Xenon v Laser energy usage

[Steve Pike]

Hi all,

We are in the process of looking to upgrade to laser - and as part of this we are looking at grants available from environmental organisations. I just need some help with finding out some stats to help with our application.

Our current projector is using a xenon bulb ( Christie CDXL-30 but we are hopefully looking to go to laser.

Can anyone please help with providing info or links to stats about the efficiency of operation when using laser vs xenon?

For example, per hour, how much electricity does xenon use over laser (typically)

Many thanks,
Steve

[Carsten Kurz]

Is your screen equipped for 3D?

[Steve Pike]

We have had 3D, but used the xpand system so we still have a white screen

[Leo Enticknap]

If you look up the manufacturers' tech spec sheets for the projector you currently have and the one you're looking to buy, they should give you the projectors' power consumption in kilowatts. It'll likely be a figure based on the biggest bulb or laser configuration running maxed out (which might not be what you do), but for grant writing purposes it should do, and it's official evidence. Then guesstimate the number of lamp on hours per week your projector does, and from that figure out the number of kWH of electricity a week it consumes. Your most recent electricity bill will give you the price per kWH you pay, which will enable you to calculate the projector's electricity cost per week. Multiply that by 52, and there is your annual power bill for the projector.

In direct answer to your question, a laser-illuminated projector will typically give you a 40-70% power saving over its xenon equivalent, based on a number of factors. Steve Guttag has argued many times here that the economic case for conversion to laser is at best questionable for lower powered projectors: it's a similar syndrome whereby if you have a 20-year old car that is fully paid off, buying a new one may save you a few bucks a month on gas, but if you're also having to pay a few hundred a month on a car loan that you previously weren't, then maybe sticking with the older car makes more sense. However, if this projector is to be bought using a grant rather than out of your pocket, regular economics go out the window.

A couple of years ago my wife (a nonprofit executive, and so knows a lot about grant writing) tipped me off about a Department of Agriculture program to enable rural communities to replace energy inefficient infrastructure with Greta Thunberg-approved stuff. I had previously mentioned a customer in a small town in central Nevada with 15-year old projectors with deteriorating reliability, and she thought that this might be worth investigating. It was so annoying - I spent several hours reading a couple of hundred pages of government gobbledegook, only to find at the end of it that the specific legal category of nonprofit that this theater is was excluded from the program. It is a 501(c)(3), and pretty much all the numbers from 1 to 8 except 3 were eligible to apply. Grrr....

[Steve Guttag]

In general, Laser projectors use about 33% - 50% (depending on who you ask and how you measure, and what projectors you are comparing) of the electricity of their xenon counterparts, for similar lumen outputs. It is a significant drop. Since you say you are using a CDXL-30, I'm going to make a presumption that you are using a CP2220 (or possibly a CP4220). Looking at the Christie specs, they are calling for a 23A maximum at 200VAC (since you are in the UK, your current will be a bit less but power is power you still still have a 4500W maximum consumption).

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Compare that to the CP2420-RGB

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Just 11A or about 48%.

For the 4K version, it is a little thirstier at 13A.

For comparison, the Barco SP2K-S series has a 10A rating and 14A on their SP4K-C series. So, essentially the same.

A Sharp (NEC NC1803ML, 2K projector) would like 18.1A. And for 4K (NC1843ML) would like 19.1A, please. I don't know how they figured a way to keep their electrical consumption up!

[EDIT]

I see that Leo posted just before me with essentially the same information and how to find it. He mentioned about my position on laser conversion for electrical savings...to be clear, my position is strictly based on converting an existing xenon projector by removing the lamp house/reflectors ballast...etc. an putting in a laser light source in their place but retaining the rest of the projector. My argument is that, unless you catch the projector before it gets to year 6 or 7, you are now investing, significantly, into an aged projector that will still have all of the issues of an old projector (failing parts, degrading light path, stuck pixels) that you just sunk an expensive light source into. When you are running smaller lamps, particularly 2KW or less, there is never a return on investment. You'll never consume enough xenon lamps to ever cover the cost of the new laser light source, let alone to start factoring the nominal electrical savings. In this day and age, unfortunately, you'd be better served to automate ensuring that the lamp isn't running when no tickets are sold.

Now, as you go above 2KW, particularly if you are at 4KW and above, that shifts the advantages a bit. a 6KW lamp is both very expensive and short lived...plus it is consuming 6KW (plus parasite electronics and inefficiencies) of electricity. A 6KW xenon system is hoping for 33,000-35,000 lumens.

