sus ainabili y
A icle
Speci ica ion o Glazings o Façades Based on
Spec opho ome ic Cha ac e iza ion o T ansmi ance
Helenice Ma ia Sach 1,*, Luís B agança 2, Manuela Almeida 2and Rosana Ca am 3


Ci a ion: Sach , H.M.; B agança, L.;
Almeida, M.; Ca am, R. Speci ica ion
o Glazings o Façades Based on
Spec opho ome ic Cha ac e iza ion
o T ansmi ance. Sus ainabili y 2021,
13, 5437. h ps://doi.o g/10.3390/
su13105437
Academic Edi o : Tomonobu Senjyu
Recei ed: 22 Ap il 2021
Accep ed: 11 May 2021
Published: 13 May 2021
Publishe ’s No e: MDPI s ays neu al
wi h ega d o ju isdic ional claims in
published maps and ins i u ional a il-
ia ions.
Copy igh : © 2021 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
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A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
1La in Ame ican Ins i u e o Technology, In as uc u e and Te i o y (ILATIT), Fede al Uni e si y o La in
Ame ican In eg a ion (UNILA), Foz do Iguaçu, PR 85867-970, B azil
2Depa men o Ci il Enginee ing, Uni e si y o Minho, 4800-533 Guima ães, Po ugal;
[email p o ec ed] (L.B.); [email p o ec ed] (M.A.)
3
Ins i u e o A chi ec u e and U banism (IAU), Uni e si y o São Paulo (USP), São Ca los, SP 13566-590, B azil;
[email p o ec ed]
*Co espondence: [email p o ec ed]
Abs ac :
The co ec speci ica ion o glazings o açades can educe he ene gy consump ion in
buildings. The hea exchange occu s h ough anspa en su aces and adia ion eaches he building
as ligh and hea . The e o e, glazings signi ican ly con ibu e o he hea ans e be ween ou doo
and indoo spaces and ac di ec ly on dayligh ing and he mal com o . This pape epo s on
he spec opho ome ic cha ac e iza ion o glazings ansmi ance o he s udy o componen s o
a modula açade sys em and i s sui abili y o he clima e o Po ugal ( empe a e clima e). The
s udy ocused on esul s o spec opho ome ic measu emen s o op ical p ope ies, speci ically he
ansmi ance o some ypes o glazings (sola con ol, sel -cleaning, low-e, loa , and ex a-clea ) and
wo ypes o double glazings. The esul s show he pe cen age o ansmission o ul a iole , isible,
and nea -in a ed egions and i s impo ance, which enabled he analysis o he glazing e iciency
ega ding dayligh ing and he co ela ion o he mal pe o mance. Subsidies and indica ions o he
speci ica ion and adequa e uses o anspa en su aces ha e been p esen ed and complemen ed he
da ashee s a ailable om he manu ac u es.
Keywo ds: açade; glazing; speci ica ion; ansmi ance; spec opho ome e es s; ene gy e iciency
1. In oduc ion
A la ge a ie y o anspa en ma e ials is a ailable o use in buildings açades. How-
e e , all glazing p ope ies mus be conside ed in he choice o ma e ial. The selec ion o
glazings should be a ca e ul p ocess o e alua ion and weighing o adeo s. Among he
cha ac e is ics equi ed o he speci ica ion o anspa en ma e ials, he spec opho o-
me ic beha io is an impo an ac o o be conside ed, as i enables imp o emen s in he
he mal and isual com o o a building.
Many s udies ha e been ca ied ou in his espec , bo h o glass and o he anspa en
ma e ials, mainly ocused on pene a ion o UV ays h ough he glazings. In o de o cu b
excessi e pene a ion o UV ays, op ically unc ional glasses ha e been p oposed and he
pe o mance assessmen s o he glazed ma e ials ha e been measu ed and epo ed by
Kim e al. [
1
]. Resul s ha e shown ha UV p o ec ion glass is mo e e ec i e in con olling
he UV ays o na u al ligh ; clea glass ea ed wi h a UV p o ec ion ilm would p o ide
excellen con ol o UV pene a ion and a pai o clea and UV p o ec ion glass shee s ea ed
wi h a UV p o ec ion ilm should be ecommended; his achie es 96.7% UV p o ec ion
pe o mance om na u al ligh .
Goia e al. [
2
] in es iga ed he spec al and angula beha io o di e en PCM glazing
samples, cha ac e ized by di e en hicknesses o PCMs, by means o a comme cial spec-
opho ome e , and by means o a dedica ed op ical es bed ha includes a la ge in eg a ing
sphe e wi h a diame e o 0.75 m. The expe imen s ha e poin ed ou he highly di usi e
Sus ainabili y 2021,13, 5437. h ps://doi.o g/10.3390/su13105437 h ps://www.mdpi.com/jou nal/sus ainabili y
Sus ainabili y 2021,13, 5437 2 o 19
beha io o he PCM laye , wi h inc easing weigh o he di ec - o-di use ansmission
mode as he PCM laye hickness inc eases.
