This is called useful lumens per circuit watt – a widely used term that sounds simple, but turns out to be rather complicated, and can be used by different suppliers to make wildly differing claims.

What is a ‘useful lumen’?
Let’s start breaking it down. Lumens, as mentioned in last month’s column, are determined by what the human eye perceives, and that depends on how the eye responds to light. Efficacy is literally in the eye of the beholder. We determine it by measuring spectral information using a spectrophotometer, or simulating it using a photometer, and converting the result into lumens.

But we’re not just talking about lumens, we’re talking about useful lumens, and whether or not a lumen is useful depends on the context. Lamps and luminaires can be direct or indirect and have characteristics that are directional or non-directional. By classifying the type of directionality we can work towards a meaningful measure of the number of lumens that are ‘useful’ for a directly illuminated task.

The European Union has defined a ‘directional lamp’ as having at least 80 per cent light output within a cone of 120 degrees (defined by a solid angle). Any other lamp is ‘non-directional’.

For a non-directional light source, the useful lumens figure is the total amount of luminous flux coming from the source. For a directional light source it’s a bit more complex. The EU’s latest approach is to promote lamps that have good efficacy for lighting a task, and therefore focus the maximum amount of light into the useful 90-degree cone (defined by a solid angle). The system then measures only the light captured in this 90-degree cone and reports it as useful lumens.

What is a watt?
Now we’ve pinned down useful lumens, let’s talk about watts. Light sources can be battery operated or driven by AC or DC mains power. DC power is particularly efficient when coupled with LED lamps and luminaires, and is becoming more important.

An important consideration for the luminous efficacy calculation is that the correct watts values are used for the product being tested. The efficacy of a self-ballasted lamp will be determined by the total power drawn from the mains supply. That means that the power in watts will include the conversion from high-voltage AC to lower-voltage DC and then to a constant-current driver circuit. Each step has inefficiencies built in which reduce the overall efficacy.

Another lamp may be designed to be purely DC driven, without conversion. An assessment might give the impression that such a DC-powered product is more efficient, but remember that AC power will have been converted to DC power somewhere else down the line (this will become more interesting when homes and buildings start to be powered directly from mains DC supplies). This causes confusion and it is important to check whether product performance figures are derived from a DC or AC supply.

There are many elements that make up solid-state lighting and most of them affect efficacy (see above). As we’ve seen, useful lumens per circuit watt is what we’re really interested in, but some manufacturers may use datasheet values for the LED package, which may not represent the lumens emitted under the conditions in which the source will be used.

The LED package can be tested in a number of ways. The first is the quick screening test performed on the LED, in which a current pulse is applied to the LED and the light output is measured. This is the ‘cold’ lumen test and results in the highest lumen value that can be achieved. The second way is to apply constant DC current to the LED with the case at a temperature that represents the temperature that may be reached inside a lamp or luminaire. The is the ‘hot’ lumen value and is much closer to the value that the LED package will emit in real world conditions.

Specifiers should always make sure that ‘hot’ lumens are used as the starting point for any discussion of luminous efficacy.

Of course most LED lamp or luminaire products have lenses or reflectors on top of the LED. These optics introduce losses and so the number of lumens emitted from the LED will not be the same as the number emitted from the lamp or luminaire.

The driver circuitry will also introduce losses and further lower the efficacy.

So, manufacturers can make a number of different claims, but if specifiers ask the right questions, they should get the right answers. A group of UK lighting bodies has developed guidelines for specification of LED products – bit.ly/ledspecs – and I’ll discuss the questions specifiers should ask about product efficacy in more detail in a future column.

When do you consider power factor?
When using AC power, you may also need to consider a product’s power factor. For a DC-powered device it’s easy: the watts value is the voltage in volts multiplied by the current in amps. But for an AC-powered device, volts and amps are not always in phase, meaning the power will fluctuate. This means you have to calculate the true power in watts by multiplying the volts by the amps at each moment in time and take the average.

The fact that current and voltage may be out of phase means you need to know the maximum volts and amps at any one time. Multiplying these maximum V and A values gives the apparent power (VA), which is also measured in watts.
If the volts and amps are in phase, true power and apparent power will be the same. The power factor is the ratio between the true power and the apparent power – a value between 0 and 1. The higher the number, the closer the true power is to the apparent power.

For LED products, electronic drivers can provide power factor values as low as 0.5 and as high as 0.95. Power factor is becoming more important for specifiers because it affects the total electrical loading of the installation.

