Cap_8_Libro Jeffrey D. Spitler

8/12/2019 Cap_8_Libro Jeffrey D. Spitler

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Chapter 8

CLTD SCL CLF METHOD

The cooling lo ad for a building or zone results from foursources: conduct ive heat gai n through surfaces such as windows, walls, and roofs; so lar heat gain through fenestrations; interna heat gain from lights, people, and eq uipment; and heat gain from infiltration. The CLTD/SCL/CLF method is a hand calculation procedure, based on theTransfer Function Method (TFM), to determine the cooling load corresponding to the first three modes of heat gain.The acronyms are defined as follows:

CLTD-Coo ling Load Temperature DifferenceSCL-Solar Co o lin g LoadCLF-Coo ling Load Factor

Infiltration calculations are discussed in Chapter 6. The

TFM procedure is discussed in Chapter 2 and Appendix ABackground and development of the CLTD/SCL/CLFmethod is given in Appendix C.

The CLTD/SCL/CLF tables given in this chapter werege nerat ed using a program based on the Transfer FunctionMethod, Chapter 2, and are Iimited in their scope of application. Therefore, the user may wish to generate differenttables. The computer program CLTDTAB resides on DiskNo. 2 and is described with inst ructi ons for u se in Appendix C. The program has two options.

Option 1-Thi s option generates CLTD/SCL/CLFvalues for a particula r Iatitude, month, 21st day, and zoneas described by 14 zone parameters. Al 41 wall and 42 rooftypes may be accessed with this option. The zone

parameters were previously discussed in Chapter 2.Option 2- This option generates CLTD / SCL values for

a particu lar latitud e, 21st day of any month, a range ofzones, and 9 roofs and 15 walls. The purpo se of this optionis to modify the given CLTD/SCL tabl es for months otherthan July and latitudes other than 24, 36, and 48. In the caseof the CLTDs, a representative zone is selected for each walland roof, which results in one set of tables for each lat itudeand month. In the case of SCLs, the permutations of a subset of the 14 zone parameters are u sed to place a zone in oneof four categories.

Tables were developed to guide the user to the properSCL or CLF table for a given situation.

The tabu lar values for CLTD/SCL/CLF Iiste d in thismanual are identical to those generated using Option 2 andnorth latitudes of 24, 36, and 48 degree s for the 2 1st da y ofJuly andan ar b itrary set of design condition s given be lowand in the table no t es .

Using the computer program CLTDTAB with Op t ion 2elimin ates the need for interpolation between latitudes, andeliminat es error caused by int erpolation. Using th e computer program with Option 1 a lso e limin ates thi s error, anderror caused by gro upin g in a particular zo ne.

Table 8.1 summarizes the various eq uations used with theCLTD/SCL/CLF method. (The rema inin g design tablesmay be found at the end of t he c hapter.)

8.1

Limitations o CLTD SCL CLF Methods

Results obtained from using CLTD/CLF data in theform presented depend on how the character istic s of thespace vary from tho se used to generate the weighting factors. Variations can appear in the amplitude and delay ofradiant heat gain components being felt as cooling Ioads,which affect the hourly coo ling Ioads for the space in question. Three types of error are possible:l The computer software provided for generating

CLTD/SCL / CLF tab les uses the Transfer FunctionMethod TFM) described in Chapter 2 to determinecooling Ioad s based on various types of heat gain. Thecooling loads for each type of heat gain are normalized

appropriately to obtain CLTDs, SCLs, or CLFs. Exceptas discussed below, use of t he CLTD / SCLICLF methodin conjunction with these table s will yie ld the sameresults as the TFM, when the s me 4 zone parametersare specifiedDesigners should be aware of three inherent errors in theTFM that are carr ied through to the CLTD/SCL/CLFdata:a. Each set of weighting factors or conduction transfer

function coefficients are used for a group of walls,roofs, or zones with similar thermal response characteristics. Groups were chosen so that error would beminimal and conservative (Harris and McQuiston1988, Sowell 1988 .

b. The scheme used for calculating weighting factors isbased on 14 discrete parameter s applied toa rectangular room. t is rare for a real room to fit exactly intothe discrete parameteriza t ion scheme. Therefore,designers must use engineer ing judgment to choosethe values of the 14 discrete parameter s t hat mostclosely represe nt the room for whic h load calculations are being performed. De viations of the roomfrom the available leve ls of the 14 parameters mayresult in erro rs that are not easily quantifiable. Fo rbuildings that sign ificantly deviate from the available levels ofthe 14 parameters, designers may wish touse a heat balance -based building simulation program (Walton 1982, University of Illinois 1991 . (Theweighting factors were develo ped using a heat balancemodel of a room with all reasonab le permutations ofthe 14 parameters modeled. A heat balance-basedbuilding simulation pro gram is not limited to discreteparameter levels.)

c. A fundamental presupposition of the TFM is thattotal cooling load for a zone can be calculated by simple addition of t he indi vidu al components. For example, radiation heat transfer from individua l walls androofs is assumed to be independe nt of the other surfaces. This has been shown to ca use sorne error(O'Brien 1985).


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8.2 Load alculation Manual

Load Source

Ex terna

Ro of

Walls

G lass

Conduction

Gl a ss

Solar

Partition sCe ili ngs,F lo ors

InternaLi ght s

PeopleSens ible

La tent

Ap p lia nces

Se ns ib le

Laten

Power

InfiltrationA irSe nsible

LatentTota l

Table 8.1 Procedure for Calculating Space Design Cooling LoadSummary of Load Sources and Equations

Equation

q UA CLTD)

q UA(CL TD)

q UA CLTD)

q A SC SC L

q UA TD)

q I NPUT (CLF)

q 5 No. (Se ns. H.G.) C LF

q N o. (Lat. H.G.)

q5 = H EAT GAIN CLF)

q HEAT GA IN

q H EAT GAIN CLF)

q5 1.10 CF M (At)

q 4840 CFM (AW)q 4.5 CF M (Ah)

Reference, Table, Description

D esign heat transmission coe fficien ts, Chapter 4Areas calculate d from archite ct ur al plansRo o f type, Tab le 8.4Cooling load temperature difference base

Conditions for roofs, Table 8.2 and notesCorrect for ou tsid e dr y-bulb tempe rat ur e a nd daily rangeCorrect for in s ide dry-bulb te mper ature

Des ign heat transmissio n coefficients, C hapter 4Area calculated fro m architectural plansWall t ype, Table 8.6CLTD at base con ditions, Table 8.3 and note s

Correct fo r outs ide dry-bulb temper a tu r e a nd daily rangeCorrect for inside dr y-bulb temperature

Type of glass and inter ior shading, if used, C hapter 4G lass a rea calc u lated from plan sCLTD for co nduction load tlirough gla ss, Table 8.7

Co rrect for outs ide dry-bulb temperature and daily rangeCo rrect for in side dry-bu lb temp er a tu r e

Net glass area from plansShad i ng coefficie nt for co mbina tion o f gla ss and interna sh a ding,

Table s 8.10 to 8 .15Zone type, Tab le 8.8Solar Cooling Load factor, Table 8.9Ex te rn ally shaded glass, use north orientat ion

Compute shaded a rea usin g Tabl e 8. 16

D es ign h eat transmission coe ffi cient s, C hapte r 4Area ca lculated from a rch itectura l pla nsDes ig n t empe rat u re diff erence

Input ra ti n g from e lec t rical plans or lighti ng fixture data, C hap ter 5a nd Eq uati o n (8.4)

Zone type, Tabl e 8 .8C LF based on total hours of operation and time, Ta bl e 8 7

N um b er o f people in space, from s urvey or Table 10.2Se nsibl e heat gain from occupant s Table 8.18 o r 5.2Zone type, Table 8.8C LF for people; based o n duration o f occ up ancy and tim e from en tr y

Table 8.19Co rr ect for space temperatur e a nd/or d ensity of occupan t s;

C LF 1.0 if th ere i s var ia b le space temperat ur e an d /orhig h peo p le de nsit y

Late nt heat ga in from occupants, Table 8.18 or 5.2

Recommended rate of heat gain S e nsib le heat, Tables 5.5, 5.6, a nd 5.7Fo r use wi th hood, Tab le 8.20For use with o ut hood, Ta ble 8.19Recomme nd ed rat e of hea t ga in a te n t heat without ho od ), Tables

5.5, 5.6, and 5.7Set eq ua l t o ze ro when hood is used over applia nces

Manu facturer's data or Tables 5.3 a nd 5.4Thble 8. 19 or CL F 1.0 if coo ling system is not operated continuously

lnfil trat ion air, s tandard cfm, C hapt er 6In side -out side a ir tempera ture diff e rence, f, C hapter 3Constants ar e defin ed in C ha p te r 10Inside -o ut s ide a ir humid ity ratio diff ere nce, lb vl lba , Chapter 3Inside-out s ide air entha lpy d iff e renc e Bt u / lba, psychrom et r ic chart


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CLTD SCL CLF Method

2. Designers who wish to use the printed tables shou ld beaware that the CLTDs, SCLs, and CLFs ha ve undergonea further grouping procedure. The maximum poten iaerrors dueto the second group ing procedure have beenanalyzed and are tablu lated in Tables 8.8, 8.21, and 8.22.These errors are in addition to those inherent in theTFM. However, for usual construction, these errors aremodest.

3. Externa shading devices presentan additional complication to the CLTD / SC L / CLF method. Using theTFM, it is quite feasible to determine the effects of anexterna shading device on hourly solar heat gain, andin turn the hourly cooling load. Howver, todo so usingthe CLTD/SCL/CLF method would require an impractically Iarge set of tables. Therefore, an approximatemethod for estimating the effects of externa shadingdevices is given in this chapter. An alternate, moreaccurate method is given by Todorovic and Curcija(1984) and Todorovic (1987). However, for buildingswhere externa shading devices ha ve significant impacton peak co o lin g Ioads, designers shou ld use the TFM for

maximum accuracy.In summary, the CLTD/SCL/CLF method, as with any

method, requires engineering j udgment in its application.When the method is used in conjunction with custom tablesgenerated by Option 1 of the computer software, and forbuildings where externa shading is nota significant factor,it can be expected to produce results very clase to thoseproduced by the TFM. When the printed tables or Option2 of the computer software are used, sorne additiona l ,quant i f iable error is introduced. In many cases, theaccuracy s hould be sufficient.

8 1 ooling Load ueto Heat Gain

through Walls and RoofsThe Cooling Load Temperature Difference (CLTD) is

used to determine the cooling load for walls and roofs asfollows:

q = UA(CLTD)where:

U = ove rall heat transfer coefficie nt for surface,Btu/ h ft 2 F)

A = area o f surface, ft 2

(8.1)

The potential deviations from the TFM associated with thetabulated CLTD for each wall and roof, Tables 8.2 and 8.3,are listed in Tables 8.21 and 8.22.