Mo e ia e al. [
3
] s udied he he mal and op ical cha ac e iza ion o h ee polyca bon-
a e sys ems o buildings (wi h di e en numbe s o chambe s and geome y). The mal
ansmi ance measu emen s we e ca ied ou using a ho -box appa a us, in o de o as-
sess he impac o he connec ion join s on he e ec i e U- alue and o compa e i wi h
da a decla ed by manu ac u e s, usually e e ed o as he cen e o he componen . The
in es iga ed polyca bona e sys ems could be a alid solu ion in place o classic windows
in comme cial buildings and he s udy p o ides deepened knowledge abou he polyca -
bona e panels’ he mal and op ical beha io and a se o use ul da a o accu a e analyses
in building in eg a ion.
Baldinelli [
4
] p esen ed he spec al da a on he wa eleng h ield o in e es o sola
adia ion, showing he high anspa ency le els o glazing sys ems made by an in e nal
laye (s a i ied glass, ai gap, loa glass) and ex e nal laye (s a i ied glass), as well as he
good e lec i e p ope ies o he aluminum in he shading sys em. Acco ding o he same
au ho , glazing op ical p ope ies depend on he inciden angle be ween he su ace and he
ay di ec ion: as his angle de ia es om he no mal di ec ion (0
◦
), ansmissi i y dec eases,
e lec i i y inc eases, and abso p i i y inc eases. The a ia ion o op ical p ope ies wi h he
incidence angle depends on glass ype and hickness; in pa icula , i is mo e p onounced
o mul iple-pane glazing sys ems.
Be a di [
5
] poin s ou ha wi h ecen ad ances in glazing echnology, manu ac u e s
can con ol how glazing beha es in he di e en po ions o he spec um. Coa ings may
con ol he passage o long-wa e sola adia ion h ough ansmission and/o e lec ion.
In he pas , coa ings on windows ha educed he sola gain also educed he isible
ansmi ance and we e ha dly accep ed by occupan s. Howe e , new high-pe o mance
in ed glass and low sola -gain (o low-E) coa ings make i possible o educe he sola
hea gain wi h li le o no educ ion in he isible ansmi ance. A low-E coa ed glass has
a mic oscopically hin anspa en me al coa ing ha e lec s longwa e in a ed ene gy
du ing win e and blocks ex e nal sho wa e gains du ing summe .
Despi e he e being s udies on he de e mina ion o op ical p ope ies o glazing and
o he ma e ials o açades, wi h he de elopmen o new ma e ials, u he s udies a e
needed o di e en ypes o glass, as well as conside ing he beha io o double glazings and
analyzing he ela ionship be ween hose p ope ies wi h he mal and dayligh ing beha io .
1.1. Glazings and Sola Spec um
People ypically spend many hou s in buildings ba hed in he ul a iole , isible, and
in a ed adia ion p oduced by na u al o elec ic ligh ing. This adia ion can damage
issue ega dless o whe he o no i a ec s he isual and ci cadian sys ems [6]
The adia ion ansmission h ough glazings depends mainly on ac o s, such as angle
o adia ion incidence, hickness, chemical composi ion, and supe icial cha ac e is ics o
he glazing. The angle o adia ion incidence is he angle be ween he di ec ion o he
adia ion and he no mal one (90~) o he su ace unde analysis [
7
]. The ansmission o
glazings also depends on he wa eleng h o he inciden adia ion. The glazing ac s as
an opaque ma e ial o ce ain egions o he spec um, o example, i exhibi s opaque
beha io and p e en s he c ossing o adia ion o wa eleng hs sho e han 300 nm and
longe han 5000 nm [
8
]. The main he mal exchanges, as well as he passage o ligh
in o he in e io o a building, occu on anslucen o anspa en su aces. The e o e,
such su aces ac di ec ly on he mal com o and dayligh ing. Rega ding anspa en
glazing, pa o he ene gy om he sola adia ion (Figu e 1a) is di ec ly ansmi ed o he
in e io o he en i onmen , which dis inguishes opaque su aces om anslucen ones.
Re lec ion, abso p ion, and ansmission also occu on anslucen su aces (Figu e 1b),
howe e , he ansmission akes place in a di e en way. The ligh p opaga es when i
pene a es anslucen glazing and lea es i as a di use ligh , and no as a di ec one.
Sus ainabili y 2021,13, 5437 3 o 19
Sus ainabili y 2021, 13, x FOR PEER REVIEW 3 o 20
he ansmission akes place in a di e en way. The ligh p opaga es when i pene a es
anslucen glazing and lea es i as a di use ligh , and no as a di ec one.
Figu e 1. Beha io o adia ion on a anspa en su ace (a) and on a anslucen su ace (b).
The beha io o anspa en ma e ials when hey ecei e sola adia ion is o eac
selec i ely, ha is, he amoun o ene gy hey abso b, e lec , o ansmi depends on he
wa eleng h o he inciden ay. When he angle o incidence is no no mal o he plane
and is inc eased, he e lec ed ene gy becomes mo e and mo e, while he ansmi ed and
abso bed ene gy dec eases, al hough he ela ionship ha co esponds o he no mal in-
cidence app oxima ely emains he same be ween hem.
The o al alue o he adia ion ansmi ed, e lec ed, and abso bed by glazings is an
impo an a iable o he calcula ion o he sola hea gain coe icien , which depends on
he op ical p ope ies o he ma e ial, sola ac o , inciden sola adia ion, o e all hea
ans e coe icien (U ac o ), and di e ence o empe a u e be ween he ou doo and in-
doo en i onmen s.
