LEDs are the answer, now what’s the question? · 2015. 11. 23. · BS 7920:2005 Luminance meters....
Transcript of LEDs are the answer, now what’s the question? · 2015. 11. 23. · BS 7920:2005 Luminance meters....
LEDs are the answer, now what’s
the question?
20th February 2014
James Duff Arup Lighting & Dublin Institute of Technology
Dr. Kevin Kelly Dublin Institute of Technology
15 Ways to save energy with lighting and only one is LED
- SLL Code changing the emphasis for lighting designers
- Lighting Controls & LENI (EN 15193)
• Recommendations, SLL Code for Lighting 2012
- lighting to perform the task efficiently and accurately
• SLL code for Lighting - Quantitative
• Target lighting more carefully
• Qualitative aspects - Cylindrical illuminance for example
SLL code for lighting
Major change happening in lamp technology
- Solid state lamp technology
- Collateral damage-
Philips Lighting (2012) - 6% of lighting was solid state in 2010 – 75% by 2020
McKinsey - LED lighting - a 65billion Euro industry by 2020
At present biggest applications of LED lighting is for :
- stage, external lighting, architectural lighting, retail, cold rooms, transport and
hospitality.
LED lamp technology is expected to impact upon office and general lighting in more
interiors in the future but expensive to install at present
More research needed – Post Occupancy Evaluations
LED
LED lighting focused on the task
One kettle load
• OLEDs an emissive electroluminescent layer
• Emit light in response to an electric current
• Diffuse soft light
• Predicted efficacy - 35 lumens/watt to 130 in next 6 years
• Applications in diffuse soft lighting and architectural
applications
OLEDs
Critical Review of LEDS and
How to Specify them
A Radical rethink about
Lighting Design
• A large number of ceiling
luminaires providing a uniform
horizontal illuminance over the
working plane in a Drawing
Office.
• “shadow free” lighting
• Bland uninteresting lighting
scheme?
• 750 Lux????
60’s design
Visual demands have changed
Better quality required
Lower energy usage
Changing needs to present
• Glare, contrast
• Luminance rather than illuminance – Exitance?
• Reflectance
• Colour Rendering
• Colour Temperature
• Modelling – cross vector of light (Higher Reflectance)
• Cylindrical Illuminance
• Variety, sparkle, visual stimulation, focus
• Highlighting of Texture and more nuanced
• Local Control & local needs
- Lifting the Spirit!
Qualitative aspects
Compare?
Daylight quantified
10,000 lux for 70% of
working day
5000 lux for 85% of
working day
If DF = 5% average?
* Mardalevic research
argues for change
Daylight factor
Reducing Power
Maximise efficiency of luminaire
(UF)
Use highest efficacy lamp
acceptable
Dim for:
- Daylight
- Early stage of MF cycle
Reducing Time Used
Dedicated Control Systems
Switch Off
- Occupancy sensors
- Timers
- Photocells
- Manually
To reduce energy requires a reduction in power and / or time used
Doyle Research SDAR*
http://arrow.dit.ie/sdar/
Other issues
• Part L?????
• Targets set by EN 15193 with respect to LENI are modest
• Good quality LENI will aid lighting designers to move away from
installed load benchmarks to more meaningful consumption targets
• Particularly beneficial in buildings where daylight penetration is high
or intermittent occupation of the building
Lighting energy numeric indicator (LENI)
BIM
Input needed by; architect, structural engineer,
surveyor, heating and ventilation engineer,
electrical engineer, lighting designer,
interior designer, control systems engineer
Modern Building Information Modelling (BIM)
software facilitates this holistic,
multidisciplinary interaction
Holistic Approach
Modern approaches are essential
• Exciting and challenging time for lighting with huge growth potential for
LED lighting and improved controls performance linked to better informed
holistic building design.
• Challenged to provide robust solutions that satisfy clients and maximise the
benefits of new technologies – evaluation (research)
• Appropriate combined daylight and artificial light in a way that lifts the spirit
and minimises overall energy use
• Override automatic lighting controls when required – keep users satisfied
Summary
How do we design light?