The tabulated values were generated for standard condition s listed below.Outdoor conditions:

July 21 at 24, 36, and 48 o north latitude No exterior shad ing Ground reflectance of 0.20 Clear sky with clearness number of 1.0 Outside surface of roofs and walls with a ra t io of the

absorptance to the fi lm coefficient (alh) of 0.30 Outside air maximum dry-bulb temperature of 95 op with

a daily range o f 21 F

8.3

Inside conditions : Room dry-bulb temperature constant at 78 F lnside film coefficient for still air

The tabulated CLTDs must be corrected for inside andoutside temperature and daily range as follows:

CLTD = CLTDr (78 - t om - 85)where:

CLTD 7 = tabular CLTD , op = actual inside design dry bulb temperature, op

t 111 = - DR/2), mean outside design dry bulbtemperature, F

where:lo = outside design dry-bulb temperature, op

DR = daily range, op

Roof LTD Selection

To obtain CLTDs for a particular roof, fou r characteristics of the roof must first be determined: Mass placement with respect to insulation Overall R-value of the roof, 11 U Principal roof material Presence or absence of suspended ceiling

Mass Placement. Table 8.4 has provisions for roofs witha massive layer(s) placed inside insulati ng layers; no massive ayer, no insulation, or mass evenly distributed; andmassive .layers placed outside ofthe insulation. Inside refersto the location in the surface neare st the conditi oned space.

A massive ayer is any ayer of building material composed of brick, concrete, concrete block, or clay tile with athickness of 2 in. or more. Referring to Table 8.5, thisincludes materials A2, A 7, and C1 through C20 only. Againreferring to Table 8.5, the insulati ng materials include B2through B6 and B12 through B27.

OverallRoo

R-Value.The

R-value for a givenroof

isgenerally calculated by summing all the individual thermalresistances of the roof components, including the insideand outside film resistances EO and AO from Table 8.5. Thethermal response of the roof is greatly dependent on the R-value. Care should be taken to account for t hermal bridging. See Chapter 4 for a comp lete discussion.

Principal Rooj Material. The principal roof materials arethe massive material previously mentioned as well as thenonma ss ive wood layer s B7 , B8, and B9, the nonmassi vesteel deck A3 and B7 E4, and the attic -ceiling combination. Note that Table 8.4 contains only one massive andthree nonma ssive materials. These were judged to be adequate for normal calculations.

Suspended Ceiling. Table 8.4 provide s information forroofs with and without suspended ceilings . A suspendedceiling is defined asan air space and acoustic tile or similar materia l, with or without insulation, located below theroof assembly.

With these four roof characteristics, the roof type can bedetermined from Table 8.4, which contains ten roof types,covering the range of roof characteristics most commonlyused. The roof type and the Iatitude then define the CLTDvalues in Tables 8.2A, 8.2B, and 8.2C. Note that the CLTDvalues may require correction for indoor and outdoor temperature and daily range . Refer to the notes in the tables.


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8 4

Wall CLTD SelectionTo obtain CLTDs for a particular wall, the following

three characteristics of the wall mu st first be determined:

Mass placement with respect to insu lation Overall R-value of wall, l U Principal wall material

ass Placement. Table 8.6A is for walls with a massiv elayer(s) placed inside insulating la ye rs. Table 8.6B is forwalls with no massive ayer, no insulation, or mass evenlydistributed; Table 8.6C is for walls with massive layersplaced outside of the insulation.

A massive ayer i s defined as any ayer of buildingmaterial composed of brick, concrete, concrete block, orclay ti e with a thickne ss of 2 in. or more. Referring to Table8.5, this include s materials A2, A7, and C l through C20only. Again referring to Table 8.5, the in sulating materialsinclude B2 through B6 and B12 through B27.

Overol/ Wa 1 R Va/ue. The R-va lue for a g iven wa ll is calculated by summing all the individual thermal resistances

o f the wall components, including the inside and outsidefilm resi stance s EO and AO from Table 8.5. The thermalresponse o f the wall is dependent on the R-value. Caresho uld be taken to account for thermal bridging. See Chapter 4 for further information.

Principal Wa 1 Material. The principal wall materials arethe mas s ive materials previously d ef ined as well as the nonmassive wood layer s B7, B8, and B9, and the nonmassivestee llayer A3.

With these th r ee wall chara cte ristics and the seco ndar ywall material, the wall type can be determined in Table 8.6,which contains 15 wall types covering the range of wallcharacteristic s mo st co mmonl y used. The wa ll type, latitude, and direction define the CLTD value s in Table 8.3 .Note that the CLTD va lues may requ ir e correction forinside and outdoor temp erature and daily ran ge. Refer tothe note s in Table 8.3.

8 2 Heat Gain through Fenestration

To determine the cooling load du e to fenestration, theheat gain is divided into radiant and conductive loads. Thecooling load dueto conduction is ca lcul a ted using theC LTD method:

Q cond = UA CLTD) (8.2)where:

U = overall heat tra nsfer coef fi cient for fenest rat ionC h ap ter 4, Btu / h ft 2 F '

A = area of fen est ration norm al to heat flow ft 2

C LTD = equiva lent temperature difference, based on so lartim e Tab le 8.7, oF

Dueto the genera lly light we ight and t he s mall ma gnitude of these compone nt s, the effects of mass and la tit ud ea re negl ected. The CLT Ds from Table 8.7 can also be u sedfor door s with reasonable accuracy. Cor rect ion s for indoorand outdoor desi gn temperatures a nd the d a ily range aregiven in th e no t es for Table 8.7.

Load Calculation Manual

Solar Cooling Load

In an effort to reduce the number of table s, the CLTD/CLF method di scussed in the 1989 Handbook o f Fun-damentals and it s previous editions used Cooling Load Factors (CLFs) in conjunction with maximum Solar Heat GainFactors (SHGF) to predict so lar cooling load s. Solar cooling loads obtained with this method do not recognize thesig nificant variation of so lar cooling load pro file s duetodifferent latitude s, months, and other factors . In order tomore closely approximat e cooling Ioad s dueto solar radiation transmitted through fenestration, a new term So larCooling Load (SCL) i s introduced.

The cooling load per square foot of un shaded fenestrat ion du e to solar radiation transmitted through andabsorbed by the glass is determined by:

Qrad = A(SC)SCLwhere:

A = area of fenestration, 2se = shading coefficient, dimension less

SCL = solar cooling load, Btu / (h ft

2)

(8.3)

The total cooling lo ad dueto fenestration is then the sumof the conductive and radiant components qcond and Qra d

The Solar Coo ling Load (SCL) for a particular zone isdependent on Iatitude, direction, and interna zo ne parameters, which affect the absorption and relea se o f radiantenergy. To deter min e the correct SCL table for a zone, referto Tabl es 8.8A through 8.8E where zo ne types (A, B C, orD) are given as a function of the vario us zo ne parameters.The SCLs for three latitudes; 24, 36, and 48 o north; and onemonth, July, are tabulated in Tables 8.9A through 8 .9C foreach zo ne type. ln t e rpolation between lat itude s can beperformed with so rne lo ss of accuracy. Supp lementary

tabular data m ay also be generated by the user for other latitudes, months, and zo ne types.

Shading Coefficient

The shadin g coeff icie nt (SC) i s th e ratio of so lar heatgain through a glazing system to the so lar h eat gain of thereference glass use d to d ete rmine the SCL.

SC = Solar Heat Gain of Fenestration SystemSolar H eat Gain of Refe ren ce Glass

Not e that th e fenestration system is a combinationof type of glass and type of shading. Additional di scussion

of the shading coeff icient i s given in C hapter 2 and Appendix CInterna/ Shading D evices . Table 8.10 Iists shad ing coeffi

cients for unshaded glass, venetian blind s and roller shadesfor commonly us ed types of flat glass. The va lue s areapplicable to both su nlit and shaded glass; are ba sed on st illair (natura l convection) at the inn er surface; and are givenfor externa heat transfer coef ficient s 0 of 4.0 an d 3.0Btu / h ft 2 F), whic h correspo nd to wind veloc ities of7.5mph and 5 mph , respectively .

The shading coefficients for venetian blinds and rollershades when u se d with insulating glass are a lso given, a nd


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CLTD SCL CLF Method

the shad ing coefficient w ith no in ter ior shad ing is incl ud edfor each classification. Table 8.11 provides shading coeff icients for doubl e g lazin g with between-glass sha ding.

Shad in g coefficients for fenestration shaded on theinside by fabric drapes can be found from Table 8 .12.Although flat fabri c properties of refl ec tance and transmittanc e are used to enter the figure, the resultin g s hadin gcoeff icien t (a s read from Table 8.12) is for the se lected glasstype in com bination with a Ioo se-hanging drap e with 100%fulln ess, i.e. where fabric width is twice the width of th ewindow opening. The notes accompanying Table 8.12describe the use s and Iimitations of the table.

P/astic Sheeting and Domed Sky/ights. Table 8.13 givessh ad ing coeff icient s and solar tran sm itta nce of transparent acrylic and polycarbonate plastic sheet in g, which canbe used for fenestration. Table 8.14 Iists shading coeff icient sfor clear and tr a nsluce nt domed sky ligh ts.

Shading Coefficients for Externa/ Louvered Sunscreens.Table 8.15 Iists shadin g coefficients for seve ra types of horizonta l-Io uvered sun scree ns. The definitions of six gro up s(Group 1 through Group 6) are g iven with t he tab le. Theseare the onl y types of externa shadin g devices where th es e can be used w ith co nfidence . Other types of externashad ing devices are treated in the ne xt sect io n. Note thatthe s e decreases as the ratio S / P in creases (see sket chwith Table 8.15).

eommercially available sun sc reen s will completelyexclude dire ct solar radiation, but not reflect ed radiationwhen th e ratio S / P exceeds approximately 0.488 forGro up s 1, 2, and 5, or when it exceeds approxi m ate ly 0 .839for Groups 3, 4, and 6.

External Shade from Roof Overhangsand/or Side Fins

Rigorous calcu lati on of t he solar cooling load due towind ows is diffi cult du eto th e ever-changing position oft hesun and the resulting movement of the area w here the sun' srays st r ike the in t erior surfaces o f a space. When ex terna shad in g d ev ices are added, the probl em is further co m pijca ted. A basic approach using TFM shou ld b e followed.This problem ha s been investigated (Todorovic 1984) a ndan impro ved ca lculation procedure presented . Ho wever, forhand calc ulation s, th e ad ded co mpl ex ity of the procedureca nn ot be ju s tifi ed a nd the conserva ti ve proceduresdescribed here are reco mm end ed.

When exterior s had in g is u niform over t he en tire fenestration, as with horizontal-louvered sun screens, the s e maybe used as previo usly discussed. Nonuniform exter ior shad

ing, caused by roof ove rhan gs o r side fins, must be handleddifferently. Separate calc ulat ions for th e externally shad edand unshaded areas a re required. The s e is st ill u sed toaccount for any in terna s hadi n g devices. The SeL for thenorth orien ta tion is a clase approximation for the s h adedglass area at latitudes greater than 24 I t is no t as accurateto use the north o ri entat io n as a s ha d ed surface below 24 onor th Iat itud e. During part of the year , the north ern s urfacein those Ioca t ion s receives direct so lar radiat io n in the ea rlymornin g and late afternoon . For latitud es from Oto 24 th eco mputer pro gram e LTDTAB, with option 2, is recommend ed fo r best results .

8.5

The areas, shaded and unshaded, depe nd on the Iocat ionof the shado w Iine on a surface in the pla ne of the glass.Thus, they depend on the shadow width per foot of ho rizo ntal projection, / P and o n t he shadow width per footof vert ical sid e project ion Swl P v. The values of Sh p andS,J P vare given in Table 8.16. (Figure 8.3 gives the physicaldescri ption for u se ofTable 8 .16.) P rogram SHADE ma y beused to generate da ta for other months and latitude s.

After the loca tion s of shadow Iine s on t he glass ha ve..beenfound (Table 8.16A, '8 6B, or 8.16C), the glass sola r cooling load is calculated separate ly for the externally u nshadedand externally sha d ed port ion s by Equation (8.3).

