01002
A e minimum indoo ai quali y equi emen s
combined wi h passi e e o i solu ions enough
o gua an ee he mal com o in sou he n Spain
High Schools?
Ca men Ma ía Calama-González1,*, Rocío Escandón2, and Ra ael Suá ez2
1Depa amen o de Cons ucciones A qui ec ónicas y su Con ol. Escuela Técnica Supe io de
Edi icación. Uni e sidad Poli écnica de Mad id. A da. Juan de He e a 4, 28040, Mad id, Spain.
2Ins i u o Uni e si a io de A qui ec u a y Ciencias de la Cons ucción, Escuela Técnica Supe io de
A qui ec u a, Uni e sidad de Se illa, A . de Reina Me cedes 2, 41012 Se ille, Spain.
Abs ac . This s udy add esses he challenging esea ch gap o assessing
whe he passi e ene gy e o i solu ions a e adequa e o simul aneously
achie ing indoo ai quali y and he mal com o in educa ional buildings,
gi en he minimum en ila ion a e equi ed by Spanish egula ions. A
ep esen a i e educa ional building is selec ed as case s udy o simula e he
pe o mance o he exis ing high school s ock in sou he n Spain. Then, a
mul i-objec i e op imisa ion app oach based on NSGA-II gene ic
algo i hms is used o he e alua ion o a ange o passi e ene gy e o i
s a egies, wi h he aim o iden i ying he mos e ec i e. The indings
indica e ha , e en hough he minimum en ila ion a e ensu e indoo ai
quali y, i is ine ec i e o main ain he mal com o . This s udy highligh s a
clea o e hea ing p oblem, especially in summe , ha is agg a a ed when
inco po a ing insula ion o he en elope, gi en he high in e nal loads and
he di icul y o hea dissipa ion o he en elope. I is concluded ha
op imising en ila ion acco ding o he seasonal pe iod and applying highe
en ila ion a es han he ones es ablished in he applicable egula ions a e
c ucial o eaching bo h indoo ai quali y and he mal com o only
conside ing passi e e o i solu ions.
1 In oduc ion
Since he COVID-19 global pandemic, he e has been a g owing awa eness o he impo ance
o main aining adequa e indoo ai quali y (IAQ) and educing pollu an exposu e o ai -bo ne
pa hogens [1]. This all has led o an inc eased ocus on his conce ning issue by bo h public
au ho i ies and he gene al popula ion. Educa ional buildings a e o pa icula conce n due o
se e al ac o s, including hei high occupancy le els and in e nal loads o he ex ended daily
hou s spen in hese en i onmen s by child en [2]. Fu he mo e, he heigh ened suscep ibili y
and ulne abili y o illness obse ed in child en se es o exace ba e his p oblem [3].
* Co esponding au ho : [email protected]
© The Au ho s, published by EDP Sciences. This is an open access a icle dis ibu ed unde he e ms o he C ea i e Commons
A ibu ion License 4.0 (h ps://c ea i ecommons.o g/licenses/by/4.0/).
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
The assessmen o indoo en i onmen al quali y emains con ingen upon he
conside a ion o he mal com o as a p ima y ac o [4]. In sou he n Spain, he lack o
he mal condi ioning sys ems, coupled wi h he ypically poo na u al en ila ion in schools,
low-e iciency cons uc ions and inadequa e ope a ional s a egies, can lead o signi ican
heal h conce ns [5]. Se e al s udies ha e iden i ied ad e se e ec s o poo IAQ, equen ly
associa ed wi h ele a ed s ess, inc eased absen eeism o lowe academic pe o mance [6].
The e is a clea consensus among he scien i ic communi y on he impo ance o na u al
en ila ion as a means o ensu ing IAQ, ye no s anda d p oposes a combined IAQ and
he mal com o analysis [7]. Fo ins ance, Spanish egula ions p opose an ou doo
en ila ion a e based on occupa ion, indoo CO2 o su ace wi h no conside a ion o ou doo
o indoo empe a u es. Mo eo e , se e al s udies ha e al eady demons a ed he nega i e
impac o en ila ion on indoo he mal com o and wo n abou o e hea ing isks, which
may be wo sen by excessi e buildings’ ai igh ness and clima e change. In hei analysis o
he he mal pe o mance o a ep esen a i e seconda y school in Nicosia (Cyp us),
He acleous and Michael [8] conclude ha , while day ime en ila ion main ains adequa e IAQ
du ing summe , i ails o ensu e he mal com o condi ions o mos o he ime. These
au ho s ad oca e o he use o na u al nigh - ime en ila ion as a means o educing peak
indoo empe a u es. Zinzi e al. [9] ind ha nea ly ze o ene gy building e o i solu ions in
I alian schools can signi ican ly enhance building pe o mance in he hea ing season.
Howe e , hey also epo inc eased o e hea ing isk du ing he emaining mon hs, wi h
a e age indoo empe a u es exceeding 28°C du ing mos o occupied hou s.
I is he e o e e iden ha one o he key challenges ou socie y aces is o simul aneously
ensu e adequa e IAQ and he mal com o in indoo en i onmen s, pa icula ly in educa ional
buildings, gi en he highe child en’s heal h ulne abili y. The objec i e o his esea ch is
o add ess he exis ing esea ch gap in his ield by esponding o he ollowing ques ions:
• A e passi e ene gy solu ions enough o main ain IAQ and he mal com o in sou he n
Spain schools, conside ing minimum en ila ion a es equi ed by egula ions?
• Which passi e e o i s a egies a e mos e ec i e in hese educa ional en i onmen s
o simul aneously gua an ee adequa e IAQ and he mal com o ?
To do so, a ep esen a i e educa ional building o he exis ing High School s ock in
sou he n Spain (Medi e anean a ea) is selec ed as case s udy h ough a clus e ing analysis.
