June 2014

With LEDs at the forefront of energy efficient lighting trends, it was only a matter of time before their organic counterparts gained momentum.

Organic Light Emitting Diodes (OLEDs) are already being used in television sets and in automobile taillights, but they are gaining more traction as they are light, flexible and provide warm and even illumination.

“Within the same LED family, Organic LED, which are light emitting panels made from organic carbon based materials that emit light when electricity is applied seem to have received some attention from the lighting industry lately,” said Kevin Dinh, a partner at Light Box Studio. “The technology has been popular in the TV and handheld device industry but not so much in lighting.”

“As OLED panels can be made flexible or transparent, they can open a whole new world of luminary design and applications to be seen in the new future.”

LG Chem had unveiled the world’s largest OLED lighting panel

While there are not extensive differences between LED lights and OLEDs, the latter come are built as extremely thin and small panels, which makes them more versatile.

Last year, IDD Aerospace/Zodiac Lighting Solutions announced it would design an OLED lighting prototype for aircraft interiors which could lower fuel consumption, carbon emissions and energy costs.

Its “extremely thin, lightweight utility light design” make it ideal for aircraft and for small urban spaces by requiring little space.

LG Chem OLED table lamp

Phillips has conducted research that reveals how electricity passes through the one or more organic semi-conductive layers in OLEDs.

“These layers are sandwiched between a negatively charged layer of aluminium, and a positively charged, transparent layer of indium tin oxide,” Phillips’ website reads.

“The whole ‘sandwich’ is attached to a sheet of glass or other transparent material, known as a ‘substrate.’ When current is applied to the aluminium layer, it is conducted to the positive layer through the organic film. As the current passes through the film, the film emits light. Different materials in the films emit different colour light.”

Last month, LG Chem unveiled the world’s largest OLED light panel and its own OLED Table Lamp at Light + Building 2014 exhibition.

According to LG Chem, OLED offers illumination that mirrors natural light more closely than other artificial lighting forms. The company added that OLED’s spectral power distributions allow people to feel “emotionally comfortable” within the light.

Andy Zhou’s OLED Plus Pendant

LG Chem’s table lamp is the first product of its kind to utilise a curved OLED panel as a light source, with the panel but a millimetre thick. It provides no glare or shadow and, unlike LEDs, produces very little heat (below 35 degrees Celsius).

It can be remotely controlled with a compatible smartphone or tablet using the LG lighting control app. The light can last up to 40,000 hours, with LG hoping to increase this to 60,000 hours by 2016.

This year, Australian designer Andy Zhou unveiled her OLED Plus Pendant, a luminary  that combines a series of flexible OLED panels that move to create illumination that ranges from an area light to a spotlight. This is enabled through the use of magnets and tensile wiring mechanisms, and is designed to demonstrate the capability of the technology.

OLED Application in a retail environment

“It uses 36 rigid OLED panels to emulate future capabilities of organic technology such as its razor thin profile and flexibility,” Zhou says on her website.

The project was supported by Australia’s national research agency CSIRO and was constructed with environmental ethics in mind.

Timber components that make up the suspended column of the light are from “century-old recycled timber” sourced from the original Princes Pier in Port Melbourne, Australia, while Zhou notes “the fabric cover is manufactured by a process called 3D CNC Knitting…This process uses white polyester and grey wool thread to create a seamless textile in a single piece.”

OLED lighting could be the next big thing in energy efficient lighting. This makes for an exciting prospect for architects and designers seeking a more flexible application for their luminaries and small installation spaces.

LED lighting is booming in popularity, and stands as one of the fastest developing technologies in the lighting sector.

There are limitations to LEDs, however, including their thermal properties, expensive production and costly maintenance.

Kevin Dinh, a partner at boutique light firm Light-Box Studio in Melbourne, has noticed a strong trend toward LED lights.

“LED seems to be the magic word associated with energy saving and long lasting lamp life at the moment,” he said.

He noted, however, that architects and designers need to be diligent with their light sources, with three options standing out.

1. Linear Fluorescent Lighting 

Linear fluorescent lighting still remains the ideal choice for commercial applications and workplaces.

“There are other electric lighting technologies that are, we believe, still relevant and still have their own use in certain applications,” Dihn said. “For example, linear fluorescent light is still energy efficient and effective in office and task lighting applications; metal halide is still usable in large area lighting and road lighting.”