So when you want to know how much the electricity is costing you, you use watts. When you are specifying equipment loads, fuses, and wiring sizes you use the VA values, which refer to the maximum current and voltage. When you want to know efficacy, you need to know true power in watts.

LIFE launched this month at Vinopolis, London

LIFE covers all aspects of lighting, including design, installation, energy supply and technical upgrades. For example, Mitie will update LED chips in luminaires to more efficient versions when they become available. Kerry Sheehan, national mobile services director, said: ‘We’re forcing manufacturers to push ahead and develop advanced parts, so it’s not the whole system that has to be replaced.’

So various organisations – including lighting manufacturers and publicly funded bodies – are offering buyers ways to spread the upfront cost, paying gradually as they save on their bills.

Alastair Keir, Salix

Sustainable investment

Although the Carbon Trust is no longer able to offer interest-free loans after government funding was withdrawn, it now runs an Energy Efficiency Financing scheme with Siemens Financial Services to offer loans and equipment leases on favourable terms for energy-efficiency projects. The idea is to invest in projects that save as much or more than the cost of repayments, meaning no capital outlay for the user. The scheme finances projects ranging from £1,000 to millions of pounds.

‘Lighting is the most common category of investment that we advise clients on,’ says Myles McCarthy of the Carbon Trust’s implementation services division. ‘It’s number one across pretty much all sectors in terms of good investment opportunities – that includes hospitality, offices, retail and manufacturing.’

‘By structuring the finance in the right way we can make sure the benefits exceed or match the repayments on the investment. That’s a really compelling sell – although you’re investing in the equipment you don’t need to spend more. Energy prices going up makes it even more compelling.’

Finance, McCarthy says, is one of the key barriers that prevents businesses from investing. Another is simply awareness of the options available to them. and confidence about what technology to invest in.

Access to finance is a ‘key enabler’ for businesses to embark on energy-efficiency projects such as lighting upgrades, McCarthy says. ‘There is competition for financial resources in businesses, and linking energy-savings to cost of their projects and delivering a way to finance that helps projects to be approved and taken forward in business.’

Independent assessments

The Carbon Trust also offers independent energy-saving assessments of projects, allowing customers to invest with confidence. ‘It’s ensuring they’re making the right decision and not locking in inefficiency,’ says McCarthy. But with new lighting, he says, there’s a compelling business case in ‘almost all’ the proposals they see.

And lighting companies are offering financing options independently. UK manufacturer Dali Lighting (which bought the products of Lighthouse Electronics after it went into administration in 2010) is one of the companies seeking to entice customers with a ‘buy now, pay later’ option. Dali is offering to install halogen replacement LED lighting for free, allowing customers to pay over 12 or 18 months as they save money on their bills.

Empowering efficiency

For customers in the public sector, interest-free government-funded loans are available from Salix Finance for energy-efficiency projects that can be shown to pay for themselves in five years or less. Lighting projects have been Salix’s largest area of investment this year, and its loans have allowed numerous public sector organisations to move to more efficient lighting schemes.

Salix provides interest-free loans and match funding to remove the upfront capital barrier faced when investing in energy-efficient technology. It has funded more than 2,500 lighting projects worth more than £50 million, and claims to have saved the taxpayer more than £188 million and prevented the emission of a million tonnes of carbon dioxide.
Salix CEO Alastair Keir says: ‘Our aim is to empower public sector organisations across the UK – from schools and universities to local councils and NHS trusts – to take the lead in tackling the various issues around climate change.’
‘Our clients generally forecast savings of 45 to 60 per cent for high-efficiency electronic ballast lighting upgrades and 60 to 90 per cent for LED installations,’ says Keir.

‘The incorporation of discrete controls such as passive infrared detectors and daylight dimming can increase these savings by a further 10 to 40 per cent. As well as the savings in energy use, clients reap huge financial benefits from reduced maintenance and longer lifespan.’

The narrow-beam projects are threatened

We love you. And your dough balls. The ones you can have as a starter and then again with chocolate as a dessert. We love your pizzas, especially the Diavolo. We love the fact that you donate 5p from every Veneziana pizza to the Venice in Peril Fund.

We don’t love jazz, obviously, but love the fact that you have live musicians in your trendier branches.

We love the fact you don’t sell stuffed crust pizzas. Or chicken tikka masala ones. Because you’re too classy for that.