Unde a minimum en ila ion scena io in acco dance wi h Spanish egula ions, an a ay o
passi e ene gy e o i solu ions, ocused on he e ical en elope, a e p oposed and analysed.
The sui abili y o hese s a egies is e alua ed om a he mal com o pe spec i e h ough a
mul i-objec i e op imisa ion analysis, which iden i ies he mos app op ia e op ions.
2 Me hodology
The me hodology applied o he p esen ed esea ch includes he de elopmen o se e al wo k
packages (Fig. 1), which a e de ailly desc ibed in he ollowing subsec ions.
Fig. 1. Wo k low and wo k packages de eloped.
2.1 Educa ional building a che ype cha ac e iza ion
In his s age, a ep esen a i e educa ional building which ep oduces he ypical he mal
pe o mance o he High School s ock in sou he n Spain (Csa Medi e anean Köppen’s
clima e [10]) is selec ed as case s udy, a e conduc ing a clus e ing analysis in ol ing o e
870 public seconda y schools in he egion [11]. The building selec ed co esponds o he
Poly echnic High School loca ed in Se ille, which was buil a ound he ea ly 70s, be o e he
implemen a ion o he i s he mal ene gy pe o mance egula ion [12].
Two simila class ooms ha e been analysed in de ail (Fig. 2). Each class oom in he
building is 6.30 m by 6.60 m, wi h a ceiling heigh o 3.15 m, and is sepa a ed om he o he
by a 2 m wide co ido . Rega ding he class ooms’ o ien a ion, one o hem is acing
sou heas (SE), while he o he one aces no hwes (NW).
Each class oom is equipped wi h wo 6 mm single glassing windows wi h 5 cm
aluminium ame wi h no he mal b idge b eak (UWINDOW = 5.70 W/m²·K) a 1 m om he
loo , which esul s in a window- o-wall a io o abou 31% pe class oom. Addi ionally, all
windows ea u e ex e nal PVC olle blinds o sola p o ec ion. Rega ding he opaque
e ical en elope, he açade comp ises a 24 cm pe o a ed b ick wall, 2 cm o cemen mo a ,
a 2.5 cm un en ila ed ai ca i y, a 10 cm hollow b ick laye , and 2 cm o gypsum (UFACADE
= 1.03 W/m²·K). The pa i ion wall ha sepa a es he class ooms om he co ido is a 12
cm hollow b ick wall wi h 2.5 cm o gypsum on bo h sides (UPARTITION = 1.80 W/m²·K).
Fig. 2. Floo plan o he class ooms analysed and example o indoo en i onmen .
The occupa ion in he class ooms is 24 people, including s uden s and eache . The
occupancy p o ile was de e mined based on he school’s academic schedule: class ooms a e
in use om 8:00 o 11:00, ollowed by a 30-min b eak, and hen om 11:30 o 14:30. The
academic yea uns om Janua y 9 o June 23 and om Sep embe 15 o Decembe 22. No
occupa ion has been conside ed du ing weekends o egional and na ional holidays.
As o he in il a ions, alues in he ooms a e app oxima ely 0.35 ACH. And ega ding
na u al en ila ion, i occu s only h ough he sliding windows when he ooms a e occupied.
Na u al en ila ion a es ha e been se a he minimum alue es ablished by he Spanish
egula o y amewo k [13], which conside s a minimum o 12.5 l/s pe pe son. This alue
co esponds o 8.24 ACH, conside ing he occupa ion and olume (m3) o he class ooms.
In e nal loads ha e also been conside ed: ligh ing loads a e 5 W/m2 and equipmen loads
a e 30 W/m2 (se e al pe sonal compu e s, a huge sc een and a p ojec o ha e been ins alled
in each class oom). The in e nal loads schedule has been se as equal o he occupancy p o ile.
I is also impo an o highligh ha , e en hough he school has no mechanical en ila ion
no cooling ai -condi ioning sys ems, he class oom has wo ceiling ans.
2
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
The assessmen o indoo en i onmen al quali y emains con ingen upon he
conside a ion o he mal com o as a p ima y ac o [4]. In sou he n Spain, he lack o
he mal condi ioning sys ems, coupled wi h he ypically poo na u al en ila ion in schools,
low-e iciency cons uc ions and inadequa e ope a ional s a egies, can lead o signi ican
heal h conce ns [5]. Se e al s udies ha e iden i ied ad e se e ec s o poo IAQ, equen ly
associa ed wi h ele a ed s ess, inc eased absen eeism o lowe academic pe o mance [6].
The e is a clea consensus among he scien i ic communi y on he impo ance o na u al
en ila ion as a means o ensu ing IAQ, ye no s anda d p oposes a combined IAQ and
he mal com o analysis [7]. Fo ins ance, Spanish egula ions p opose an ou doo
en ila ion a e based on occupa ion, indoo CO2 o su ace wi h no conside a ion o ou doo
o indoo empe a u es. Mo eo e , se e al s udies ha e al eady demons a ed he nega i e
impac o en ila ion on indoo he mal com o and wo n abou o e hea ing isks, which
may be wo sen by excessi e buildings’ ai igh ness and clima e change. In hei analysis o
he he mal pe o mance o a ep esen a i e seconda y school in Nicosia (Cyp us),
He acleous and Michael [8] conclude ha , while day ime en ila ion main ains adequa e IAQ
du ing summe , i ails o ensu e he mal com o condi ions o mos o he ime. These
au ho s ad oca e o he use o na u al nigh - ime en ila ion as a means o educing peak
indoo empe a u es. Zinzi e al. [9] ind ha nea ly ze o ene gy building e o i solu ions in
I alian schools can signi ican ly enhance building pe o mance in he hea ing season.
