A simple Google search landed me on the correct Academy of Motion Picture Arts and Sciences page discussing their report on solid state lighting (i.e. LEDs). Going further down the rabbit hole there was the Academy's 1928 report on the "new" incandescent bulb technology on the right side of the page.
Oh, how technology changes. Now days incandescent lighting is considered that old power hungry technology that your local congress member wants to outlaw! However, back then it was arc lights or the new fangled incandescents. Some of the interesting comments I saw in the report include... (please note that "Mazda" was used interchangeably with incandescent in the AMPS report)
Replies from nine studios, to Questionnaire No.1, brought forth a uniformity of opinion that the substitution of Incandescent lighting would reduce electrical labor costs approximately 50%.
"Lightness of equipment and hence ease of portability which insures quicker setups as well as lining up of sets; quick adjustment to photographic alignment and subsequent accessibility."
-Karl Struss, Chief Cinematographer for D. W. Griffith
Labor-7 men $7.00 per day. 49.00
There was general agreement in the replies that current costs were materially reduced by the substitution of Incandescents, The current costs on Universals "No. 13 Washington Square" was given by F. Graves as $41.08, as compared with an estimated current cost had Arcs been used of $615.93. Paramount estimated 78 cents current cost per hour for Incandescent, as compared with $1.38 for Arcs.
"In photographing small or medium sized sets of no bigger floor space than 750 square feet or 18 feet in height, the Mazda units, such as broadside domes and strips are very practical for general illumination, but for sets of. larger area or greater height, from my experience, I believe one should incorporate Arcs in the lighting."
Harvey Leavitt, DeMille Studio
"Arc equipment give more general and concentrated light than Mazda on large exterior shots. We can never hope to get as concentrated light source in Incandescents using Tungstens, as we now get from Arcs"
-Paramount Experimental Department.
"Incandescents, due to the filament, cast a "fuzzy" shadow regardless of the reflector being used or the number of lights."
-R. B. Mclntyre,Production Manager, Samuel Goldwyn.
"We get a greater degree of roundness and softness with the Incandescent light."
-J. M. Nickolaus,M. G. M.
Mazda will be used almost exclusively in the future."
-Paramount Experimental Dept.
These are almost the same arguments given for and against tungsten incandescent lights today! Speed, ease of setup, operating cost, quality of light, lighting crew costs...etc, still apply. Only now days people are using Kino's and Litepanel's to substitute in for incandescents.
It's also interesting to note that they studied the spectral characteristics of each light type since even black and white film stock has it's own spectral response, much the same way CMOS sensors do today through their Bayer Pattern color filters!
Technology moves on. I'm going to try to dig into the solid state lighting discussion they offer through a series of symposium videos.