The isible spec um is he mos known sola adia ion. Howe e , wo o he im-
po an bands a e ul a iole (UV) and in a ed (IV). Figu e 2 shows he sola adia ion
incidence di ided by spec a. Al hough he sun emi s adia ion in an ex ensi e band o
elec omagne ic wa es, only a na ow band o he sola spec um is pe cep ible. Wa e-
leng hs longe han 1500 nm each he e es ial su ace in small p opo ions.
Figu e 2. Sola Spec um [9].
UV Visible IR
0,00
0,25
0,50
0,75
1,00
1,25
1,50
1,75
2,00
250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000
Spec al I adiance W m
-2
nm
-1
Wa eleng h nm
ASTM G173-03 Re e ence Spec a
E W*m-2*nm-1
Global il W*m-2*nm-1
Di ec +ci cumsola W*m-2*nm-1
Figu e 1. Beha io o adia ion on a anspa en su ace (a) and on a anslucen su ace (b).
The beha io o anspa en ma e ials when hey ecei e sola adia ion is o eac
selec i ely, ha is, he amoun o ene gy hey abso b, e lec , o ansmi depends on he
wa eleng h o he inciden ay. When he angle o incidence is no no mal o he plane
and is inc eased, he e lec ed ene gy becomes mo e and mo e, while he ansmi ed
and abso bed ene gy dec eases, al hough he ela ionship ha co esponds o he no mal
incidence app oxima ely emains he same be ween hem.
The o al alue o he adia ion ansmi ed, e lec ed, and abso bed by glazings is
an impo an a iable o he calcula ion o he sola hea gain coe icien , which depends
on he op ical p ope ies o he ma e ial, sola ac o , inciden sola adia ion, o e all hea
ans e coe icien (U ac o ), and di e ence o empe a u e be ween he ou doo and
indoo en i onmen s.
The isible spec um is he mos known sola adia ion. Howe e , wo o he impo an
bands a e ul a iole (UV) and in a ed (IV). Figu e 2shows he sola adia ion incidence
di ided by spec a. Al hough he sun emi s adia ion in an ex ensi e band o elec omag-
ne ic wa es, only a na ow band o he sola spec um is pe cep ible. Wa eleng hs longe
han 1500 nm each he e es ial su ace in small p opo ions.
Figu e 2. Sola Spec um [9].
Fo he use o sola ene gy, he only adia ion conside ed is he one whose wa eleng h
anges be ween 290 and 1800 nm, o , mo e speci ically, up o 1500 nm [
10
], as wa eleng hs
longe han hose each he e es ial su ace in a e y educed way and a e abso bed by
he wa e apo and ca bon dioxide p esen in he a mosphe e. Wa eleng hs sho e han
290 nm a e abso bed by he ozone laye [7].
Sus ainabili y 2021,13, 5437 4 o 19
The sola spec um is di ided in o he ul a iole UV egion (100 o 380 nm), isible
egion (380 o 780), and in a ed egion (780 o 3000). The ansmission o he glazings o
each in e al in luences some cha ac e is ics.
1.1.1. Ul a iole (UV) (100–380 nm)
The ul a iole band is mo e ene ge ic han he ligh (i has a sho e wa eleng h),
he e o e, i pene a es he skin mo e deeply and causes bu ns depending on he ime o
exposi ion o he sola adia ion. Al hough only 1 o 5% o he ul a iole adia ion eaches
he e es ial su ace, i mus no be igno ed due o he e ec s i exe s.
In some si ua ions, such adia ion may no be impo an , as in eco e y a eas in
hospi als, as i is esponsible o he syn hesis o Vi amin D h ough he skin and exe s a
bac e icide e ec . Howe e , i comp omises he du abili y o ma e ials by he discolo a ion
o he issues, as i has pho ochemical capaci y. The ul a iole egion ha causes he
discolo a ion o he ma e ials is be ween 315 and 380 nm. Such adia ion is also esponsible
o anning.
The ul a iole adia ion is subdi ided in o h ee in e als: UV-C (be ween 100 and
280), UV-B (be ween 280 and 320), and UV-A (be ween 320 and 380). The UV-A adia ion
(be ween 320 and 380) causes he di ec anning o he skin wi h weak e y hema o sun-
bu n. The maximum eac ion o he e y hema occu s 72 h a e he exposi ion o he sun.
The con inuous exposi ion causes no only as aging o he skin bu also ca cinogenic
implica ions. The UV-B adia ion causes an e y hema esponse and, in associa ion, indi ec
anning. Unde in ense and equen adia ion, UV-B may p oduce skin ca cinomas. In
such a case, he maximum eac ion occu s be ween 6–20 h a e exposi ion. UV-C adia ion
does no each he Ea h, as wa eleng hs below 290 nm a e abso bed by he ozone laye o
he a mosphe e. Such adia ion is a ge micide and highly ha m ul o he human skin, due
o i s high ene gy con en [11].
