LED power savings

[Gfergie]

Thinking of replacing a majority of our auditorium lighting fixtures with LED lighting. To help get the buy in from the accountants, I'd like to actually show the estimated yearly money savings if we upgrade to LED. How would you guys gather such data?

How do I contrast power consumtion betwen what we have now and what LED would consum and then turn that into a dollar amount?
I assume lamp life would play a role in savings?

Anybody been down this road before?

-grant

 

[ccm1495]

What fixtures in your auditorium??? For general stage wash i don't believe that led's are economical to install. I am really not a fan of LED's and don't have any and don't want any. (right now or near future) They are good for DJ's and small things but without buying incredibly expensive fixtures they just can't compete with conventional fixtures.

 

[Les]

The main thing I would find out is what your venue's cost is per Kilowatt Hour (kW h). With some math, you can then determine how much it costs to run your current fixtures per hour, and you can compare that data with how much it would cost to run a similar output LED unit.

From Wikipedia:

The kilowatt hour, or kilowatt-hour, (symbol kW·h, kWh) is a unit of energy equal to 1000 watt hours...

A heater rated at 1000 watts (1 kilowatt), operating for one hour uses one kilowatt hour (equivalent to 3,600 kilojoules) of energy.

Using a 60 watt light bulb for one hour consumes 0.06 kilowatt hours of electricity. Using a 60 watt light bulb for one thousand hours consumes 60 kilowatt hours of electricity.

If a 100 watt light bulb is on for one hour per day for 30 days, the energy used is 100 W × 30 h = 3,000 W·h = 3 kW·h, the equivalent of 10.8 million joules.

So it is possible that two houselights (I'm assuming we're talking houselights here) run at full for one hour will equate to 1 kW h (assuming they're 500w each), whereas you could possibly run close to an entire LED system for an hour for 1 kW h, fixture make/model dependent.

Note that this doesn't factor in savings on cooling costs. LED's will run cooler, so the savings are there too.

For lamp life estimates, figure out how long your incandescent lamps usually last. (Hint: you may have to do a survey on it -- since houselights are usually run at reduced levels, they may last longer than what the lamp data states).
When you find out how long they last, estimate how much you spend per fixture per year. Then multiply by how many years the LED lamps are supposed to last. That will be the lamp cost that you are trying to beat. Hopefully the cost of ~8 years worth of incandescents will be more than a single LED replacement, but if it's not; all is not lost since you still have the energy savings.

 

[SteveB]

Before you get everyone hot to trot on the idea, find a fixture you think might work and TEST it in the space. One reason I say this is if you get the powers-that-be to start analyzing the current power usage as well as lamping costs, they may take the matter out of your hands and give you a bunch of CFL's. Best to do a lot of research before the proposal is presented.

Note that the things to determine are do YOU like the color rendition/light quality and/or are you happy with the overall intensity, which might bust the budget if you need to match illumination levels with more fixtures then you planned.

Other factors to consider are:

- Control - how do you switch on/off the head(s) and how do you control the DMX if that's what the fixture requires ? Is there a current house light control system and if so, can it be modified to control LED's

- Are the current house lights part of any kind of emergency lighting system, or is that a stand-alone ?. How do the LED fixtures fit in ?.

 

[jmabray]

Well this should be a pretty simple math problem.

But before we get to the math, you do have to consider what type of fixtures you are looking at using. Can you be more specific in the types of fixtures you intend to purchase?

 

[derekleffew]

Thinking of replacing a majority of our auditorium lighting fixtures with LED lighting. ...

Houselights? Aisle lights? Worklights? Stage lights? Running lights?

 

[mrb]

doing the math on the power consumption is going to have more to it than just calculating the kwh used unless you are a small facility with a small service (200 amps and less than 5000kwh used per month usually) the electric bill includes a demand charge which recoups the cost of having the available supply and transmission and distribution facilities to serve you. The meter makes note of your highest kw usage during a 15 min period and that becomes your demand. That charge is usually a few dollars per kw.