The total glass solar cooling load is g iven by:

Eq uation s (8.3a) and 8 .3b) are applied as fo llows :

(8.3a)

(8.3b)

(8.3c)

l Uns haded and shaded glass areas calculated f rom the Iocation of the glass relative to shade-p rod ucing membersby use of S p and Swl P v must sum to the total area.

2. SeLs are obtained from Tables 8.9A, 8.9 B, or 8.9e aft erthe zo ne type is deter mined f ro m Tabl es 8.8A, 8.8B,8.8e, 8.80, or 8.8E. SeLun sh is based on the true window orientation, wh ile the SeL s at la ti tudes greaterthan 24 s based on the north orientatio n regardless ofthe actual o rientation . For north latitudes Iess than 24 oat early morni ng a nd late evenin g hours, the north orientation is no t as good an approximatio n for SeL s Theno rth orientation can be used with sorne Ioss of accuracy; fo r more accurate results the comp uter programeL T

DTAB may be used to generate a ta ble.3. The SC is obtained fo r the glass or glass plus in terna shadin g devices as discussed ear lier in this sect ion. Thes e is used wit h bo t h the shaded and unshaded portio nsof the g la ss. If more than o ne s e va lue appl ies in t hesame ap p licat ion, they are mu lt ip lied together to obtainan approximate effective s e .

f here is a ny do ub t regard in g the exterior s had in g or ifthe glass a rea is cove red by exte r io r shade for only shortperiods during the day, the SeLs for s unli t glass sho uld beused. Alternatively, methods that accou nt for the effects ofexterior sh ading in a more rigo ro us manner have beenp rese nt ed by Todorovic ( 1982) a nd Todorov ic a nd eurcija(1984).

8 3 Cooling Load uetolnternal Heat Gain

In te rn a sou rces of heat energy contribute sign ifica n iyto th e tot a l coo lin g lo ad of a st ru cture, and poor ju d gmentin the est im atio n of their magnitude can Iead to unsa t isfacto r y operation a nd high operating cos ts. These internasou r ces includ e lights, people, and miscellaneous equ ipment. Interna heat gains are discussed in e hapte r 5.


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8.6

To calculate the cooling load dueto interna heat gains,a Cooling Load Factor (CLF) is used. The CLF is the fraction of the sensible heat gain that appears as cooling loadfor the hour in question.

Lights

The CL dueto lighting in a particular zone is calculatedas follows:

where:3.41 = conversion factor, Btu / h W

W = totallamp wattage, WF 11 = use factor, fraction of W in useF 5 = special ballast allowance factor

(8.4)

CLF = Cooling Load Factor (Table 8.17, aided by Table 8.8)

Further discussion of the heat gain from lights is given inChapter 5.

Table 8.8 gives the proper zone type based on the variouszone parameters. The CLF are then read from Table 8.17as a function of the zone type and time. The CLF tableshave provisions for 8, 10, 12, 14, and 16 h of continuouslight use, and the hours that best suit the situation shouldbe used. The tables are based on the assumption that theconditioned space temperature is constant when the lightsare off. f he coo ing system is to be operated only duringthe period when the lights are on, then Table 8.17 shouldnot be used, and the CLFshou d be taken as 1.0. Ifthe portion of the heat from the lights absorbed by the structureis not removed during nonoccupied hours, it must beremoved the following day. When the cooling system operates on a 24-h basis, part of the heat from the lights isremoved during the occupied hours and the remainderduring the unoccupied hours (Figure 8.1). When the lightsare vented or installed in a ceiling return system, allowances must be made for heat transferred directly to returnair. Briefly, any heat transferred directly from the lights tothe return air should be deducted from the total heat gainbefore Equation (8.4) is applied. The heat transferred tothe return a ir must, however, be added to the coi load. Forpurpo ses of de sign load calculations, an assumption isusually made of the fraction of the heat gain tran sferredto the return air. Details of this problem are discussed inChapter 5.

f a portion of the Jights is on one schedule and anotherportion is on a different schedule, the cooling load for eachportion is computed separately and the results summed .

Shaded area represents storedheat removed trom structure provided ~ r conditioning system is on

l igh t sOff

= LF X q,

Fig. 8.1 Effect of Thermal Storage onCooling Load Due to Lights

Load alculat ion Manual

Appendix C gives further in formation on dealing withvented fixtures and ceiling plenums. Methods for adjust-ing the CLFs for nonstandard radiative/convective components are also discussed.

People

Heat gain from people has both sensible and latent components (see Table 8.18 for abridged data and Table 5.2,Chapter 5, for more complete data). The latent heat gainis assumed to go directly into the air; therefore, this componen t immediately beco mes cooling load and is calculatedas follows:

(8.5)where:

q = latent heat gain per person, Table 8 .18 or Table 5 .2,Chapter 5, Btu / h person

N = number of peopleFd = diversity factor (Chapter 5

The CLF for people is used to calculate the cooling loaddueto the sensible portion of the heat gain from people asfollows:

(8.6)where:

q; = sensible heat gain per person, Table 8.18 or Table 5.2,Chapter 5, Btu / h per son

N = number of peopleFd = diversity factor (Chapter 5

CLF = Cooling Load Factor, Table 8.19 (aided by Table 8.8)

The CLF is 1.0 when the cooling system does not opera e 24 hada y and the CLF is 1.0 jor auditoriums, theaters, or when peo-pledensity is high, such asjor more than 100 peop eper 1000jt 2 The CLF is dependent on the various zone parameters.Table 8.8 gives the proper zone type based on the various

zone parameters. Using the zone type obtained from Table8.8, the CLF is read from Table 8.19.

ppliances and Equipment

Many appliances have both a sensible and latent componen . The latent component of heat gain immediatelybeco mes cooling load. The sensible component of heat gainfrom unhooded appliances and equipment is assumed tohave the same radiant and convective split as people, allowing use of the same tables to obtain the CLF.

The convective portion of the heat gain from hoodedappliances is assumed to be completely exhausted from thespace, Jeaving only the radiant portion to influence the

cooling load. Separate CLFs for hooded appliances areIisted in Table 8.20.When details about the appliance are known (size and

input), the sensible cooling load dueto the appliance is calculated as follows:

(8.6a)where:

q sa = sensible heat gain per appliance, Tables 5.5 , 5 .6, and 5.7,Chapter 5, Btu/h

CLF = Cooling Load Factor, Table 8.19 or 8.20 (aided by Table8.8)


7/44

CLTD / SCL / CLF Method

T he latent coo ling load q1 is given b y Table s 5.5, 5.6, and5.7 directl y. Tot a l co o ling l o ad per appliance is q5 q1in Btu / h. f details about the applianc e are unknown, referto C hapter 5 for appro xim a te method s of estimatin g th ehea t g ain.

The CLF is dep end ent on th e zo ne type. Ag ain , Table 8. 8gives t he zone type ba sed o n the zon e p arameter s, an d Tables

8.19 and 8.20 g ive th e CLF; Tabl e 8.19 i s for unhooded a ndTable 8.20 fo r ho od ed a ppli anc es. Th e CLF = 1.0 when th ecooling syst em doe s no t op er a te 24 h pe r d ay.

Po we r Equipmen t

T h e cool ing l o ad du e t o eq uipm ent o p erated b y elect ricm ot o r wi thin a co nditi o ned space is ca lcul ate d as fo llows:

8.7)where:

HP = motor horsepowe r rat ing shaft)F 1 = load factor-power used divided by rated horsepower

use Tab le 5.4, Chapter 5, for overloa ds)

Fu = motor use factor-accoun ts for in termitte nt useCLF = Cooli ng Load Factor - Tab le 8.19 aided by Table 8.8) .CLF = 1 when the cooling system does not ope ra e 24h per day

When the motor is outside the space or ai rstream and thedriven equipment within the space:

Qs = 2545 HP)FFu CLF) 8.8)

f he motor is inside the conditioned space or airstreambut the driven machine is outside:

q 5 = 2545 HP)[ l.O - E 1E ]FFu CLF) 8.9)

Equation 8.9) also applies toa fan or pump in the conditioned space that exhausts air or pumps liquid outside thatspace.

Table 5.3 gives heat gain data based on the abovementioned relations for typical motors which are then multiplied by the CLF to obtain cooling load for examples, seeChapter 5).

8 4 Cooling Load ueto lnfiltration

AII structures have sorne air leakage or infiltration. Thisproduces a heat gain because the hot, wet outdoor air mustbe cooled to the inside design temperature, and moisture

must be removed to decrease the humidity to the designval u e.Procedures for estimating the infiltration rateare dis

cussed in Chapter 6; the details of computing the coolingload dueto the infiltrating air are discussed in Chapter 10and Appendix D. The sen sible cooling load is given by:

Q 5 = 60 cfm / v) Cp t 0 - t) 8.10)where :

cfm = volume flow rate of infi ltrating air, 3/ mincP = specific heat capacity of moist air, Btu / lbm F)

v = specific volume of air, ft3 / lb m

8 7

The specific vo lum e depend s on loc al condition s a nd ca nbe es timate d from :

v = RTI Pwhere:

R = gas co nstant for a ir, 53.35 ft l b r / lbm RT = abs olute t emp eratur e l 460), 0 RP = loca l abs olut e pr ess ure, lbr /f t 2

Fo r sta nd ar d air conditi on s:

Q5 = l.IO cfm ){t0 - l)

8.10a)

8.10b )

T he infiltra t ing a ir a lso int ro du ces a la tent coo lin g loadgiven by:

q 1 = 60 cf m /v) W 0 - W;) J.h 8.11)where:

W = hum id ity rat io for i nside s pace ai r, lb vl lb aW 0 = humidity rat io for o utdoor a ir, lbv/ lbat1h = change in ent hal py to change ll bv from vapor to liquid,

Btu/lbv

For standa rd a irand nomina

lindoor comfort

conditions,the latent load may be expressed as:

q 1 = 4840 cfm) W 0 - W) 8.11a)

The constants in Equat ions 8.10 b) and 8 .11a) can beadjusted for local conditions as described previously. Amore complete explanation of Equations 8.10) and 8.11)is given in Appendix D.

Outdoor air may be supplied direct ly to the space for ventilation purpose s. The resulting cooling load is computedin the same way as infiltration air.

8 5 Heat Gain nAir Distribution System

The heat gains of the duct system must be consideredwhen the ducts are not in the conditioned space. Properinsulation will reduce the se losses but cannot completel yelimina e them. The heat gain may be estimated using thefollowing relation:

where:U = overall heat tran sfer coefficient, Btu / h ft 2 F)

A 5 = outside surface area of duct, 2

8.12)

t1t = mean temperature difference between a ir in duct and theenvironment, F

When the duct is covered with 1 or 2 in. of insulation witha reflective covering, the heat gain will usually be reducedsufficiently to as sume that the mean temperature differenceis equal to the difference in temperature between the supply air temperature and the temperature of the environment. Since the duct surface area is not known at this point,it is common practice to assume that a small percentage ofthe sensible load is a loss or gain. When the ducts are insulated, 1 to 30Jo is reasonable.

These heat gains are often included in the psychrometric analysis rather than the space load analysis Chapter 10and Appendix D).


8/44

8 8

8 6 Air Quantities

The preferred method of computing air quantity forcoo ling and dehumidification is described in Chapter 10and Appendix D That method should always be used whenthe conditions and size ofthe cooling load warrant specification of spec ial equipment. This means that the coolingand dehumidifying coi is designed to match the sensibleand latent heat requirements of a particular job and that thefan is sized to handle the required volume of air. The designengineer usually specifies the entering and leaving moist airconditions, the vo lume flow rate of the air, and the totalpressure the fan must produce.

