Architectural Engineering Design: Mechanical Systems

703 Pages·2002·0.24 MB·English

by  Robert Brown Butler

01. MECH Anterior 2/21/02 9:56 AM Page 21
Source: ARCHITECTURAL ENGINEERING DESIGN: MECHANICAL SYSTEMS
1
˛
¯¸ çÂ˙Â∏´ÂÒÂŲ¢
INTRODUCTION
1.A. GENERAL
This publication includes two Æ (architectural engineering) hand-
books,thisonedealingwiththedesignofmechanical systemsand related
components,the other doing the same with structural systems. Each vol-
ume also contains an interactive CD-ROM of its algebraic formulas that
enableseachequationtobesolved quicklyand accuratelybycomputer.
These handbooks and their accompanying disks contain architec-
tural engineering information and algebraic equations for conceptualiz-
ing,selecting,and sizingvirtuallyeveryfunctional componentinanykind
ofbuilding,fromshed toskyscraper,anywhereintheworld.Withtheseref-
erences,anÆdesignercanquicklydeterminewhetherafunctional compo-
nentis largeenoughto besafeforits intended purpose,yetnotso large
thatmoneyiswasted.Certainlythesevolume-cum-disksarethoroughcom-
pilations of technical knowledge acquired from academic study, official
research,and established officepractice. Buttheyalsocontaincountless
practical, insightful, and even a few horrifying anecdotes gleaned from
constructionexperiences,water-coolerdissertations,trademagazineedi-
fications, and numerous other in-the-field events as they relate to our
species’ongoingneed forsafeand comfortableshelter.
Thesepublicationsalsoemphasizethelatestcomputerized controls
being incorporated into every functional aspect of today’s buildings.
Today’s Æ designers cannot claim to be up with the times if they do not
understand TBM systems. This includes the incredible production and
energysavingstheycanbring,theproblemstheycreate,and thesolutions
today’sengineersareevolvingtoeliminatethelatter.
Thesevolumesalsostressthatavital aspectofanyfunctional com-
ponent’s design involves adequate access for maintaining it after con-
struction; because it can be said that no matter how good any part is, it
alwaysfailseventually. Architectsmaythink,and rightfullyso,thatmain-
tenance is not their problem; but accessing maintenance is no one else’s
problem. Morethanever before,occupants ofmodern buildings arepris-
onersofmaintenance; and today’sÆdesignersshould beanallytothese
¸
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01. MECH Anterior 2/21/02 9:56 AM Page 22
INTRODUCTION
2 ¯¸˛ÂçÂ˙Â∏´ÂÒÂÅÂ¿Â˘
often-overlooked confinementsand notanadversary.
These volumes also emphasize environmentally appropriate archi-
tecturewheneverpossible. Theyexpostulatetheviewthatnotonlyshould
every building inflict minimum damage to its site and environs, but every
material in them should inflict minimum environmental damage, undergo
minimum processing,create minimum packaging waste,and consume mini-
mum energy on its journey from its home in the earth to its grave on the
site. Indeed, the hallmarks of environmental design —more than econo-
mizingenergyuseand minimizingtoxicwaste— arecreatingmaximumcom-
fortinminimumvolumeand assemblingnatural materialssimply.Thereisa
vital reasonforthis: thewildernessratio,whichstatesthat
Everyurbansquaremilerequiresaboutfiftysquaremilesofwilderness
to purify its air,recycle its water,absorb its wastes,modify its climate,
and provide a substantial portion of its food and fiber needs without
economiccostorhumanmanagement.•
In architecture this is the ultimate catchment. The wilderness ratio indi-
catesthatweall mustdoeverythingwecantopreservenatureasmuchas
possible —notso our children may enjoy its serene majestysomeday,but
simplysotheymaybreathe.Thisisespeciallyimportantwithbuildings,for
their construction and operation is a conspicuously consumptive use of
natural resources; thusthispublicationpromoteseverypossibleenergy-
conserving measure involved in erecting and occupying built environ-
ments. Such concern certainly includes conservation of electricity; as in
theUnited Statesanestimated 35 percentofall CO (agreenhousegas),
2
65 percentofall SO (a leadingcontributorofacid rain),and 36 percent
2
ofall NO (amajoringredientofsmog) areproduced bythegenerationof
X
electricity.° Butsuch concern also involves advocating thicker envelope
insulation, structure with maximum strength-to-weight ratios, efficient
lighting and climate control systems,occupancy sensors that turn lights
and heatingoffwhenaspace isunoccupied,daylight harvestersthatdim
artificial lights when sunlight enters interior spaces, plumbing fixtures
with no-touch controls that reduce water consumption,TBM systems that
lead to lowerenergyuse,and anyothermeans ofproducing thegreatest
effect with the smallest mass or means. Each comprises environmental
designsofarasarchitecture isconcerned,asawayofprovidinggreater
opportunitytodothesameinthenearand farfuture.