“Long life linear fluorescent lamps with rated lamp life up to 50,000 hours for T5 and 80,000 hours for T8 can also be a cost effective and considerable option.”

Linear fluorescent lights remain best for offices

An interview debate conducted last year by Cundall, an international multi-disciplinary consultancy saw two light experts battle out the question: Are LED luminaries ready to replace fluroescents in office applications?

Peter Raynham of the Bartlett School of Graduate Studies and the Society of Light and Lighting said LEDs are expensive to produce and maintain.

“The fact that LEDs are expensive and difficult to make is perhaps just a reflection of where we are in the current state of LED technology; it is likely that, in future, LEDs will be both easier and cheaper to make,” he said. “This will solve a lot of problems but, for the present, my feeling is that they do not quite have the edge on linear fluorescent lamps when it comes to office lighting.”

2. Daylighting

Daylighting works to complement circadian rhythms

In recent years, architects have been opening building envelopes through atria, skylights and floor to ceiling windows, allowing natural light to flow inside and minimising the need for artificial lighting.

“Daylight can be harvested in a numbers of ways such as directly through glazed windows/ façades, atriums, light wells or through the use of light shelves, solar tubes, and solar reflective mirrors to redirect into the internal spaces,” Dinh said.

Daylighting also provides heat in cold weather, though in summer, glazed windows and curtain walls may be required to keep temperatures down.

Along with energy savings, natural daylight has also been linked to improving human health and well-being.

According to Ali Sayigh’s 2013 book, Sustainability, Energy and Architecture: Case Studies in Realising Green, “natural changes in daylight synchronise and reinforce the body’s circadian rhythms, which help determine sleeping and eating patterns, brain wave activity and hormone secretion to affect a cascade of responses throughout the human body.”

Saffron’s Drift Light mimics sunset

Sayigh notes that “optimised daylighting increases the quality, economy and sustainability of buildings” and that horizontal skylights are the most efficient for daylighting “because they face the full sky’s hemisphere of 180 degrees receiving relatively high luminance from its zenity.”

3. Circadium Rhythm Electric Lights

“Circadian rhythm electric lights, which change colour temperature according to time of the day to mimic the natural daylight cycle (cooler, bluish in the morning, warmer in the afternoon, and cool white at twilight), have also been considered,” Dinh said. “Studies have shown that (these lights) can be used to aid sleep/wake cycle in nursing homes and hospitals or improve concentration in education facilities or be beneficial to areas where access to natural daylight is limited.”

The Drift Light, a self dimming light bulb, was designed to mimic the natural daily occurrence of sunset while “promot(ing) relaxation and an increase in melatonin.”

It moves away from the “bluer” light commonly associated with LEDs, which has been linked to surpressing melatonin.

Daylighting is best for the environment

A 2013 case study by the University of North Carolina entitled The Visibility of Research highlights the benefits of mimicking a natural environment for a building inhabitants. Doing so can lessen symptoms of dementia in the elderly, help patients concentrate and improve sleeping patterns.

“Maintaining circadian rhythmicity in a postindustrial society is becoming increasingly difficult for a culture that spends a disproportionate amount of time indoors in artificially illuminated environments facing electronic screens that largely emit light in the blue spectrum,” the report states.

Modern architecture and design projects continue to deem energy reduction a top priority, and LED lighting is one of the core elements used to accomplish this goal.

The market for halogen and incandescent light bulbs has dimmed, with LED lighting taking their place due to its energy efficient nature.

Thel movement has been recognised by environmental groups, industry members and even governments, many of which are now implementing policies to formalise the use of LED lighting.

Kevin Dinh, partner at Light-Box Studio

When considering its application in a commercial setting, it is crucial that LED lighting design contributes both practically and environmentally.

In offices, lighting is required to support productivity, be kind to human eyes and be automated for flexible working hours. In a retail environment, lighting is used to highlight point of sale items and encourage customers in store, while hotel use lighting to create guest room ambiance.

Before architects and designers instantly seek LED lighting for their next project, however, there are plenty of benefits and limitations they may not be aware of.

Kevin Dinh, partner at Light Box Studio in Melbourne, a boutique lighting design firm providing architectural lighting design review and assessment, has worked with his team on an array of projects, including the lighting design of 41X, the new Australian Institute of Architects Building in Melbourne.