Specially const ru cted equipment cannot be justified forsmall building applications. Furthermore, these applications generally have a higher sensib le heat factor, anddehumidification is notas critica as it is in large buildings.Therefore, the equipment is manufactured to operate at ornear one particular set of conditions. When the peak cooling load and latent heat requirements are appropriate, thisless expensive type of equipment may be used. In this case,the air quantity is determined differently. The unit is firstse lected on the basis of the block sensible cooling loadusing the nea rest available size but not less than the sensible cooling load. Next, the latent capacity of the unit mustbe equal to or greater than the computed latent coolingload. This procedure ensures tha t the unit will handle boththe sensible and latent load even though an exact matchdoes not exist. The air quantity specified by the manufacturer for each unit is about 400 cfm per to n , plus or minuslO OJo The total air quantity is then divided among the various rooms according to the cooling load of each room.

8 7 CalculationsThe material presented in this chapter is designed for

manual calculations. This is a tedious task at best, especially when the building or zone has many rooms. Therefore , a procedure must be devised to eliminate as muchrepetition as possible and to ensure that a thorough jobis done. For handwork, this is best accomplished with aworksheet (Figure 8.2). The form in Figure 8.2 is designedfor entry of coefficients, CLTDs, SCLs, CLFs, and so forthcommon to the zone on the left side wh ile entry of roomspecific data is entered on the right side where calcu lations are carried out. The right side of the form may beduplicated for as many rooms as required. When the calculation is completed for al rooms, the loads may besummed and summarized in the lower left portion of theform. The form provides a concise but detailed record ofthe load calculation.

Note that the calculation form shown in Figure 8.2 provides for calcu lations at three different hours if de sired.Generally, the hours are se lected so that the peak coolingload for each room will be obtained and when the loads aresummed for al rooms, the peak load for the zone willre su t. I t is advantageous to accurately estima e the hourswhen the load will peak to avoid extra work . The followingrules are helpful.


l The orientation of fenestration is important, especiallyif a wall has a large amount of glass. The SCL tables area guide in this caseto the time when the solar componentwill peak.

2. Heavy walls and roofs tend to have peak cooling loadslate in the day, but these surfaces are usually not criticain determining the time for the zone peak load.

3. Internalloads (lights, equipment, and people) in occupied spaces usually determine the time of peak load thatwill usually occur at the time when lights and equipmentare turned off and the people leave the space. For anoffice space, this will be about 5:00p.m.

4. The cooling load due to infiltration will peak at about3:00p.m., but this is usually nota factor in determiningthe time of peak load.

Typically, cooling load calculations are made for themonth of J uly (21st day) beca use this is when weather conditions are usually most severe for cooling. However, thereare special cases where a combination of solar effects andinternal heat gains may produce higher cooling loads inother months. For example, a building with large amountsof south-facing glass may experience peak cooling loads inDecember for southern exposures.

8 8 Examples

The examples that follow illustrate the calculationsrequired for the various cooling load components and theworksheet shown in Figure 8.2.

Example 8 1 Selection o Roof Type andCLTD Determination

A roof is constructed with a steel deck, 2 in. of concrete, and2 in. of insulation on top of the concrete with typical feltmembrane, slag, and stone. There i s a suspe nded ceiling below theroof with an unvented air space. Determine the roof type for usein Tab le 8 .2, CLTDs for roofs, and the CLTD for 5:00p.m. solartime at 36 o north latitude in July. The inside design temperatureis 75 F, the outdoor design temperature and daily range are 98 and24 F, respectively.

tem

Parameters

Mass location

Principa l materialCeilingR-value

Roof typeCLTD

Table

8.4

8.5

8.48.28

Description

Mass location, principalmaterial, ceiling, R-valuelnside insulation

2 in. concrete, Cl2With suspe nded ceilingR = R R 5 Rins e

d Ras Rsc R = 0.33 0.05 0.29

6.67 0.17 0.0 1.01.79 0.69

= 10.99 orll h ft 2 F)/Btu

No. 13Hour 17, 36 north, July,RoofNo . 13 ,CLTD = 47F


9/44

CLTD/SCL/CLF Method

Correct for inside 8.2 (note) CLTDci = CLTD (78 - )= 47 (78 - 75)emperature= 50F

Correct for outside 8.2 (note)temperature and

CLTDcia =CLTci m - 85)

lm = t 0 - DR/2aily range

Corrected CLTD= 98 - 24/2) = 86 F

CLTDc = 50 (86 - 85)

= 51 F

Example 8.2 Selection of Wall Type andCLTD Determination

A wall is constructed of 4 in . heavyweight concrete and finishedon the inside wit h 3 112 in . of batt insulation and 5/8 in. gypsumwallboard. Assume resistances compat ible with a 7 112 mph windoutdoors and sti ll air indoors. Determine the wall type for use inTable 8.3, CLTDs for walls, and the CLTD for 5:00p.m. solar timeat 36 o north latitude in July. The wall faces the so uthwest. Theinside design temperature is 76 F and the outside design temperature and daily range are 96 and 22 F, respective y.

ltem

Parameters

Mass location

Principal materialSecondarymaterial

R-va lu e

Wall type

CLTD

Correct for insidetemperature

Table

8.6C

8.5

Description

Mass location, principalmaterial, secondarymaterial, R-valueOutside insulation4 in. heavy concrete, C5

Gypsum wallboard, El

R = Ro Rcon RinsRgyp R

R = 0.33 0.333 ll.O0.149 0.685

R = 12.5 (h ft 2 F) / 8tu8.6C No. 6

8.38 Hour 17, 36 o north, July,Wall No. 6 Southwest,Standard design condit ions ,CLTD = 35F

8.3 (note) CLTDci= CLTD (78 - l= 35 (78 - 76)= 37F

Correct for outside 8.3 (note) CLTDctemperature = CLTDci m -

85)1

=

0 - DR/2)= 96 - 22/2) = 85 F

Corrected CLTD CLTDc = CLTDci = 37F

Example 8.3 Determination o Cooling Load for SunlitWindow with Interna Shade

A window 4 ft wide by 6 ft high is an insulating type made upof ordinary double glass with a 114-in. ai r space. The glass is setin an aluminum frame with thermal break and is shaded on thein side by white venetian blinds, assumed closed. The window faceswest in a first-floor room of a multifloor building . The floor is aslab type with carpet, and intern a partitions are concrete block.There is one exposed wall, and the room ha s a ceiling. Find thecooling load for the window at 4:00p.m. solar time in July at 36 onorth latitude

8.9

Table/ltem Equation) Description

Parameters for 8.8C No. o f walls: onezone type Ceiling: with

Floor cover: carpetPartition: concrete blockFloor: concrete slab

Zone type 8.8C For glass solar gainType = 8

Solar cooling load 8.98 1600 h, west glassSCL = 166 8tu/ h 2)

Are a Allow 1 in. all around forframeAnet

Anet

[(48 - 2)(72 - 2)]1144= 22.4 ft 2

Shading coefficient 8.10 Clear double glass withlight color blindss e o.s1

Solar cooling load (8.3) qrad = SCL A)SC= 166 X 22.4 X 0.51

Qrad = 1896 8tu/hConvective cooling (8.2) Qcond = UA(CLTD)load

4.7 U 5 = 0.65 8tu/ h ft2 F)correct to 7.5 mph wind

4.8 U 75 = 0 .6 1 8tu/ h ft2 F)A = 4 X 6 = 24 ft21600 h

8.7 CLTD = 14 op assumestandard condition)

Qcond = 0.61 X 24 X 14= 205 8tu /h

Total cooling load q = Qrad Qcond= 1896 205

q = 2101 8 tu / h

Example 8.4 Cooling Load for Windowwith Externa Shade

Assume the window ofExample 8.3 is set back into the walll2in., and compute the cooling load at 2:00 p.m. so lar time.

ltem

Procedure

Shaded area

Total window area

Exposed glass area

Table/Equation) Description

Compute arcas of the sunlitand shaded portions o f theglass. Calc ulation procedurefor sunlit portion same asthat in Example 8.3. Calculation for shaded portion isbased on north-facing glass.

8.168 Sh P = 1.8; S,. Pv = 0 .4Refer to F igure 8.3 forgeome tryP = P v = 12 in. or 1 ftSh = 1.8 X 12 = 21.6 in.

= 1.8 ftSv = 0.4 X 12 = 4.8 in.

= 0.4 ftRecall that the window hasa 1-in. frame all aroundA = 72 X 48 = 3456 in 2Ag = 70 X 46 = 3220in2


10/44

8 10

>m- Oo D >oo.~

< ~ G) ~ D ~t: o -o

U .. o b ,

1

~ u 4it:o

Q )-

-> ea .o - - - - - - -

{/

o


11/44

CLTD/SCL/CLF Method

ROOM NO

AREA 0 SENSIBL ;r BTUIHAF T 2

H R H A K R

AREA

AREA

1111 _ R -K*

SUBTOTAL

WATTAGE

NO. OF PEOPLE

1 1

AREA

REFT2

AREA

8.11

ROOM NQ .. . . . . . . . . ~ ~

Hfl Hfl

SUB TOTAL - - - - - - - - - - - - - - - - -

WATTAG EHR

N O. OF PEOPL E

1 1

SENS. HEAT GA IN SENS. HE AT GAIN

lf-------1-t-1----+-- ------r----r---- :1 1 1 1CFM

1S U B T O T~ROOM O J SENSIBLE ._I_ _ _ ....L.. _ _

1

SUP P LY DUCT HEAT G A I N~ - - - - - - - - - - - 1ROOM TOTAL ._ _ _ _ -.J.... ....J... J

lftlloUIU. OFliACHITEM

HR

CFM1 1

HR

Q LATENT SUBTOTALDUCT LEAKAG E

ROOM 0 LATENT

0-LATEJIIT BTU:/ HR ._ Hf l

ROOM SENSIBLE ROOM L A T ~ -- - - - - - - -- - - 1ROOM SENSIBLE HEAT RATIO ~ - - - - -

1

C F M

SUB TO T L ROOM O~S E N S I B E...._ _ _ _ _ _ JSUPPLY DUCT HEA T G A I N~ - - - - - - - - t - - -- - t

ROOM TOTAL __ - - . . . . . . . - - - ~ - - - -

Q .LATENT BTUIHRHR

CFM1 1

Q L ATENT SUBTOTA LDUCT LEAKAGE

ROOM 0 L ATENT

ROOM SENSIBLE ROOM LA T I ~ - -- - - - - - - - - - 1ROOM SENS IB LE HEAT R A T IO - - - - ~ - - - - - - -- - -

Fig . 8.2 Co o ling Load Calculation Sheet Concluded)


12/44

8 12

Sunlit area (glass)

Shaded area (glass)

Solar load sunlitportionSCL Factor

Shading coefficientSolar coo ling load,sunlit

Solar load shadedportionSCL Factor

Shading coeff icientSolar coo ling load,shaded

Convective coo lingload

Total cooling load

8.98

8 .3)

8.98

(8.3)

(8.2)

8.7

A sun = 72 - 21.6 - 1) X(48 - 4 .8 - 1)= 2085 in 2

Ashd = Ag - Asun= 1135 in 2

Zone type = 8 fromExample 8.3SCL = 101 8t u / (h ft2) at2:00p.m . or 1400 h, westfacings = 0.51, Examp le 8.3q n = 101 X 0.51 X

2085 / 144qsun = 746 8t u / hZone type = 8, Example 8 .3

North-facing glass at 1400 hSCL = 38 8tu/(h ft2)s = 0.51, Example 8.3qshd = 38 X 0.51 X

1135 / 144qshd = 153 8t u / hU = 0.61 8tu(h ft2 F );Example 8.3A = 3456/144 = 24CLTD = 13Fqcond = 0.61 X 24 X 13 =

190 8tu/hq = qsun qsh qcondq = 746 153 190 =

1089 8tu/h

Example 8 5 Cooling Load for Lightsin Suspended Ceiling

A first-floor room in a two- story building has 1000 W of ordinary fluorescent lighting in a suspended ceiling. The lights are onfrom 7:00a.m. to 5:00p.m. solar time . The building is of heavyconstruction with carpeted floors and glass shaded on the inside .