1.1.2. Visible (Vis) (380–780 nm)
The isible egion is associa ed wi h he in ensi y o he whi e ligh ansmi ed and
in luences di ec ly he deg ee o dayligh o an en i onmen . I is also called luminous and
enables he isual sensa ion o days passing. I is he isible po ion o he inciden sola
adia ion in he di ec ion no mal o he su ace plane.
The isible ligh ca ies enough ene gy o s imula e chemical eac ions in he eyes
and he unc ioning o he isual sys em. This wa eleng h ollows he sequence: iole ,
blue, g een, yellow, o ange, and ed, howe e , he human isual sys em is mo e e ec i e
in he wa eleng h ha co esponds o g een and yellow. Besides being undamen al o
humans, he isual sys em is indispensable o he de elopmen o ege ables, because o
he pho osyn hesis p ocess, which equi es isible ligh . Chlo ophyll, he agen esponsible
o he ege able cellula espi a o y p ocess, abso bs speci ic egions o he spec a.
1.1.3. In a ed IR (780–3000 nm)
The in a ed egion is in isible o he isual sys em, al hough i is no iced in he o m
o hea . I in e e es wi h he indoo condi ions o he en i onmen h ough sola hea
gain, he e o e, i canno be igno ed. I is di ided in o h ee bands: sho -wa e in a ed,
o nea -in a ed, whose wa eleng hs ange be ween 780 and 1400 nm, mid-wa eleng h
in a ed, which anges om 1400 o 3000 nm, and, inally, long-wa eleng h in a ed, which
includes he adia ion ha esul s om hea ed bodies, whose wa eleng hs a e longe han
5000 nm.
The nea -in a ed co esponds o he la ge pa o he sola spec um ha c osses a
colo less glass, o ins ance, in high p opo ions. Re e ences o some speci ie s ega ding
such a egion o he spec um include s a emen s as “glass is gene ally opaque o he
in a ed”, howe e , his is w ong in o ma ion [8].
A spec opho ome ic cha ac e iza ion o glazings was accomplished o he s udy
o componen s o a modula açade sys em in Po ugal. The s udy ocused on esul s o
Sus ainabili y 2021,13, 5437 5 o 19
spec opho ome ic measu emen s o op ical p ope ies, speci ically, he ansmi ance o
some ypes o simple glazings and wo ypes o double glazings [12–14].
The esul s enabled he e i ica ion o he glazing e iciency in e ms o dayligh
and he co ela ion o he mal pe o mance and p o ided subsidies and indica ions o
he speci ica ion and adequa e uses o anspa en su aces. They also complemen ed
he da ashee s o he manu ac u es. An e alua ion o he ansmission o glazings by
spec opho ome ic es s enables he analysis o he di e en egions o he spec um
(ul a iole , isible, and in a ed) indi idually and no as a whole, as i occu s wi h
pa ame e s, such as sola ac o and shading coe icien , which a e calcula ed in a global
way wi hou aking in o accoun he di e ences o beha io pe egion o he spec um.
2. Ma e ials and Me hods
The de elopmen o his esea ch included he ollowing asks: I. Cha ac e iza ion o
glazing ma e ials; II. P epa a ion o he spec opho ome e ; III. Cleaning, Iden i ica ion, and
Fixa ion o he Specimen on he De ice; and IV. Desc ip ion o he Spec opho ome ic Tes s.
2.1. Cha ac e iza ion o he Glazing Ma e ials
Samples o 6 mm hick glazings we e used in he spec opho ome ic es s. Ten ypes
o simple glazings and wo ypes o double glazings we e analyzed. The double glazings
we e moun ed on ha d pape wi h he aid o a de ice (Figu e 3a,b).
Sus ainabili y 2021, 13, x FOR PEER REVIEW 5 o 20
The nea -in a ed co esponds o he la ge pa o he sola spec um ha c osses a
colo less glass, o ins ance, in high p opo ions. Re e ences o some speci ie s ega ding
such a egion o he spec um include s a emen s as “glass is gene ally opaque o he in-
a ed”, howe e , his is w ong in o ma ion [8].
A spec opho ome ic cha ac e iza ion o glazings was accomplished o he s udy o
componen s o a modula açade sys em in Po ugal. The s udy ocused on esul s o
spec opho ome ic measu emen s o op ical p ope ies, speci ically, he ansmi ance o
some ypes o simple glazings and wo ypes o double glazings [12–14].
The esul s enabled he e i ica ion o he glazing e iciency in e ms o dayligh and
he co ela ion o he mal pe o mance and p o ided subsidies and indica ions o he
speci ica ion and adequa e uses o anspa en su aces. They also complemen ed he
da ashee s o he manu ac u es. An e alua ion o he ansmission o glazings by spec o-
pho ome ic es s enables he analysis o he di e en egions o he spec um (ul a iole ,
isible, and in a ed) indi idually and no as a whole, as i occu s wi h pa ame e s, such
as sola ac o and shading coe icien , which a e calcula ed in a global way wi hou aking
in o accoun he di e ences o beha io pe egion o he spec um.
2. Ma e ials and Me hods
The de elopmen o his esea ch included he ollowing asks: I. Cha ac e iza ion o
glazing ma e ials; II. P epa a ion o he spec opho ome e ; III. Cleaning, Iden i ica ion,
and Fixa ion o he Specimen on he De ice; and IV. Desc ip ion o he Spec opho ome ic
Tes s.
