LEDs are the answer, now what’s

the question?

20th February 2014

James Duff Arup Lighting & Dublin Institute of Technology

james.duff@arup.com

Dr. Kevin Kelly Dublin Institute of Technology

kevin.kelly@dit.ie

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

http://arrow.dit.ie/sdar/ Young Lighter 2012

Lighting research at DIT

• 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

22

Guidance documents?

23

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

24

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

25

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

26

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

27

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

28

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

29

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