Estima e the cooling load at 3:00p.m. solar time for both ventedand unvented ceiling plenums. The cool ing equipment operates24 h per day.

Item

Zone type parameters

ZonetypeCooling load factor

Co o ling load for unvented ceiling plenum

Cooling load forvented ceil ing plenum

Table

8.8C

8.8C8.17

8.4

Description

Assume: 1 or 2 exterior wall sFirst floor of multistorybuilding with ceilingHeavy construction-2.5 in.concrete floor with concreteblock partitionearpeted floor, full shadeTypeCLights on for JO hCoolload at 3:00p.m. is 8 h

after light s onCLF = 0.92q = 3.41 WFuF 5 (CLF)Assume Fu = 1.0; F 5 =1.20q = 3.41 X 1000 X 1.0

X 1.2 X 0.92q = 3765 8tu/hAssume 20 Jo of light heatgain goes to return air.Assume the radiative-convective sp lit is the standardcondition of 59 - 41 .

Heat gain to return

Cooling load forspace

Coilload due tolights

8.4


qr = 3.41 X 1000 X 1.2X 0.2

qr = 818 8tu/hq = 3.41 X 1000 X 1.2 X

0.8 X 0.92q = 3012 8t u / hqc = qr q = 818 3012

= 3830 8t u / h

Example 8 6 Cooling Load for Vented Lightswith Ducted Return

Assume the lightin g system of Example 8.5 ha s vented light fix-tures with 30 of the heat gain transferred to the return air.Assume the remaining 70 of the heat gain to the space is all radia t ive. See Appendix C for further information on non st a ndardradiant /c onvective sp lits.

Item

Heat gain to returna r

Heat gain to space

CLF, corrected

Table CLFRadiant portion oftable CLFCorrected radiantfraction

CL F , corrected

Space cooling load

Coi l l oad due tolight s

Table

8.17

8.4

Description

qr = 3.41 X 1000 X 1.2X 0.3

qr = 1228 8t u / hq 5 = 3.41 X 1000 X 1.2

X 0.7q5 = 2864 8tu/hTable CLF must be corrected for the newradia i ve-convective splitCLF T = 0.92 (Example 8.5)CLFTR = C L F T- 0.41 =

0.92 - 0.41 = 0.51CLFcR = CLFTR x

(Actual radiantfraction) / 0.59= 0.51 X 1.0/ 0.59= 0.86

CLFc = CLFcR (Actualconvective fraction)

CLFc = 0.86 0.0 = 0.86q = q 5 XCLFc=2864x0 .86q = 2463 8tu/hqc = qr q = 1228

2463qc = 3691 8tu/h

Example 8 7 Cooling Load ueto People

An interior room on the top floor of a multistory building ha san occupancy of 20 people arriving for work at 7:00a.m. so lartime and leaving the space at 3:00p.m. solar time. The buildingis of heavy construction with ceiling and carpeted floor s. Theoccupants are engaged in moderate office work. Estmate the cooling load at 1:00 p.m. so lar time. The cooling equipment opera es24 h per day.

Item

Sensible heat gainper personLatent heat gain perpersonLatent cooling load

Table/(Equation) Description

8.18

8.18

8.5

q = 250 8t u / (hperson)

q = 200 Btu / (h person)

q = q FdNAssume: Fd = 1.0q = 200 X 20

= 4000 Btu / h


13/44

CLTD SCL CLF Method

Sensible cooling loadCLF

Total coo ling load

(8.6)8.8E

8.19

s = FdN CLF)Top floor, heavy floor, withce ilin g and carpetZone type = DPeople in space 8 hLoad required after 6 hCLF = 0.83qs = 250 X 1.0 X 20 X 0.83

s = 4150 Btu/hq = Q s

= 4000 4150= 8150 Btu/h

Example 8.8 Cooling Load Dueto People Two Groupson Different Schedules

Suppose in Example 8.7 another group of 10 peopleenters thespace at 10:00 a.m. solar time and leaves at 4:00p.m. solar time.Assume they are standing and walking . Estmate the cooling loaddueto both groups at 1:00 p.m. so lar time.

ltem

Procedure

Sensible and latentheat gain per personLatent cooling load

Sensib le cooling load

Cooling load, secondgroupTotal cooling load,both groups,1:00p.m.

Table Description

Find total cooling load at1:00 p.m. for second groupand add to cooli ng load forfir st group from Example 8.7

8.18 = 250 Btu/hq = 250 Btu/h

8.5 Q = 250 X 10q1 = 2500 Btu / h

8.19 Zone type = D (fromExample 8 .7)People in space 6 hLoad required after 3 hCLF = 0.73

s = 250 X 10 X 0.73 =1825 Btu/h

q 2=

2500 1825= 4325 Btu/hq = 8250 4325

= 12,575 Btu/h

Example 8.9 Cooling Load Dueto PeopleTwo Groups on Different SchedulesLoad after Occupancy

Refer to Examp les 8.7 and 8 .8 and estmate the cooling load dueto both groups at 6:00 p.m. solar t im e.

Item

Procedure

Group 1

Cooling load

Group 2

Table/(Example) Description

Both groups have departed;therefore, the latent portion ofthe cool ing load is zero

8.7) Zone type = DOccupants in the space 8 hLoad required after h

8.19 CLF = 0.20Q = 250 X 20 X 0.20

= 1000 Btu/h(8.8) Zone type = D

.Occupants in the s pace 6 hLoad required after 8 h

8.19

Total cooling load

8 13

CLF = 0.20q 2 = 250 X 10 X 0.20

= 500 Btu/hq = q q 2 = 1000 500q = 1500 Btu/h

Example 8.10 Cooling Load Dueto UnhoodedEquipment in Conditioned Space

A room contains miscellaneous computers, printers, wordprocessors, etc. Using data from Table 5.7, it is estima ted that onegroup of equipment operating from 8:00a .m. to 4:00p.m. solartime has a sensible heat ga in of 4500 Btu/h; a second gro up oper-at ing from 1:00 p.m. to 11:00 p.m. solar time has a sensible heatgain of 2500 Btu/h A minicomputer opera es continuously witha sens ible heat gain of 5000 Btu/h. Estmate the total cooling loadfor the equ ipment at 4:00p.m. so la r time. Assume a zone type B(Table 8.8). The cooling equipment operates 24 h per day.

ltem

Procedure

Group 1

droup 2

Group 3(minicomputer)

Total cooling load


Three different groups oritems of eq uipment operate

on different schedu les. Findcooling load for each groupat 4:00p .m. or 1600 h solartime, and sum results.

8.19 Equipment operates 8 hLoad after 8 h desiredCLF = 0.95

(8.6a) q 1 = 4500 x 0.95= 4275 Btu/h

8.19 Equipment operates 10 hLoad after 3 h desiredCLF = 0.81

(8.6a) q 2 = 2500 x 0.81= 2025 Btu / h

Equipment operates con-tinuotisly; therefore,CLF = 1.0, and the coolingload is constantQ3 = 5000 Btu/h

q = Q z Q3q = 4275 2025 5000q = 11,300 Btu / h

Example 8 11 Cooling Load Dueto UnhoodedRestaurant Equipment

The kitchen for a school cafetera contains typical equipment,all unhooded. The equipment is in operation from 8:00a.m. to2:00p .m . solar time . t s estimated, using Table 5.5 that the sen-sible and latent heat gains are 4800 Btu/h and 1700 Btu /h, respec-

tively. Assume a zone type D Tab le 8.8). Estmate the cooling loaddueto the equipment at 1:00 p.m. and 4:00p.m . solar times. Thecooling equipment operates 24 h per day.

Item

Procedure


Sensible and latent compo -nents are present. ApplyCLF to sensible portion.Latent heat gain is assumedto become cooling load in-stantly while equipment isoperating.


14/44

8.14

Sensible coo ling load (8.6a)at 1:00 p.m.

Latent coo ling loadat 1:00 p.m.

Total cooling load at1:00p.m .

Sensib le cooling loadat 4:00p.m.

Latent cooling loadat 4:00p.m.Total cooling load at4:00p.m.

8.19

Equipment in operation 6 hLoad after 5 h desiredZo ne type DCLF = 0.80 at 1300 hq5 = 4800 X 0.80

= 3840 Btu / hq 1 = 1700 Btu/h

QJ3oo = s q= 3840 1700q13 00 = 5540 Btu / hEquipment in operation 6 hLoad af ter 8 h desiredZo ne type DCLF = 0.17 at 1600 hq5 = 4800 X 0.20

= 960 Btu / hEquipment is off; therefore,q = 0.0Ql600 = qs ql

= 960 0.0q 1600 = 960 Btu/h

Example 8 12 Cooling Load ueto HoodedRestaurant Equipment

Refer to Example 8.11 a nd assume that the equipment is alhooded and est imate the cooling load.

ltem

Procedure

Cooling load at1:00p.m.

Table/Equation) Description

(8.6a)

8.20

Same as Example 8 .11, exceptTable 8.20 is used for the CLFand there are no latent or convective component s .Equipment in operation 6 hLoad after 5 h desiredZone type D

CLF = 0.71

Actual heat gain tospace

Cooling load at

4 :00 p .m .

References


8.20

Approx imately 300Jo of sensib le heat gain is convective andis exhausted by the hoodsThen q 5 = O. 70 X 4800 =3360 Btu / hq l3 = 3360 X 0.71

= 2386 Btu / hEqu ipment in operation 6 h

Load after 8 h desiredZone type DCLF = 0.29ql6 = 3360 X 0.29

= 974 Btu/h

Harris, S.M. and F.C. McQuiston. 1988. A study to categorizewa lls and roofs on the basis of thermal response. ASHRAETransactions 94(2):688-715.

O'Brien, J.M. 1985 . A stud y into the effects of interna radiantin tercha nge on building cooling load analysis. M.S. Thesis,University of lllinois at Urbana-Champaign.

Sowell, E.F. 1988. Load calculations for 200,640 zones. ASHR AETransactions 94(2):716-36.

Todorovic, B. 1982. Cooling load from so lar radiation throu ghpartially shaded windows, taking heat storage effect intoaccount. ASHRAE Transactions 88(2).

Todorovic, B. and D. Curija. 1984. Calculation procedure forestimating cooling loads influenced by window shadowing,using negative cooling load method. ASHRAE Transactions90(28).

University of lllinois, 1991. BLAST User Rejerence. UrbanaChampaign.

Walton G.N. 1982 . Thermal analysis research program referencemanual. National Bureau of Standards, U.S. Department of

Com mer ce Washington, D.C.