Also let itnever besaid thatthesetwovolumes,intheirpreoccupa-
tionwitha building’ssolid parts,implythattheyaremore importantthan
the spaces they enclose. On the contrary! Obviously the Essence of
Architecture is creating habitable and comfortable interior spaces —for
without the voids,you have no solids. But just as obviously,you cannot
havethespaceswithouttheirdefiningsolids,afactthatLaotzepoetical-
lydescribed twenty-fivecenturiesagowhenhesaid:
•TheEcological House,RobertBrownButler(Morgan& Morgan,DobbsFerry,
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INTRODUCTION
INTRODUCTION 3
Thirtyspokesconvergeinthehubofawheel;
Butuseofthecartdependsonthepart
Ofthehubthatisvoid.
Aclaybowl ismolded byitsbaseand walls;
Butuseofthebowl dependsonthehole
Thatformsitscentral void.
Floor,walls,and roofformtheshapeofahouse;
Butuseoftheplacedependsonthespace
Withinthatisvoid.
Thusadvantageishad fromwhateverthereis;
Whileusederivesfromwhateverisnot.
Inthisendlessarchitectural interplay,theessenceofhabitablespaceun-
derlinestheneed foritsphysical imperatives —and thesebooks,bytheir
preoccupationwiththelatter,hopetoennoblethenatureoftheformer.
Finally, these volumes’ methods of selecting and sizing virtually
everyfunctional componentinabuilding—ofparingeachdowntoitsele-
mental natureand nothingmore— promoteall thatisbeautiful inarchitec-
ture. Forthetruestbeautyresultsfromdoingwhatissupremelyappropri-
ate and the subtraction ofall else. Forexample,takethecaryatids ofthe
ErechtheioninAthens,perhapstheloveliestcolumnseverdevised:onlywhen
eachslenderfemininewaistwasgiventheslimmestsectionthatwould support
the mass above could these graceful forms transcend the bland loyalty of
posts to become a beauty so supreme that they hardly seem like structural
supportsatall. Suchfunctional modelingisall abuildingneedstobebeau-
tiful. No excess. No frills. No confections masquerading as purpose. No
appliques àasaresooftenborrowed fromthealmsbasketofhistoricallyworn
architectural motifs whose perpetrators typically have no more concept of
theirmeaningthandid Titaniaofthedonkeyshecaressed.
Indeed, regarding architectural beauty, an Æ designer needs no
moreinspirationthanasimpleflower.Fromwhatdoesitsbeautyderive? Not
fromperpetratorsofvanity lurkingwithinthat blossom’scorm,yearningto
conjureatitillatingaspectuponaninnocenteye.And notfromanyexternal
molderswhoavertodothesame. No,its beautyderivesfromnothingmore
than the stern utilitarian arrangement ofeach tiny part,wherein each ele-
menthasthemostutilitariansize,eachhasthemostutilitarianshape,each
connectstoeachother inthemostutilitarianway,and each interfunctions
withtheothersinthemostutilitarianmanner,whereineachmoleculeineach
partislocated forapurpose—inwhicheventhedabsofgarishcoloronthe
frillypetalsare,atleasttoa bee’seye,nomorethanapplicationsofstern
utility.
Sobeitwithbuildings.
