ASHRAE HVAC APPLICATIONS IP CH 5-2015 PLACES OF ASSEMBLY.pdf

1、5.1CHAPTER 5PLACES OF ASSEMBLYGeneral Criteria. 5.1Houses of Worship . 5.3Auditoriums 5.3Arenas and Stadiums 5.4Convention and Exhibition Centers . 5.5Natatoriums 5.6Fairs and Other Temporary Exhibits 5.8Atriums . 5.9SSEMBLY rooms are generally large, have relatively high ceil-A ings, and are few in

2、 number for any given facility. They usuallyhave a periodically high density of occupancy per unit floor area, ascompared to other buildings, and thus have a relatively low designsensible heat ratio.This chapter summarizes some of the design concerns for en-closed assembly buildings. (Chapter 3, whi

3、ch covers general criteriafor commercial and public buildings, also includes information thatapplies to public assembly buildings.)1. GENERAL CRITERIAEnergy conservation codes and standards must be consideredbecause they have a major impact on design and performance.Assembly buildings may have relat

4、ively few hours of use perweek and may not be in full use when maximum outdoor tempera-tures or solar loading occur. Often they are fully occupied for as littleas 1 to 2 h, and the load may be materially reduced by precooling.The designer needs to obtain as much information as possible aboutthe anti

5、cipated hours of use, particularly times of full seating, so thatsimultaneous loads may be considered to optimize performance andoperating economy. Dehumidification requirements and part-loaddehumidification requirements should be considered before deter-mining equipment size. The intermittent or in

6、frequent nature of thecooling loads may allow these buildings to benefit from thermal stor-age systems.Occupants usually generate the major room cooling and ventila-tion load. The number of occupants is best determined from the seatcount, but when this is not available, it can be estimated at 7.5 to

7、10 ft2per person for the entire seating area, including exit aisles butnot the stage, performance areas, or entrance lobbies.Safety and SecurityAssembly buildings may need new safety and security consider-ations regarding extraordinary incidents. Designers should followthe recommendations outlined i

8、n Chapter 59.Outdoor AirOutdoor air ventilation rates as prescribed by ASHRAE Standard62.1 can be a major portion of the total load. The latent load (dehu-midification and humidification) and energy used to maintain rela-tive humidity within prescribed limits are also concerns. Humiditymust be maint

9、ained at proper levels to prevent mold and mildewgrowth and for acceptable indoor air quality and comfort.Lighting LoadsLighting loads are one of the few major loads that vary from onetype of assembly building to another. Levels can vary from 150 foot-candles in convention halls where television cam

10、eras are expected tobe used, to virtually nothing, as in a movie theater. In many assemblybuildings, lights are controlled by dimmers or other means to presenta suitably low level of light during performances, with much higherlighting levels during cleanup, when the house is nearly empty. Thedesigne

11、r should ascertain the light levels associated with maximumoccupancies, not only for economy but also to determine the properroom sensible heat ratio.Indoor Air ConditionsIndoor air temperature and humidity should follow ASHRAEcomfort recommendations in Chapter 9 of the 2013 ASHRAE Hand-bookFundamen

12、tals and ASHRAE Standard 55. In addition, thefollowing should be considered: In arenas, stadiums, gymnasiums, and movie theaters, people gen-erally dress informally. Summer indoor conditions may favor thewarmer end of the thermal comfort scale, and the winter indoortemperature may favor the cooler e

13、nd.In churches, concert halls, and theaters, most men wear jackets andties and women often wear suits. The temperature should favor themiddle range of design, and there should be little summer-to-wintervariation.In convention and exhibition centers, the public is continuallywalking. The indoor tempe

14、rature should favor the lower range ofcomfort conditions both in summer and in winter.In spaces with a high population density or with a sensible heatfactor of 0.75 or less, reheat should be considered.Energy conservation codes must be considered in both the designand during operation.Assembly areas

15、 generally require some reheat to maintain the rel-ative humidity at a suitably low level during periods of maximumoccupancy. Refrigerant hot gas or condenser water is well suited forthis purpose. Face-and-bypass control of low-temperature coolingcoils is also effective. In colder climates, it may a

16、lso be desirable toprovide humidification. High rates of internal gain may make evap-orative humidification attractive during economizer cooling.FiltrationMost places of assembly are minimally filtered with filters rated at30 to 35% efficiency, as tested in accordance with ASHRAE Stan-dard 52.1. Whe