15/44

CLTD/SCL/CLF Method 8.15

Table8.2A Cooling Load Temperature Differences for Calculating Cooling Load from Fla t Roofs-24 North Latitude, July

Roof Solar Time, h

No . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

1 o 2 4 5 6 6 3 9 26 44 62 76 87 92 92 86 74 58 39 23 14 8 4 22 2 o 2 4 5 6 5 1 14 30 48 64 77 86 90 89 82 70 53 36 23 14 8 53 12 8 2 o 2 2 3 11 22 35 47 59 68 74 77 74 68 58 47 37 29 22 164 16 6 3 o 2 3 4 - 1 5 15 27 41 55 67 75 80 80 76 67 55 43 32 235 21 16 12 8 5 3 1 1 4 1 19 30 42 52 61 68 71 70 66 59 50 41 33 278 28 24 20 17 14 11 9 9 10 14 20 27 35 43 49 54 58 58 56 52 47 42 37 329 31 25 20 16 12 9 6 4 3 5 10 17 26 36 46 54 61 65 66 63 58 51 44 37

10 36 31 27 22 19 15 12 9 8 8 11 16 22 30 37 45 52 56 59 59 6 52 47 4113 34 31 28 25 22 20 17 16 15 16 19 23 28 33 38 43 47 49 50 49 46 43 40 3714 34 32 30 27 25 23 21 19 19 19 21 24 27 32 36 40 43 45 46 45 44 42 39 37

Notes: l Direct application of data where Da r k surface 1, = in sid e temperatu re lndoor temperature of 78 F tm = mean outdoor temperature Outdoor maximum temperature of 95 F wit h mean temp eratu re of m = maximum outdoor temperature - (daily range)/2

85 F and daily range of 21 F No adjustment reco mmended for color Solar radiation typical of clear day on 21st day of month No adjustment reco mm ended for ventila tion of air space above a Outside sur f ace film resistance of 0.333 h ft ' F)/Btu cei ling With or wit hou t suspended ceiling but no ceiling ple num air return Latitudes ot h er than 24, 36, and 48 north

systems - Linear interpolation is acceptable ora table for a specific latitude lnside surfa ce resistance of 0.685 (h ft F)/Btu may be generated. See text.

Months other than July2: Adjustments to-table-da For-design -purposes;-the-tlata -wil l-suf-fice-f l r abGur-2-week-s-from-the-2+sl

Design temperatures: day of given month.Corr. CLTD = CLTD (78- t, (1 ' - 85), - Tables ma y be generated for a s pecific month. See text.

Table 8.28 Cooling Load Temperature Differences for Calculating Cooling Load from Flat Roofs-36 North Latitude, July

Roof Solar time, hNo. 1 2 3 4 S 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

1 o 2 4 5 6 6 o 12 28 45 61 75 84 90 90 84 74 60 42 26 15 9 5 22 2 o 2 - 4 5 6 4 4 16 32 48 63 76 84 88 87 81 70 55 39 25 15 9 53 12 8 5 2 o 2 1 4 13 24 35 47 58 67 73 75 74 68 59 48 38 30 23 174 17 11 7 3 1 - 1 3 3 o 7 17 29 42 66 74 78 79 75 67 56 45 34 24

21 16 12 8 3 1 2 5 12 21 31 42 52 61 67 70 70 66 59 51 42 34 278 29 25 21 17 14 12 10 9 11 15 21 28 35 42 49 54 57 58 56 53 48 43 38 339 32 26 21 16 13 9 6 4 4 7 12 19 27 37 46 54 60 64 65 63 59 52 45 38

10 37 32 27 23 19 15 12 1 9 9 12 17 23 30 38 45 51 56 58 58 56 52 47 4213 34 31 28 25 23 20 18 16 16 17 20 24 28 33 38 43 47 49 50 49 47 44 41 3714 35 32 30 28 25 23 21 20 19 20 22 25 28 32 36 40 43 45 46 46 44 42 40 37

For not es , see Table 8.2A .

Table8.2C Cooling Load Temperature Differences for Calcula ting Cooling Load from Fla t R o o f s -48 North Latitude, July

Roof Solar Time, hNo. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

1 o 2 4 5 6 5 3 15 29 44 58 69 78 83 83 79 71 59 44 29 17 9 5 22 2 o 2 - 4 5 5 - 2 6 19 32 47 60 70 78 82 81 76 68 55 41 27 16 10 53 12 8 5 2 o - 1 1 6 14 24 35 45 55 63 68 71 70 65 58 48 38 30 23 174 17 12 7 3 1 -1 3 2 2 8 18 29 40 52 62 69 73 74 71 65 55 45 34 255 21 16 12 8 5 3 2 3 7 13 21 31 40 49 57 63 66 66 63 58 50 42 34 278 28 24 20 17 14 1 10 12 16 21 27 34 40 46 51 54 55 54 51 47 42 37 329 31 26 21 16 12 9 6 5 5 8 12 19 27 35 43 51 57 60 62 61 57 51 44 38

10 36 31 27 22 19 15 12 10 9 10 13 17 23 29 36 43 48 53 55 56 54 51 46 4113 33 30 27 25 22 20 17 16 1; 18 20 24 28 32 37 41 44 47 48 47 45 43 40 3714 34 32 29 27 25 23 21 20 19 20 22 24 27 31 35 38 41 43 44 44 43 41 39 36

For notes, see Table 8.2A.


16/44

8.16 Load Calculation Manual

Wall

Table 8.3A Cooling Load Tempera u re Differences for Calculating Cooling Load from Sunlit Walls24 Nortb Latitude July

Wa11No 1 Solar Time hFacing 1 2 3 4 S 6 7 8 9 10 11 12 13 14 1S 16 17 18 19 20 21 22 23 24

NNE

E

SES

sww

NW

Wall

11111122

o - 1 2 - 3 2 5o 1 2 3 o 17o - 1 - 2 3 o 18o - 1 2 3 2 8o - 1 2 3 - 3 - 1o - 1 2 3 3 - 1o - 1 - 2 - 2 - 3 - 1o - 1 2 2 3 - 1

WaliNo. 2

13

394425

3333

17 1851 5359 6338 448 128 138 138 13

19 2248 3959 4845 4218 2417 2217 2217 22

2632363529292727

2830323231

404237

30303131

31

51595

3230303030587362

34 3428 2428 2427 2427 2359 5280 7569 67

2718191818365248

Solar Time h

171313131320

2725

11101010

9121413

777

77898

555

5

455

5

33333333

Facing 1 2 3 4 S 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

NN

E

SES

SWw

NW

Wall

555

55

687

Facing 1

N 8N 7

E 7SE 7

S 7sw 1

w 13NW 12

Wall

Facing 1

N 12NE 10

E 10SE O

S 1sw 15

w 20NW 18

Wall

3333345

4

2

55

55

5

798

2

87877

111413

2222

1222

3

433335

66

3

655

55

799

Facing 1 2 3

N 13N 13

E 14

SE 13

S JIsw 18

w 23NW 21

Wall

11

11

11

10

9151917

Facing 2

N 14 12N 14 12

E 15 13SE 14 12

S 12 10SW 19 16

w 24 21NW 22 19

98987

12

1514

3

1

1

11

10

8141716

o 1 2 - 1 2 7 12 15 1844 4652 5535 40

o - 1 - 2 o 9 23 36o 1 - 2 o 1 26 42o 1 2 - 1 4 14 26o 1 2 2 - 1 1 4 8 13

9 139 139 13

4

2

22

21344

4

433335

66

- 1 2 2 - 1 1 5o 1 2 - 1 1 5

1 - 1 - 2 - 1 1 5

Wall No.3S 6 7 8 9 10 11 12

1 o 11 o 41 o 5o o 2

5 814 2516 29

8 17

11 14 1634 38 3839 45 4625 31 34

o 1 11 o o

o 2 5 9 131 3 6 9 13

2 1 o 1 3 6 9 132 1 o 1 3 6 9 13

Wall No 4S 6 7 8 9 10

2 1 o o 3 62 o o 3 10 202 1 o 3 IJ 222 o o 1 5 132 o - 1 - 1 - 1 13 1 o - 1 o 14 2 o o o 23 1 o o o 2

Wall No S

11 12

10 1329 3634 432J 28

4 74 74 74 7

20435241

1918

1717

13

19364335

1817

17

17

13

15

3947

3311

11

11

11

2338

4438242423

22

142135

4034222424

22

14

183946351615

1515

25 2834 3238 3535 3327 2932 4233 4630 40

30 3231 2932 3031 2929 285 5459 6951 60

3226272626527162

29

2223

2222446155

1S

2433373325323430

1S

21

37433520212120

16

2632353226404639

Solar Time h17 18 19 20

29 30 30 2631 29 26 2233 30 27 2331 29 26 2226 26 23 2046 48 45 3756 62 59 548 54 53 45

Solar Time h16 17 18 19 20

23 26 28 30 30

35 34 32 30 2740 37 34 32 2835 33 32 30 2724 26 27 27 2529 37 43 47 4730 41 52 60 6127 36 45 52 54

Solar Time h

2318

181817

334541

21

21

191918J7303935

1714141413223028

22

1715J61514233027

21 22

28 24

24 2025 2124 2022 1942 3556 465 42

121010101015

1918

23

13

12J21211

182321

23

20

1617

1616273633

87877

101212

24

10

910

99

141716

24

15

13

13

J312

212725

4 S 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

777669

12 11

4

88987

11

1413

55

55

4798

334335

76

2332235

4

Wa11No . 6S 6 7

7 5 47 5 57 6 67 5 45 4 39 7 6

12 9 811 8 7

36641343

8

5

89635

76

5 7 10 1212 20 26 31

13 22 31 368 14 20 251 3 5 73 4 5 84 4 6 83 4 6 8

9 10

6 814 2015 2210 14

3 45 66 7

6 6

11 12

10 1125 2829 3319 23

5 87 98 17 9

143339281111

11

11

13

13

2935

2P11

11

12

11

16 19 2133 32 3239 37 3630 30 3014 18 2014 20 2615 20 28J4 J9 25

14

15

30352714151514

1S

17

30342816192018

16

20303428

19252724

23 25 2731 31 2935 33 3130 30 2822 23 2332 38 4137 45 5132 40 45

Solar Time h

27272926

224051

46

17 18 19 20

22 24 25 2530 29 28 2633 32 30 2828 28 27 2520 21 21 2130 34 36 3635 42 46 4631 37 41 41

25 2224 2126 2224 2120 1836 3147 4142 37

21

2324262319

334238

22

212223

2J17293734

1918

1918

16273431

23

191920J9162633

29

1616

1615

14222826

24

16

1718

1614222825


17/44

CLTD/SCL/CLF Method

Table 8.3A Cooling Load Temperature Differences for Calculating Coo ling Load from Sunlit Walls240 North Latitu de July Continued)