¸
NY,1981) °fromp. 2:OccupancySensorand LightingControls,aproduct
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INTRODUCTION
4 ¯¸˛ÂçÂ˙Â∏´ÂÒÂÅÂ¿Â˘
1.A.1. Terms & Symbols
The architectural symbols and abbreviations used throughout this
textarelisted below. Familiarquantities havetheusual letters (e.g.d for
thedepthofabeam),butmostaresymbolized bytheletterthatbesttypi-
fies them in each problem. Thus one letter may denote differentvalues in
differentformulas. Inthisbook,formulascontainnofractionsunlessuna-
voidable (e.g. A = B/ is written as A C = B or B = A C), partial integers
C
appearasdecimalsinstead offractions(e.g.™appearsas0.5),feet-and-
inchdimensionsusuallyappearasdecimalstothenearesthundredthofa
foot (thus 2'-45/" is written as 2.39 ft), and degree-minute-second angle
8
measures are expressed in degrees to four significant figures (thus 31˚-
43'-03" becomes 31.7175˚); as in each instance such notation is cleaner
and takesuplessspace. Also,numerical valuesareusuallytakentothree
significantfiguresinexact-valueequations(A =B) and totwosignificant
figuresinestimate-valueequations(A ≈B); and mostweightand measure
abbreviationsarenotfollowed byaperiod (e.g. ft,lb,sec). However,inch
is abbreviated as in. to differentiate it from the word in; but even this
measuremayhavenoperiod afteritifitsmeaningisobvious,asinin/¬.
Throughoutthistext,takecaretousethesameunitsofmeasureas
listed in each equation’s menu ofunknowns. For example,ifa quantity is
in feet and your data are in inches, be sure to convertyour data to feet
beforesolvingtheequation.
1.A.1.a. Mathematical Symbols
Symbol Meaning
= Leftsideofequationequalsrightside.
≈ Leftsideofequationapproximatelyequalsrightside.
≠ Leftsideofequationdoesnotequal rightside.
≥ Leftsideofequationequalsorisgreaterthanrightside.
≤ Leftsideofequationequalsorislessthanrightside.
» Twostraightlinesorflatplaneareperpendiculartoeach
other.
|| Twostraightlinesorflatsurfacesareparallel toeachother.
A0.5 SquarerootofA; Atothe0.5 power. Thisbook’sexponential
expressionsarenotwrittenwithsquarerootsigns.
|A| UseonlytheintegerportionofvalueA. E.g. |2.39| =2.
|Aã| UsenexthighestintegerabovevalueA.E.g. |2.39 ã| =3.
|Aã| Usethenexthighestmultipleof0.5 aboveA. E.g. |2.39 ã| =
0.5 0.5
2.50. Similarly,|Aã| meanstousethenexthighestmultiple
2.0
brochureforLevitonMfg. Co. (LittleNeck,NY,1996),p. 3.
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INTRODUCTION
INTRODUCTION 5
of2 aboveA; e.g. |2.39 ã| =4.00.
2.0
sinA SineofangleA. Inarighttriangle,sinA=opposite
side/hypotenuse,cosA=adjacentside/hypotenuse,and tan
A=oppositeside/adjacentside.
sin«1 A ArcsinA,orsineoftheanglewhosevalueisA.IfsinA=B,then
sin«1B=A; alsotrueforcos«1Aand tan«1A.Thisbookdoesnot
usethetermsasin,acos,and atan.
π Pi,equal to3.1416.
5'-11" Fiveftelevenin,or5.92 ft.
31˚43'03" 31degrees,43 minutes,3 seconds; or31.7175˚. 1˚=1.0000˚,
01'=0.0167˚,and 01"=0.000278˚. Inthisbook,anglemeas-
uresareneverinradians.
ª (1) Themostdesirableofseveral valuesunderconsideration.
(2) Desirablecharacteristicsofabuildingcomponent.
ª Undesirablecharacteristicsofabuilding component.
1.A.1.b. Abbreviations and Terms in the Text
Symbol Meaning
A Amp,amps,ampere,amperes.
Æ Acronymforarchitectural engineering.