Howe e , hey also epo inc eased o e hea ing isk du ing he emaining mon hs, wi h
a e age indoo empe a u es exceeding 28°C du ing mos o occupied hou s.
I is he e o e e iden ha one o he key challenges ou socie y aces is o simul aneously
ensu e adequa e IAQ and he mal com o in indoo en i onmen s, pa icula ly in educa ional
buildings, gi en he highe child en’s heal h ulne abili y. The objec i e o his esea ch is
o add ess he exis ing esea ch gap in his ield by esponding o he ollowing ques ions:
• A e passi e ene gy solu ions enough o main ain IAQ and he mal com o in sou he n
Spain schools, conside ing minimum en ila ion a es equi ed by egula ions?
• Which passi e e o i s a egies a e mos e ec i e in hese educa ional en i onmen s
o simul aneously gua an ee adequa e IAQ and he mal com o ?
To do so, a ep esen a i e educa ional building o he exis ing High School s ock in
sou he n Spain (Medi e anean a ea) is selec ed as case s udy h ough a clus e ing analysis.
Unde a minimum en ila ion scena io in acco dance wi h Spanish egula ions, an a ay o
passi e ene gy e o i solu ions, ocused on he e ical en elope, a e p oposed and analysed.
The sui abili y o hese s a egies is e alua ed om a he mal com o pe spec i e h ough a
mul i-objec i e op imisa ion analysis, which iden i ies he mos app op ia e op ions.
2 Me hodology
The me hodology applied o he p esen ed esea ch includes he de elopmen o se e al wo k
packages (Fig. 1), which a e de ailly desc ibed in he ollowing subsec ions.
Fig. 1. Wo k low and wo k packages de eloped.
2.1 Educa ional building a che ype cha ac e iza ion
In his s age, a ep esen a i e educa ional building which ep oduces he ypical he mal
pe o mance o he High School s ock in sou he n Spain (Csa Medi e anean Köppen’s
clima e [10]) is selec ed as case s udy, a e conduc ing a clus e ing analysis in ol ing o e
870 public seconda y schools in he egion [11]. The building selec ed co esponds o he
Poly echnic High School loca ed in Se ille, which was buil a ound he ea ly 70s, be o e he
implemen a ion o he i s he mal ene gy pe o mance egula ion [12].
Two simila class ooms ha e been analysed in de ail (Fig. 2). Each class oom in he
building is 6.30 m by 6.60 m, wi h a ceiling heigh o 3.15 m, and is sepa a ed om he o he
by a 2 m wide co ido . Rega ding he class ooms’ o ien a ion, one o hem is acing
sou heas (SE), while he o he one aces no hwes (NW).
Each class oom is equipped wi h wo 6 mm single glassing windows wi h 5 cm
aluminium ame wi h no he mal b idge b eak (UWINDOW = 5.70 W/m²·K) a 1 m om he
loo , which esul s in a window- o-wall a io o abou 31% pe class oom. Addi ionally, all
windows ea u e ex e nal PVC olle blinds o sola p o ec ion. Rega ding he opaque
e ical en elope, he açade comp ises a 24 cm pe o a ed b ick wall, 2 cm o cemen mo a ,
a 2.5 cm un en ila ed ai ca i y, a 10 cm hollow b ick laye , and 2 cm o gypsum (UFACADE
= 1.03 W/m²·K). The pa i ion wall ha sepa a es he class ooms om he co ido is a 12
cm hollow b ick wall wi h 2.5 cm o gypsum on bo h sides (UPARTITION = 1.80 W/m²·K).
Fig. 2. Floo plan o he class ooms analysed and example o indoo en i onmen .
The occupa ion in he class ooms is 24 people, including s uden s and eache . The
occupancy p o ile was de e mined based on he school’s academic schedule: class ooms a e
in use om 8:00 o 11:00, ollowed by a 30-min b eak, and hen om 11:30 o 14:30. The
academic yea uns om Janua y 9 o June 23 and om Sep embe 15 o Decembe 22. No
occupa ion has been conside ed du ing weekends o egional and na ional holidays.
As o he in il a ions, alues in he ooms a e app oxima ely 0.35 ACH. And ega ding
na u al en ila ion, i occu s only h ough he sliding windows when he ooms a e occupied.
Na u al en ila ion a es ha e been se a he minimum alue es ablished by he Spanish
egula o y amewo k [13], which conside s a minimum o 12.5 l/s pe pe son. This alue
co esponds o 8.24 ACH, conside ing he occupa ion and olume (m3) o he class ooms.
In e nal loads ha e also been conside ed: ligh ing loads a e 5 W/m2 and equipmen loads
a e 30 W/m2 (se e al pe sonal compu e s, a huge sc een and a p ojec o ha e been ins alled
in each class oom). The in e nal loads schedule has been se as equal o he occupancy p o ile.
I is also impo an o highligh ha , e en hough he school has no mechanical en ila ion
no cooling ai -condi ioning sys ems, he class oom has wo ceiling ans.
3
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
2.2 Cons uc ion o a pa ame e ized building simula ion model
A building simula ion model is cons uc ed in he open-access Ene gyPlus simula ion engine
.9.1.0, a widely alida ed ool commonly used by he scien i ic communi y, using he
mo phological, cons uc i e, physical and ope a ional in o ma ion o he case s udy.
Howe e , due o he limi a ions o he physical simula ion ool, se e al assump ions a e
equi ed du ing he modelling p ocess. Fi s ly, a simpli ied simula ion model based on he
ypical and ep esen a i e space scheme “class oom – co ido – class oom” is de eloped.