Source Standard
ISO ISO 23539:2005 Photometry. The CIE system of physical photometry
ISO 15469:2004 Spatial distribution of daylight — CIE standard general sky
CEN EN 12193:2007 Light and lighting. Sports lighting
EN 12464-1:2011 Light and lighting. Lighting of work places. Indoor work places
EN 12464-2:2007 Lighting of work places. Outdoor work places
EN 12665:2011 Light and lighting. Basic terms and criteria for specifying lighting requirement
EN 13032-1:2004 Light and lighting. Measurement and presentation of photometric data of
lamps and luminaires. Measurement and file format
EN 13032-2:2004 Light and lighting. Measurement and presentation of photometric data of
lamps and luminaires. Presentation of data for indoor and outdoor work places
EN 15193:2007 Energy performance of buildings. Energy requirements for lighting
EN 13201-2:2003 Road lighting. Performance requirements
EN 13201-3:2003 Road lighting. Calculation of performance
EN 13201-4:2003 Road lighting. Methods of measuring lighting performance
BSI BS 667:2005 Illuminance meters. Requirements and test methods
BS 7920:2005 Luminance meters. Requirements and test methods
BS 8206-2:2008 Lighting for buildings. Code of practice for daylighting
BS 4589-1:2013 Code of practice for the design of road lighting Part 1: Lighting of roads and
public amenity areas
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Guidance documents?
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Recent additions to Code for Lighting
• Increased room surface reflectances
• Minimum illuminance on room surfaces
• Definition of task, surrounding and background areas
• Cylindrical illuminance
• Modelling index
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Increased room surface reflectances
Usually a parameter that is outside of our control, but..
2009 SLL Code (%) 2012 SLL Code (%)
Ceiling 60 – 90 70 – 90
Walls 30 – 80 50 – 80
Working Plane 20 – 60 Not specified
Floor 10 – 50 20 – 40
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Illuminance on room surfaces
Illuminance in enclosed spaces
Walls Em > 50 lux with Uo ≥ 0.10
Ceiling Em > 30 lux with Uo ≥ 0.10
Illuminance in enclosed spaces where visual communication is important
Walls Em > 75 lux with Uo ≥ 0.10
Ceiling Em > 50 lux with Uo ≥ 0.10
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Task, immediate surrounding and background areas
No longer a reference to a working plane
Instead, schedules of illuminance are given for the task area
Illuminance in the immediate surrounding area and the background area are then derived from this
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Task, immediate surrounding and background areas
Ratio between illuminance on the task area, the illuminance in the
immediate surround area and the background area
Task area Immediate surrounding area Background area
>750 500
33% of the immediate
surrounding area
500 300
300 200
200 Etask
150 Etask
100 Etask
>50 Etask
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Cylindrical illuminance
The luminous flux falling on the curved surface of a very small cylinder, divided by the curved surface area of the cylinder
Required to highlight objects, reveal texture and improve the appearance of people within spaces
Standard areas Areas where visual communication is important
> 50 lux with Uo ≥ 0.10 > 150 lux with Uo ≥ 0.10
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Modelling & modelling index
Modelling is the balance between direct light and diffuse light
Modelling index provides an indicator of good modelling and is defined as the ratio of cylindrical illuminance to horizontal illuminance at a point
Recommended to be between 0.3 – 0.6
Standards - The recipe for good quality lighting?
Right?
What is lighting quality?
Defining lighting quality is not easy. A number of approaches
have been suggested
• Single number indices
• Holistic design based on light patterns
• Lighting necessary for good performance, health and
behaviour
• Lighting that allows us to discriminate colour, form, texture
and surfaces without discomfort
What is lighting quality?
Despite these attempts the most universal definition remains the
extent to which the lighting meets the objectives and constraints
set by the client and the designer
These can include meeting all relevant regulations, enhancing
performance, ensuring visual comfort, creating the right
impression, generating the desired behavior, meeting budget and
energy costs
Disappointing?