A Barco SP4K-35B wants just 20A SINGLE PHASE power for that (or 10A 3-phase WYE; or 15A 3-Phase Delta).
Christie's CP4435-RGB, 17A max or 2394W. This is the sort of difference that sends you closer to ⅓ of the electrical power of xenon.

[Marcel Birgelen]

We see a roughly 60% decrease in power usage on the projector itself between a DP4K-23B with 4KW lamp and SP4K-23C running at comparable light output. There are other benefits though, which are somewhat harder to factor in:

- HVAC needs to extract way less heat when running on laser. Our HVAC is on a different circuit and I have no reliable readouts for the projection room itself.
- Often times, xenon bulbs are kept on running between shows, to save on strikes.

[Randy Stankey]

For writing a proposal, wouldn't it be better to frame it as something like Watts/Hour or something?

The average person at a given granting agency isn't likely to have a lot of technical background. In my opinion, it would be better to boil things down to a simpler, easier to understand, concept. You can also say that it's an X% savings but I think that saying something like "'Projector A' uses X watts/hr while 'Projector B' uses Y watts/hr, yielding a Z% savings in electricity." would be something that your average person can read and understand.

Often times, the people who read grant proposals will just skim the highlights. Even if they do understand technical terms, they might not read them unless something catches their eye. Heading up your argument with a simpler phrase might make it more likely to get your proposal put on the top of the stack.

[Stefan Scholz]

About two years ago, I was asked to hold a lecture on current projection upfront an audience of theatre owners in our federal state during a conference on exhibition.
One of the topics included energy consumption, and I had a slide with comparing different projectors.
And old Gen 1 Christie CP 2000 Xenon, with a rated 7000 Watt power consumption plus a storage server at 155/ 180 Watts, vs the same light output RGB laser Gen 4sold in 2023, rated at 1550 Watts including IMS.
Compared to the very early ones, the savings are significant. And, the comparison applies to new projectors, whereas after 15 years the old light path, mirrors and light engine will have degraded significantly.
I also had a comparison of the first NEC over the current RB Sharp NEC laser. Interesting to note, the old one at 5500 Watts plus storage server, and the RB laser still taking 2988 Watts.

I have recently replaced our own Sony 515 with a Christie 4435 RGB. The Sony ate around 3780 Watts plus Storage server, and helped keeping the quite large booth cosy and warm in winter. I haven't measured the consumption of the Christie, but the feeling in the room, it's winter, is damn cold. According to the leaflet, this model using a High Brightness lens is around 15 lumens per Watt towards the screen. As projector electronics are basically identical, the efficiency goes up with larger light output, until you reach the step, where they still sell the older constructions involving an active chiller unit. Then, it drops significantly. The 4435 model seems to be the latest addition, and can rely on onboard passive cooling.
Another factor is the ageing of Xenon bulbs. Within the first 20% of their lifespan, they loose around 30% of the light output, which then lowers, and at 100% warranty life you're ending around 50% of the initial light output.
RGB laser is claimed to reach 40 or 50 k hours with a drop to 80% of the initial light output, as long as it is not driven near to full power setting.
Whereas a Xenon bulb can be easily replaced to gain new brightness upfront an important screening, lasers are not.
Theoretically your Xenon projector has to be chosen at 50% maximum light output to enable constant light steering over bulb lifetime, whereas a laser unit would allow for a smaller headroom of 20 to 25% only.
It's just the thing, you can prematurely change a Xenon bulb, as said before.

There are significant savings in modern light sources, the power usage is only a factor in some areas, where electricity is expensive. Replacement cost of bulbs is a factor with larger, short lived lamps and will compensate for a large part of the price of a new projector. Thinking of the 35k lumen model we installed, this would have been a 6 kW bulb at least. With a rated lifespan of 750 hours, 45k hours equal around 60 lamps. Including the energy usage, the savings over bulb purchase nearly cover the projector price. In this power region, laser is a no brainer.
As Steve pointed out, it is different with small power units, where it is hard to gain any benefit, when prematurely replacing a projector is planned.

[Mark Gulbrandsen]

You still have to factor in the cost to re-laser the projector if it is a long-term investment. And once it goes out of warranty if a certain group of laser components will have to be replaced all together or just the one part that failed. I don't trust most manufacturers because the market changes and that affects what they can offer down the road. Like Oh, sorry, those laser components are no longer available. That last line is actually petty common in any industry that uses solid state components.

[Marco Giustini]

Theoretically your Xenon projector has to be chosen at 50% maximum light output to enable constant light steering over bulb lifetime, whereas a laser unit would allow for a smaller headroom of 20 to 25% only.