We aren’t against change. We love the new meatball bolognese pizza. And the new ones with the holes in the middle. We even like the new black and white stripes that you have going on. Very smart, very now.

But Peter. We need to talk. It’s not us, it’s you.

There’s no one else in our lives. Nando’s or GBK cannot replace you. But you have changed. And it’s undermining our relationship. You have changed your lighting.

For 47 years, you had narrow-beam accent lighting cast into the middle of the table from projectors with honeycomb filters. It was your look. It was iconic. Lighting professionals held it up as an example of ‘branding with light’.

Now look at you. With your decorative pendants that scream mid-life crisis. And your vertical illumination (*sobs*).

We can fix this, Peter. So come back to us and bring back the old lighting, and the old Peter.

Yours sincerely,
Lux magazine

GRASS THEM UP
Tell us who we should name and shame next month at shamed@luxmagazine.co.uk

]]> http://www.luxmagazine.co.uk/2012/05/pizza-express/feed/ 0 http://www.luxmagazine.co.uk/2012/05/breakthrough-lamp-hits-all-the-numbers/ http://www.luxmagazine.co.uk/2012/05/breakthrough-lamp-hits-all-the-numbers/#comments Mon, 14 May 2012 14:58:57 +0000 admin http://www.luxmagazine.co.uk/?p=6862 Ray Molony reports]]> Of all the Wrongs Inflicted By The Lighting Industry On An Unsuspecting Public, the halogen lamp with a GU10 base has to be near the top of the list.

When it was launched in 1997 by Sylvania, the mains source was a major technical innovation. Installers loved it, because it obviated the need for a transformer and made lamp and luminaire combinations much cheaper. But a tsunami of poor quality copies followed and the GU10 – as it has been dubbed – rapidly got a bad name.

With the advent of LEDs, the format has been given a new lease of life. But the quality of the LED versions has, for the most part, been deplorable. For a start, many aren’t the same size as the halogen originals, and the ones that are have dismal outputs.

Splodgy and inconsistent

The worst aspect of most LED GU10s in our view is beam quality – they’re splodgy and inconsistent, with green or blue striations at the edges. Ugh!

So when Sylvania, the originator of the format, came to create an LED version of the GU10, the engineers at the company’s labs in Tienen, Belgium, must have felt the pressure of history.

According to tests we have conducted on the new lamp – the Hi-Spot RefLED ES50 – they have delivered. In spades.
The first thing you notice is the quality of the heatsink compared with most GU10s. It’s like comparing the engine of a BMW with a tricyle. But best of all is the beam – so consistent and uniform you could draw a line around it.

Our lab tests made us love it even more. The output we measured, 344 lm, was as near as dammit that of a standard halogen output of 350 lm.

An LED GU10 that stacks up

So it’s a true, direct LED replacement for standard GU10 halogen lamps – the first one we’ve seen that stacks up in the lab.

We measured the peak intensity at 742cd – 142cd more than Sylvania claims for this, the 40-degree wide flood version.

The colour rendering index is good at 80, but remember that, like most LED lamps, it has a spike in the blue, with weaker red.

It’s LED, so energy costs are low. In our test, efficacy was 46.5 lm/W compared with a paltry 7 lm/W for the halogen. Life expectancy is in another league: nominal life is 25,000 hours compared with 4,000 hours for the halogen – and in practice, few halogen GU10s hang on until 2,000 hours.

Power factor is a much overlooked metric for lamps, but it is important because it affects the total electrical loading of the installation (read more about power factor on page 65). We measured a power factor of 0.78 which is the highest we’ve seen in this class.

]]> http://www.luxmagazine.co.uk/2012/05/breakthrough-lamp-hits-all-the-numbers/feed/ 0 http://www.luxmagazine.co.uk/2012/05/as-fast-as-light/ http://www.luxmagazine.co.uk/2012/05/as-fast-as-light/#comments Mon, 14 May 2012 13:18:49 +0000 admin http://www.luxmagazine.co.uk/?p=6851 Pennie Varvarides discovers how a lighting upgrade is giving an up-and-coming Formula 1 team a head start]]> Formula 1 racing dates back to the 1940s and many of the top teams have been racing for decades. Marussia F1, however, is the new kid on the block.

The team started life in 2010 as Virgin Racing before Marussia, the Russian sports car maker, bought it from its original owner Manor Motorsport. Having finished last in the 2011 constructor’s championship Marussia is hoping for a better performance in the current season with the help of drivers Timo Glock and Charles Pic.

