ASHRAE HVAC APPLICATIONS IP CH 7-2015 EDUCATIONAL FACILITIES.pdf

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1、7.1CHAPTER 7EDUCATIONAL FACILITIESPreschools 7.1K-12 Schools 7.2Colleges and Universities 7.11Sustainability and Energy Efficiency . 7.13Energy Considerations. 7.15Energy Measurement and Verification (M consider treating this area asa separate zone.Preschool facilities generally operate on weekdays

2、from early inthe morning to 6:00 or 7:00 PM. This schedule usually coincides withthe normal working hours of the childrens parents plus one hour fordrop-off and pick-up. The HVAC systems therefore operate 12 to14 h per workday, and may be off or on at night and weekends,depending on whether setback

3、is applied.Supply air outlets should be positioned so that the floor area ismaintained at about 75F without introducing drafts. Both supplyand return air outlets should be placed where they will not beblocked by furniture positioned along the walls or where childrencan reach them. Coordination with

4、the architect about locating theseoutlets is essential. Proper ventilation is crucial for controlling odorsand helping prevent the spread of diseases among the children.Floor-mounted heating equipment, such as electric baseboardsheaters, should be avoided because children must be prevented fromcomin

5、g in contact with hot surfaces or electrical devices. However,radiant-floor systems can be used safely and effectively.Design CriteriaTable 1 provides typical indoor design conditions for preschools.Table 2 provides typical ventilation and exhaust design criteriausing the ventilation rate procedure

6、of ANSI/ASHRAE Standard62.1-2013. Table 3 lists design criteria for acceptable noise in pre-school facilities.Load CharacteristicsPreschool cooling and heating loads depend heavily on ambientconditions, because the rooms typically have exterior exposures(walls, windows, and roofs) and also relativel

7、y higher needs for ven-tilation. Although preschool facilities are relatively small, the designengineer must pay special attention to properly calculate the cooling,heating, dehumidification, and humidification loads. Sizing andapplying the HVAC equipment is critical for handling the loads andthe la

8、rge amounts of outdoor air from a capacity and occurrencestandpoint (peak sensible and latent loads do not always coincide).Humidity ControlPreschool classrooms require humidity control to provide humancomfort and prevent health problems. Maintaining humidity levelsbetween 30 and 60F dew point satis

9、fies nearly all people nearly allthe time. However, the designer should discuss comfort expectationswith the owner, to avoid misunderstandings.In hot and humid climates, it is recommended that air condition-ing and/or dehumidification be operated year-round to preventgrowth of mold and mildew. Dehum

10、idification can be improved byadding optional condenser heat/reheat coils, heat pipes, or air-to-airheat exchangers in conjunction with humidity sensors in the condi-tioned space or return air.Additional information on humidity control is in the section onK-12 Schools.Systems and Equipment Selection

11、HVAC systems for preschools are typically decentralized, usingeither self-contained or split air-conditioners or heat pumps (typicallyThe preparation of this chapter is assigned to TC 9.7, Educational Facilities.Table 1 Recommended Temperature and Humidity Design Criteria for Various Spaces in Presc

12、hoolsCategory/Humidity CriteriaIndoor Design Conditions, FWinter SummerInfant, Toddler, and Preschooler Classroomsa30% rh 72.2 to 79.1 76.2 to 81.540% rh 72.2 to 78.5 75.8 to 81.050% rh 71.8 to 78.0 75.3 to 80.560% rh 71.3 to 77.5 74.9 to 80.0Administrative, Offices, Lobby, Kitchen30 to 60% rh 72.2

13、to 77.5 76.2 to 80.0StorageNo humidity control 64.0Mechanical RoomsbNo humidity control 61.0Notes:aBased on ASHRAE Thermal Comfort Tool (ASHRAE 2010) v. 2.0.03, for peoplewearing typical summer and winter clothing, 0.6 and 0.9 clo, respectively, at sedentaryactivity (1.0 met). Air speed assumed at 1

14、9.7 fpm and mean radiant temperature(MRT) assumed equal to air temperature. Temperature range is within acceptableASHRAE Standard 55 range (0.5 Predicted mean vote (PMV) +0.5) using theanalytical comfort zone method, section 5.3.2 of ASHRAE Standard 55-2013.bUsually not conditioned.7.2 2015 ASHRAE H

15、andbookHVAC Applicationsair- or water-source). When the preschool is part of a larger facility,utilities such as chilled water, hot water, or steam from a central plantcan be used. When natural gas is available, the heating system can bea gas-fired furnace, or, when economically justifiable, electri

16、c heatcan be used.The type of HVAC equipment selected also depends on the cli-mate and the months of operation. In hot and dry climates, forinstance, the primary type of cooling may be evaporative. In colderclimates, heating can also be provided by a hot-water hydronic sys-tem originating from a boi