Lighting design at AIA 41X building

In recent years, Dinh has noticed a steady increase in clients requesting LED lighting, saying the technological improvements to LED have been “tremendous.” He attributes the appeal of LED lighting to its flexibility – it can be used indoors and out – along with its “efficiency and effectiveness” compared to other lighting sources.

“We have also seen many manufacturers focussing a large portion of their research and development on LED technology and luminaire development with some even phasing out other light sources all together,” he said.

Despite LED lighting’s growing popularity, Dinh noted several technical parameters that designers and users should be aware of before making their lighting decision.

Luminous efficacy

Luminous Efficacy – how well a light source produces visible light

“Luminous efficacy indicates how efficiently a light source can produce visible light,” he said. “Currently, white LED can produce up to 130 lumens per watt which outshines the linear fluorescent technology at around 100 lumens per watt and certainly is a big improvement from the once popular halogen light source at around 20 lumens per watt.”

“LED efficacy continues to improve substantially. We can either have the same LED lumen package for less energy consumption or have the same energy consumption with much more light generated from the newer chips.”

Colour Rendering Index (CRI)

Colour Rendering Index

CRI denotes the ability or a light source to reveal the colour of an object it is illuminating. The maximum CRI value is 100.

“This is particularly important in applications where colour matching is required (e.g. dental labs, paint shops, etc.) or merchandise display (e.g. retail shops),” Dinh said. “CRI80+ for LED has become the norm in the industry while CRI90+ has become readily available and CRI100 is not far behind.”

Thermal Management

Designers need to consider optical control and glare reduction

Dinh says heat is LED lighting’s biggest limitation.

“Overheating is one of the main reasons for light output reduction and premature failure. This generally happens when the ambient temperature exceeds the manufacturer’s recommendation of +40 to +55. Better thermal management means improved lamp life and luminous efficacy, which is the main focus of many researches,” Dinh said.

A 2014 study on the Effect of LED lighting on the cooling and heating loads in office buildings found that while LED lighting has the potential to provide energy savings, 75 to 85 per cent of the light electric power in LED lights is still generated at heat levels which could in turn have a negative effect on the cooling load.

Glare

Glare is another issue Dinh has come across.

The small-scale design of LED chips allows them to fit into an array of lights, offering flexible application. There is, however, a drawback.

“With so much visible light produced from a small surface area, they can produce obtrusive glare,” Dinh said. “Optical control and glare reduction are important considerations. We find that concealed LEDs rather than LEDs close to the surface tend to address this issue.”

Colour control

Colour control is a limitation to LED lighting

“Another issue with LED technology is colour control and colour variations in the light output, especially in white LEDs,” said Dinh. “White LEDs generally comprise blue LEDs and a yellow phosphor coating. The colour output depends largely on the phosphor components.”

Dinh referred to MacAdam Ellipses – an industry term used to describe colour variations in terms of perception of LEDs produced by the same manufacturer.

“Some manufacturers choose to follow an international standard of seven step MacAdam at +/- 3500 Kelvin. However, there are manufacturers who don’t recognise this standard,” he said. “It’s important to note that the higher MacAdam step, the greater the variance in LEDs’ light output colour from one to another, making a constant colour surface. Some higher quality LEDs are manufactured to 2-3 step MacAdam, which means a more consistent in colour appearance to the naked eye.”

Cost

The Indigo Hotel in Shanghai demonstrates LED lighting design

While LED lighting can offer savings of up to 80 per cent on energy costs and require less maintenance, their replacement costs remain a significant limitation. LEDs cost more to replace compared to other light sources and in some cases, an entire luminaire (LED lamp and housing) needs to be replaced once the LED has reached its end of life or failed.”

“In certain applications, once examined over a long period of time, say 100,000 hours, taking into account capital costs, lamp replacement costs and energy consumption savings, an LED light source still struggles to be more cost effective than other light sources,” Dinh said.

All things considered, LED lighting remains a developing technology, though Dinh predicts it will continue to dominate the lighting market, particularly once some of its limitations are addressed.

“We will see the energy efficiency improves further with even higher efficacy, increased CRI and better thermal control,” he said. “With mass productions and the competitive market, the price will be even more affordable which will see a further growth in applications and projects. We have seen an increase in LED panels with opal diffuser on the market to combat the glare issue, making them a considerable option for office lighting. These panels’ prices have dropped significantly to be almost on par with the traditional linear fluorescent option. This might be the next trend in office lighting.”