The Exhibitor (Nov 1938-May 1939)

BM-8 The engineers have found that humidities above 70 percent are too damp and below 30 percent are too dry to be truly comfortable, at the temperatures maintained. Accordingly, the table omits these uncomfortable extremes. The dashes represent uncomfortable extremes of humidity, and the blank spaces indicate saturation (100 percent humidity) or super-saturation, both conditions, of course, being unknown in theatre operation— and seldom encountered, save in experimental laboratories. • COMFORT ZONES for the summer and the winter, of course, are different. For summer the human body demands a higher temperature for comfort than during the colder months. In the table the right-hand series of bold figures (found under dry-bulb temperatures of 74, 75, 76, 77, and 78 degrees) indicate the conditions under which 98 percent of the tested audience were entirely comfortable. From these points the number of people that felt comfortable decreased as the conditions on the right third of the table were employed, to a point where — at 8 5 degrees and 3 0 percent humidity — only about 5 0 percent of the people felt comfortable. A similar situation obtains in the winter comfort zone, the best part of which is represented by the bold figures in the left portion of the table, at which point some 97 percent of the tested audiences were entirely comfortable. The degree of comfort decreases as the leftward conditions prevail. The portion of the table between the two sets of ideal figures represents the over-lay of the two comfort zones. • IN USING THE CHART, the dryand wet-bulb reading are noted, and the humidity determined from the chart. Then the mechanism is adjusted to bring the humidity closer to the indicated ideal. For example: suppose the dry-bulb temperature is 76 degrees and the wet-bulb temperature is 59 degrees. From the chart, we note that the humidity is 34 percent, which, being below the desirable 51 percent for a temperature of 76, means that the atmosphere is too dry and that probably many people are uncomfortable. To remedy the situation, the humidity can be increased until the wetbulb records a temperature of 64, which will mean that the humidity has been increased to 5 1 percent. Or, to achieve the same degree of comfort for the patron, the temperature of the theatre may be raised to 78 degrees, at which point, then, the humidity would be the ideal 3 0 percent. A similar procedure would be followed if the dry and wet-bulb temperatures were, for example, 78 and 67 degrees, respectively. It would be a case of dehumidifying the atmosphere until the wet bulb read 59 degrees, or lowering the house temperature to 74 degrees (dry bulb) . BETTER MANAGEMENT Outside Temper ature Inside Temper ature Wet-Bulb Temper ature Relative Humidity 95 80 65 44 90 78 64 46 85 76 /2 64 50 80 75 64 54 75 73/2 64 60 70 72 63 61 • THE PROBLEM of what temperature to maintain when certain temperatures prevail on the outside perplexes many exhibitors. Time was when a standard temperature of 68 degrees was maintained regardless of the outside temperature, but time has proved that it is dangerous to maintain such a temperature when the higher summer temperatures prevail. Although the theatre man, inside his theatre, would not be very conscious of the temperature, many would be the complaints that patrons would register, one to another, if not to the management, if the theatre was maintained at 68 when the sun outside was broiling the populace with a temperature of 90 or 95. Nor does the frequently used 10-degrees-below-street-temperature standard always prove satisfactory. Accordingly, the American Society of Heating and Ventilating Engineers has The Views of Experts That Should Be Heeded By All Showmen *HILE A SUBJECT of greater interest to architects, builders, and theatre owners, the general public should also be informed of the safety angle in the installation of air-conditioning equipment. One hears infrequently of fires in connection with an air-conditioning installation, yet there have been such, and so long as this equipment is installed there will be that ever-present hazard. Contractors installing air-conditioning equipment are, as a rule, closely observant of the rules and regulations of fire departments and the National Board of Fire Underwriters and of specifications of the particular city in which the installation is located. Yet there are some who, when unforeseen difficulties have cut into prospective profits, have cut corners (where something to say on this point. The table at the left is suggested by the Society as a good basis on which to start. • IN DISCUSSING humidity as a seatselling possibility, it was indicated that by juggling humidity, the same effect could be obtained as by changing the temperature. For example: At 76 degrees, the relative humidity of 51 is indicated by a wet-bulb temperature of 64 degrees. Suppose that the humidity were increased to 5 9 percent, with the same temperature, you would have the same effect as lowering the temperature (with the humidity apparatus untouched) to slightly below 74 degrees. Which method — changing the temperature or changing the humidity — is to be employed would largely depend on which of the factors is off at the time the change is desired. Where temperatures exceed 78 or are below 64 degrees, it is manifest from the Comfort Chart that a change of temperature must be effected, and where humidities are below 30 or over 70 percent, a change in the moisture content of the air must be made. But where the conditions to be changed are represented on the Comfort Chart, it is a matter of convenience and, for the large part, choice which is changed, the temperature or the humidity. it would not be seen in routine inspections) and used verboten materials or ignored special protective materials and equipment. The theatre man may well take a personal interest in his air-conditioning installation, where the workmen are just putting it in or where installation has already been made. There is nothing that the owner of a property, or the public that utilizes it, fears more than a fire during a period of occupancy. So what more valuable knowledge can a theatre man have than that his property is as near absolutely fire-proof as it is humanly possible to make it. • IT IS FITTING, therefore, at this time to give you a summary of a recent address by H. E. Newell, assistant chief engineer of the National Board of Fire Underwriters, on "Air-Conditioning Systems and Their Effect on Fire-Fighting Operations.” "Developments in modern building construction and the ever-present demand for greater comfort and luxury on the part of the public frequently bring about conditions, which, unless properly regulated, tend to increase the fire and life hazard. For this FIRE HAZARDS AND INSURANCE RULES ON AIR CONDITIONING March If, 19)9