Fu he mo e, he en elope is de ined by de ailing each cons uc ion laye and including hei
physical p ope ies (densi y, conduc i i y, sola abso p ance, and/o speci ic hea ), which
ha e been sou ced om he Spanish Technical Da ashee s and Regula ions, so ha he
speci ic U- alues desc ibed in sec ion 2.1 a e ob ained. Only he e ical en elopes and he
pa i ion walls a e modelled o accu a ely ep esen hea ans e be ween he class oom,
co ido , and adjacen class oom. In o he wo ds, he emaining cons uc ion su aces a e
ea ed as adiaba ic in he simula ion model. Mo eo e , due o so wa e limi a ions, o
simula e a 50% blind ape u e le el in he Ene gyPlus en i onmen and closely ma ch eal
condi ions, bo h windows and ex e nal blinds a e modelled in wo sec ions (uppe and lowe ),
allowing he blind ape u e o be se in he model o 0%, 50% o 100% open.
Once he single-case s udy simula ion model is de eloped, i unde goes a calib a ion and
alida ion s age based on hou ly on-si e moni o ing da a, gua an eeing i s easibili y o
ep esen he eal he mal and ene gy pe o mance o he building. The calib a ion and
alida ion o he model may be ound in a p e ious wo k [14], whe e Bayesian calib a ion
echniques we e implemen ed, as in simila s udies [15]. La e , a pa ame e iza ion o he
simula ion model is ca ied ou using he open-access jEPlus so wa e e sion 2.1 and EP
Mac o p og amming code. The pa ame e iza ion p ocess enables au oma ic simula ion uns
and he explo a ion o a ious possible alues o he pa ame e ized a iables, educing he
need o manual adjus men s o he inpu s in he model. Addi ionally, i allows o he
simul aneous simula ion o di e en case s udies by a ying speci ic a iables, such as
o ien a ion o physical p ope ies. This is conduc ed so ha he se e al passi e e o i
s a egies and simula ion condi ions de ined in he ollowing s age may be easily impo ed
in o he model.
2.3 P oposal o passi e e o i s a egies
In his s age, se e al passi e ene gy e o i s a egies a e de ined o imp o ing he mal
com o in he case s udy. The p oposed e o i s a egies a e mainly ocused on he ex e nal
e ical en elope, including bo h opaque and glazed elemen s. The selec ed solu ions a e
based on he mos commonly e o i s a egies used in public Medi e anean school buildings,
widely alida ed and included in e o i plans p oposed a he poli ical le el by public
au ho i ies. Mo eo e , gi en he low-e iciency cons uc ion solu ions in sou he n Spain
schools and he high cos s o ac i e e o i solu ions, only passi e measu es we e conside ed.
Passi e s a egies ha e been de ined based on he anges o he mal ansmi ance alues o
ypical ene gy e o i solu ions used in açades and windows in sou he n Spain.
Addi ionally, as an ope a ional measu e, he le el o ape u e o he sola p o ec ion
sys em (ex e nal olling blinds), has been inco po a ed o assess i s in luence on imp o ing
he mal com o , gi en i s high ope a ional dependency on he occupan s. Table 1 p esen s a
compa ison o he alues o he building a iables de ining he simula ion model o he
speci ic case s udy, as well as o he inal pa ame e ised simula ion model ha will be used
o op imise he p oposed e o i s a egies. I can be obse ed ha o he op imisa ion
analysis No h, Sou h, Eas and Wes o ien a ions (0, 90, 180 and 270º No h) ha e been
conside ed o de e mine he in luence o building o ien a ion on he e o i esul s.
Rega ding in il a ion and en ila ion a es, as well as in e nal loads and schedules, hey
a e desc ibed in sec ion 2.1 o his pape .
Table 1. Fo ma ing sec ions, subsec ions and subsubsec ions.
Va iables
Speci ic alues
o case s udy
Va iabili y ange o pa ame e ised
model
O ien a ion (º) 35 0, 90, 180, 270
Class oom leng h / wid h
/ heigh (m) 6.60 / 6.30 / 3.15 6.60 / 6.30 / 3.15
Co ido wid h (m) 2.00 2.00
U- alue: açade / window
/ pa i ion (W/m²·K) 1.03 / 5.70 / 1.80 0.35 o 1.85 / 1.70 o 5.70 / 1.80
Façade sola abso p ance 0.40 0.30 o 0.90
Blinds ape u e le el 50 % open 50 % open / 100 % open / 50% open
in summe & 100% open in win e
2.4 Nume ical op imisa ion o he p oposed e o i s a egies
A mul i-objec i e analysis is conduc ed o nume ically op imise he p oposed ene gy e o i
solu ions unde he scena io o he minimum en ila ion a e es ablished by Spanish
egula ions [13]. To do so, he open-access jEPlus+EA e sion 2.1 ool is used, inco po a ing
NSGA-II gene ic algo i hms, highly compu a ionally e icien , obus and ad an ageous o
mul i-objec i e asks. The op imiza ion objec i e a iables co espond o he pe cen age o
annual o e hea ing and unde cooling hou s calcula ed om he adap i e he mal com o
model in EN 16798-1:2019 [16]. This model calcula es he adap i e com o empe a u e
based on he unning mean d y-bulb ou doo empe a u e o oday (T) and he daily mean
d y-bulb ou doo empe a u e o he p e ious 1 o 7 days (T1-7) (Equa ions 1 and 2).
Tcom o = 0.33 x T + 18.8 (1)
T = (T1+ 0.8 T2+ 0.6 T3+ 0.5 T4+ 0.4 T5+ 0.3 T6 + 0.2 T7) / 3.8 (2)
In his s udy, he empe a u e ange o he com o band has been de ined wi h an uppe
limi o +3 °C and a lowe limi o -4 °C. This ange co esponds o a maximum p edic ed
pe cen age o dissa is ac ion (PPD) o 10% and a p edic ed mean o e (PMV) o ±0.5. In
o de o calcula e he pe cen age o o e hea ing hou s, i is necessa y o de e mine he amoun
o hou s in which he uppe limi o he adap i e com o band is exceeded. Simila ly, he
pe cen age o unde cooling hou s is calcula ed by iden i ying he p opo ion o hou s in
which he lowe com o band limi is no eached. In he op imiza ion p oblem, bo h he
pe cen age o annual o e hea ing and unde cooling hou s a e minimised.