Last year Marussia F1 moved to a new UK headquarters in Banbury, Oxfordshire, which it swiftly redeveloped to create a modern workspace – including an upgrade of its lighting.

Technicians need good lighting to help in their detailed assembly work

Detailed work

Making and maintaining F1 cars isn’t easy, and technicians at the factory do detailed assembly work, so it’s vital that they work in the best possible conditions. Marussia specifically wanted LED lighting, believing the technology had several advantages over fluorescent systems, and started a search for the best equipment. The team hoped LED would also help it keep maintenance costs down.

The brief was to supply good quality light for the assembly of cars in the workshop. Kevin Lee, operations manager for the Marussia F1 team, says they wanted to ‘fit and forget’ the lighting.

‘We chose the JCC Skytile to ensure a reduction in our energy and maintenance costs,’ says Lee, ‘and to create a lighting scheme that would support us for many years.’

The even light distribution on walls and ceilings means the installation is in line with guidance in the Society of Light and Lighting’s LG3 and LG7 workplace illumination guides.

The 4700K cool white recessed LED flat panels are rated IP44, so the fittings are protected against water spray and the ingress of small objects.

The JCC Skytile illuminates the Oxfordshire factory, where 140 technicians are responsible for building sophisticated Formula 1 cars, while the manufacturer’s LED downlighters are used in the reception area. Lee says the fittings give the right standard of light for the team’s ‘critical assembly work’.

The 34W LED fittings are expected to reduce energy costs across the site – cutting consumption by 60 per cent compared with T8 fluorescent tubes. Of course, the new fittings don’t just save energy, they also cut maintenance costs because the LEDs have expected lives of 40,000 hours and a five-year warranty. Also, the panels are easy to wipe clean.

Carbon curtailed

JCC supplied Marussia F1 with 113 Skytile fittings, which consume a total of 3.84kW compared with 11.75kW with T8s. The fall in energy use has led to a cut in CO2 emissions of 18.78t.

The building is in use for about 12 hours a day all year round, and the LEDs are expected to last for nine years before they have to be replaced. In contrast, the fluorescents had a life expectancy of about two-and-a-half years and the total maintenance cost for the T8s came to nearly £2,000 a year.

Total annual savings from the new lighting are over £6,000 – including energy, maintenance and general operational costs, meaning the scheme should pay for itself in less than two years.

]]> http://www.luxmagazine.co.uk/2012/05/as-fast-as-light/feed/ 0 http://www.luxmagazine.co.uk/2012/05/see-yourself-in-a-different-light/ http://www.luxmagazine.co.uk/2012/05/see-yourself-in-a-different-light/#comments Mon, 14 May 2012 12:13:45 +0000 admin http://www.luxmagazine.co.uk/?p=6841 Pennie Varvarides tries on John Lewis’s new LED fitting room lighting for size]]> When buying clothes, you want to find the perfect outfit – be it an evening gown or casual attire. Ideally you need to know how your evening wear is going to look in the evening and how your work clothes will look at work, which isn’t necessarily the same as the way they looked in the shop.

In fact, most changing rooms have a single downlight in the middle of the ceiling that casts ugly shadows and is singularly ineffective when it comes to rendering colours accurately. This is not ideal if you’re about to shell out for the perfect outfit for a big occasion.

The right impression

John Lewis is determined to change this. The department store chain is running a trial at its flagship Oxford Street branch in a changing room dedicated to men’s bespoke suits. Tailor-made suits aren’t cheap, and John Lewis wants the lighting to give customers an accurate impression of the clothing.

Barry Ayling, lighting design manager at John Lewis, says: ‘I wanted to enhance the John Lewis offer in our changing rooms. A refurbishment project was available to support our men’s bespoke tailoring, and that offered the perfect opportunity to test out new lighting.’

John Lewis is hoping that giving its customers the ability to see their suits under different lighting conditions will ensure they get what they came for and reduce the number of returns.

The changing room (modelled here by Osram’s Tim Higgs) has been fitted with Lunis Q LED downlighters from Osram subsidiary Siteco. The colour temperature of the light sources can be changed so customers can view their outfits in four different settings: normal shop lighting (3000K), evening (2700K and dimmed a little), office (4000K) and daylight (6500K).

Ayling also wanted to tackle the problem of heat generated by the MR16 halogen lamps that are typically used for changing room lighting. He hopes the LEDs will eliminate the problem and make the fitting room experience more enjoyable.

