P ocedia Enginee ing 21 (2011) 106 – 113
1877-7058 © 2011 Published by Else ie L d.
doi:10.1016/j.p oeng.2011.11.1993
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P ocedia Enginee ing 00 (2011) 000–000
P ocedia
Enginee ing
www.else ie .com/loca e/p ocedia
2011 In e na ional Con e ence on G een Buildings and Sus ainable Ci ies
Analysis o he mal emissions om adia o s in class ooms in
Medi e anean clima es
Miguel A. Campanoa∗, Juan J. Send aa, Samuel Domíngueza
a Ins i u e o A chi ec u e and Building Science. 2 Reina Me cedes A enue, Se ille 41012, ES.
Abs ac
Using compu a ional luid dynamics (CFD), his s udy ocuses on he analysis o he he mal emissions o a ypical
class oom in an educa ional es ablishmen in he sou h o Spain, and hea ed by adia o s si ua ed unde he windows.
I aims o s udy he way o exchange ene gy wi hin he enue wi h his sys em.
In o de o do so a wo k me hodology is de eloped which applies he Fange me hod (PMV and PPD indica o s) and
he local he mal discom o me hod o he iso he mal cu e sec ions gene a ed by he CFD calcula ions, d awing up
a se ies o lineal a ia ion g aphs on he empe a u e. This allows us o no only e alua e he deg ee o he mal
com o o he occupan s in acco dance wi h ASHRAE s anda ds bu also o ca y ou u u e compa isons be ween
di e en he mal exchange sys em a ian s a ising om he HVAC sys em. Following he applica ion o his analysis
he pape concludes ha e iciency o he adi ional adia o sys em o cope wi h he ene gy demand o he loca ion is
limi ed, gi en i s incapaci y o ca y ou a uni o m exchange o ene gy be ween i sel , he con ec i e phenomena i
gene a es, and he low ela ion be ween ai olume/emi ing su ace, which ansla es in o a lack o ene gy e iciency
in he sys em, an aspec which is no usually con empla ed in adi ional analysis me hods.
Keywo ds: Indoo com o c i e ia; CFD; ene gy e iciency; HVAC design; class ooms.
1. In oduc ion
In he choice o sys em o HVAC planned o he hyg o he mal and ai quali y condi ioning o
buildings he e is usually some unce ain y as o how he sys em o he di usion/emission o ene gy will
beha e in eali y in he enues es ed, as well as how ene gy-e icien i is in ela ion o o he al e na i e
∗ Co esponding au ho . Tel.: +34-95-455-6595; ax: +34-95-455-7018.
E-mail add esses: [email protected].
© 2011 Published by Else ie L d.
Selec ion and/o pee - e iew unde esponsibili y o APAAS
Open access unde CC BY-NC-ND license.
Open access unde CC BY-NC-ND license.
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sys ems wi h simila cha ac e is ics. The e a e many measu emen s, simula ions, and e i ica ions o he
o m o ope a ion o each o hese HVAC sys ems in gene ic loca ions, bu he e is also a ce ain lack o
knowledge as o whe he he ene gy use in he building is co ec , gi en i s ansmission e iciency in
habi able enues conside ed as idimensional spaces, wi h occupan s, u ni u e, equipmen , and o he
sou ces o wa m h ha ac i ely in e ene in he sys em.
In o de o p edic he beha iou o hese exchange sys ems i is necessa y o eso o compu a ional
luid dynamics (CFD), a b anch o luid mechanics which up un il now has no been applied o
cons uc ion much, wi h he excep ion o s udies like hose o Qiong Li e al [1] on he simula ion o
clima ised ain s a ions, o he design by Yingchun Ji e al [2] o a building wi h many passi e and
ac i e measu es o he mal con ol, ca ied ou wi h he help o CFD calcula ions, and subsequen ly
con as ed when i was moni o ed a e cons uc ion. Ne e heless, CFD has been widely de eloped in he
ields o ae onau ical enginee ing, chemis y, biology, me eo ology, oceanog aphy, e c.
Wi hin his gene al con ex we p opose o s udy esea ch in he ield o school buildings, as hey a e
p esen ed as one o he mos common and widesp ead building ypologies, cons an ly in use and wi h
majo in e nal loads (occupancy, ligh ing and pa icula ly, compu e equipmen , which gene a e
dis o ions in he dis ibu ion o ene gy) and he ele a ed deg ee o com o demanded by he occupan s.
