chain transportation costs)
○ Disposal, incineration (or recycling, if possible and likely to occur)
○ Energy inputs during use phase Energy factor depends on the electricity generation profile in the region.
LCA of LED Lighting System The following LCA covers the LEDs, the clips, copper wires, portion of an LED driver, shield, and heat sink for 1 metre of strip lighting, consisting of 6 LEDs, each drawing 2 Watts and running for 100,000 hours. Total lifespan is 22.8 years, assuming the LEDs are on 50% of the time. Below are the Okala points accrued in this 22.8 year period. 20 366 . 25
18 000 ( 88 . 4 %)
2366 . 25 ( 11 . 6 %) Electricity
Material 66 . 25 ( 0 . 33 %)
1840 ( 9 . 03 %) LED Driver Circuits
Further Consideration
460 ( 2 . 26 %) LED Lamps
*
All other materials and processing impacts
○ Solar power would require batteries, but it reduces the electricity impact by 75%. ○ Almost all of the material impacts come from electronic components, particularly the driver circuits. Economy of scale may help, i.e. using large centralized DC sources instead of the commercially available 50~100 W units used in this analysis. ○ Replacing LEDs as they gain efficiency will reduce the electricity impact over time.
User Testing Focus on Serviceability Five
electricians
maintenance
from
department
the at
Carleton University agreed to perform simulated servicing tasks and provide comments.
First, they were introduced to my project, prototypes of the parts, and the objective of making it serviceable. They were also given a briefing on how the LEDs would be wired.
They were asked to assemble four LEDs to the clips, then mount them on a heat sink. I mounted one LED first. They were also given a pop-quiz, which involved depicting the wiring on paper.
Quiz completed by participant â–ş
Positive Feedback
Negative Feedback
○ They appreciated not needing tools
○ Small size of parts, difficult to manipulate
○ Installation and servicing tasks seemed like they would be easy
○ Ambiguity of fit (backwards install
(Prototype tolerances were a bit low,
possible)
occasionally affecting the experience) ○ Tendency to forcefully pinch the clip ○ Low skill requirement
where the delicate wire clasps are
○ Straightforward circuitry ○ Safe system to work on
Other Insights With low voltages involved, electrical connections may be weak, especially outdoors. Corrosion could be a serious problem if not properly sealed or enclosed. However, the use of pierce technology was accepted, since it is used in the automotive industry. This prompted a focus on controlling the environment surrounding the electronics. Ultimately an extrusion solution was developed. It also brought the project much closer to being a complete field-ready product.
Design Consultation Almag Aluminum, Brampton ON â–ź I gave depictions and explanations of design intent for my aluminum extrusion. FOR SHAWN COMFORT | Director, New Business Development ALMAG ALUMINUM This is a housing for highpower LED arrays, providing shelter, heat-sinking, wire management and fastenability to various surfaces. A model of a Luxeon LED is shown in place. The housing snap-fits to brackets (blue) designed for wall-mounting. Other such brackets could be designed for round surfaces like railings.
Removal would be done by prying with a screwdriver. Removal should not be possible by simply pulling on the housing.
#4 machine screw taps here Wire mgmt. Lens / Shield
light block end cap fastening feature, possibly another #4 screw
heat sink area
Actual size (LED included). ▼ Wall thickness is .06” TYP.
By sharing my design intent and concerns with an extrusion expert, the profile was improved.
Concerns: ○ Weatherproof (lens to extrusion) ○ Weatherproof (extrusion to end caps) ○ Would screws inflict a wedging force, causing the outermost regions to tip away? ○ Should the profile have a hollow in it? ○ How flexible is this extrusion? (mounting on curved surfaces)
serrated groove hidden end cap boss improved interface to wall mount
Finished Product
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Benefits Light fixtures can be made to virtually any length. LED spacing is also fully adjustable. Fixtures can be repaired or customized on or off site. Materials are identifiable, and separable for easy recycling.
DRAWING NUMBER Sheet of DRAWING
◄ Technical drawing
11" x 17" DIMENSIONS UNTOLERANCED DIMENSIONS UNTOLERANCED ANGLES
Date
1
3
5
4
2
6
Initials
Issue
Revisions
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1 Slot for light shield 2 Wire mgmt, supply 3 Self-tap LED screws, also wire mgmt between LEDS 4 Light blocker (optional) 5 End cap screw 7 Snap fit to wall-mount extrusion
▼ Tamper-proof screws to restrict access
Matl: 6063 T6 2
Quantity
Details
0.419 in 0.495 lb/ft Number
▲ Neoprene end cap with feed-thru wiring
6 Heat sink features
Description
▲ Profile view of assembly
SCHOOL OF INDUSTRIAL DESIGN
CARLETON UNIVERSITY COLONELBY DRIVE OTTAWA CANADA K1S 5B6 DRAWN DATE CHECKED DATE CLIENT PROJECT DRAWING NUMBER Sheet of DRAWING
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R.010 TYP outside corners .032 1.806 Note: CCD is 1.822 SCALE 2:1
Thank you for reviewing my work.
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