17、re smoking is permitted, however, filters with a min-imum rating of 80% are required to remove tobacco smokeeffectively. Filters with 80% or higher efficiency are also recom-mended for facilities having particularly expensive interior decor.Because of the few operating hours of these facilities, the

18、 addedexpense of higher-efficiency filters can be justified by their longerlife. Low-efficiency prefilters are generally used with high-efficiencyfilters to extend their useful life. Ionization and chemically reactivefilters should be considered where high concentrations of smoke orodors are present

19、.Noise and Vibration ControlThe desired noise criteria (NC) vary with the type and quality ofthe facility. The need for noise control may be minimal in a gymna-sium or natatorium, but it is important in a concert hall. Multi-purpose facilities require noise control evaluation over the entirespectrum

20、 of use.The preparation of this chapter is assigned to TC 9.8, Large Building Air-Conditioning Applications.5.2 2015 ASHRAE HandbookHVAC ApplicationsIn most cases, sound and vibration control is required for bothequipment and duct systems, as well as in diffuser and grille selec-tion. When designing

21、 a performance theater or concert hall, anexperienced acoustics engineer should be consulted, because thequantity and quality or characteristic of the noise is very important.Transmission of vibration and noise can be decreased by mount-ing pipes, ducts, and equipment on a separate structure indepen

22、dentof the music hall. If the mechanical equipment space is close to themusic hall, the entire mechanical equipment room may need to befloated on isolators, including the floor slab, structural floor mem-bers, and other structural elements such as supporting pipes or sim-ilar materials that can carr

23、y vibrations. Properly designed inertiapads are often used under each piece of equipment. The equipmentis then mounted on vibration isolators.Manufacturers of vibration isolating equipment have devisedmethods to float large rooms and entire buildings on isolators.Where subway and street noise may be

24、 carried into the structure ofa music hall, it is necessary to float the entire music hall on isolators.If the music hall is isolated from outdoor noise and vibration, it alsomust be isolated from mechanical equipment and other internalnoise and vibrations.External noise from mechanical equipment su

25、ch as cooling tow-ers should not enter the building. Avoid designs that allow noises toenter the space through air intakes or reliefs and carelessly designedduct systems.For more details on noise and vibration control, see Chapter 48 ofthis volume and Chapter 8 in the 2013 ASHRAE HandbookFun-damenta

26、ls.Ancillary FacilitiesAncillary facilities are generally a part of any assembly building;almost all have some office space. Convention centers and manyauditoriums, arenas, and stadiums have restaurants and cocktaillounges. Churches may have apartments for clergy or a school.Many facilities have par

27、king structures. These varied ancillary facil-ities are discussed in other chapters of this volume. However, forreasonable operating economy, these facilities should be served byseparate systems when their hours of use differ from those of themain assembly areas.Air ConditioningBecause of their char

28、acteristic large size and need for considerableventilation air, assembly buildings are frequently served by single-zone or variable-volume systems providing 100% outdoor air. Sepa-rate air-handling units usually serve each zone, although multizone,dual-duct, or reheat types can also be applied with

29、lower operatingefficiency. In larger facilities, separate zones are generally providedfor entrance lobbies and arterial corridors that surround the seatingspace. Low-intensity radiant heating is often an efficient alternative.In some assembly rooms, folding or rolling partitions divide the spacefor

30、different functions, so a separate zone of control for each resultantspace is best. In extremely large facilities, several air-handling sys-tems may serve a single space, because of the limits of equipment sizeand also for energy and demand considerations.Peak Load ReductionThere are several techniq

31、ues currently in use to help address peakloads. Thermal storage is discussed in Chapter 51 of the 2012ASHRAE HandbookHVAC Systems and Equipment. Another pop-ular technique, precooling, can be managed by the building opera-tor. Precooling the building mass several degrees below the desiredindoor temp

32、erature several hours before it is occupied allows it toabsorb a part of the peak heat load. This cooling reduces the equip-ment size needed to meet short-term loads. The effect can be used ifcooling time of at least 1 h is available prior to occupancy, and thenonly when the period of peak load is r

33、elatively short (2 h or less).The designer must advise the owner that the space temperaturewill be cold to most people as occupancy begins, but will warm upas the performance progresses; this should be understood by all con-cerned before proceeding with precooling. Precooling works bestwhen the spac