Ou me hodologies will be based on he wo k ca ied ou by S amou e al [3] on a ypical o ice module
wi h one occupan and one desk op compu e , he s udies o T. Ka imipanah e al [4], which
simul aneously ca ied ou CFD simula ions and measu emen s in eaching class ooms wi h di e en
sys ems o demons a e he p ecision o hese simula ions, and inally he com o c i e ia es ablished by
he Fange me hod and included in EN 7730 on E gonomics o he he mal en i onmen [5].
This wo k and i s me hodology pa e he way o compa a i e s udies wi h o he al e na i e sys ems,
mainly wi h he in oduc ion o con olled mechanical en ila ion.
2. Me hodology
2.1. De ini ion o he model unde s udy
The model unde s udy is a ypical 50 m2 class oom in a non-uni e si y eaching cen e, designed o
accommoda e 25 s uden s and hei eache [6], and i ed wi h a adia o hea ing sys em wi hou
combined mechanical en ila ion, lea ing he ask o en ila ion o he uncon olled in il a ion h ough
he en elope, an example o he mos common ins alla ion in he egions o Sou he n Eu ope.
The measu emen s o he class oom a e 7.25 me es in leng h, 6.4 me es in dep h and 3 me es in
heigh . The placemen o desks in he in e io lea es he windows o he le , o ensu e na u al ligh o
w i ing ( ig. 1(a)). This enue is delimi ed by i s no h- acing açade (a desi able o ien a ion o his
s udy), and by (ho izon al and e ical) pa i ions common o class ooms o a simila size and sha ing an
indoo access co ido . We conside ed his ypical class oom o belong o he Spanish p og amme
‘Escuela T.I.C. 2.0’ [7], which es ablishes ha all s uden s and he eache will ha e ‘ne book’ po able
compu e s.
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The building da a o he en elope a e shown in able 1.
Table 1. En elope
Elemen T ansmi ance
(W/m2·K) Elemen T ansmi ance
(W/m2·K)
Façade 0.45 Slab 1.98
Ve ical pa i ions 2.09 Insula ed doo 0.84
Fenes a ion Double glazed window (4/6/4 mm)
wi h he mal b eak 3.4
Sola p o ec ion: 20 cm ho izon al sla s a 45º e e y 20 cm
The building housing his class oom is loca ed in G anada, whe e he clima e condi ions a e simila o
many o he loca ions in Sou he n Eu ope ( able 2), hus making i highly ep esen a i e. The s a ic
calcula ion hypo hesis was execu ed a 8:00 am on he 21s o Janua y.
Table 2..Loca ion da a
Loca ion G anada (Spain) Time zone GTM + 1:00
La i ude 37.18º Longi ude -3.78º
Ele a ion abo e g ound le el 559.0 m Clima ic da a empla e ESP_G anada.swec
Ex e io calcula ion empe a u e 1.9 ºC Rela i e humidi y o calcula ion 90 %
Wind speed 10.1 m/s Wind di ec ion 0.0º (No h)
2.2. Desc ip ion o he sys em s udied
The ene gy exchange sys em ha will be used as an example in his s udy is ha o adia o s, placing
h ee s eel adia o panels unde he windows, wi h an a e age emission empe a u e o 70 ºC and a
Fig. 1. (a) Floo plan o he class oom unde s udy; (b) Posi ioning o elemen s and he sys em o he mal exchange ( adia o s) in
he model.
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he mal di e ence o 20 ºC in he wa e I/O.
2.3. Condi ions o use and ope a ion
The elemen s included in his s udy a e hose included in able 3, and displayed in he model as hey
appea in igu e 1(b):
Table 3. Elemen s included in he calcula ions.
The mal
con ol
21 ºC se empe a u e
Tables and
chai s
26 ( able and chai pe occupan ).
Ligh ing 6 o e head ligh s, measu ing 30x100x5 cm, indi idual emission o 58 W (con ec i e componen only).
Ne books One pe occupan , wi h an indi idual low emission o 30 W (E. Lim e al [8] and Jung-Mi Lee e al [9]).
Occupan s Teache , s anding, and 25 s uden s, si ing, wi h an indi idual low emission o 45 W (con ec i e componen
only) and clo hing 1.2 clo. 0.52 pe sons/m2.
Openings In il a ion a e o 0.5 eno a ions pe hou .
Radia o s Indi idual low emission equal o he powe equi ed by he loca ion di ided by he numbe o elemen s
placed.
A ea
occupied
Acco ding o EN 13779 on en ila ion o non- esiden ial buildings [10] ( ig 2(a)).