2.1. Cha ac e iza ion o he Glazing Ma e ials
Samples o 6 mm hick glazings we e used in he spec opho ome ic es s. Ten ypes
o simple glazings and wo ypes o double glazings we e analyzed. The double glazings
we e moun ed on ha d pape wi h he aid o a de ice (Figu e 3a,b).
(a) (b)
Figu e 3. De ice made wi h ha d pape o he con o ma ion o he double glazing (a); de ice wi h
he specimens posi ioned (b).
This de ice enabled he con igu a ion o he double glazings wi h an indoo ai laye .
The samples we e placed 6 mm om each o he in he spec opho ome e , di e en ly
om he usual posi ion, ha is, 12 mm. Howe e , he esul s would be signi ican o he
analysis o he in luence o he ai laye on he ansmission o he double glazings.
Rec angula samples o 50 mm × 50 mm we e used o all eigh ypes o glazings. The
in e al o he spec um was 200 o 1100 nm, which comp ised h ee egions: ul a iole
(200 o 380 nm), isible (380 o 780 nm), and nea -in a ed (780 o 1100 nm). Table 1 shows
he cha ac e is ics o he samples analyzed.
Figu e 3.
De ice made wi h ha d pape o he con o ma ion o he double glazing (
a
); de ice wi h
he specimens posi ioned (b).
This de ice enabled he con igu a ion o he double glazings wi h an indoo ai laye .
The samples we e placed 6 mm om each o he in he spec opho ome e , di e en ly om
he usual posi ion, ha is, 12 mm. Howe e , he esul s would be signi ican o he analysis
o he in luence o he ai laye on he ansmission o he double glazings.
Rec angula samples o 50 mm
×
50 mm we e used o all eigh ypes o glazings. The
in e al o he spec um was 200 o 1100 nm, which comp ised h ee egions: ul a iole
(200 o 380 nm), isible (380 o 780 nm), and nea -in a ed (780 o 1100 nm). Table 1shows
he cha ac e is ics o he samples analyzed.
The glazings we e selec ed mainly acco ding o hei cha ac e is ics ega ding o e all
hea ans e (U- alue) and Visible T ansmi ance. The equisi e o he mal quali y is he
U- alue, o which accep able maximum alues (Umáx) a e limi ed and e e ence alues
(U e ) a e ecommended, acco ding o RCCTE Po uguese Code [
15
]. The maximum
supe icial U- alues (Umáx) accep able in a cu en zone and he e e ence alues (U e )
o he elemen s o he buildings en elope a e shown in Table 2.

Sus ainabili y 2021,13, 5437 6 o 19
Table 1. Cha ac e is ics o he Glass Specimens.
Iden i ica ion Type o Glass Thickness
Numbe o Specimens
Posi ion o Coa ing
Dimension
50 ×50 mm
Glass A Glass wi h a sola con ol me allic oil ha
con e s i s cha ac e is ics o sola con ol. 6 mm 3 Face 2
Glass B G een glass wi h a sola con ol me allic oil
ha con e s i s cha ac e is ics o sola con ol. 6 mm 3
Glass C
Sel -cleaning glass manu ac u ed by deposi ing
a anspa en laye o pho oca aly ic and
hyd ophilic mine al ma e ial on o clea glass.
6 mm 3 Face 1
Glass D Glass wi h a low-emissi i y oil. 6 mm 3 Face 2
Glass E Glass wi h an ex emely low-emissi i y oil. 6 mm 3 Face 2
Glass F
Clea loa glass, which has been coa ed wi h
me allic oxides by magne ically enhanced
ca hodic spu e ing unde acuum condi ions.
6 mm 3 Face 2
Glass G High quali y, clea annealed glass,
manu ac u ed by he loa p ocess. 6 mm 3 No coa ing
Glass H
Highly anspa en ex a clea glass, which has
e y li le esidual colo . 6 mm 3 No coa ing
Glazing 04 Glass B 6 mm 3 Bo h in Face 2
Glass E
Glazing 07 Glass C 6 mm 3 Glass C: Face 1
Glass G
Faces o Double Glazing
Sus ainabili y 2021, 13, x FOR PEER REVIEW 6 o 20
Table 1. Cha ac e is ics o he Glass Specimens.
Iden i ica ion Type o Glass Thickness
Numbe o
Specimens Posi ion o
Coa ing
Dimension
50 × 50 mm
Glass A
Glass wi h a sola con ol me-
allic oil ha con e s i s cha -
ac e is ics o sola con ol.
6 mm 3
Face 2
Glass B
G een glass wi h a sola con-
ol me allic oil ha con e s
i s cha ac e is ics o sola con-
ol.
6 mm 3
Glass C
Sel -cleaning glass manu ac-
u ed by deposi ing a ans-
pa en laye o pho oca aly ic
and hyd ophilic mine al ma-
e ial on o clea glass.
6 mm 3 Face 1
Glass D Glass wi h a low-emissi i y
oil. 6 mm 3 Face 2
Glass E Glass wi h an ex emely low-
emissi i y oil. 6 mm 3 Face 2
Glass F
Clea loa glass, which has
been coa ed wi h me allic ox-
ides by magne ically en-
hanced ca hodic spu e ing
unde acuum condi ions.
