Par Lamp Efficiency

[drsound]

Does anyone know roughly how efficient a Par lamp is? We need to calculate heat output for a given number of lamps.

 

Obviously all lamps vary but if anyone has a ballpark figure that would be great. Lets assume they're running at their full nominal power to make it easier as I assume they become less efficient at lower outputs. Ideally Par 64 1kw but any lamp will be fine.

[Biskit]

Does anyone know roughly how efficient a Par lamp is? We need to calculate heat output for a given number of lamps.

 

Obviously all lamps vary but if anyone has a ballpark figure that would be great. Lets assume they're running at their full nominal power to make it easier as I assume they become less efficient at lower outputs. Ideally Par 64 1kw but any lamp will be fine.

 

Not sure why you'd need to calculate this... but if it is for some kind of H&S issue (whether lights will set heat detectors off, or set fire to something etc) I'd simply assume that the lamps are 0% efficient - ie. all the power becomes heat. In actual fact, the true figure is probably 2 to 5% or so (max), but assuming 0% means estimates are on the cautious side. In practice, heat dissipation etc is subject to so many environmental factors you will always be more than 5% out anyway so I wouldn't wory about it.

 

HTH

 

Ben.

[drsound]

Thanks Ben. We need it for, among other things, CIBSE requirements on a new install in a small venue. Normally the heat produced by lights can be neglected but in the case of lots of lights in a small area you have to make sure the heat is dissipated removed from the area at a reasonable rate. 24kw of par cans can obviously skew any calcs made for ventilation requirements.

[Dmills]

Assume all the input power ends up as heat (it does eventually), even the power carried as light in the beam gets absorbed by the surfaces it hits, so unless the beam leaves the venue, 0% efficiency is about right.

 

About the only way to get an architect to understand this is to bring a couple of 2ks with 13A adapters to a meeting at their office and to leave them running during the meeting, air handling will suddenly get a much higher priority.

 

In particular, discourage monitoring space temperature by means of measuring the air return temperature, it doesn't work if the return duct connects above the stage (BTDT)....!

 

Regards, Dan.

[Dmx512]

Blimey!! Cant we install the tried and very tested parcan these days without questions? what ever next!

Dave www.q-lights.co.uk

[Don Allen]

This is where consultants have to actually do some work to earn there fees.

 

You need to look at lamp efficiency in terms of lumens per watt, one example is lamp efficiency example , light needed on stage or wherever, cost of running HighVolumeAirConditioning, savings in electricity costs from using energy efficient lamp and reduced building costs etc.

 

You need to look at expensive, energy efficient lights such as the Selecon Pacific MSR with a douser and see how long before you break even with the enrgy saving costs, dont just look at a parcan and say they are cheap so we will use them, as they can be expensive to run due to building cabling costs, aircon etc.

[drsound]

It's silly isn't it? It would be great to just whack in the lights and be done with it. I always thought we were here to make things look and sound good but we spend more time on bloody H&S now than anything else! I must admit as far as I'm concerned if someone is stupid enough to go near something that is obviously extremely hot they deserve everything they get. I believe Darwin had something to say on the subject.

 

Don, absolutely, this is why we can charge so much We have a number of chartered engineers on the books (PEs in Australia) and we do try to work in the same way as contractors would be expected to do in any other industry. This has so far avoided any nasty insurance claims...

 

Interesting point about the energy savers but we have never been able to make a business case for energy saving lamps. We looked at it for this but with the client's capex limit and relatively healthy operating budget the inverse to the usual is true. Of course, as legislation becomes tighter and the cost of energy saving products reduces they will become a viable option with very little justification required.

 

As a nerdy and pointless point: oddly HVAC in the UK stands for Heating Ventilation and Air Conditioning. Spooky!

[Andrew C]

You need to look at expensive, energy efficient lights such as the Selecon Pacific MSR with a douser and see how long before you break even with the enrgy saving costs, dont just look at a parcan and say they are cheap so we will use them, as they can be expensive to run due to building cabling costs, aircon etc.

Hmmm Are they more efficient over all? If I need a PAR can on for a 5 min scene it will use one twentieth of a kWH, if I use a MSR it will be on for the whole show from the half until the punters have left. Say a couple of hours...

 

575W MSR for 2 hours = 1.15kWH

1Kw PAR can for 5 mins = 0.05 kWH

 

And cans are MUCH cheaper.

 

OK that all falls down if you are lighting long scenes with the cans.

[drsound]

Exactly my point - even with a 5 hour night in a club the cans will only be used for 3 x 1 hour sets (for example) where they will be dimmed, flashed, chased and whatever else the op chooses to do. It might be more like 20% duty cycle (in terms of power consumption) than the 100% often assumed when calculating the potential saving of energy efficient products.

[bjkered]

Blimey!! Cant we install the tried and very tested parcan these days without questions? what ever next!

Dave www.q-lights.co.uk

 

 

 

Its not that Dumb, Lights make places HOT even more so in small areas.

 

The heat has to be got rid of ( not going down the environmental route) Once sat in the GODs of Bristol Hipodrome and got so hot as to leave theatre as not enjoyable ( and the show want that good either) Not H& Safety as comfortable environment.

[drsound]

Yup, that was the original point of my post. A lot of lighting in a small area can be a problem. Having said that it's a common misconception that there are legal limits for maximum and minimum temperatures - there aren't. There are guidelines but if you've got a reason not to follow them you don't have to. On a practical note though, who wants to pay money to go back to a place where they have been so uncomfortable? It can ruin a performance or other event.

[adam2]

The efficiency of PAR lamps is very roughly 5%, but for all practical purposes may be taken as zero.

Even the 5% or so turned into light ultimatly ends up as heat.

 

With the rising cost of energy I believe that energy use should be considered more, and LED or discharge sources used when suitable.

LEDs are very much more efficient than halogen if deep saturated colours are required, on white or light colours they are less impressive.

Discharge sources also have a better efficiency than halogen, but as noted above may be burnt for hours for only a few minutes light, no saving in that case.

 

I believe that halogen is going to be around for a long while yet, but more efficient sources should be considered when suitable.

[drsound]

Quite right, once the technology is mature they will be a much more viable option. Like it or not most companies' environmental policies are still governed by cost-effectiveness.

 

What I find difficult to understand is the time taken for new technologies to even come to the market in our industry, let alone become mature enough for widespread use. Organic LEDs for example were one the verge of being commercialised by a large chamical company I worked for in 2001. At PLASA this year I only saw one or two attempts to exploit the technology.

 

The discussion over LED vs any kind of incandescent lamp is one I have had in another thread so I won't reiterate it here. Suffice it to say that while we embrace LEDs as one of the ways of the future, they are still no substitue for good old par cans to produce certain effects (particularly in rock and roll) effectively and cheaply and they are another tool to be used, not a replacement for everything we hold dear.