3 Analysis and Resul s
Figu e 3 p esen s he esul s ob ained om he op imisa ion analysis, displaying he da a
acco ding o he p edominan o ien a ion o he class oom. Up o 1,760 simula ions we e
conduc ed wi h he jEPlus+EA so wa e, yielding a ound 8.5% op imal solu ions. Calcula ion
4
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
2.2 Cons uc ion o a pa ame e ized building simula ion model
A building simula ion model is cons uc ed in he open-access Ene gyPlus simula ion engine
.9.1.0, a widely alida ed ool commonly used by he scien i ic communi y, using he
mo phological, cons uc i e, physical and ope a ional in o ma ion o he case s udy.
Howe e , due o he limi a ions o he physical simula ion ool, se e al assump ions a e
equi ed du ing he modelling p ocess. Fi s ly, a simpli ied simula ion model based on he
ypical and ep esen a i e space scheme “class oom – co ido – class oom” is de eloped.
Fu he mo e, he en elope is de ined by de ailing each cons uc ion laye and including hei
physical p ope ies (densi y, conduc i i y, sola abso p ance, and/o speci ic hea ), which
ha e been sou ced om he Spanish Technical Da ashee s and Regula ions, so ha he
speci ic U- alues desc ibed in sec ion 2.1 a e ob ained. Only he e ical en elopes and he
pa i ion walls a e modelled o accu a ely ep esen hea ans e be ween he class oom,
co ido , and adjacen class oom. In o he wo ds, he emaining cons uc ion su aces a e
ea ed as adiaba ic in he simula ion model. Mo eo e , due o so wa e limi a ions, o
simula e a 50% blind ape u e le el in he Ene gyPlus en i onmen and closely ma ch eal
condi ions, bo h windows and ex e nal blinds a e modelled in wo sec ions (uppe and lowe ),
allowing he blind ape u e o be se in he model o 0%, 50% o 100% open.
Once he single-case s udy simula ion model is de eloped, i unde goes a calib a ion and
alida ion s age based on hou ly on-si e moni o ing da a, gua an eeing i s easibili y o
ep esen he eal he mal and ene gy pe o mance o he building. The calib a ion and
alida ion o he model may be ound in a p e ious wo k [14], whe e Bayesian calib a ion
echniques we e implemen ed, as in simila s udies [15]. La e , a pa ame e iza ion o he
simula ion model is ca ied ou using he open-access jEPlus so wa e e sion 2.1 and EP
Mac o p og amming code. The pa ame e iza ion p ocess enables au oma ic simula ion uns
and he explo a ion o a ious possible alues o he pa ame e ized a iables, educing he
need o manual adjus men s o he inpu s in he model. Addi ionally, i allows o he
simul aneous simula ion o di e en case s udies by a ying speci ic a iables, such as
o ien a ion o physical p ope ies. This is conduc ed so ha he se e al passi e e o i
s a egies and simula ion condi ions de ined in he ollowing s age may be easily impo ed
in o he model.
2.3 P oposal o passi e e o i s a egies
In his s age, se e al passi e ene gy e o i s a egies a e de ined o imp o ing he mal
com o in he case s udy. The p oposed e o i s a egies a e mainly ocused on he ex e nal
e ical en elope, including bo h opaque and glazed elemen s. The selec ed solu ions a e
based on he mos commonly e o i s a egies used in public Medi e anean school buildings,
widely alida ed and included in e o i plans p oposed a he poli ical le el by public
au ho i ies. Mo eo e , gi en he low-e iciency cons uc ion solu ions in sou he n Spain
schools and he high cos s o ac i e e o i solu ions, only passi e measu es we e conside ed.
Passi e s a egies ha e been de ined based on he anges o he mal ansmi ance alues o
ypical ene gy e o i solu ions used in açades and windows in sou he n Spain.
Addi ionally, as an ope a ional measu e, he le el o ape u e o he sola p o ec ion
sys em (ex e nal olling blinds), has been inco po a ed o assess i s in luence on imp o ing
he mal com o , gi en i s high ope a ional dependency on he occupan s. Table 1 p esen s a
compa ison o he alues o he building a iables de ining he simula ion model o he
speci ic case s udy, as well as o he inal pa ame e ised simula ion model ha will be used
o op imise he p oposed e o i s a egies. I can be obse ed ha o he op imisa ion
analysis No h, Sou h, Eas and Wes o ien a ions (0, 90, 180 and 270º No h) ha e been
conside ed o de e mine he in luence o building o ien a ion on he e o i esul s.
Rega ding in il a ion and en ila ion a es, as well as in e nal loads and schedules, hey
a e desc ibed in sec ion 2.1 o his pape .
Table 1. Fo ma ing sec ions, subsec ions and subsubsec ions.
