[SML] LED lights in the Scene Shop

[PJ Veltri]

I finally got a chance to sit down and read the wonderful white paper
that Ford provided and the results, as far as shop lighting were
concerned, seem to resonate with what Duncan was saying, in that the
cost was quite high, and in a shop where many of the fixtures are
non-functioning and there isn't really adequate light to begin with
the costs are quite high. What was interesting though was that the CRI
was, in fact, higher in the shop with the LED fixtures. At the same
time, though, the wattage of a switch from T8 Fluorescent Tube to
Linear LED Pendants was only about 15%.  The last thing I saw of note
was that at the entire range of dimming there was no noticeable strobe
that affected the perception of safe operation of the power tools with
the LEDs.


All in all, I'd like to thank everyone in helping me to confirm my
suspicions that a simple retrofit of lamps in the existing halogen
fixtures would be a huge waste of money and that if we are looking to
decrease our energy use it would be worth looking into a full upgrade
of the Shop and Rehearsal rooms which are pretty much lit from 8am
until 6 pm daily with something more energy efficent than the current
500w work lights.

Thanks
PJ

On Fri, Sep 12, 2014 at 11:29 PM, Duncan Mahoney via Stagecraft
<stagecraft at theatrical.net> wrote:
> I have been keeping an eye on LED lighting for a while, and I'm not sure LED
> technology is really ready for use as work light in areas where you need
> reasonable color rendering and are on a budget.  There are bright fixtures
> available, some with decent CRI ratings, but the prices do not compare
> favorable with existing (almost equally efficient) "energy saving" lighting
> technologies like T5/T8 fluorescent or Ceramic Metal Halide.
>
> See if you can get the PTB to consider something besides LEDs.  T5 and T8
> fluorescent tubes with a CRI of 85 are readily available and about $3 per
> tube or less, T8 lamps with a CRI of 98 are available, but are about 3X the
> price.  Our paint area is lit with 4000K Ceramic Metal Halide lamps with a
> CRI of 92.  The law limits buildings to so many watts per square foot for
> lighting and that was the best CRI we could get with the efficiency required
> when the building was built.  The fixtures do require a bit of ongoing
> maintenance so I'm always looking for a better option that is brighter
> and/or more efficient with at least the same CRI, and not hopelessly
> expensive.  I have not found it yet. The metal and wood working areas of the
> Shop are lit with T8 fluorescent fixtures.
>
> One thing to remember and impress upon the PTB, just because the lamps might
> last practically forever does not mean they should be left in service until
> they fail.  For maximum efficiency the lamps should be replaced every 3
> years or so.  Last year I noticed that the Shop seemed a bit dark.  The
> lamps had mostly been in service 5+ years and many of the Ceramic Metal
> Halide had been replaced at various times with different brands by the
> maintenance staff, so there was a variety of color temperatures.  We
> re-lamped the CMH lamps and saw an immediate 20% boost in the light levels
> in that area and when the T8 fixtures were re-lamped there was a 25% boost
> in the light levels measured on the workbench surfaces.
>
> And here's a dirty little secret about LEDs ...their output will also
> degrade over time, pretty quickly too if the heat management of the fixture
> is poorly designed
>
> Invest in a light meter if you don't have one, try to specify an adequate
> light level at the workbenches.  Document the light levels of the newly
> installed system and test yearly to monitor any degradation.
>
> Our Shop averages about 300 lux at bench height, which is bright for a
> warehouse, but a bit dim for a workshop according to most sources I've read.
> As a result we have task lighting at a lot of the tools.
>
> Duncan Mahoney
> Director of Technical Direction
> Associate Professor of Theatre Practice
> University of Southern California School of Dramatic Arts
>
>
>
>
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