Å Sabin(s): ameasureofsound absorption
ac Acre(s). 1ac=43,560 ft2. Asquareacre=208.71ftoneach
side. 640 ac=1sqmi.
ach Airchangesperhour.
apsi Atmosphericpressurebased on0 psi atacompletevacuum.
14.7apsi =0.0 spsi.
ASL Abovesealevel; e.g. 5,280 ftASL.
ß Total rayorbeamconcentrationfactor: alightfixture’sratio
ofspherical-to-axial output.
Btu BritishThermal Unit(s):amountofheatrequired toraisethe
temperatureof1lbofwater1˚F. 1Btu=0.293 watts.
C Celsius,aunitoftemperaturemeasurebased ontheKelvin
scale; alsoCentigrade. Waterfreezesat0˚Cand boilsat
100˚C. 1˚C=1.8˚F. 0˚C=273 K=32˚F.
∫ Coolingload: atermused inclimatecontrol systemdesign.
cd Candela: thebasicmetricunitofluminousintensity.
1.00 candelas=12.6 footcandles.
CDCP Centerbeamcandlepower,measured incandelas; lightoutput
alongtheaxisofalampwithaspecified beamspread.
ç Centerline. Center-to-centerisç-ç,and çofgravityrefersto
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INTRODUCTION
6 ¯¸˛ÂçÂ˙Â∏´ÂÒÂÅÂ¿Â˘
ashape’senterofgravity.
¢ Unitcostincents.
‹ Circuitryload: capacityofanelectrical circuitorcomponent
inamps,volts,orwatts.
cf Cubicfeet. cfm=cubicfeetperminute.
cmil Circularmil,(alsoCM),aunitofsizeforelectricwire. 1cmil =
areaofacircle1mil (0.001in.) indiameter. C-Sareaofa1
in.diameterwire=1,000,000 cmil.
Ç RoomCoefficientofUtilization: theratioofuseful lightto
actual lightinanarchitectural space.
Î Amountofdaylightingarrivingataninteriorspaceorvisual
task,measured infootcandles(fc).
fi Decibel,ordecibels: ameasureofsound intensity.
∆ differenceorchangeofaquantitysuchastemperature,
pressuredrop,operatingcosts,etc.
∂ (1) diameterofacircle; (2) depreciationofilluminationdueto
factorssuchasvoltagefluctuation,dirtaccumulation,temper-
atureincrease,maintenancecycles,and rated lamplife.
$ Unitortotal costindollars.
é Efficiencyofamechanical orelectrical componentorsystem,
usuallymeasured inpercent.
É Total electrical load ofaconductororsystem.
F Fahrenheit: aunitoftemperaturebased ontheRankine
scale. Waterfreezesat32˚Fand boilsat212˚F. 1˚F=
0.556˚C. 32˚F=0˚C=273 K=492˚R.
fc Footcandle(s): aunitoflightintensityarrivingfromanatu-
ral orartificial lightsource; alsoilluminance. 1.0 fc=amount
oflightincidentona» surface1.0 ftfromacandle.
ft Foot,orfeet. ft2 =squarefoot,ft3 =cubicfoot. 1ft3ofwater=
7.48 gal =62.4 lb.
ft2/min Squarefeetperminute.
fall/ft Fall perlinearfoot: e.g. 0.5 in/ft=™in.downward foreach
horizontal footoutward.Alsoknownasslope,incline,orpitch.
All thesetermsaredenoted bythesymbol å.
fpm Feetperminute. fps=feetpersecond.
f.u. Fixtureunit: aunitforestimatingwaterflowintooroutofa
plumbingfixture. 1f.u. ≈2 gpmoffluid flow.
gal Gallon(s). gpm=gallonsperminute.
gr Grain: aunitofweight. 7,000 gr=1lb.
˙ Heatingload: atermused inclimatecontrol systemdesign.
Ó Horsepower. 1Ó=746 watts=33,000 ft-lb.
hr Hour(s). 8,760 hr=1yr. 720 hr≈1month.