Wall

Facing 1 2 3 4

N 14 12 JI 9NE 16 14 12 JI

E 17 15 13

SE15

1312

JOS 12 10 9 8sw 19 17 15 13w 24 21 19 16

NW 21 19 17 15

Wall

Facing 1 2 3 4

N 19 16 14NE 18 16 13 11

E 19 17 14 12SE 18 15 13

S 15 13 9sw 26 22 18 15w 33 28 23 19

NW 30 25 21 18

Wall

Facing 1 2 3 4

N 18 16 14 12NE 19 16 14 12

E 20 17 15 12

SE 18 16 13 11S 15 14 12 10

sw 26 22 19 16w 32 28 24 20

NW 29 25 22 18

Wall

Facing 1 2 3 4

N 17 16 14 13

NE 19 17 16 14E 21 19 17 15SE 18 17 15 13

S 14 13 12 11sw 23 21 19 17w 29 26 24 21

NW 26 24 21 19

Wall

Facing 2 3 4

N 17 16 14 13NE 20 18 16 15

E 21 19 18 16

SE 19 17 16 14S 14 13 12 JI

sw 23 21 19 17

w 29 26 24 22NW 26 24 22 20

Wall

Facing 2 3 4

N 16 15 14 13NE 19 18 17 16

E 21 20 18 17SE 18 17 16 15

S 14 13 12 11SW 22 20 19 17w 27 25 23 22

NW 24 23 21 20

Wall No 75 6 7

8 7 79 8 9

JO 9 9

9 7 77 6JI JO 814 12 JI13 JI JO

Wall No.95 6 7

9 79 79 7 69 7 58 6

12 10 816 13 1014 11 9

Wall No lO

5 6 7

10 8 69 8 6

10 8 69 7 68 6

13 817 14 1115 12 10

Wall No.115 6 7

11 JO 8

12 11 1013 12 1012 10 99 8 7

15 13 1219 17 1517 15 13

Wall No 12

5 6 7

12 10 913 12 1114 13 1213 11 1010 9 816 14 12

20 18 1618 16 14

Wall No 13

5 6 7

12 11 1014 13 1215 14 1313 1210 9 816 15 1320 18 1718 16 15

8

71213

9

8JO

9

8

44

43687

8

6654798

8

8

9JO86

JO

1312

8

8JO

97

1413

8

9121311

71215

14

9

917

1913

8JO

9

9

46642465

9

7863

76

9

8

12959

1210

9

8121310

6JO

13JI

9

91315

JI7

_14

13

10

JO

21

2416

68

JO

9

10

910

624

10

6

1283566

10

8

1415

911

10

10

91416

6JO

12

10

101617

137

14

12

11 12

JI 1224 2628 3020 22

7 99 JI

JI 12JO JI

11 12

6 815 20

17 24JO 15

3 44 5

66

11 12

7 816 2018 24

16

3 46

6 76 6

11 12

9 10

17 2119 2414 17

6 69 9

11 11

10 10

11 12

9 JO17 2019 2314 16

6 79 JO

12 12JI JI

11 12

10 11

18 2020 23

15 177 8

11

13 1312 12

13

142631

24JI1314

13

13

JO

25

3020

6777

13

10242920

67

88

13

11

2327

198

101211

13

JI22

2619

8JI

1212

13

1222

25199

121413

14

1527312514161716

14

12

2934

248999

14

1227

3223

99

1010

1412

25292110

JI1312

14

12242821

JO12

1313

14

132327201013

1514

15

1727312516202220

15

14303627

JI121212

15

1429

342511121312

15

14

26302312141514

15

14

252922

J I14

1514

15

142427211215

1615

16

1928312617242824

16

1631

362814

161615

16

16

3034271416

1716

16

15

2630241417

1817

16

1525292313

17

1817

16

1524282213171917

So lar Time h17 18 19

20 22 2328 27 2630 30 2826 26 25

18 19 1928 31 3234 39 4030 34 36


18 21 2331 31 3136 35 3429 29 2917 20 21

21 27 3222 30 3720 26 33


18 20 2230 30 3035 34 3328 29 2917 19 2021 26 3123 30 3721 27 32

Solar Time h17 18 19

17 18 20

27 27 2730 30 3025 25 2515 17 1820 24 2823 28 3320 25 29


16 18 1926 26 2629 29 2924 24 2515 16 1720 23 26

22 27 3120 24 28

Sola r Time h17 18 19

16 17 1925 25 2528 28 2823 23 2314 15 1620 23 2523 27 3020 24 27

20

22252723

1830

3935

20

25

30322922

36

38

20

24293228

21344237

20

21

262925

18303632

20

2026282417

28

3531

20

192527231626

3329

21

21232522

17283632

21

2628302722374741

21

242830272135

39

21

22

26282418

3037

33

21

212527241728

3532

21

2024262316263329

22

19

21232016263229

22

2526282521364641

22

24262825203443

38

22

21

2426231829

3633

22

202426231728

3531

22

1923252216263229

8.17

23

171921181523

2926

23

23

24252319

3343

38

23

2224252319

324036

23

20

2325221727

3431

23

192325211626

3330

23

18222421152531

28

24

1617191713212624

24

2121

2221

18

3038

34

24

2121

2321

172937

33

24

19

2 1232016253229

24

182123201525

3128

24

1721

232015232926


18/44


Table8.3A Cooling Load Temperature Differences for Ca lculating Cooling Load from Sunlit Walls-24 No rth Latitude, July Con c/uded)

Wall Wall No . 14 Solar Time, hFaci ng 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

N 17 16 15 14 13 12 JI JO JO JI 11 12 12 13 14 15 16 17 18 18 18 18 17NE 20 19 18 17 16 15 14 13 14 15 17 19 21 22 22 23 24 24 24 24 24 23 22 21

E22 21 20 19 17 16

1515 15 17

19 2 123 25 26 26 27 27 27 27 26 25 24 23

SE 19 18 17 16 15 14 13 J2 12 13 J4 J6 18 19 20 21 2J 22 22 22 22 22 21 20S 14 13 12 12 10 9 9 8 8 8 8 9 JO 11 12 13 14 15 15 J5 J5 J5 15

w 22 2J 20 J8 J7 16 J5 J4 13 J2 J2 J2 13 J3 J4 J6 J8 20 22 24 25 24 24 23w 27 26 24 23 21 20 19 J7 16 16 15 15 15 15 16 18 21 24 27 29 30 30 30 29

NW 24 23 22 2J 19 18 17 16 15 J4 14 14 J4 14 15 17 19 21 24 26 27 27 27 26

Wall Wa ll No.15 Solar Time, hFacing 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

N 21 19 17 15 13 J I 9 8 7 6 6 7 8 9 JI 13 15 17 19 21 22 23 23 22NE 22 20 18 16 14 IJ JO 8 7 8 JI 14 18 22 24 26 28 29 29 29 29 28 26 24

E 24 22 19 17 14 12 JO 9 8 9 12 16 21 25 29 31 32 33 33 33 32 30 29 26SE 22 20 17 15 13 JI 9 8 7 7 8 JI J4 17 20 23 25 26 27 27 27 26 25 24

S 17 16 14 13 9 8 6 5 4 4 4 5 6 8 10 13 15 17 19 19 20 20 19sw 29 26 24 21 18 J5 13 JI 9 7 6 6 6 7 9 11 15 19 23 27 31 32 32 31

w 37 33 30 26 23 20 16 14 JI 9 8 8 8 9 JO 12 16 2 J 26 32 37 40 40 39NW 33 30 27 24 21 18 15 12 JO 8 7 7 7 8 9 12 15 19 23 28 33 35 36 35

Wall Wall No. 16 Solar Time hFacing 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

N 20 18 17 15 14 12 11 9 8 8 8 8 9 JO JI 13 14 16 17 19 20 21 21 21NE 22 21 J9 17 15 13 12 JO 10 10 12 15 18 21 23 24 26 27 27 27 27 26 25 24

E 24 22 20 18 16 14 12 JI 10 JI 13 17 20 24 26 28 30 30 31 31 30 29 28 26SE 21 20 18 16 14 13 11 JO 9 9 10 12 14 17 J9 21 23 24 25 25 25 25 24 23

S 17 16 14 13 12 JO 9 8 6 6 5 5 6 7 8 JO 12 14 16 17 18 18 18 17sw 27 25 23 21 19 17 15 13 JO 9 8 8 9 10 12 15 18 22 25 28 29 29 28

w 34 32 29 26 24 21 J8 16 14 12 10 10 JI JJ 13 16 20 25 30 33 36 36 35NW 30 28 26 24 21 19 17 14 12 10 9 9 JO 11 12 15 18 22 26 30 32 32 32

Notes: l . Direc t appli ca t ion o f da ta where Dar k sur face 1 = in side temperature lnd oor temperature of78F t mean ou td oor temperatu re Outdoor maximum tempe rature of 9 F with mean temperature of 1 m = maximum outdoor temperat ur e - (daily ra nge) /2

85 p and dail y range of 2 1F No adjustment recommended for color

So lar radiation typical of clear da y on 21st da y of month Latitud es othe r than 24, 36, and 48 north Outside su rfa ce film resistance of0.333 (h ft f) / Btu - Linear interpo latio n is acce ptable o ra tab le for a specific latitude may be gene r- lns ide surface res istan ce of 0.685 (h ft F) / Btu ate d. See text.

Month s ot her than J uly2. A dj u st ment s to table da ta - Fo r design purposed the data w ill suffice for about 2 weeks f rom th e 2 1st day

Design temperatur es: of given month.Corr. CLTD = CLTD + 7 8 - 1, ) + t m 85) - Tables may be generated fo r a specific month. See text.


19/44

CLTD SCL CLF Method

WallFacin g

N 1N 1

E 1SE 1

S 1sw 2w 2

NW 2

WallFacing

N 5N 5

E 5SE 5

S 5sw 7w 8

NW 7

WallFaci ng

N 7N 7

E 7SE 7

S 8sw 11w 14

NW 12

WallFacing 1

N JIN 1

E 1SE 1S 11

sw 17

w 21NW 18

WallFacing 1

N 13N 13

E 14SE 14

S 14sw 21

w 24

NW 21

Wa llFacing 1

N 13N 14

E 16SE 15

S 15sw 22w 25

NW 21

Table 8.38 Cooling Load Temperature Differences for Calculating Cooling Load from Sunlit Walls -360 North Latitude, July

Wall No. 1

2 3 4 5 6 7 8 9 w

o - 1 - 2 3 - 1 7 12 12 14o - 1 2 3 1 23 41 48 46O - 1 - 2 3 1 M Mo 1 - 2 - 3 - 1 13 31 44 52

o - 1 - 2 - 3 3 o 4 9 18o -1 - 2 2 2 o 4 8 131 -1 - 2 2 - 2 o 4 8 13o - 1 - 2 - 2 2 o 4 8 13

2

3333345

4

2

5

5555

8108

2

87

888

121513

2

11

111 1

172

17

2

3

22222232

3

33444676

3

65

555

8109

3

88999

13

1613

3

Wall No. 2

4 5 6 7 8 9 1

o - 1 2 1 3 7 9o - 1 2 1 12 26 36o - 1 - 2 2 14 31 46o - 2 o 7 19 31o - 1 - 2 - 2 - 1 2 6