Va iables
Speci ic alues
o case s udy
Va iabili y ange o pa ame e ised
model
O ien a ion (º) 35 0, 90, 180, 270
Class oom leng h / wid h
/ heigh (m) 6.60 / 6.30 / 3.15 6.60 / 6.30 / 3.15
Co ido wid h (m) 2.00 2.00
U- alue: açade / window
/ pa i ion (W/m²·K) 1.03 / 5.70 / 1.80 0.35 o 1.85 / 1.70 o 5.70 / 1.80
Façade sola abso p ance 0.40 0.30 o 0.90
Blinds ape u e le el 50 % open 50 % open / 100 % open / 50% open
in summe & 100% open in win e
2.4 Nume ical op imisa ion o he p oposed e o i s a egies
A mul i-objec i e analysis is conduc ed o nume ically op imise he p oposed ene gy e o i
solu ions unde he scena io o he minimum en ila ion a e es ablished by Spanish
egula ions [13]. To do so, he open-access jEPlus+EA e sion 2.1 ool is used, inco po a ing
NSGA-II gene ic algo i hms, highly compu a ionally e icien , obus and ad an ageous o
mul i-objec i e asks. The op imiza ion objec i e a iables co espond o he pe cen age o
annual o e hea ing and unde cooling hou s calcula ed om he adap i e he mal com o
model in EN 16798-1:2019 [16]. This model calcula es he adap i e com o empe a u e
based on he unning mean d y-bulb ou doo empe a u e o oday (T) and he daily mean
d y-bulb ou doo empe a u e o he p e ious 1 o 7 days (T1-7) (Equa ions 1 and 2).
Tcom o = 0.33 x T + 18.8 (1)
T = (T1+ 0.8 T2+ 0.6 T3+ 0.5 T4+ 0.4 T5+ 0.3 T6 + 0.2 T7) / 3.8 (2)
In his s udy, he empe a u e ange o he com o band has been de ined wi h an uppe
limi o +3 °C and a lowe limi o -4 °C. This ange co esponds o a maximum p edic ed
pe cen age o dissa is ac ion (PPD) o 10% and a p edic ed mean o e (PMV) o ±0.5. In
o de o calcula e he pe cen age o o e hea ing hou s, i is necessa y o de e mine he amoun
o hou s in which he uppe limi o he adap i e com o band is exceeded. Simila ly, he
pe cen age o unde cooling hou s is calcula ed by iden i ying he p opo ion o hou s in
which he lowe com o band limi is no eached. In he op imiza ion p oblem, bo h he
pe cen age o annual o e hea ing and unde cooling hou s a e minimised.
3 Analysis and Resul s
Figu e 3 p esen s he esul s ob ained om he op imisa ion analysis, displaying he da a
acco ding o he p edominan o ien a ion o he class oom. Up o 1,760 simula ions we e
conduc ed wi h he jEPlus+EA so wa e, yielding a ound 8.5% op imal solu ions. Calcula ion
5
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
ime was a ound 4 hou s, conside ing a compu e wi h i7-8700 CPU 3.20 GHz o 12 co es
and 64 GB RAM.
Fig. 3. Op imal e o i s a egies esul s shown pe building o ien a ion.
I can be obse ed ha he pe cen age o unde cooling hou s in all o ien a ions is below
15%, while o e hea ing hou s a y om 44 o 67%, being especially signi ican in he Eas
and Wes , as well as in he Sou h, due o highe sola adia ion in luence. This ansla es o a
mon hly mean empe a u e du ing occupied hou s in win e o 20.7°C in he No h, 22.3°C
in he Sou h, 21.6°C in Eas and 21.2 in Wes . In summe , he mon hly mean empe a u es
egis e ed du ing occupied hou s a e 25.6°C in he No h, 26.8°C in he Sou h, 28.8°C in he
Eas , and 28.0°C in he Wes , simila o he ones epo ed by Zinzi e al. [9]. This clea ly
demons a es ha he e is a signi ican indoo o e hea ing p oblem in schools in sou he n
Spain and ha , no only simply insula ing he en elope o using mo e-e icien windows does
no sol e he issue, bu i may also wo sen i .
Fo he No h, Eas , and Wes o ien a ions, he U- alue o he opaque e ical en elope
a ies signi ican ly wi hin a ange om 0.46 o 1.61 W/m²·K in he op imised solu ions. The
lowes alues (0.56 and 0.46 W/m²·K), which would o ally ensu e compliance wi h he
maximum hea ans e limi s pe mi ed by Spanish egula ions in he case o ene gy e o i
in e en ions, is especially signi ican in he Eas , accoun ing o 51% o he op imal
solu ions. Also, i ep esen s 40% o he op imised solu ions in he No h and 30% in he
Wes o ien a ion. Fo he Sou h, i is pa icula ly no ewo hy ha 100% o he op imised
solu ions conside U- alues anging om 1.26 o 1.61 W/m²·K, in o he wo ds, a non-
e o i ed acade. This highligh s he o e hea ing issue in he sou h- acing o ien a ion, gi en
he highe di ec sola adia ion on his açade.
Sola abso p ance also plays a c ucial ole in indoo he mal com o in all o ien a ions,
as mos o op imised solu ions selec he lowes alue wi hin he calcula ed ange (i.e., 0.3),
p o ing ha sola e lec ance is key o educe indoo o e hea ing.
Rega ding windows, i can be said ha gene ally he op imal solu ions in ol e a
signi ican imp o emen in he ene gy e iciency o he o iginal windows (5.70 W/m²·K).
Howe e , among all he glazing solu ions, he he mal ansmi ance alues ange be ween
1.89-1.98 W/m²·K (co esponding o ypical double-glazing windows) in app oxima ely 53.1%
o he solu ions in he No h, 100% in he Sou h, 60.5% in he Eas , and 68.1% in he Wes .
This means ha al hough he pe o mance o he glazed su ace is signi ican ly imp o ed,
op ing o much mo e e icien glazing solu ions does no no ably educe he p oblem o
indoo o e hea ing. Mo eo e , gi en he minimal in luence o he ame due o i s small
hickness in he case s udy, among he op imal solu ions, bo h aluminium ames wi h he mal
b idge b eak and h ee-chambe PVC ames a e conside ed.
Finally, in ela ion o he ex e nal sola shading, he mos op imal solu ion o any
o ien a ion is gene ally o se i s ape u e le el o 50% du ing he occupied pe iod.
Conside ing an op imised ope a ion ape u e o 100% open in win e and 50% open in
summe , was ound o be op imal o only 24% o he simula ed cases in he No h.