There are three arguments in favour of this definition
• Lighting is a means to an end not an end in itself
• What is desirable lighting depends on context
• There are many physical and psychological processes that
influence the perception of lighting quality. It is this variability
that makes a single, universal photometric recipe for good
quality lighting an unreal expectation
A simple classification of lighting quality
Lighting installations can be divided into three classes
• Bad lighting does not allow you to see what you need to see,
quickly and easily, and/or causes visual discomfort
• Indifferent lighting does allow you to see what you need to
see, quickly and easily, and does not cause visual discomfort,
but does nothing to lift the spirit
• Good lighting does allow you to see what you need to see,
quickly and easily, does not cause visual discomfort and does
raise the spirit
Bad quality lighting
Bad lighting can be achieved:
• By ignoring authoritative
guidance
• By giving undo emphasis
to a single lighting
criterion
• By thinking energy
efficient lighting is, by
definition, good lighting
Indifferent quality lighting
Indifferent lighting can be
achieved:
• By following authoritative
recommendations
• By giving undo emphasis to
quantitative advice and
ignoring qualitative
guidance
• By acting without thought,
or experience
Good quality lighting
Good lighting can be achieved:
• By following authoritative
recommendations, where
applicable
• By paying attention to
context and fashion
• By integrating lighting with
the architecture
• By acting with thought
What distinguishes good lighting from indifferent
lighting?
• Attention to context, fashion and opportunity
• At the moment, good quality lighting most frequently occurs at
the conjunction of a talented architect and a creative lighting
designer, neither of which are slavish followers of numerical
lighting criteria
• Numerical lighting criteria should act as a floor not a ceiling
Good quality lighting for all?
At present, access to a creative lighting designer is limited to a
few. How might good quality lighting be provided for many
more?
There are four possible approaches
• Develop more lighting criteria
• Make more use of daylight
• Give every one individual control of lighting
• Change the basis of design from the task to the space
Develop More Lighting Criteria?
This is unlikely to be a success as numerical criteria inhibit
innovation and their underlying purpose is to stop indifferent
quality lighting slipping back into bad quality lighting
Make More Use of Daylight
Attractive lighting has two
independent dimensions:
Brightness and Interest
Daylight through windows
provides variable and
meaningful changes in the
lighting of a space as well as a
view out thereby adding
brightness and interest
Give Every One Individual Control of Lighting
• People like having individual
control of their lighting
• Technology is making
individual control of the
amount, spectrum and
distribution of light much
easier
• But will it lead to chaos?
Change the Basis of Design from the Task to the Space
Develop a lighting design procedure that considers the
appearance of the entire space and not just a task plane
LEDs are the answer!!
The growth of LED
1. Vast quantities of money invested in the technology and it has
seen dramatic improvements in recent years
2. Enthusiasm of regulators who see LED as the ultimate
replacement for incandescent
3. Fashion
The grim reality
The grim reality
The grim reality
The grim reality
The grim reality
A level playing field?
Standard Function
IES LM-79 Tests LED luminaires
IES LM-80 Tests LED modules
IES TM-21 Estimates lumen maintenance
IEC/PAS 62717 Performance requirements for LED modules
IEC/PAS 62722 Performance requirements for LED modules
LED performance criteria
• input power
• luminous flux
• luminaire efficacy
• luminous intensity distribution
• correlated colour temperature (CCT)
• colour rendering index (CRI)
• chromaticity co-ordinate values (initial and maintained)
• lumen maintenance code
• photometric code
LED performance criteria
• life in hours and the associated rated lumen maintenance (Lx)
• failure fraction (Fy)
• ambient temperature (tq)
• power factor and drive current
Colour Rendering Index
Despite its prominence, it has several shortcomings
• White sources are comprised of a mix of wavelengths
• Constituent wavelengths reflected at varying extents
CRI not suitable for estimation of LED colour rendition
capability, but we have no alternative!
Code CRI range Colour rendering properties
6 57 – 66 Poor
7 67 – 76 Moderate
8 77 – 86 Good
9 87 – 100 Excellent
Chromaticity coordinates
Define colour variation, in terms of MacAdam ellipses
Chromaticity coordinates
Initial and maintained colour variation
Size of MacAdam ellipse Colour
variation
category
Initial
Colour
variation
category
Maintained
3-step ellipse 3 3
5-step ellipse 5 5
7-step ellipse 7 7
> 7-step ellipse 7+ 7+
Lumen maintenance
Measure of light output after a minimum of 6,000 hours
Defined in terms of Lxx, where xx denotes a percentage value
Code Lumen maintenance (%)
9 ≥ 90
8 ≥ 80
7 ≥ 70
IEC/PAS photometric code
Code XXX / XXX
Colour rendering index
Initial colour variation
Maintained
luminous flux
Maintained colour variation Correlated colour temperature
Other important parameters
Rated life – Given in hours and in terms of LxxFxx - representing
parametric and catastrophic failure rates
Ambient temperature – Higher ambient temperatures will
decrease efficacy and shorten LED life
Drive current – higher drive currents will increase lumen output,
decrease efficacy and shorten LED lfie
Believe manufacturer data?