Hz Hertz,orcyclespersecond:(1) aunitoffrequencyforalternat-
ingelectrical current,usually60 Hz.; (2) thevibrationfrequency
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INTRODUCTION
INTRODUCTION 7
ofasound,usuallybetween20 and 8,000 Hz.
Ï Illuminance: theamountofillumination,measured infootcan-
dles(fc),arrivingatavisual taskfromalightsource.
IIC Impactisolationclass: aunitformeasuringsolid-borne
sound absorbed byatypeofbuildingconstruction; alsoI .
IC
in. Inch(es). in2 =squareinch. in3 =cubicinch.
in.wc incheswatercolumn: ameasureofairpressure; alsoin.wg
(incheswatergauge). 407.4 in.wc=33.95 ftwc=14.7psi=
30.0 in.Hg(mercury) =1.00 atmosphereat62˚F.
 Atermused todenoteaconstantorcoefficient.
k unitofthermal conductivityforaninsulationortypeofcon-
struction. k=Uperin. thicknessofinsulation.
K Kelvin: aunitofabsolutetemperatureontheCelsiusscale.
1K=1˚C. 0˚K=absolutezero=273˚C.
kWh Kilowatt-hour: aunitofelectrical powerequal to1,000 watts
ofelectricityconsumed perhour.
¥ (1) unitlightsourcelengthorwidthfactor: theeffectivedis-
tancebetweenalightsourceand itstaskplanebased ona
ratioofthelightsource’sfacelengthorwidthand thedis-
tancebetweenitand thetaskplane; (2) wavelengthofa
sound,measured incyclespersecond (Hz).
lb Pound(s). 13.8 cfofdryairatroomtemperatureweighs1lb.
lb/ft2 Poundspersquarefoot; alsopsf. Lb/in2=psi =poundsper
squareinch; lb/in3 =poundspercubicinch; lb/lf=p¬ =
poundsperlinearfoot.
¤ Outputofanartificial lightsource,measured inlumens(lm).
¬ Linearfootorfeet.
lm Lumen: aunitoflightenergyemitted fromanatural orartifi-
cial lightsource. Onecandleemits12.6 lmoflight.
log Logarithm. Inthisvolumeall logarithmsaretothebase10.
Ò Loudnesslimit:differencebetweentheemitted and received
soundsoftwoadjacentspaces,measured infi.
max. Maximum.
min. (1) minimum; (2) minute.
mi Mile(s); mi2 =squaremile(s). mph=milesperhourormi/hr.
mo Month.
ı Unitnear-field lengthorwidthfactor: theeffectiveamountof
lightemitted fromanatural orartificial lightsourcebased
onaratioofthelightsource’sfacelengthorwidthand the
distancebetweenitand thetaskplane.
˜ Lightsourcenear-field factor: theeffectiveamountoflight
arrivingatataskplanebased onthelightsource’slampand
near-field factors¥ ,¥ ,ı and ı .
L W L, W
NG Nogood:thevaluebeingconsidered isnotacceptable.
¸
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INTRODUCTION
8 ¯¸˛ÂçÂ˙Â∏´ÂÒÂÅÂ¿Â˘
N2G Nottoogood: thevaluebeingconsidered maybeacceptable
butisnotverysatisfactory.
¸ Numberorquantityofabuildingmaterial,component,orsim-
ilarentity; usuallyanunknownfactor.
ΠOccupancyfactor: thenumberoffeasibleoractual occu-
pantsoccupyingafloorareainabuilding.
o.c. Oncenter: referstoadimensionfromthecenterlinesoftwo
materialsorassemblies; alsocenter-to-centerorç-ç.
OK Okay: thevaluebeingconsidered isacceptable.
? Aquantityortermwhosevalueispresentlyunknown.
ø Phasefactor(e.g.singleorthreephase) forelectricwiring.
∏ Pipeflow:volumeofliquid orgasflowingthroughaplumbing
pipe,conduit,orsystem.
p¬ Poundsperlinearfoot.
ppd Pipepressuredrop: theamountofpressurelossexperienced
byaliquid orgasflowingthroughalengthofpipedueto
friction; alsoknownas∆P.
ppm Partspermillion.
psf Poundspersquarefoot.
psi Poundspersquareinch.