4 Conclusions
This pape p esen s an analysis o de e mine whe he i is possible o main ain indoo he mal
com o condi ions in sou he n Spain schools, while conside ing he minimum en ila ion
a e o ensu e IAQ acco ding o he Spanish egula ion and inco po a ing passi e ene gy
e o i solu ions o imp o e he açade’s pe o mance. The main esul s ob ained a e:
- While limi ing he na u al en ila ion a e o he minimum egula o y alues is an
e ec i e me hod o ensu ing IAQ, i is insu icien o main aining he mal com o .
- The high in e nal loads in class ooms ha e a posi i e impac on he indoo he mal
pe o mance in win e by inc easing hea gains and imp o ing he mal com o . As a esul ,
he pe cen age o unde cooling hou s is d as ically educed. Ye , hese high loads wo sen he
pe o mance in summe by dec easing he hea dissipa ion capaci y h ough he he mal
en elope, hus exponen ially inc easing o e hea ing hou s.
- The e o e, he e is a clea o e hea ing p oblem whe e e en inc easing he insula ion o
he he mal en elope can lead o g ea e cases o o e hea ing, no only in summe bu also in
win e . This is mainly due o he high in e nal loads in he class ooms and limi ed en elope
hea dissipa ion.
- F om he abo e, i is concluded ha i is essen ial o con ol en ila ion based on he
seasonal pe iod, using sys ems ha allow o he op imiza ion o hea exchange wi h he
ou side, such as implemen ing e apo a i e cooling sys ems o p omo ing he need o nigh
en ila ion a es in summe o ensu e he mal dissipa ion when ex e io condi ions a e mo e
a ou able.
- Mo eo e , u u e ex ensi e e o i esea ch will assess in de ail he economic cos s and
policy implica ions o possible ecommended e o i s a egies.
The au ho s wish o acknowledge he inancial suppo p o ided by G an (PID2020-117722RB-I00)
“Re o i en ila ion s a egies o heal hy and com o able schools wi hin a nea ly ze o-ene gy building
ho izon” unded by MICIU/AEI/10.13039/501100011033. C.M. Calama-González: Da a cu a ion,
6
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
ime was a ound 4 hou s, conside ing a compu e wi h i7-8700 CPU 3.20 GHz o 12 co es
and 64 GB RAM.
Fig. 3. Op imal e o i s a egies esul s shown pe building o ien a ion.
I can be obse ed ha he pe cen age o unde cooling hou s in all o ien a ions is below
15%, while o e hea ing hou s a y om 44 o 67%, being especially signi ican in he Eas
and Wes , as well as in he Sou h, due o highe sola adia ion in luence. This ansla es o a
mon hly mean empe a u e du ing occupied hou s in win e o 20.7°C in he No h, 22.3°C
in he Sou h, 21.6°C in Eas and 21.2 in Wes . In summe , he mon hly mean empe a u es
egis e ed du ing occupied hou s a e 25.6°C in he No h, 26.8°C in he Sou h, 28.8°C in he
Eas , and 28.0°C in he Wes , simila o he ones epo ed by Zinzi e al. [9]. This clea ly
demons a es ha he e is a signi ican indoo o e hea ing p oblem in schools in sou he n
Spain and ha , no only simply insula ing he en elope o using mo e-e icien windows does
no sol e he issue, bu i may also wo sen i .
Fo he No h, Eas , and Wes o ien a ions, he U- alue o he opaque e ical en elope
a ies signi ican ly wi hin a ange om 0.46 o 1.61 W/m²·K in he op imised solu ions. The
lowes alues (0.56 and 0.46 W/m²·K), which would o ally ensu e compliance wi h he
maximum hea ans e limi s pe mi ed by Spanish egula ions in he case o ene gy e o i
in e en ions, is especially signi ican in he Eas , accoun ing o 51% o he op imal
solu ions. Also, i ep esen s 40% o he op imised solu ions in he No h and 30% in he
Wes o ien a ion. Fo he Sou h, i is pa icula ly no ewo hy ha 100% o he op imised
solu ions conside U- alues anging om 1.26 o 1.61 W/m²·K, in o he wo ds, a non-
e o i ed acade. This highligh s he o e hea ing issue in he sou h- acing o ien a ion, gi en
he highe di ec sola adia ion on his açade.
Sola abso p ance also plays a c ucial ole in indoo he mal com o in all o ien a ions,
as mos o op imised solu ions selec he lowes alue wi hin he calcula ed ange (i.e., 0.3),
p o ing ha sola e lec ance is key o educe indoo o e hea ing.
Rega ding windows, i can be said ha gene ally he op imal solu ions in ol e a
signi ican imp o emen in he ene gy e iciency o he o iginal windows (5.70 W/m²·K).
Howe e , among all he glazing solu ions, he he mal ansmi ance alues ange be ween
1.89-1.98 W/m²·K (co esponding o ypical double-glazing windows) in app oxima ely 53.1%
o he solu ions in he No h, 100% in he Sou h, 60.5% in he Eas , and 68.1% in he Wes .
This means ha al hough he pe o mance o he glazed su ace is signi ican ly imp o ed,
op ing o much mo e e icien glazing solu ions does no no ably educe he p oblem o
indoo o e hea ing. Mo eo e , gi en he minimal in luence o he ame due o i s small
hickness in he case s udy, among he op imal solu ions, bo h aluminium ames wi h he mal
b idge b eak and h ee-chambe PVC ames a e conside ed.
Finally, in ela ion o he ex e nal sola shading, he mos op imal solu ion o any
o ien a ion is gene ally o se i s ape u e le el o 50% du ing he occupied pe iod.
Conside ing an op imised ope a ion ape u e o 100% open in win e and 50% open in
summe , was ound o be op imal o only 24% o he simula ed cases in he No h.
