Pre & Post Production > Lighting

Greener Lighting Design

Lighting is a major opportunity to address energy use in a theatrical production.  Intelligent lighting design and new technologies can help balance the aesthetic demands of the creative team with the environmental concerns of the production. By using more energy-efficient instruments and employing a holistic approach to lighting design, a production’s energy use can be significantly reduced. Theatrical lighting designers aiming to reduce the environmental footprint of their designs should be aware of the benefits and constraints of emerging lighting technology.

Lighting Instrumentation

The light sources you choose for your design will be a key factor in the environmental impact of the lighting rig. Review the following comparative metrics when considering instruments:

  • Lumens per watt / center beam candle power per watt: This metric, also called luminous efficacy, describes a light source’s efficiency: how much light is being generated by the instrument for each watt of electricity consumed. This metric can be calculated by dividing brightness in lumens or center beam candle power by the wattage of the instrument.
  • Quiescent load: This metric demonstrates how much power an instrument consumes when it is idle, or not producing light. Ask the manufacturer about the quiescent load if this metric is not provided.  Typically, traditional moving lights and high-intensity discharge lamps (HIDs) will have a high quiescent load.
  • Rated source life: The lifespan of the light source (usually in hours), which can factor into maintenance and replacement costs.
  • Heat load: Since most theatrical lighting is mounted high above the playing space and closer to the HVAC system, higher heat output from the lighting rig means higher HVAC demand in the theatre. By evaluating the heat load of each instrument and choosing sources with lower heat output, the cumulative heat load of your lighting rig can be reduced, reducing HVAC needs in the theatre. (Heat load is generally a function of wattage and heat dissipation. The higher the wattage and the more static the heat dissipation, the higher the relative heat load.)

Common Theatrical Light Sources

Tungsten / halogen lamp (incandescent)

Tungsten/halogen sources are found in the majority of theatrical lighting spot and wash lights.  Halogen is a classic technology in theatrical wash, strip, and spot lights of all types. While these light sources are still the mainstay of most theatrical productions, they are very inefficient compared to newer lighting sources.

LEDs (light emitting diodes, or solid state lighting)

LEDs are rapidly being employed throughout the lighting industry and are increasingly being used in theatrical lighting. LED technology is consistently improving and dropping in price, resulting in the use of LED sources in more theatrical lighting designs—replacing tungsten/halogen sources in many common applications.

PROS

  • Significant reduction in electrical power consumption for light output (high lumens/watt).  Generally, LEDs use 1/5 of the energy to produce the equivalent light output of a tungsten/halogen source.
  • Generate very little radiant heat, which results in lower HVAC demand.  If gels are used (with “white” LEDs), the lower temperature of the LED source would require fewer gel replacements over time (since gels fade as a result of heat).
  • Higher rated lifespan for both instruments and sources compared to tungsten/halogen or HIDs, reducing maintenance needs related to relamping. (The best extended lamp life of a halogen high performance lamp (HPL) is 2,000 hours vs. a typical rated life of an LED source at 25,000 hours.)
  • Color-changing instruments offer instantaneous color changing, averaging 16 million distinct colors. A single fixture can mix colors instantly, as opposed to using additive mixing of several light sources, or subtractive mixing which reduces light output.   Color-changing instruments also eliminate the need for gels, reducing maintenance and costs.
  • Many manufacturers offer “dynamic white” LED instruments. These instruments are capable of shifting their tone of white along a wide range in the Kelvin scale, ranging from a warm 2800K to a cooler 5000K.

CONS

  • Compromised color rendering when compared to tungsten; LEDS often have lower CRI.
  • Inconsistent color temperature (particularly among white LEDs) between sources manufactured by different companies, or manufactured in different batches or different years by the same company.  This can become an issue for long-running shows that may need to replace light sources.
  • Complicated dimming and control (every LED instrument handles power differently and is controlled differently), resulting in difficulty when fading. More complicated controls lead to longer tech time, increasing the upfront cost of mounting a production.
  • Currently LEDs have a higher upfront cost than other sources, though prices are decreasing each year.  For shorter running shows, this might be cost-prohibitive.

High intensity discharge (HID) lamps

HIDs are associated primarily with moving lights and followspots.  HID sources are being replaced by LEDs in many moving light applications.

PROS

  • HID sources offer a very high lumens per watt ratio compared to tungsten/halogen.
  • HID sources enable higher light output in a more durable form factor than tungsten/halogen sources, making them more practical for use in moving lights from a technical and maintenance standpoint. Tungsten lamps would not be able to perform under the high heat and high demand applications of moving lights.

CONS

  • HID sources have a high quiescent load. HID sources have to be activated (“struck”) at the beginning of a rehearsal or performance and remain on for the duration of the performance.  When not being used to produce light during a scene or portion of the performance, the instrument closes a shutter to prevent light output, while the source remains on and consuming energy.
  • HID sources require cooling to maintain operation (a fan must be running in addition to the light source), resulting in higher energy consumption.
  • Must be color corrected to match tungsten.
  • Comparable rated life to tungsten/halogen sources.

Spotlight on ETC Source 4: Halogen vs. LEDs by the numbers

Light Source

Source Four 19 Degree           (575 W Halogen)

Source Four LED Lustr+ 19 EDLT (Tuned to 3200K)

Source Four LED Lustr + 19 EDLT (Tuned to 5600K)

Candela (lm/sr)

206492

40404

51800

Field Lumens

9168

2691

3450

Beam Lumens

7204

2621

3360

Wattage

575

130

130

Delivered Lumens Per Watt

14

20

26

Rated Source Life (Hours)

300

50000

50000

Correlated Color Temperature (Kelvins)

3265

3200

5600

Color Accuracy (CRI)

100

84

92

Environmental Benefits

More efficient light sources consume less electricity and reduce HVAC energy use. By choosing more efficient lighting, your design can help reduce a production’s consumption of fossil fuels and emissions of greenhouse gases like carbon dioxide and methane, as well as other pollutants such as sulfur dioxide (causes acid rain), nitrous oxide (creates ground level ozone and causes respiratory disease), mercury (poisons streams and lakes and causes neurological damage), and fine particulate matter (causes respiratory disease).

Additional Resources