2.4. Tool o ene gy simula ion
The so wa e chosen o ca y ou node calcula ions and he CFD o which his wo k me hodology
ough o be applied is he Design Builde , ollowing he ecommenda ions o Z. J. Zhai [11], who
es ablished ha o a model o hese cha ac e is ics (simple, wi hou con inuous empo al e olu ions and
applied o a chi ec u e), he use o a pu e CFD ool is no necessa y as i is possible o use mixed
calcula ion me hods o e en a single exchange o in o ma ion be ween adi ional node calcula ion and
luid dynamics (one-s ep s a ic in e ac ion).
2.5. Me hod o compa ison o esul s
In o de o assess he esul s o he calcula ions i is necessa y o es ablish a compa ison me hod,
ollowing EN ISO 7730 on E gonomics o he he mal en i onmen [5], which se s common analysis
pa ame e s depending on he he mal sensa ion expe ienced by a ypical human being. The Fange
me hod and he local he mal discom o me hod, bo h included in his no m, will be used o ob ain he
ollowing indica o s:
• P edic ed Mean Vo e (PMV).
• P edic ed Pe cen age Dissa is ied (PPD).
• Le el o local he mal discom o due o D augh Ra e (DR).
• Le el o local he mal discom o due o e ical ai empe a u e di e ence (PD).
110 Miguel A. Campano e al. / P ocedia Enginee ing 21 (2011) 106 – 113
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A se ies o lineal g aphs o he mal a ia ions a e gene a ed as aids o hese indica o s and o acili a e
analysis using a se ies o iso he mal cu e cu s in he sec ions we wish o s udy ( ig. 2(b)). In his way
hese g aphs can be supe imposed on each o he o a compa a i e analysis wi h o he he mal exchange
sys ems.
Fig. 2. (a) Zone occupied in ho izon al and e ical sec ion o he class oom (EN 13779);
(b) Cu s in ho izon al and e ical sec ion o he model selec ed o empe a u e a ia ion g aphs.
3. Resul analysis
3.1. Node calcula ions
The he mal demand o he enue is 5,073 W, so 3 adia o s o 1,690 W we e used, wi h a Δ =20 ºC
he mal di e ence, and each o hem measu ed 5 x 80 x 135 cm. Ai empe a u es and he empe a u es
adia ing om walls o he 21s Janua y, a 8:00 (ze o ins an ), a e included in able 4.
Table 4. A e age empe a u es o ai and wall adian s (21s Jan a 8:00)
Ai o he enue
Ou doo ai
Ex e nal wall
Windows
Pa i iion 1
Pa i iion 2
Doo 1
Doo 2
Pa i iion 3
Pa i iion 4
Floo
Ceiling
To al
Su aces (m2) - - 23.8 7.3 18.1 5,7 1.3 1.3 21.5 21.5 45.1 45.1 190.8
A e age empe a u e
(ºC) 11.0 1.7 14.0 8.5 13.6 13.8 11.6 11.6 14.2 14.2 14.5 15.4 14.3
No e: Pa i ion 1 is a pa i ion wi h co ido . Pa i ion 2 is a pa i ion se back be ween doo s. Pa i ion 3 is a pa i ion wi h igh -
hand class oom. Pa i ion 4 is a pa i ion wi h le -hand class oom. Doo 1 is doo 1 o co ido . Doo 2 is doo 2 o co ido
3.2. CFD Calcula ions
F om he model we ake he wo mos signi ican sec ions, which mus show he ene gy s a us o he
en i e enue, wi hou dis o ions caused by he excessi e p oximi y o occupan s o equipmen , o by he

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ope a ion o possible sys ems. We will he e o e use a e ical sec ion cu ing ac oss he class oom
ans e sally, and ano he ho izon al one ( igs. 3(a) and 3(b)). The esul s o he calcula ions a e
ep esen ed in igu e 3(c) and able 5.
Fig. 3. (a) Posi ion o he s udy sec ions in he model; (b) Sec ion A o he model wi h a 10 cm double s ip in an a ea occupied a
heigh s o 10 and 140 cm, wi h iso he mal lines; (c) Sec ion B o he model wi h iso he mal lines; (d) Sec ion A o he model wi h
iso he mal lines.
Table 5. Resul s o he mal dis ibu ion in sec ion A o he ai o he model om 21s Janua y a 8:00 (ze o ins an ).
