Is all the hype surrounding LED justified?
- Published: Wednesday, 05 September 2012 07:57
Aurora’s technical trainer and sales development manager Paul Davidson takes a holistic look at LED and gives a straightforward manufacturer’s account of what the benefits are and how this technology can be best employed.
Firstly, what is an LED?
Answer: a Light (visible radiation) Emitting (to give off) Diode (an electrical device that passes current in one direction). LED is dramatically changing the lighting market by delivering technical lighting solutions that only a short time ago would have been thought inconceivable. This tiny semi-conductor light source has become the principal solution for accent and architectural lighting; when combined with utilising control systems, LED can be considered the greatest development in illumination since the incandescent lamp.
So, why has LED emerged as the definitive lighting solution?
Solid state lighting technology is on an exponential drive of development. The amount of light being produced is increasing at a rate of 2,000% over each decade, while the cost of producing that light reduces by 90% over the same ten year period.
Time has proved these figures to be accurate but there is still a reluctance to embrace LED as the solution for all lighting needs. Lack of adoption could relate to factors such as high installation cost, thermal management, consistency of colour across different lamps/luminaires, etc. But what is the alternative?
Compact and linear fluorescent lamps, while certainly more cost effective as an initial installation, face three issues: low outputs during run-up times and certain limitations on using sophisticated lighting control over short operating periods that will minimise energy usage. They also have higher on-going maintenance costs that will increase the life cost of any installation.
So is LED the one-stop solution for lighting applications?
Compared with previously developed light sources, LED has many benefits. They have an extended lamp life and require little on-going maintenance. There’s also a choice of white and coloured sources for different applications, an insensitivity to vibration, and the promise of light with virtually no Infra-red or Ultra-violet radiation. In addition, LEDs are of a compact design that provides instant and flicker free lighting. However, the main benefit must be considered to be energy efficiency leading to high lighting efficacy.
LED can be designed into virtually all lighting applications including hotel and leisure, retail outlets, museums and art galleries, the health sector, education establishments and commercial premises of all types. It is also an ideal light source for emergency lighting as its low operating wattage requires lower charging loads to maintain a healthy system.
In studying the commercial application, zones within a building generally fall into a number of groups comprising entrance and features, transit and amenity, break-out areas, person interaction, individual offices, group offices, open-plan offices and prestige offices.
Each of these spaces could require a different approach, but one constant remains in that LED lighting can provide an ideal solution for all spaces.
So what do we need to take into account?
Of prime consideration is the efficiency of the luminaire. Conventional light source fittings typically use omni-directional lamps. This means that the light source produces illumination in all directions and it is the luminaire that provides the focus for the light in a given direction. The efficiency of such fittings is always less than 100% because a proportion of the light produced by the source is lost within the luminaire.
LED is totally different in that the light has focus at source and can be considered to be 100% efficient. This means that an LED with a lower lumen output than its equivalent conventional light source can provide either the same or greater levels of illumination and with a lower power consumption.
The opportunity to control LED luminaires is also significant. Unlike compact and linear fluorescent light sources that require warm up periods, LED switches on at full brightness and provides full illumination instantly. There is no restriction on having the light source illuminated for a set period, nor on the number of switching procedures for the LED source. This makes it an ideal light source for areas where multiple switching and short-duration lighting is required. It is also ideal for applications where dimming is required to aid energy conservation.
Typically in excess of 30,000 hours, the lamp life of an LED is significantly greater than that of a conventional light source and has the added benefit that during the life of the installation, LED requires little or no maintenance.
So which LED technologies are available for commercial applications?
Currently, the most common solutions for office lighting applications are recessed linear or compact fluorescent fittings because they fit easily within suspended ceiling installations and offer a ‘clean’ finish.
LED lighting panels offer a beneficial alternative to the fluorescent fitting in many ways, from the low height allowing installation into reduced depth ceiling voids to the low glare illumination and energy saving benefits. Typically, the power consumption of a standard fitting is around 60Watts and because many LED Panels are around 44Watts, they offer energy savings of 25-30%. While this may not be considered significant, recent developments in chip manufacture have now resulted in light panels achieving an output performance close to 3,500 Lumens; when you consider that this figure is at 100% efficiency, their performance is certainly equal to, and in many cases in excess of, that of conventional light sources.
