Theatre Catalog (1948-49)

The Problem of Air Distribution in a Theatre A Round-table Miecnssion of A Specific Question on Heating and Cooling A Theatre by Forced Air In July, 1947, the following letter from a consulting engineer was published in the “Question of The Month” department of the national trade journal, “Heating, Piping & Air Conditioning”: “An architect has presented a problem of heating and cooling a theatre by forced air. The auditorium is 51 x 188 in plan. The ceiling height is 25 ft. at the screen and 8 ft. at the rear, the seating being sloped accordingly. “The requirements are for the use of sidewall outlets, with return air intakes located at the screen only, leading direct back to the fan. There is no provision for exhausting the ventilation or fresh air. “My conclusion is that such a system, to both heat and cool this building, would be faulty and unsatisfactory, and I have declined to prepare designs on such a basis. “The architect insists that other advice is to the contrary and that the system will be satisfactory in every way. “T. will appreciate comments.”—T. L. Interested readers were invited to comment. So prolific was the response to this invitation to controversy and of such high calibre that the correspondence touched off by the original letter should make interesting and informative reading for theatre men. The symposium on heating and air conditioning is presented below through the courtesy of Mr. C. M. Burman, Jr., Editor of “Heating, Piping and Air Conditioning.” S. R. L. opens the discussion, in the August, 1947, issue. “TL.” indicates there is no provision for exhausting any air outdoors or for replacing it with new air from outdoors. He gives no information as to the volume of air to be handled or the design temperature of the air when cooling or when heating. I do not know enough about the project to criticize or endorse any part of it except the suggested locations for intake and outlet. I do feel able to lay down (for reaction by ever-critical readers) a few precepts, as follows: Some Points to Consider 1) The air delivery volume should be not less than 2 cfm per sq. ft. of audience-occupied room. This includes aisles, columns, and other nonpaying areas inside the walls of the room. Less volume than this will require that the entering air shall be so much cooler than the air in the room at the level of the inlets, that complaint of drafts will be made. 2) Air delivery well overhead, along the side walls through several grilles (say one every 15 ft.) generally is not objectionable and such delivery from high-up grilles at the stage end so that the air currents face the audience, is usually acceptable. Air delivery through 438 The owners of the several thousand air conditioned U. S. theatres are well aware of the fact that the key to adequate, year-round results is in the mixing and distributing system that must be designed to fit each particular auditorium box. In only a a very few other structures are the design engineers faced with ‘such large area conditioning and with | such a concentration of patrons to be made comfortable. As a result the Editors of THEATRE CATALOG watched the following conflicting views of qualified experts with considerable interest and now present them for the thoughtful consideration of the owner or architect who may have a similar problem. the ceiling in such a room has been found usually free from trouble. 3) Removal of the air from such a picture theatre as is described, limited to grilles at the floor only, at the deep end, generally is unacceptable. The only exception is in very cold weather if there is no carrier of the heat except the air, in which case, unless there is means for the relatively heavy cold air to escape at the deep end, the floor down there may be cool. It has been well proved by experience that when we attempt to cool a room in hot weather, and have recirculating or exhaust openings only at the floor, we can be very sure of trouble, The relatively heavy cool air, entering the-room at, say, 60 deg. into a zone where the room air may be at 80 deg., or even warmer, tends to fall toward the bottom of the room and if there is an escape opening there, as for recirculation, the cool air will slide happily out, leaving the lighter-weight hot air in the room to rise toward the ceiling and become hotter—to discredit the designer. If, when cooling such a room as that described, the return air or exhaust air openings are overhead, the hottest air will skim off like dross in a lead melting pot, and the cool entering air will settle gracefully and gratefully around the people. If—in such a théatre as that described —there are a few radiators down in the low zone, there will be no trouble if the year-around return air outlets are high overhead. It is not usually too difficult to arrange for seasonal or even for hourly switching of the air removal leyel from low-down to high-up. If the room gets too warm, just open the overhead vents. . Use Outdoor Air 4) I know no area in the United States in which at some considerable time during each year, the untreated outside air is not delightful to feel and breathe. I know of no audience room in the United States in which this outside air—moved in copious quantities, and neither heated nor refrigerated—is not desirable: in order to control temperature and odor. Any designer of a theatre should be excommunicated if he fails to provide ventilating equipment capable of introducing and removing 100 per cent of this outside air when no heating or cooling is needed. He should be shot at daybreak if he fails to teach the operator to introduce and remove enough outside air to dilute the characteristic and not always pleasant odor of too-warm humans. 5) In North Dakota we are called upon to redesign the ventilating of a very large and otherwise attractive assembly room because of failure by the designer to provide any openings (to say nothing of fans) for removal of spent, hot, smelly air. No appreciable volume of new air can enter unless there is a vent for escape of the original, old, wornout air. In Pennsylvania we are compelled to reverse the unfortunate original designs of a theatre ventilating system (and we should like to do so in many local theatres) where the entering air emerges through openings in the floor under “mushrooms” and escapes through the ceiling. The entering air currents in these cases are too intimately located with reference to the ankles of the audience. In California we are correcting an exceedingly flagrant case of air introduction for cooling a theatre where the air supply: was delivered into the room through grilles behind the audience. The ticket purchasers for years have emerged as nervous wrecks following fear of a cold due to the impact of the cooling air on areas of their bodies, from directions that their bodies are not trained to accept. Incorrect Equipment Location In Chicago we are spending a lot of dollars to correct a case in which the designer filled with machinery the basement under an otherwise attractive and useful place of assembly. There are nine fans and electric motors, 12 pumps of various kinds, and hundreds of feet of hot pipes under this room, with only a thin concrete floor as a barrier. Bach machine tells the audience of its coming: on and going off and the audience suffers from the hot-foot disease due to the very warm floor. That reminds me of another large theatre that for years endured under its THEATRE CATALOG 1948-49