Sec ion A ( e ical ans e sal): 6.24 m2
Tempe a u e (ºC) 17.5 18.0 18.5 19.0 19.5 20.0 20.5
Su ace (m2) 0.25 1.23 1.54 0.56 0.59 1.96 0.12
A e age empe a u e sec ion A: 19.00 ºC
Sec ion B (ho izon al): 20.55 m2
Tempe a u e (ºC) 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 23.5 24.0
Su ace (m2) 13.89 4.75 0.47 0.28 0.15 0.15 0.18 0.20 0.17 0.31
A e age empe a u e sec ion B: 19.86 ºC
The a e age ai empe a u e in he enue is ob ained h ough he weigh ed a e age o bo h sec ions,
depending on he su ace o each o hem, and his gi es a esul o 19.7 ºC.
3.3. Applying he E gonomics o he The mal En i onmen egula ion
Wi h his a e age empe a u e o 19.7 ºC o he d y ai con ained in he occupied olume o he enue,
and wi h an a e age empe a u e o 14.3 ºC ( able 4) adia ed om he walls, we ob ained an ope a ional
empe a u e o 17 ºC. The a e age speed o ai in hese sec ions is 0.10 m/s acco ding o he CFD model
112 Miguel A. Campano e al. / P ocedia Enginee ing 21 (2011) 106 – 113
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esul s. The di e ence be ween he a e age empe a u e alues o bo h ho izon al s ips measu ing 10 cm
and placed a heigh s o 10 and 140 cm ( igu e 4(b)) is 2.5 ºC ( om 17.6 ºC o 20.1 ºC). Using his da a,
we applied he indica o calcula ions o he Fange and he local he mal discom o me hods, desc ibed in
EN ISO 7730, ob aining he ollowing alues and ca ego ies ( able 6):
Table 6. The mal en i onmen ca ego ies
The mal s a us o he body in i s ensemble Local discom o
PMV PPD DR (ai cu en s) ΔT (ai e ical) Global class
Value class Meaning % class % class % class Class
-0.68 C sligh ly cool 15 C 8.4 A 2.6 A C
3.4. Lineal g aph analysis o he mal a ia ions acco ding o sec ion
The esul ing g aphs a e shown in igu e 4, acco ding o he p e iously selec ed cu s included in igu e
2(b).
Fig. 4. Resul s o empe a u es in he cu s in sec ions A and B o he model unde s udy
F om hese g aphs, he mal homogenei y can be obse ed in each o he ho izon al cu s, and his only
disappea s as we app oach he emission zone o he adia o s (se ies C1 and C4). This he mal egula i y
can be no ed especially when compa ing cu C1.2 and he C3 and C4 se ies, all ob ained a a heigh o one
me e, wi h a p ac ically cons an empe a u e alue o 20 ºC.
In con as , when we conside he ho izon al g aphs o he di e en heigh s (se ies C1), and especially
in he e ical cu s (se ies C2), he he mal s a i ica ion wi hin he 3-me e-high enclosu e is clea ly
isible and anges om 17 ºC a loo le el o 21 ºC a ceiling le el, a o al di e ence o 4 ºC. In he
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occupied zone, om 10 o 150 cm, we ind a di e ence o 2.5 ºC.
4. Conclusions
The adia o sys em unde he windows a ains ca ego y C in e ms o he mal com o , gi en ha he
sys em is no capable o uni o mly exchanging he ene gy equi ed acco ding o node calcula ions o he
loca ion s udied, as ine i ably con ec i e and s a i ica ion phenomena educe e iciency o he poin
whe e hea ing needs a e no esol ed and com o is no a ained. The eason o his inabili y o each he
equi ed ope a ional empe a u e alues is a esul o he need o each high ai empe a u es o
compensa e o he lowe empe a u es adia ing om acings, and inc eased wi h he low co ela ion
be ween he olume o ai o be condi ioned and he emi ing su ace. Gi en he abo e, he use o his
sys em o ces an inc ease in he ene gy consump ion o he enue and inc eases discom o in he hea ed
a ea. The sys em also gene a es an a ea o discom o wi hin a adius o one me e om each o he
exchange elemen s, and he e o e occupying his a ea is discou aged as com o wi hin i canno be
gua an eed.
The abo e app oach allows us o make p og ess in e ms o he adi ional calcula ions in he
assessmen o how ene gy is ac ually used in spaces and pa es he way o he es ablishmen o a
me hodology o he analysis o he e iciency o sys ems o he ea men o high-densi y enclosu es.
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