Whilst all the standards mentioned previously offer the prospect
of a level playing field, this information is not yet freely available
on manufacturer product data sheets
Engineers and designers must ask questions!
Questions and acceptable responses
Q Is this LED luminaire tested in accordance with ‘IESNA LM-
79-08, IES Approved Method for the Electrical and
Photometric Measurement of Solid-State Lighting
Products’? If so, please provide a results certificate.
No results cert = impossible to independently compare product
Questions and acceptable responses
Q Are the LEDs within this luminaire tested in accordance with
‘IESNA LM-80-08, IES approved Method: Measuring Lumen
Maintenance of Light Emitting Diode Light Sources’? If so,
please provide a results certificate.
No results cert = impossible to independently compare product
Questions and acceptable responses
Q Is luminaire life extrapolated in accordance with ‘IESNA TM-
21-11, IES Approved Method: Making Useful LED Lifetime
Projections’? If it is not, is it estimated in accordance with any
other standard procedure or extrapolation method?
No results cert = impossible to independently compare product
Ensure life stated alongside Fxx (failure fraction) and be wary
of Bxx and Cxx values
Questions and acceptable responses
Q Is the data in your product specification sheet presented in
accordance with ‘IEC/PAS 62717 Performance requirements,
LED modules for general lighting’ and ‘IEC/PAS 62722
Performance requirements, LED luminaires for general
lighting’?
Yet to find a single manufacturer that will provide all
necessary information upfront on data sheets
Questions and acceptable responses
Q Who supplies the LEDs within your LED luminaires?
Refusal to disclose information is a serious warning sign
Cree, ASM Pacific, Philips, Osram, Epistar / Intermolecular,
Nichia, Xicato, Citizen, Bridgelux, Tridonic and Sharp
This list is far from exhaustive
Questions and acceptable responses
Q State the luminaire photometric code, as defined within
IEC/PAS 62722 and IEC/PAS 62717, where the six digit code
displays the important ‘quality of light’ parameters of an LED
luminaire. It should state initial CRI, initial CCT, initial and
maintained colour variation and lumen depreciation
code. Please provide a lumen depreciation curve.
840 / 339, for example
XXX / 339 has become standard for good quality products
Questions and acceptable responses
Q What is the driver power factor and is the driver replaceable
PF > 0.9
Take care with replaceable drivers
Q What is the total luminaire Wattage, including control gear?
Luminaire Wattage, inclusive of control gear losses
Questions and acceptable responses
Q What is the ambient temperature for which the luminaire
performance is rated? Please provide information on how at
least three ambient temperatures will affect the performance
and life time of the LED luminaire.
Three different temperatures, as required in LM-80
Compare test ambient temperature with the estimated ambient
temperature on project specific basis
Questions and acceptable responses
Q What is the initial luminaire lumen output, for the specified
driver current? If the luminaire is to be driven at a current that
is not the standard, please provide information on how this
will affect luminaire performance and life.
Check luminaire lumen output against information used for
design
Check drive current is same as proposed for use on project
Check drive current is what has been tested within LM-80
Questions and acceptable responses
Q For what length of time is the complete luminaire warrantied
for? Please supply a copy of the warranty.
5 years has become standard with reputable manufacturers
Ensure that warranty clearly states parameters that need to
shift and that it covers all luminaire components – driver,
electronics, housing, modules, etc.
Mock - ups
Examine
Flicker
Dimming capabilities
Colour variation with surrounding sources
Conclusions
Solid state lighting is a new, and rapidly developing, technology
that is difficult to specify correctly
In addition to this, it is an exciting time to be in lighting – the
way we design light is being challenged and constantly evolving