17、ler plant in conjunction with radiant flooror hot-water coils. For small, decentralized systems without centralbuilding control, a zone-level programmable temperature control isrecommended (if not required by local code).Decentralized systems are dedicated systems serving a singlezone, and typically

18、 include the following:Direct-expansion (DX) split systemsRooftop packaged air conditioners or heat pumps with or withoutoptional enhanced dehumidification (condenser reheat coil)Rooftop packaged air conditioners or heat pumps integrated withan energy recovery module, with optional enhanced dehumidi

19、-fication (condenser reheat coil; see Figure 5). Consult ANSI/ASHRAE/IESNA Standard 90.1-2013, section 6.5.6.1, for caseswith a high percentage of outdoor air.Water-source heat pumps (with cooling tower and supplementaryboiler)Geothermal heat pumps (ground-coupled, ground-water-source,surface-water-

20、source)Packaged dedicated outdoor air systems with DX system for cool-ing and gas-fired furnace, electric heating, or part of water-sourceand geothermal heat pump systemInformation about decentralized systems can be found inChapters 5, 18, 49, and 50 of the 2012 ASHRAE HandbookHVACSystems and Equipm

21、ent. Additional information on geothermal heatpumps can be found in Kavanaugh and Rafferty (1997) and Chapter34 of this volume. Chapter 6 of the 2012 ASHRAE HandbookHVAC Systems and Equipment provides information on radiantheating.Note that some decentralized systems may need additionalacoustical mo

22、difications to meet the design criteria in Table 3.Therefore, it is strongly recommended to carefully check the acous-tical implications of applying these systems.Dedicated Outdoor Air Systems (DOASs). SpecializedDOASs should be used to treat outdoor air before it is introducedinto classrooms or oth

23、er areas. DOAS units can bring 100% out-door air to at least space conditions, which allows the individualspace units to handle only the space cooling and heating loads. Adetailed description of DOAS is provided in the K-12 Schoolssection of this chapter. Additional information can be found inChapte

24、r 25 of the 2012 ASHRAE HandbookHVAC Systems andEquipment.Systems Selection by Application. Table 4 shows the applica-bility of systems to areas in preschool facilities.2. K-12 SCHOOLSGeneral and Design ConsiderationsK (kindergarten)-12 schools typically include elementary, mid-dle (or junior high),

25、 and high schools. These facilities are typicallyone- to three-story buildings.Elementary schools are generally comprised of 10 to 15 class-rooms plus cafeteria, administration, gymnasium, and library areas.Elementary schools are typically used during the school season (lateAugust to June); during s

26、ummer, they are typically closed or haveminimal activity. Current trends include science classrooms and aTable 2 Typical Recommended Design Criteria for Ventilation and Filtration for PreschoolsCategoryVentilation and Exhausta, g, jMinimum Filtration Efficiency, MERVhOutdoor Air, cfm/PersonOccupant

27、Densitykper 1000 ft2Outdoor Aircfm/ft2cfm/UnitInfant, Toddler, and Preschooler Classroomsb17 25 6 to 8Administrative and Office Spacec17 5 6 to 8Kitchend0.3 (exhaust)iToiletse50 (exhaust) NAStoragef0.12 1 to 4Notes:aBased on ANSI/ASHRAE Standard 62.1-2013, Table 6.2.2.1, default values for ven-tilat

28、ion, and Table 6-5 for exhaust rates.bBased on ASHRAE Standard 62.1-2013, Table 6.2.2.1, default values for educationalfacilities-daycare.cBased on ASHRAE Standard 62.1-2013, Table 6.2.2.1, default values for office build-ings/office spaces.dBased on ASHRAE Standard 62.1-2013, Table 6.5, for kitchen

29、ettes.eBased on ASHRAE Standard 62.1-2013, Table 6.5, for private toilets (rate is for toiletroom intended to be occupied by one person).fBased on ASHRAE Standard 62.1-2013, Table 6.5, for storage rooms.gThis table should not be used as the only source for design criteria. Governing localcodes, desi

30、gn guidelines, and ASHRAE Standard 62.1-2013 with current addendamust be consulted.hMERV = minimum efficiency reporting values, based on ASHRAE Standard 52.2-2012.iSee Chapter 33 for additional information on kitchen ventilation.jConsult local codes for exhaust requirements.kUse default occupancy de

31、nsity when actual occupant density is not known.Table 3 Typical Recommended Design Guidelines for HVAC- Related Background Sound for Preschool FacilitiesCategorySound Criteriaa, bCommentsNC/RCInfant, Toddler, and Preschooler Classrooms30Administrative/Office Areas 40 For open-plan officeService/Supp

32、ort Areas 35 to 45Notes:aBased on Chapter 48.bRC (Room Criterion), from Chapter 8 of 2013 ASHRAE HandbookFundamentals.Table 4 Applicability of Systems to Typical AreasdTypical AreaDecentralized Cooling/Heating SystemscHeating OnlyRadiant FloorbPSZ/SZSplitPSZ with Energy Recovery and Dehumidification