34、e is used only occasionally during the hotter part ofthe day and when provision of full capacity for an occasional pur-pose is not economically justifiable.StratificationBecause most assembly buildings have relatively high ceilings,some heat may be allowed to stratify above the occupied zone,thereby

35、 reducing load on the equipment. Heat from lights can bestratified, except for the radiant portion (about 50% for fluorescentand 65% for incandescent or mercury-vapor fixtures). Similarly,only the radiant effect of the upper wall and roof load (about 33%)reaches the occupied space. Stratification on

36、ly occurs when air isadmitted and returned at a sufficiently low elevation so that it doesnot mix with the upper air. Conversely, stratification may increaseheating loads during periods of minimal occupancy in winter. Inthese cases, ceiling fans, air-handling systems, or high/low air dis-tribution m

37、ay be desirable to reduce stratification. Balconies mayalso be affected by stratification and should be well ventilated.Air DistributionIn assembly buildings with seating, people generally remain inone place throughout a performance, so they cannot move awayfrom drafts. Therefore, good air distribut

38、ion is essential. Airflow-modeling software could prove helpful in predicting potential prob-lem areas.Heating is seldom a major problem, except at entrances or duringwarm-up before occupancy. Generally, the seating area is isolatedfrom the exterior by lobbies, corridors, and other ancillary spaces.

39、For cooling, air can be supplied from the overhead space, where itmixes with heat from the lights and occupants. Return air openingscan also aid air distribution. Air returns located below seating or ata low level around the seating can effectively distribute air with min-imum drafts; however, regis

40、ter velocities over 275 fpm may causeobjectionable drafts and noise.Because of the configuration of these spaces, supply jet nozzleswith long throws of 50 to 150 ft may need to be installed on side-walls. For ceiling distribution, downward throw is not critical ifreturns are low. This approach has b

41、een successful in applicationsthat are not particularly noise-sensitive, but the designer needs toselect air distribution nozzles carefully.The air-conditioning systems must be quiet. This is difficult toachieve if supply air is expected to travel 30 ft or more from sidewalloutlets to condition the

42、center of the seating area. Because mosthouses of worship, theaters, and halls are large, high air dischargevelocities from the wall outlets are required. These high velocitiescan produce objectionable noise levels for people sitting near theoutlets. This can be avoided if the return air system does

43、 some of thework. The supply air must be discharged from the air outlet (pre-ferably at the ceiling) at the highest velocity consistent with anacceptable noise level. Although this velocity does not allow theconditioned air to reach all seats, the return air registers, which arelocated near seats no

44、t reached by the conditioned air, pull the air tocool or heat the audience, as required. In this way, supply air blan-kets the seating area and is pulled down uniformly by return air reg-isters under or beside the seats.A certain amount of exhaust air should be taken from the ceilingof the seating a

45、rea, preferably over the balcony (if there is one) toprevent pockets of hot air, which can produce a radiant effect andcause discomfort, as well as increase the cost of air conditioning.Where the ceiling is close to the audience (e.g., below balconies andPlaces of Assembly 5.3mezzanines), specially

46、designed plaques or air-distributing ceilingsshould be provided to absorb noise.Regular ceiling diffusers placed more than 30 ft apart normallygive acceptable results if careful engineering is applied in selectingthe diffusers. Because large air quantities are generally involved andbecause the build

47、ing is large, fairly large capacity diffusers, whichtend to be noisy, are frequently selected. Linear diffusers are moreacceptable architecturally and perform well if selected properly.Integral dampers in diffusers should not be used as the only meansof balancing because they generate intolerable am

48、ounts of noise,particularly in larger diffusers.Mechanical Equipment RoomsThe location of mechanical and electrical equipment roomsaffects the degree of sound attenuation treatment required. Thoselocated near the seating area are more critical because of the normalattenuation of sound through space.

49、 Those near the stage area arecritical because the stage is designed to project sound to the audi-ence. If possible, mechanical equipment rooms should be in an areaseparated from the main seating or stage area by buffers such as lob-bies or service areas. The economies of the structure, attenuation,equipment logistics, and site must be considered in selecting loca-tions for mechanical equipment rooms.At least one mechanical equipment room is placed near the roofto house the toilet exhaust, general exhaust, cooling tower, kitchen,and emergency stage exhaust fans, if any. Individual roof-mo