Courtroom Lighting Criteria Evaluation
Task 1 Report
Based on our extensive studies, the following conclusions can be drawn:
All of the courthouses studied exceed the allowable lighting power density. This is due
to the use of incandescent tungsten-halogen lighting, which is not as efficient as other
Using metal halide downlighting as a primary light source is undesirable, since color
rendering (as observed) and control of this source is limited.
Designing a successful lighting solution and assuring it is successfully installed during
construction is critical, because revising the lighting in courtrooms once installed leads
to more power use and added construction expense.
The recommendations of the Design Guide are not always followed. This could be
due to the design team not knowing or intentionally not complying with the guidelines.
It may also be because of breakdowns in the construction process, perhaps in the
submittal phase. The submittal phase is critical for the design team to confirm with the
contractor what will be installed.
More horizontal illuminance does not necessarily mean better performance. The best
performing courtroom was the Montgomery courtroom, which had the lowest overall
illuminance and power density, based on subjective ratings such as surface
brightnesses, glare, and color rendition. The subjective ratings of the Montgomery
and Pearl St. courtrooms show that a good lighting solution can be provided with
regards to the standards in the Design Guide and IESNA Handbook using relatively
low horizontal illuminances. This suggests that the illuminance recommendations in
the Design Guide can be lowered if the design is geared towards these qualities, such
Daylight is not critical, but if controlled well, it can greatly improve the perception of the
courtroom. The Tallahassee courthouse has a skylight system that is easily controlled
to eliminate glare due to sunlight, and the windows at the Montgomery courthouse
provide a visual connection to the outside.
Most of the courtrooms observed did not have lighting specifically designed targeted to
task areas. This leads to excessive energy use because light levels remain high in
areas that they are not needed.
Most courtrooms have a significant amount of dark wood finishes, which leads to more
installed lighting because the surfaces do not reflect as much light as lighter colored
walls. Courtrooms that only had wood paneling at low levels generally performed
better than those with full wall height wood covering. During the design process
contrast must be balanced adequately.
Providing dimming control to for lighting in courtrooms is critical for video and evidence
presentation. A system that allows individual zones and types of light to be easily
controlled is preferable. Links to the AV system should be provided for integrated
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Ove Arup & Partners Consulting Engineers PC
Issue March 1, 2006