I'm not an expert in these calculations, I understand Barco has a nice calculator on laser life expectation.
My only concern with your math, Stefan, is getting a laser projector which ends up being driven at 100% close to the end of its life: wouldn't that drastically accelerate the ageing of the lasers? Considering Lasers can't be easily replaced like an exhausted Xenon lamp, I feel that one needs to be extra careful in selecting an adequate Laser machine.

Please feel free to correct me.

[Steve Pike]

Thank you everyone. Really useful info here, and have given some stats on usage now vs proposed laser. Fingers crossed the application goes through

[Carsten Kurz]

If you operate a 3D system, you can pitch for laser with a clear goal. You should, however, when it comes to actual buying, spec the system right so that even in 3D you get a brighter picture than you had so far. Even if 'currently' not many 3D films are launched, but it's a good technical argument, as most 3D systems show a very high light loss.

[Steve Guttag]

With 3D, an advantage of laser is its ability to change output power/lumens as needed without ramifications. With xenon, it is really a 1-way street. Once you drive a lamp hard, you are consuming it that way. If you later decide to lower the output for 2D, you'll find it has a greater tendency to flicker and, after driving the lamp hard, it will need all that much more power to attain when it did before you drove it hard.

When we were putting in Dolby 3D, we used two different lamps, which gave a big edge to Barco since one could have lamphouses loaded with the appropriate lamp. The lamphouse carries the lamp information for what is in it so one could pretty quickly/easily swap lamps/lamphouses between formats though the idea was to pick one for the day (if you are running 3D that day, run all shows with that lamp). Christie allows one to swap lamps too but you are swapping lamps/re-aligning them but, at least, Christie will keep track of the two lamps you are using so that you keep an accurate log of the hours.

[Stefan Scholz]

I'm not an expert in these calculations, I understand Barco has a nice calculator on laser life expectation.
My only concern with your math, Stefan, is getting a laser projector which ends up being driven at 100% close to the end of its life: wouldn't that drastically accelerate the ageing of the lasers? Considering Lasers can't be easily replaced like an exhausted Xenon lamp, I feel that one needs to be extra careful in selecting an adequate Laser machine.

Please feel free to correct me.

With Xenon, the replacement of bulbs is easy, as I said. Remember, the internal optical surfaces also degrade, Xenon reflector in lamphouse, fold mirror, gates etc. So an older lamp projector also looses light, and this can be significantly. It is just the bulb that can be renewed. From the figures given by bulb manufacturers, we can only select a projector that is approx. 75% of the initial rated output.
So there are 2 elements that degrade the light output ß lamp or semiconductor source loosing brightness, and system components ageing. I doubt that lasers are really better in respect to system ageing. It is still high density passing through the system. Did you ever look an the output area of a 35 k lumen machine? Not more than a fingernail in area to transmit enough light to create 30 to 40 k lumens after the projection lens.
This is, why every type of projector mandatorily must be bought with enough overhead to compensate for ageing over the intended lifespan.
Bulb projectors often enable the use of different wattages, like 2kW, 3 kW, 4kW. With ageing a higher wattage bulb could be used to compensate for the brightness loss. For 3D screenings, the largest bulb at maximum drive could used for a somewhat oK result through the glasses.
This is not possible with lasers, but the in general offer a drive span from 20 to 100 %. We can start low, and automatically rise light output with degradation.
On the other hand, a community auditorium screening a single feature film every fortnight, will not require an overhead of 40 to 50% light source capacity. A Barco SP 2K-7 or 9 (or similar from the others) will do at high drive for their 27 ft screen, and the projector will fail on another part before the light source degraded beyond control range.

All manufacturers have calculator tools, Christies is called Cinemaster Calculator, can be found online, and is a good help playing with parameters like screen gain, port glass, lens quality, headroom, 2D 3D, etc.
Barco also offers a calculator. Go, and play, note results, and then decide.
Also keep in mind, higher contrast projection require a brighter peak white from our viewing mechanism. Ultra/ very high contrast machines set to 15 fl peak, simply look dull and desaturated.
If in doubt go for the next bigger model.
Sales person, in fear of not getting a deal, are often going for minimum, which do not consider honest. So best, make zour own plan using the provided calculation tools.

[Leo Enticknap]

With Xenon, the replacement of bulbs is easy,

For a trained tech it is easy, but if none is available at the theater, changing to laser illumination is another potential cost saving. I have several customers who are happy to schedule service calls for me to swap out their lamps, because they no longer have projectionists on the staff who are able to do so, and they don't want to have to get involved in the safety considerations of handling and disposing of xenon arc lamps. So there is the cost of the service call (or contract) to consider, as well as that of the lamp itself, at many theaters after the conversion to digital.