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044


PROJECT / HOTEL


Katja Winkelmann highlights the spurious promises and brutal realities surrounding the decision, faced by many hotels, on whether to switch to LED.


REFIT FOR PURPOSE?


Hotels all over the world try to keep energy used to a minimum. Whilst in existing projects, big energy consumers, like air conditioning, heating, cooling (not to mention the really big ‘wasters’, like kitchen equipment), are difficult to change and most of the time too complicated and too expensive, lighting seems to be an easy option to change and to immediately save money on. Lighting in hotel projects uses approximately 20% of the total energy needed to run a 4-5 Star hotel; so the public areas use even less than 20%, seen within the whole project’s consumption. Lighting and lamp manufacturers promise hotel operators an 80% reduction to this energy consumption if they change existing incandescent and halogen lamps to LED retrofit lamps. Promising an easy change and “exactly the same lighting”, they preach to the converted in hotel management, that this is exactly what is needed. Unfortunately, it’s often the case that these promises do not come true! There are many problems to think about when changing the existing bulbs to reftrofit lamps, which causes disappointing results in all fields of lighting. First, the worst promise is the lifetime. “50,000 hours lifetime and more!” is promised, but the LED has, besides some other technical specialities, a problem with heat. LED sources produce heat at the LED board and they are highly sensitive at a board temperature higher than 100°C. If the LED gets too hot, lamp life goes down dramatically, light output reduces and, if the board gets hotter than approximately 130°, the LED dies. So it is very important that refit lamps are designed very precisely in terms of heat management and heat reduction. Most of the reputable manufactures like Osram, Philips and GE promise only 35,000 to 45,000 hours for their refit solutions, because of these heat problems. And if a cheap product has been purchased, the lamp life could be much shorter still. With this the promised payback is lost because the lamps have to be replaced. It is easy to promise 50,000 hours when you sell – you can be quite far away after 15,000


hours of operation time... Second promise: “Energy savings of about 80%!” Most of the existing retrofit lamps - for example, for halogen low voltage lamps, which are used in their billions in hotel projects all over the world - do not reach the same light output. It is easy to compare. If you look at luminosity (candela) it is easy to realise, as you can compare 1 to 1 if you chose the same beam angle. A halogen low voltage MR16 – 24° - 35W has 4100 candela* luminosity output and the offered ‘equivalent’ refit MR16 - 24° 7W has only 1000 candela*. This is physics: less light output gives less light, so you save 80% energy, but in this case you also incur a 75.6% loss of light! Seen the other way around, it means you need more lamps/luminaires to keep the existing light level (important in, for example, meeting rooms, conference rooms and ballrooms). Third promise: “Just change – it’s easy”. Let´s continue with the example of the MR16 lamps. All – or most of them - are on dimmers, integrated on a dimming system. The problem with the LED MR16 retrofits is that they do not function with every transformer and every dimmer system; sometimes the lower wattage causes problems with the transformer (underload). The result is flickering light, broken transformers and, as a worst case, broken control equipment. If you are lucky and the transformer, retrofit and dimmer ‘speaks the same language’ (meaning LED retrofits work properly with the transformer and the control system works well), then you have to do a complete reprogramming to get the same lighting scenarios as you had before, because the light output is different! So what about “easy change”? First, I think I need to pause to state clearly that I am not against LED and also not against refitting existing projects – but I think it is important to name the ‘real life’ problems! Coming to the fourth promise, which touches me as a lighting designer - and I am probably speaking for hundreds of us here - we have to talk about “You get the same lighting!” Regarding the lighting levels we have already seen that there is a big issue with light levels,


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