For example in Los Angeles (ladwp) i believe the demand charge is around $9. So if you have a 100kw rig, you leave it dark all month and then run every lamp at full for 15 min you only used 25kw/h just a couple dollars of electricity, but your demand charge is $900.00

Other building systems such as hvac come into play and if this is a large school campus with a single meter demand might not be an issue since your running the auditorium lights after hours and that is a lower consumption than when the school is running.

I have given a very general scenario, so dont take this as gospel as every utility is different, but realize there is more to it than just kwh.

 

[David Ashton]

you can't run led lights straight off a dimmer with acceptable results, courtesy of the zener effect, unless you spend a small fortune you won't get a good CRI [colour rating index] so you would have to buy very expensive fittings and run control to each of them, generally there are better ways to spend large amounts of money.If the manufacturers are not telling lies,[would they ever] this situation will change in the future, but right now it's not a practical poposition.

 

[michaelburgoyne]

As noted above, there are many issues related to LED fixtures beyond the possible cost benefit. If you are looking at LED down lights to replace your existing incandescent or quartz house lighting fixtures, be sure to look at how (or if) the LEDs are shielded. We recently reviewed a pendant fixture that claimed to be as bright as a 1kw quartz but the LED array was not recessed at all. I'm sure it throws a lot of light, but it would be unacceptably ugly in most architectural applications.

In addition to glare; color temperature, color rendering, dimming control (especially as you fade out), noise from power supplies, are all potential problems for LED house lights.

 

[mstaylor]

In the course of your math consider the time and trouble you have to go through to replace a lamp. Some houses it is not a big deal, in others it involves bringing in equipment and sometimes even a contractor. The longer life of LEDs can make a big difference in labor, which may kill the CFL alternative. Follow the advice in the other posts about dimming and other factors on a switch. You would be unhappy to switch everything and find out you have a dark house.

 

[kendal69]

LED lights are teh way to go and soon you will no longer ne able to buy trditional bulbs. This is the same thing that happened with digital cameras and film camers. I was one of the first adapters of digital cmaeras and realized you could buy the digital camera for what you save in NOT BUYING film. Well we had millions of old school photograhers that would almost rip you a new one for saying film is dead.....fast forward a few years and film is dead and every pro is using digital.

Now back to LED. I went with LED the day they came out and have actually developed some LED products. I currently use only 3W pars that blow away anything on the market. They burn at 150 watts so I can put put nealy a dozen on a 20 amp circut opposed to only piutting 3-4 convertional lights on that same circut.

Temp wise They warm up to about 100 degrees tested with a digital lase thermometor so they can be used in and around drape with little worries.
The days of buying and cutting gels is Looooooong gone. That alone is putting major amounts of monet in my pocket. Now lets talk labor. If I have 30 lights set up and teh clients doesn't like the color, no problem instant change and all 30 change color - can't do that with a conventional light. Imagine changing 30 Gels and how long that would take?

Price for the lights they run anout $300 - $400.00 each a ETC Source Four Par runs from $150 - $200.00, plus the bulb at $20.00 - $30.00. with a gel price that will never ever end and could run as much as the light and beyond, so price is either a wash or better with LED.

Lets figure this now. On a typical stage you might want 6 lights with 6 gel colors ( red, blue, green, pale, rose, goldenrod ) so that would mean 36 lights to give you 6 colors. Ahhh here's where LED shines. You only need (6) lights for the same effect. a savings of around 6K.

Recently I just purchase 4 Qspot 60 LED moving heads. I have never been so stunned with an LED light in my life. the light weighs about 30 pounds, and is as bright as the trditional moving light they replaced wighing almost 70 pounds each. The traditional light they replaced cost 6K each tehse LED moving heads cost 1K each and do more, quicker, lighter, with more options.

So to sum things up you'll save power, gels, the amount of lights you'll need and the room will be that much cooler.

 

[David Ashton]

that's hardly relevent to auditorium house lights