6 mm 3 Face 2
Glass G
High quali y, clea annealed
glass, manu ac u ed by he
loa p ocess.
6 mm 3 No coa ing
Glass H
Highly anspa en ex a clea
glass, which has e y li le e-
sidual colo .
6 mm 3 No coa ing
Glazing 04 Glass B 6 mm 3 Bo h in Face 2
Glass E
Glazing 07 Glass C 6 mm 3 Glass C: Face
1
Glass G
Faces o Double Glazing
Ai laye : 6 mm
The glazings we e selec ed mainly acco ding o hei cha ac e is ics ega ding o e all
hea ans e (U- alue) and Visible T ansmi ance. The equisi e o he mal quali y is he
U- alue, o which accep able maximum alues (Umáx) a e limi ed and e e ence alues
(U e ) a e ecommended, acco ding o RCCTE Po uguese Code [15]. The maximum su-
pe icial U- alues (Umáx) accep able in a cu en zone and he e e ence alues (U e ) o
he elemen s o he buildings en elope a e shown in Table 2.
Ai laye : 6 mm
Table 2.
Maximum su ace hea ans e coe icien accep able and e e ence su ace hea ans e
coe icien [15].
Elemen s
Umáx (W/m2·◦C)
Clima ic Zone
I1
Clima ic Zone
I2
Clima ic Zone
I3
Ou doo elemen s in a cu en zone UmáxU e UmáxU e UmáxU e
Ve ical Opaque zones 1.80 0.70 1.60 0.60 1.45 0.50
Ho izon al opaque zones 1.25 0.50 1.00 0.45 0.90 0.40
Glazings
U e (W/m2·◦C)
Clima ic Zone
I1
Clima ic Zone
I2
Clima ic Zone
I3
- 4.30 - 3.30 - 3.30
The e o e, he U- alue o he glazings should no exceed 3.30 W/m
2·◦
C, so as o
mee mos zones. Mo eo e , maximum sola ac o s accep able (g
Sus ainabili y 2021, 13, x FOR PEER REVIEW 7 o 20
Table 2. Maximum su ace hea ans e coe icien accep able and e e ence su ace hea ans e
coe icien [15].
Elemen s
Umáx (W/m2·° C)
Clima ic Zone
I1
Clima ic Zone
I2
Clima ic Zone
I3
Ou doo elemen s in a cu en
zone
Umáx
U e
Umáx
U e
Umáx
U e
Ve ical Opaque zones
1.80
0.70
1.60
0.60
1.45
0.50
Ho izon al opaque zones
1.25
0.50
1.00
0.45
0.90
0.40
Glazings
U e (W/m2·°C)
Clima ic Zone
I1
Clima ic Zone
I2
Clima ic Zone
I3
-
4.30
-
3.30
-
3.30
The e o e, he U- alue o he glazings should no exceed 3.30 W/m2·°C, so as o mee
mos zones. Mo eo e , maximum sola ac o s accep able (g┴) a e ecommended. No
glazing o any building ha is no no he n-o ien ed (be ween he no hwes and he
no heas ) and whose o al a ea does no exceed 5% o he use ul pa emen mus show a
sola ac o co esponding o he glazed oid wi h he espec i e p o ec ion de ices 100%
ac i e ha exceeds he alues indica ed (Table 3).
Table 3. Maximum Sola Fac o accep ed o glazings [15].
The mal Ine ia
Maximum Sola Fac o Accep ed
Clima ic Zone
V1
Clima ic Zone
V2
Clima ic Zone
V3
Poo
0.15
0.15
0.10
Medium
0.56
0.56
0.50
High
0.56
0.56
0.50
Table 4 [16] shows o he cha ac e is ics o glasses, as he U- alues, sola ac o , shad-
ing coe icien , and ela i e hea gain o he glazings s udied. Rega ding he spec opho-
ome ic es s, images o he samples will be shown, so as o p o ide he isual aspec o
he selec ed ma e ial. The s udied glasses a e:
• Glass A is a glass wi h a sola con ol me allic oil ha con e s i s cha ac e is ics o
sola con ol;
• Glass B is a g een glass wi h a sola con ol me allic oil ha con e s i s cha ac e is ics
o sola con ol;
• Glass C is sel -cleaning glass manu ac u ed by deposi ing a anspa en laye o pho-
oca aly ic and hyd ophilic mine al ma e ial on o clea glass;
• Glass D is a glass wi h a low-emissi i y oil;
• Glass E is a glass wi h an ex emely low-emissi i y oil;
• Glass F is clea loa glass ha has been coa ed wi h me allic oxides by magne ically
enhanced ca hodic spu e ing unde acuum condi ions and sola con ol p ope ies;
• Glass G is a high quali y, clea annealed glass, manu ac u ed by he loa p ocess;
• Glass H is a highly anspa en ex a clea glass, which has e y li le esidual colo ;
• Glazings 04 and 07 a e double glazings.
) a e ecommended.
