ASHRAE Journal - June 2009 - 61

ASHRAE 19 50 59–2009 YE A R S JOURNAL cloud. There is a seeing distance of F I G . 1 Smoke tests were conducted in the stadium to determine acceptable limit of smoke cloud. about 540 ft, as a maximum, from which the spectators would be able to see a football clearly. Having observed the smoke cloud that occurs in open air stadiums when viewed at night over the crowd, when floodlights make the smoke particularly visible, it was realized that tobacco smoke might possibly present a real problem. If it were to be a problem, there was a question as to what l. The amount of light required for growth in the summer. the solution might be, and more than this, how it could be 2. The amount of light required for keeping the grass examined to begin with. alive in the winter. Another matter which was of particular interest in the 3. The effect of temperature variations on the grass and feasibility question was in regard to possible “weather.” An the effect of changes in humidity. experience had been reported previously regarding large 4. The kind of grass best suited for the application. dirigible hangars, where unusual weather conditions were The latter, in turn, involved the ability to grow the grass reported to have resulted in rainfall inside the hangar, even outdoors in the Houston area as well as its ability to propathough it was not raining outside. There was speculation gate properly under the limited light and controlled condithat we might have such a situation in the stadium where fog, haze, self-generated turbulence in the nature of a tortions inside. nado, cloud formations or even rain, might conceivably be The acoustical problem was studied, and it was deterexperienced. Was this something which really could hapmined that approximately 50% of the roof area must be pen or was it only a fear with no real basis? devoted to sound-absorbing materials. This limited the The next question concerned the method of temperature light-admitting areas to those not acoustically treated. In control. How could the temperature be controlled in so studying the roof problem it was realized that the amount large an area, with particular emphasis on location of ther- of light required for the grass had to be held at a minimostats, the type of control automation required, and the mum, since this also adds to the cooling load. The design type of air systems required to obtain proper temperature of the light admitting panels would also determine the control. There was some concern that temperature sensing heating load as well as affect the stratification problem. The would be difficult in the seating areas at locations where solutions to the various matters involved in the roof design it would be meaningful. There might be some question as took place in several steps. In the first, there was an inito the particular system from which the air finally reached tial consultation with a physicist regarding the amount of some specific point. That is, we might find that, due to light, in foot-candle hours, that might be anticipated from turbulence, the air in a given area was not always comthe area of the roof available for admitting light. ing from the same air handling system. Further, with the Second, a preliminary calculation of the cooling load was extreme height involved, stratification could be particularly required to prepare early cost estimates and indicate air hanserious, especially in the winter, and there was a question dling requirements. as to whether this could be avoided. Third, a search of literature was made, relating to the In arriving at solutions, each of the problems was given smoke problem and the planning of proper tests. careful consideration and answers were obtained either by Fourth, research was initiated into air distribution in a theoretical analysis, experimentation or both. In the roof large space. design, grass-growing problems had to be examined and Fifth, an analysis was made of the thermodynamics and experiments performed to provide data on such items as: psychrometrics of the possible weather problem. June 2009 ASHRAE Journal 61

ASHRAE Journal - June 2009

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