4 Conclusions
This pape p esen s an analysis o de e mine whe he i is possible o main ain indoo he mal
com o condi ions in sou he n Spain schools, while conside ing he minimum en ila ion
a e o ensu e IAQ acco ding o he Spanish egula ion and inco po a ing passi e ene gy
e o i solu ions o imp o e he açade’s pe o mance. The main esul s ob ained a e:
- While limi ing he na u al en ila ion a e o he minimum egula o y alues is an
e ec i e me hod o ensu ing IAQ, i is insu icien o main aining he mal com o .
- The high in e nal loads in class ooms ha e a posi i e impac on he indoo he mal
pe o mance in win e by inc easing hea gains and imp o ing he mal com o . As a esul ,
he pe cen age o unde cooling hou s is d as ically educed. Ye , hese high loads wo sen he
pe o mance in summe by dec easing he hea dissipa ion capaci y h ough he he mal
en elope, hus exponen ially inc easing o e hea ing hou s.
- The e o e, he e is a clea o e hea ing p oblem whe e e en inc easing he insula ion o
he he mal en elope can lead o g ea e cases o o e hea ing, no only in summe bu also in
win e . This is mainly due o he high in e nal loads in he class ooms and limi ed en elope
hea dissipa ion.
- F om he abo e, i is concluded ha i is essen ial o con ol en ila ion based on he
seasonal pe iod, using sys ems ha allow o he op imiza ion o hea exchange wi h he
ou side, such as implemen ing e apo a i e cooling sys ems o p omo ing he need o nigh
en ila ion a es in summe o ensu e he mal dissipa ion when ex e io condi ions a e mo e
a ou able.
- Mo eo e , u u e ex ensi e e o i esea ch will assess in de ail he economic cos s and
policy implica ions o possible ecommended e o i s a egies.
The au ho s wish o acknowledge he inancial suppo p o ided by G an (PID2020-117722RB-I00)
“Re o i en ila ion s a egies o heal hy and com o able schools wi hin a nea ly ze o-ene gy building
ho izon” unded by MICIU/AEI/10.13039/501100011033. C.M. Calama-González: Da a cu a ion,
7
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
Fo mal analysis, In es iga ion, Me hodology, Valida ion, Visualiza ion, So wa e, W i ing – o iginal
d a , W i ing – e iew & edi ing. R. Escandón: W i ing – e iew & edi ing, R. Suá ez:
Concep ualiza ion, Funding acquisi ion, P ojec adminis a ion, W i ing – e iew & edi ing.
Re e ences
1. WHO global ai quali y guidelines. Wo ld Heal h O ganiza ion (2021)
2. M. Oli ei a, K. Slezako a, C. Dele ue-Ma os, M.C. Pe ei a, S. Mo ais, En i on. In .
124, 180-240 (2019)
3. S. Holga e, J. G igg, H. A shad, N. Ca slaw, P. Cullinan, S. Dimi oulopoulou, A.
G eenough, M. Holland, B. Jones, P. Linden, T. Sha pe, (R.M.Ha ison, Issues
En i on. Sci. Technol, 2020)
4. U. Ciuha, K. Tobi a, A. McDonnell, I. Mekja ic, Physiol. Beha . 210, 1-18 (2019)
5. S. Sad izadeh, R. Yao, F. Yuan, H. Awbi, B. Li, J. Build. Eng. 57, 1-23 (2022)
6. L.-R. Jia, J. Han, X. Chen, Q.-Y. Li, C.-C. Lee, Y.-H. Fung, Buildings. 11, 1-30 (2021)
7. F. Babich, G. To iani, J. Co ona, I. La a-Ibeas, J. Build. Eng. 71, 1-19 (2023)
8. C. He acleous, A. Michael, Ene gy Build. 215, 1-17 (2020)
9. M. Zinzi, F. Paglia o, S. Agnoli, F. Bisegna, D. Ia au o, Ene gy P oc. 142, 1-8 (2017)
10. M. Ko ek, J. G iese , C. Beck, B. Rudol , F. Rubel, Me eo ol. Z. 15, 259–63 (2006)
11. J. Llanos, R. Suá ez, A. Alonso, J.J. Send a, A che ypes o public seconda y schools in
Medi e anean clima e. Indoo ai quali y and com o ield s udies in 42nd AIVC
Con e ence 10 h Tigh Ven Con e ence 8 h en icool Con e ence, 5-6 Oc obe 2022,
Ro e dam, Ne he lands (2022)
12. NBE-CT 1979 No ma Básica de la Edi icación. Condiciones Té micas en los edi icios.
Mad id, España
13. Spanish S anda d o The mal Ins alla ions in Buildings. Minis y o Indus y, Ene gy
and Tu ism. Spanish Go e nmen : Mad id, Spain, 2013.
14. C.M. Calama-González, R. Escandón, J. Llanos-Jiménez, R. Suá ez, Assessing
o e hea ing and unde cooling isks in exis ing public seconda y schools in
Medi e anean clima e in IOP Con e ence Se ies: Ea h and En i onmen al Science,
12-14 June 2024, Online (2024).
15. M.H. Aboke sh, M. Spiekman, O. Vijlb ie , T.A. an Goch, M. Vallès, D. Boe , Appl.
Ene gy. 281, 1-22 (2021)
16. EN 16798-1 Ene gy Pe o mance o Buildings. Ven ila ion o buildings. Pa 1:
Indoo En i onmen al Inpu Pa ame e s o Design and Assessmen o Ene gy
Pe o mance o Buildings Add essing Indoo Ai Quali y, The mal En i onmen ,
Ligh ing and Acous ics (2019)
8
E3S Web o Con e ences 636, 01002 (2025) h ps://doi.o g/10.1051/e3scon /202563601002
ICSREE 2025