No glazing o any building ha is no no he n-o ien ed (be ween he no hwes and he
no heas ) and whose o al a ea does no exceed 5% o he use ul pa emen mus show a
sola ac o co esponding o he glazed oid wi h he espec i e p o ec ion de ices 100%
ac i e ha exceeds he alues indica ed (Table 3).
Sus ainabili y 2021,13, 5437 7 o 19
Table 3. Maximum Sola Fac o accep ed o glazings [15].
The mal Ine ia
Maximum Sola Fac o Accep ed
Clima ic Zone
V1
Clima ic Zone
V2
Clima ic Zone
V3
Poo 0.15 0.15 0.10
Medium 0.56 0.56 0.50
High 0.56 0.56 0.50
Table 4[
16
] shows o he cha ac e is ics o glasses, as he U- alues, sola ac o , shading
coe icien , and ela i e hea gain o he glazings s udied. Rega ding he spec opho ome ic
es s, images o he samples will be shown, so as o p o ide he isual aspec o he selec ed
ma e ial. The s udied glasses a e:
•
Glass A is a glass wi h a sola con ol me allic oil ha con e s i s cha ac e is ics o
sola con ol;
•
Glass B is a g een glass wi h a sola con ol me allic oil ha con e s i s cha ac e is ics
o sola con ol;
•
Glass C is sel -cleaning glass manu ac u ed by deposi ing a anspa en laye o
pho oca aly ic and hyd ophilic mine al ma e ial on o clea glass;
•Glass D is a glass wi h a low-emissi i y oil;
•Glass E is a glass wi h an ex emely low-emissi i y oil;
•
Glass F is clea loa glass ha has been coa ed wi h me allic oxides by magne ically
enhanced ca hodic spu e ing unde acuum condi ions and sola con ol p ope ies;
•Glass G is a high quali y, clea annealed glass, manu ac u ed by he loa p ocess;
•Glass H is a highly anspa en ex a clea glass, which has e y li le esidual colo ;
•Glazings 04 and 07 a e double glazings.
Table 4. Cha ac e is ics o he Glazings.
Cha ac e is ics
Glazings
Glass A
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Pane Ou e 6 mm 6 mm 6 mm
U-Value (W/m2K) 5.683 5.683 5.799
Sola Hea Gain Coe icien (SHGC) 0.503 0.432 0.814
Shading coe icien 0.57 0.496 0.936
Rela i e Hea Gain (W/m2)403 351 631
Cha ac e is ics
Glazings
Glass D
(Low-E)
Glass E
(Ex emely Low-E)
Glass F
(Clea Floa -Sola
Con ol)
Pane Ou e 6 mm 6 mm 6 mm
U-Value (W/m2K) 5.665 5.665 5.661
Sola Hea Gain Coe icien (SHGC) 0.708 0.617 0.454
Shading coe icien 0.814 0.709 0.521
Rela i e Hea Gain (W/m2)551 485 366
Sus ainabili y 2021,13, 5437 8 o 19
Table 4. Con .
Cha ac e is ics
Glazings
Glass G
(Clea Floa Annealed)
Glass H
(Ex a Clea )
Pane Ou e 6 mm 6 mm
U-Value (W/m2K) 5.799 5.799
Sola Hea Gain Coe icien (SHGC) 0.85 0.898
Shading coe icien 0.976 1.032
Rela i e Hea Gain (W/m2)657 692
Cha ac e is ics
Glazings
Glazing 04
(Double)
Glazing 07
(Double)
Pane Ou e Glass B Glass C
Inne Glass E Glass G
U-Value (W/m2K) 2.363 3.102
Sola Hea Gain Coe icien (SHGC) 0.333 0.714
Shading coe icien 0.383 0.821
Rela i e Hea Gain (W/m2)260 543
Table 5shows he samples o he selec ed glazings. The glazings wi h a me allic-o igin
coa ing, mainly Glass D, Glass E, and Glass F oxidize in con ac wi h he ai . The e o e, in
he composi ions o double glazing, he coa ing mus be placed inside. In he samples, he
us y pa co esponds o he ab asion band ha shows he ace wi h he ilm, so ha he
glazings could be co ec ly posi ioned in he spec opho ome ic cha ac e iza ion es s.
Table 5. Specimens o Glasses.
Glass A
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Glass G
(clea loa annealed)
Glass H
(ex a clea )
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Sus ainabili y 2021,13, 5437 9 o 19
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [
17
], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions. I
also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he aid o
a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ainbow, wi h
he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh shea (o only
one, o almos only one wa eleng h) can pass h ough he sample. The spec opho ome e
shows he amoun o ligh abso bed a each wa eleng h and p o ides da a on abso p ion,
e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Sus ainabili y 2021, 13, x FOR PEER REVIEW 9 o 20
Table 5. Specimens o Glasses.
Glass
(Sola Con ol)
Glass B
(G een Sola Con ol)
Glass C
(Sel -Cleaning)
Glass D
(low-e)
Glass E
(ex emely low-e)
Glass F
(clea loa -sola con ol)
Glass G
(clea loa annealed)
Glass H
(ex a clea )
2.2. P epa a ion o he Spec opho ome e
Acco ding o he ASTM [17], he spec opho ome e is he ideal equipmen o p o ide
he da a o ansmission pe cen age o he ul a iole , isible, and nea -in a ed egions.