Q Airflowvelocity:speed ofsupplyorreturnairthroughaduct,
measured infps,mph,orcfm.
„ Rated power(wattage) ofagenerator,motor,pump,orother
componentthateitherproducesorconsumeselectricity.
R (1) Rankine,aunitofabsolutetemperatureonthe
Fahrenheitscale. 1˚R=1˚F. 0˚R=absolutezero=–460˚F.
(2) thermal resistanceofaninsulationorconstruction
assembly; alsoknownasR-factor. R=1/ .
U
® Rayconcentrationfactor. Alightfixture’sspherical raysmay
beconcentrated duetoanenclosurefactor® ,ageometric
e
contourfactor® ,and areflectorfinishfactor® .
c f
r.h. Relativehumidity: amountofmoistureintheairrelativetoits
saturationatagiventemperature.
å Slope,incline,orpitchofalineardirectionorsurface.
sec Second(s). 60 sec=1min.
Ï Solarheatgain: ameasureofsolarheatenergyenteringan
interiorspaceduringcold weather; alsoinsolationorinci-
dentclear-dayinsolation.
˝ Specificgravity: theunitweightofasolid orliquid compared
tothatofwater(˝ ofwater=1.00),ortheunitweightofa
gascompared tothatofair(˝ ofair=1.00).
sf Squarefoot(feet). 100 sf=1square.
spsi Standard pressurebased on0 psi atatmosphericpressure.
0.0 spsi =14.7apsi.
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INTRODUCTION
INTRODUCTION 9
STC Sound TransmissionClass: aunitformeasuringsound
absorbed byatypeofbuildingconstruction; alsoS .
TC
ton (1) ameasureofweightthatequals2,000 lb; (2) ameasureof
heatingorcoolingcapacitythatequals12,000 Btu. 1tonis
alsotheapproximateweightof32 ft3ofwater.
† Transmittance: portionoflightpassingthroughglazingor
othertransparentortranslucentmaterial.
U Aunitofthermal conductivityforaninsulationortypeofbuild-
ingconstruction,usuallypartofabuildingenvelope; also
knownasU-factor. U=1/ =k ˛thicknessofinsulation(in).
R
u.o.n. Unlessotherwisenoted: apopularabbreviationinarchitec-
tural workingdrawings.
√ Kinematicviscosityofacontained liquid,usuallymeasured in
ft2/sec.
√ Velocity,usuallymeasured infpsormph.
V Volt(s):unitofelectromotiveforceinanelectrical circuit.
VG Verygood: thevaluebeingconsidered isdesirable.
W Watts: aunitofpowerinanelectrical circuit,appliance,or
electrical component. 1watt=1amp˛1volt; orW=AV.
yd Yard(s). Yd2 =squareyard(s). yd3=cubicyard(s).
yr Year(s): aunitoftime. Ameansolaryear is365 days,
5 hours,48 minutes,and 49.7secondslong.
1.A.1.c. Unusual Terms in the Text
aspectratio Ratioofalongsidetoashortsideofarectangularduct.
azimuth Thesun’sorientationfromtruenorth,degrees; e.g.136˚E
ofN describesananglewithonesideaimed atduenorth
and theothersideaimed 136˚east(clockwise) ofduenorth.
belvedere Abox-likeventilatorwithlouversoneachsidelocated on
thepeakofagableroof; itutilizestheprevailingwindflow
todrawwarmairfrominteriorspacesbelow.
berm Ausuallylong,narrow,several-foot-highriseinterrain
thatisoftenartificiallymadetoshield abuildingfromcli-
maticforces,blockunwanted sightlines,directwater
runoff,introduceslopingcontours,protectutilitycon-
veyancesintheground below,and thelike.
bus Arigid copperoraluminumbar,tube,orrod thatconducts
electricity; alsobusbarorbusbar.
busway Arigid metal conduitthatenclosesand protectsabusor
busbar; alsobus ductorbusduct.
cobrahead Aroadwayluminairemounted onatall postwhosetop
¸
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