‘The lighting design also saves energy,’ he explains. ‘Our existing system uses two mirror lights rated at 20W each and a 32W downlight – a total of 72W. The new LED lighting uses 36W, so we’ve effectively halved the load.’

Approachable cubicle

The lighting scheme will also be fitted with an occupancy detector, and will be dimmed to 10 per cent output when the changing room is unoccupied Ayling wanted some light to remain so the cubicle always looks approachable from the outside.

John Lewis has 36 stores in the UK, and Ayling says: ‘This new lighting could become a John Lewis standard for changing rooms, and that would further differentiate our offer and service to our customers from those of our competitors.’

Dressed for Success

When Lux set out to discover the best and worst of shop fitting room lighting last year, we were faced more often than not with the dark shadows caused by the dreary single downlighter that so many retailers are still attached to.

Fitting room lighting really deserves more thought than this. You don’t need to go as far as scene setting (though it helps) but there are other options available to improve the space.

Something as simple as lighting from the front and sides can eliminate those ugly shadows as well as smoothing the contours of a person’s face, making people look and feel more attractive. At John Lewis, the three downlights work together with the mirrors to provide light from all sides.

● For more on changing room lighting, read our feature from September 2011 online.

]]> http://www.luxmagazine.co.uk/2012/05/see-yourself-in-a-different-light/feed/ 0 http://www.luxmagazine.co.uk/2012/05/leds-and-their-makers-aren%e2%80%99t-whiter-than-white/ http://www.luxmagazine.co.uk/2012/05/leds-and-their-makers-aren%e2%80%99t-whiter-than-white/#comments Mon, 14 May 2012 12:01:42 +0000 admin http://www.luxmagazine.co.uk/?p=6837 Lighting crime is rife again this month. Confidence tricksters are targeting innocent property owners and businesspeople who understand little or nothing about lux, lumens, colour temperature or how to tell the difference between a well-engineered heatsink and a lump of recycled bean tin.

The con works like this: lighting companies approach business owners with a promise of huge cash windfalls in the form of energy savings and maintenance cost reductions. The initial claims may be true on paper, but often the products installed to achieve the promised savings are, in fact, crap.

Flat, dull and dingy

Sure, they deliver the promised savings, but the lights themselves often fail to deliver the amount, quality and colour of light that we have come to expect. The result is that once well-lit spaces turn into flat, dull and dingy caves. In a few applications this may be acceptable, but in restaurants, offices and shops, lighting is a key ingredient in the overall success of a business and getting it wrong can be disastrous.

The crime scene this month is a highly regarded gastropub in North Yorkshire. The main dining area was subjected a few months ago to a retrofit of MR16 low-voltage halogen lamps. All was well for the first month or so – this is a crime story that burns slowly. After a few weeks some of the lamps had failed. This was blamed on a dodgy batch and they were promptly replaced. A few months on, a more serious problem is emerging, even if it goes undetected by the untrained eye. It’s an issue the lighting industry often refuses to discuss, but believe me it will be coming to a retrofit or new installation near you soon.

The issue is colour shift. You think you’re having some nice warm white retrofit bulbs fitted, then over a few months they change to shades of white you didn’t think were achievable (and certainly aren’t desirable) – grey white, pink white and even brown white.

So what, you might say, who cares? But when I dined at the scene of the crime, I thought they were using two colours of table cloth – one a nice crisp white, and another a dull cream colour. In fact the apparent difference was caused by the light from the offending MR16s. The result is an unhappy user, unlikely to follow up on a sensible effort to reduce energy consumption.

With the lighting industry’s marketing focus moving rapidly in the direction of LEDs, it’s time to start exploring these issues before consumers switch off. LEDs are not only about long life and low energy. Reliability and colour performance are just as important in the long term. With a raft of new methods and techniques being used to implement LED lighting, how do manufacturers prove what will happen towards the end of a product’s 50,000-hour life?

During April’s Light + Building exhibition in Frankfurt, a number of manufacturers demonstrated that they recognised this is an issue, and they have a solution. At the top of the list is Manchester-based Projection Lighting, which is offering a five-year ‘no colour shift’ guarantee on its Xicato module-based fittings – a positive step forward.
Now, who’s going to be brave and make a similar promise for a retrofit bulb?

Gordon Routledge, LEDs expert and publisher of Lux, can be found on Twitter @gordonroutledge

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