4

2

2

2224

44

4

43

4335

76

4

66777

12

1

4

1 1 2 1 2 5o - - 2 - 1 2 5

- 1 2 - 2 - 1 2 5

Wa ll No. 35 6 7 8

1 o 2 5o o 6 17

o 7 2o 4

1 o o 12 1 o 12 1 1 2

2 1 o 1

Wa ll No. 45 6 7 8

2 o o o2 o o 42 1 o 42 1 o 22 o - 1 - 13 1 o o4 2 o o3 1 o o

Wall No.5

5 6 75 3 25 3 35 4 45 4 35 3 28 6 4

1 7 5

8 6 4

Wa ll No.6

5 6 7

8

37852

343

8

9 1

7 926 3232 4221 30

3 73 64 63 6

9 1

3 512 21

14 268 16o 2o 2o 2o 2

9 1

5 614 216 251 172 44 44 53 4

9 1

11 12

17 2138 3059 48

52

29 3917 2317 21

17 21

11 12

12 1541 3954 641 4812 21

9 139 139 13

11 12

JI 14

34 3347 4737 42

14 219 139 139 13

11 12

8 129 33

37 4526 345 11

4 85 84 8

11 12

8 1025 2833 3824 307 JI6 87 96 8

11 12

11

12131313192218

910

111

161815

88999

67777

55

665

8

4665

4787

5

96

1517124

7 8 JO

131513

JI

1210

J O

8

1 1

84676

676

2 24 2625 31 3517 23 28

5 8 126 8 97 8 16 8 9

13

2528

3645

45362725

131835525

30191717

13

1731

444328

191716

13

1334

48401811

J IJI

13

12294351711

JI

13

122636

321612

12JI

14

28293136

4754229

14

21

32454737282321

14

20304

413428242

14

1633

4744251715

15

14

15294372216

1514

14

14263633

211715

14

15

2933132

4661

594

15

24

30384242393326

15

233

373837

383426

15

19

32

44433225

2119

15

1729383727232

17

15

16

2929

30304677353

16

27334374454633

Solar Time, h17 18 19 2

28 3 27 17

28 24 19 1428 24 2 14

28 24 19 14

3 1 25 2 1467 59 43 2381 78 6 3163 65 54 28

Solar Time h17 18 19 2

28 28 29 2729 28 26 2332 30 27 2334 31 27 2341 37 31 2558 62 6 51

9 69 73 6543 53 58

Solar Time, h

21

11

1

101

113

1514

21

22

1819192384942

16 17 18 19 2 21

25 26 27 27 24

30 29 28 25 2235 33 31 28 2436 34 31 28 2438 36 33 29 2547 53 52 4345 56 63 62 5333 42 49 51 44

218222344235

16

2231

4413634324

16

229

37363131

2822

16

Solar Time h17 18 19 2 21

24 26 27 27 2631 3 29 27 24

37 34 32 29 2538 35 33 29 2539 38 36 32 2743 51 54 4941 52 6 63 5931 39 46 51 48

Solar Time h17 18 19 2 21

21 23 24 25 2329 29 28 26 2435 34 32 29 2635 33 32 29 2633 33 31 29 26

38 44 47 46 4237 46 52 54 4928 35 41 43 41

Sola r Time, h

17 18 19 2 21

22

7777

7898

22

171414

1415263329

22

1615

1616

16273227

22

232

212123

405041

22

2121232323

3643

36

22

16 1827 27

35 3434 3325 2823 292 27

17 21

2 21 23 2328 27 27 25

34 33 31 2933 32 30 2830 3 29 2735 4 42 4135 42 47 4727 33 37 39

22 223 2126 2426 2325 22

38 3444 3936 33

23

5555

55

65

23

12

1011

111117

2119

23

13

12131313

202421

23

1916

17171831

3933

23

18182

2019

303630

23

1819

2 12020303429

8 19

24

3333

3333

24

87888

JI

1312

24

JO

9J OJ O

10151816

24

15

13

1414142429

2

24

151517171625

3025

24151618

181726

3025


20/44


Table 8.38 Cooling Load Temperature Differences for Calculating Cooling Load from Sunlit Walls-360 North Latitude, July Continued)

Wall

l acing

N 13NE 15

E 17SE 17

S 15W 22w 25

NW 20

Wall

Facing

2

1213

1515

13192218

3

10121313

12171916

3

4

9JO

12

10151714

4

N 17 15NE 18 15

E 20 17SE 20 17

S 19 16sw 30 25

w 35 30NW 29 25

13

13 1114 1214 1214 JI21 1725 2021 17

Wall

Facing 3

NNE

E

SE

Ssww

NW

17 15 1318 16 13

20 17 1520 17 1519 17 1429 25 2234 30 2528 25 21

Wall

Facing

N 16NE 18

E 21SE 20

S 19sw 27

w 30NW 25

Wall

Facing

N 16N 19

E 22SE 21

S 19W 26

w 30NW 25

Wall

Facing

N 15N 19

E 22SE 21

S 18sw 25

w 28NW 23

2

1517

191917242723

2

313

15

171715222521

3

15 1317 1620 1819 1717 1624 22

27 2523 21

3

14 1317 1620 1919 1817 16

23 22

26 2422 20

4

JI

1212121821

18

412

13

161514192218

4

1214

16

161420

2319

4

121517

1614202319

Wall No 7S 6 7

7 6 6

9 8 910 9 JIJO 8 99 7 7

13 1015 13 JI12 JO 9

Wall No 9

8 9 10

7 8 813 17 2115 21 2611 15 19

6 7 8

9 9 1011 JO

9 9 9

11 12

923 2330 3224 2710 1410 12

13

10

13 14 1S

12 14 1624 24 2532 32 3229 30 3017 21 2414 19 2414 17 2213 15 18

Solar Time, h16 17 18 19 20

17 19 20 21 2025 26 26 25 2431 31 30 29 2730 30 29 28 2625 26 26 25 2429 33 36 37 3528 34 39 42 4022 26 31 34 33

Solar Time h

21

1922252422323731

22

1820232220303428

23

161821

2019273125

24

1517191817242823

S 6 7 8 9 10 11 12 13 14 1S 16 17 18 19 20 21 22 23 24

99

10JO

91417

14

77887

13

5

6669

JI9

Wall No 10

45

54787

S 6 7 8

99

10101015

1815

77

888

121412

66766

JO

12JO

Wall No 11

S 6 7JO 9 812 10

914 1213 12 1012 10 917 15 1320 17 1516 14 13

Wall No 12

56765898

87

910

81214

S 6 7 8

13

1514

13

18

2017

10

13

13

16

1815

910

12

JI1014

1613

Wall No 13

8JO12

913

1512

S 6 7 8

JI 10 9 914 12 1216 15 14 1415 14 13 1213 12 JI 1018 17 15 1421 19 17 1617 16 14 13

46753575

41012

8356

5 715 2019 2613 18

4 55 66 6

6

8243224

8787

JO

26352913JO

10

9

1227373317131212

1528373422181714

17 1928 2837 3635 3426 2925 3122 3018 23

2128343431373729

Solar Time, h

22 2328 2733 3132 3131 2941 43

44 4835 38

2325292827424839

2223262525394537

202023232234

4033

9 10 11 12 13 14 1S 16 17 18 19 20 21 22 23 24

58974686

9

7

13

7

12

10

1214JO

4676

10

81417

13

7101210

6 716 2020 2614 19

4 66 77 76 6

11 12

8 9

17 2021 2516 20

8 9JO JO

9 10

8 1023 2530 3324 28

9 138 108 108 10

13

10

22282311

JI1211

14

233026141313

12

12263531

18141312

1S

12

23312817

1615

13

1527

3532221917

15

16

14

243129201918

15

1727353325252319

19 20 2228 28 2735 34 3333 33 3228 29 29

31 36 3930 37 4224 29 34

Solar Time, h17 18 19 20

16 17 18 19

25 25 25 2531 31 31 3029 29 29 2823 24 25 2524 28 32 3423 28 33 3718 22 26 30

Solar Time, h

22 2226 2531 2830 2828 2640 3945 4536 36

21 22

20 19

24 2329 2727 2624 2335 3339 3831 31

2123262524374234

23

19

22252422313629

19

20232322333832

24

17

20232220293327

9 10 11 12 13 14 1S 16 17 18 19 20 21 22 23 24

81214

128

12

14

9

913

1613

913

1512

8141713

8

1311

10

9161915

913

1412

8 917 1921 2516 20

8 9JI12 12JO JI

1021272311

12

13JI

11 12 13

9 9 1018 19 2122 25 2717 20 2310 1213 13 1314 14 15

12 12 13

112229251413

1412

14

JO

21

28241515

1513

1223302717

16

1614

1S

JI2228261717

1714

142330282019

1915

16

1322292619202016

152430282223

2318

162430282327

2722

182530282430

3225

Solar Time, h

192429282432

3528

17 18 19 20

14 15 16 1723 23 24 2329 29 29 2827 27 27 2621 22 22 2223 26 29 3123 27 31 3318 21 25 27

192428272333

3730

21

182327262231

3428

192327262332

3630

22

1822262521303327

182225

242130

3428

23

17212523

20283226

172023222028

3227

24

1620232219273025


21/44

CLTD/SCL/CLF Method 8.21

Table 8.3B Cooling Load Temperature Differences for Calculating Cooling Load fro m Sunli t Walls -36 North Latitude, July Concluded)

Wall Wall No. 14 Solar Time, hFacing 1 2 3 4 S 6 7 8 9 10 11 12 13 14 1S 16 17 18 19 20 21 22 23 24

N 15 15 14 13 12 10 10 1 1 10 10 12 13 14 15 16 16 17 17 17 16NE 19 18 17 16 15 14 13 13 14 15 17 18 19 20 21 21 22 22 23 23 22 22 21 20

E 23 22 20 19 18 17 16 15 16 18 20 23 25 26 27 27 27 28 28 27 27 26 25 24

SE 22 20 19 18 17 16 15 14 14 15 17 19 21 23 24 25 25 26 26 26 25 25 24 23S 18 17 16 15 14 13 12 12 11 11 12 14 16 17 19 20 21 21 21 21 20 19sw 25 24 23 21 20 19 17 16 15 15 14 14 14 15 16 18 21 24 26 28 28 28 28 27

w 28 27 25 24 22 21 19 18 17 16 16 16 16 16 17 19 21 24 27TNW 23 22 21 20 18 17 16 15 14 13 13 13 13 14 14 16 17 19 22 24 25 26 25 24

Wall Wall No.1S Solar Time, hFacing 1 2 3 4 S 6 7 8 9 10 11 12 13 14 tS 16 17 18 19 20 21 22 23 24

N 19 18 16 14 12 11 9 7 6 6 6 6 7 8 10 11 13 15 17 19 20 21 21 20NE 2 1 19 17 15 13 11 9 8 7 9 14 18 21 23 24 25 26 27 27 27 26 25 23

E 24 22 19 17 15 12 10 9 8 10 13 18 22 27 30 32 33 34 34 33 32 31 29 27SE 24 22 19 17 14 12 10 8 8 8 10 13 17 21 25 28 30 31 32 32 31 30 28 26

S 23 20 18 16 14 12 10 8 7 5 5 5 7 9 12 15 19 22 25 27 27 27 26 25SW 33 30 27 24 21 18 15 12 10 9 8 7 7 8 1 13 17 22 27 32 35 37 37 36

w 38 35 31 28 24 21 17 14 12 1 9 8 8 9 1 12 16 21 26 32 38 41 42 41NW 31 29 26 23 20 17 14 12 1 8 7 7 7 8 9 11 14 17 21 26 30 33 34 33

Wall Wall No . 16 Solar Time, hFacing 1 2 3 4 S 6 7 8 9 10 11 12 13 14 1S 16 17 18 19 20 21 22 23 24

N 18 17 16 14 13 10 9 8 7 7 7 8 9 1 11 13 14 16 17 19 19 20 19NE 21 20 18 16 14 13 1 10 10 12 15 17 19 21 22 24 24 25 25 25 25 24 23

E 25 23 21 19 17 15 13 11 12 15 18 22 25 28 30 31 31 32 31 31 30 28 27SE 24 22 20 18 16 14 12 11 1

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Cap_8_Libro Jeffrey D. Spitler