33、 WSHPGeothermalHeatPumpClassrooms XaXaXXXAdministrative Areas, LobbyXXXKitchenVentilation(Outdoor Air)DOAS DOAS DOAS DOASSZ = single zone PSZ = packaged single zoneWSHP = water-source heat pump DOAS = dedicated outdoor air systemNotes:aPSZ for classrooms requires individual thermostatic control.bTyp

34、ically with cooling system such as PSZ/SZ split.cHeating system for PSZ/SZ split can be gas furnace, hot-water coil, or electric.dSee Table 10 for additional systems if preschool is not a stand-alone facility.Educational Facilities 7.3preschool facility. Typical elementary schools operate between7:0

35、0 AM and 4:00 PM.Middle schools are larger than elementary schools and includeadditional computer classrooms and locker rooms. Their hours ofoperation are longer because of extracurricular activities. A recenttrend toward eliminating middle schools (retaining traditional K-8elementary and 9-12 high

36、schools) (Wright 2003) may require thatelementary school designs incorporate some middle school features.High schools also include a cafeteria and auditorium, and mayinclude a natatorium, ice-skating rink, etc. High schools operatelonger hours and are often open during the summer, either as a sum-me

37、r school or to use special facilities such as gymnasiums, natato-riums, etc.Typical areas found in K-12 schools are shown in Table 5.K-12 schools require an efficiently controlled atmosphere for aproper learning environment. This involves the selection of HVACsystems, equipment, and controls to prov

38、ide adequate ventilation andindoor air quality (IAQ), comfort, and a quiet atmosphere. The systemmust also be easily maintained by the facilitys maintenance staff.The following are general design considerations for each of theareas typically found in K-12 schools:Classrooms. Classrooms typically ran

39、ge between 900 and1000 ft2, and are typically designed for 20 to 30 students. Eachclassroom should be, at a minimum, heated and ventilated. Airconditioning should be seriously considered for school districtsthat have year-round classes in warm, humid climates. In humidclimates, seriously consider pr

40、oviding dehumidification duringsummer, even if the school is unoccupied, to prevent mold andmildew.Science Classrooms. Science rooms are now being provided forelementary schools. Although the children do not usually performexperiments, odors may be generated if the teacher demonstrates anexperiment

41、or if animals are kept in the classroom. Under these con-ditions, adequate ventilation is essential along with an exhaust fanwith a local, timer-based (e.g., 0 to 60 min) on/off switch for occa-sional removal of excessive odors.Computer Classrooms. These rooms have a high sensible heatload because o

42、f the computer equipment. They may requireadditional cooling equipment such as small spot-cooling units tooffset the additional load. Humidification may also be required. SeeChapter 19 for additional information.Educational Laboratories. Middle and high school laboratoriesand science facilities may

43、require fume hoods with special exhaustsystems. A makeup air system may be required if there are severalfume hoods in a room. If there are no fume hoods, a room exhaustsystem is recommended for odor removal, depending on the type ofexperiments conducted in the room and whether animals are keptthere;

44、 when applicable, a local exhaust with on/off switch and atimer can be considered. Associated storage and preparation roomsare generally exhausted continuously to remove odors and vaporsemanating from stored materials. The amount of exhaust and loca-tion of exhaust grilles may be dictated by local c

45、odes or NationalFire Protection Association (NFPA) standards. See Chapter 16 forfurther information. Additional information on laboratories can befound in ANSI/AIHA Standard Z9.5-2012 and McIntosh et al.(2001).Administrative Areas. The office area should be set up for indi-vidual control because it

46、is usually occupied during and after schoolhours. Because offices are also occupied before school starts in thefall, air conditioning for the area should be considered or provisionsshould be allowed for future upgrades.Gymnasiums. Gyms may be used after regular school hours forevening classes, meeti

47、ngs, and other functions. The gym may alsobe used on weekends for group activities. Loads for these occasionaluses should be considered when selecting and sizing the systemsand equipment. Independent gymnasium HVAC systems with con-trol capability allow for flexibility with smaller part-load condi-t

48、ions. If a wooden floor is installed, humidity control should beconsidered to avoid costly damage.Libraries. Libraries should be air conditioned to preserve thebooks and materials stored in them. See Chapters 3 and 23 for addi-tional information.Auditoriums. These facilities require a quiet atmosphe

49、re as wellas heating, ventilation, and, in some cases, air conditioning. Audi-toriums are not often used, except for assemblies, practice for pro-grams, and special events. For other considerations, see Chapter 5.Home Economics Rooms. These rooms usually have a high sen-sible heat load from appliances such as washing machines, dryers,stoves, ovens, and sewing machines. Different options should beconsidered for exhaust of stoves and dryers. If local codes allow,residential-style range hoods may be installed over the stoves. Acentral exhaust system could be applied to the dryers as