Energy consumption needs to be considered in every application to include daylight and occupant sensing as well as dimming. LED panels offer a light source that can meet all of those parameters.
LED panels can provide one further benefit that is not easily achieved in conventional fluorescent options. Through Colour Temperature Adjustment (CTA) it is possible to not only vary the amount of light produced but also vary the colour of that light from a warm 2700K through to a cold 6500K. CTA allows for the lighting to be controlled not only to meet the energy saving benefits of power consumption, but also to provide aesthetic harmonisation with the body clocks of the occupants.
It is well known that there is a third non-visual receptor in the eye that controls the person’s well-being. So providing blue-enriched white light at certain times of the day improves self-reported alertness and performance. Equally, evidence shows that providing a warmer illuminated environment at the end of the day will offer relaxation and assist a better sleep pattern, which allows staff to be fully refreshed for the next day.
LED luminaires offer a 100% efficient replacement for compact fluorescent downlights in transit and amenity areas where building owners and operators tend to control the lighting using PIR controls. It is generally accepted that after activation CFLs are left switched on for a period of 15 minutes to allow the lamp to achieve full output before switch off. So to deliver lighting for five minutes, the lamp is illuminated for 20 minutes – in other words, 75% of lamp life and energy is wasted. With LED you need only five minutes of energy and lamp life. Other savings include a lower wattage and power consumption, which could mount up to over 80% for the same amount of light.
For single occupancy offices and person interaction areas where lighting is usually controlled by the users, there’s a tendency to switch the lighting on at the start of the day and leave it on for the duration. Multiple switching of fluorescent in spaces where there are many periods of occupancy and non-occupancy throughout the day is not recommended. However, LED provides an ideal solution as lighting would only be required during the periods of occupancy and where the daylight factor was low and could not provide adequate natural illumination.
For other areas such as breakout zones, the lighting is usually left switched on due to the constant movement of personnel through the space. By utilising LED as the light source, both the benefits of energy saving and reduced full-life maintenance could be achieved.
What does all this mean for the average building owner or operator?
Put simply, LED now provides a credible alternative to conventional light sources as it can provide illumination levels without the need for an increased number of luminaires.
Yes, there is a cost implication because LED is a more expensive installation, but payback through energy efficiency and reduced maintenance can be realised over the short to medium term.
You might justifiably ask whether it would be worth waiting for more advances in LED technology to achieve even lower energy consumption. The answer is, of course, Yes. But there will be a waiting cost which is the amount not being saved during the period of consideration and waiting. This will very quickly reach a point where it is more advantageous to get on with the installation rather than wait for the next development. LED will continue to evolve and if you, as the client, are waiting for the definitive solution, the installation will never happen.
Finally, what can lighting manufacturers do to assist electrical contractors in offering these solutions to their clients?
Working in partnership with a reputable lighting manufacturer who fully understands LED through your electrical wholesale distributor will give you access to the technical information required to offer a client this solution. Providing a lighting design that fully meets the client’s expectations in providing illumination and reduced energy costs is the first step.
The second considers not just the cost of energy but also the cost of ongoing maintenance, the cost of conventional lamp replacement, the cost in man-hours of the work and the parasitic cost of charging emergency fluorescent lighting against LED. The opportunity to provide true life cycle costing and return on investment (ROI) rather than just a simple energy calculation will allow the financial benefits of the proposal to be considered and fully realised.
Having a comprehensive design and financial benefits package supplied and supported by a quality lighting manufacturer can make the difference in winning the project.
So is all the hype justified?
The answer must be a resounding ‘Yes’, as LED development is moving forward at a rapid pace. It’s estimated that more than half of lighting applications will be LED driven in just five years from now, making it, arguably, the greatest development in lighting since the incandescent lamp. The time to embrace LED is now!
Paul Davidson is technical trainer and sales development manager for Aurora. He joined the company in autumn 2011 and is currently expanding the technical knowledge of Aurora employees through a series of training presentations. His brief is also to enhance customers’ own professional development through a formal CPD programme.
Paul continues to develop the Aurora portfolio in the commercial lighting sector. With over 25 years’ experience in the lighting industry, he holds the CIBSE Lighting Diploma and is a member of the Society of Light & Lighting. His background includes lighting consultancy, manufacturing and the distribution channel. This article first appeared in the ECN.