I also enables a sweeping in he spec um only in he egion o in e es .
A spec opho ome e was used in he es s. I enables a monoch oma ic ligh shea o
pass h ough a sample and measu es he amoun o ligh abso bed (Figu e 4). Wi h he
aid o a p ism, i sepa a es he ligh in o shea es o di e en wa eleng hs (as in he ain-
bow, wi h he sepa a ion o he colo s o whi e ligh . The e o e, a monoch oma ic ligh
shea (o only one, o almos only one wa eleng h) can pass h ough he sample. The spec-
opho ome e shows he amoun o ligh abso bed a each wa eleng h and p o ides da a
on abso p ion, e lec ion, and ansmission o he ma e ial o di e en incidence angles.
Figu e 4. UNICAM UV/VIS Spec opho ome e .
Figu e 4. UNICAM UV/VIS Spec opho ome e .
UNICAM UV/VIS was he de ice used o he es s. I p o ides da a on abso p ion,
e lec ion, and ansmission o he es ed ma e ials. By i ue o ou objec i e, only he
ansmission mode was used. A ungs en lamp was used o he whole spec um. The
samples we e es ed a 0
◦
wi h he no mal incidence (shea pe pendicula o he sample)
and he shea incidence was in acco dance wi h he coa ing o he samples, as i ollowed
he ecommenda ions o he manu ac u e o bo h simple and double glazings analyzed.
In he speci ic case o ansmission, g aphs can be gene a ed wi h he ansmission
pe cen age o he ul a iole , isible, and nea -in a ed egions and he esul s can be
compa ed among hemsel es o wi h a colo less simple glazing, o example, o he
e i ica ion o he e iciency o he glazings ega ding he illuminance le el [7].
The in o ma ion o he glass manu ac u e s is limi ed o alues o mechanical e-
sis ance, acous ic insula ion, and ene ge ic ansmission o sola adia ion. The la e is
ea ed in a gene alized way and he da a on he isible egion and sola ac o igno e
he beha io o he ma e ial in he ul a iole and in a ed adia ion. The da a usually
ega d he ansmi ance o he incidence o no mal adia ion o he su ace, which occu s
in a minimum pe iod o ime. Some in o ma ion e e s o he sola hea gain coe icien .
Howe e , in mos cases, no da a on he in a ed a e p o ided, which hampe s an indi idual
and co ec analysis o he spec al beha io o he glass.
The highes concen a ion o in a ed is in he 780 o 1500 nm in e al and he pe cen -
age o wa eleng hs longe han 1500 nm is e y small. The e o e, analyses o he 780 o
1100 nm in e al used in ou esea ch a e alid. This is he limi ing in e al in which he
de ice u ilized pe o ms he sweeping
The da a p o ided by he spec opho ome e enabled he c ea ion o cu es wi h he
ansmission da a and analysis o he in eg a ion o bo h a eas ha co espond o each
egion o he spec um (ul a iole , isible, and in a ed) and he o al a ea o he cu es.
The e o e, he ansmission could be compa ed in cha ac e is ic in e als.
Sus ainabili y 2021,13, 5437 16 o 19
Sus ainabili y 2021, 13, x FOR PEER REVIEW 17 o 20
Figu e 13. To al T ansmission o Simple and Double Glazings.
Besides he Glass H, which can be indica ed o use in T ombe walls, Glass G and
Glass C mus be highligh ed, as hey ha e shown he highes alues o o al ansmission
in he cha ac e is ic in e als. The o al ansmission o glass 07 (Glass C-sel -cleaning in
he ou e pane and Glass G-clea loa annealed, in he inne pane), mainly in he in a ed
egion, has also p o en i s e iciency ega ding he dec ease in he hea ene gy needs. The
da a o ansmission o sola adia ion a e di ec ly ela ed o he he mal com o condi-
ions, mainly in ela ion o he esul s o he in a ed in e al.
Figu e 14 clea ly shows he maximum and minimum ansmission alues o Glass
H (ex a clea ) and glazing 04, espec i ely. Glass B (g een sola con ol) enables good
illumina ion and weakens he in a ed adia ion in he in e al analyzed, educing he
hea ing in his egion. G een glasses a e known o always end o dec ease ansmission
in longe wa eleng hs.
Figu e 14. T ansmission cu es o all glazings.
Ano he ac o ha mus be highligh ed is he di e si y o beha io s ega ding he
ansmission shown by he glasses (see abo e g aph), e en o ma e ials o simila cha -
ac e is ics in e ms o composi ion.
Figu e 13. To al T ansmission o Simple and Double Glazings.
Besides he Glass H, which can be indica ed o use in T ombe walls, Glass G and
Glass C mus be highligh ed, as hey ha e shown he highes alues o o al ansmission
in he cha ac e is ic in e als. The o al ansmission o glass 07 (Glass C-sel -cleaning in
he ou e pane and Glass G-clea loa annealed, in he inne pane), mainly in he in a ed
egion, has also p o en i s e iciency ega ding he dec ease in he hea ene gy needs. The
da a o ansmission o sola adia ion a e di ec ly ela ed o he he mal com o condi ions,
mainly in ela ion o he esul s o he in a ed in e al.
Figu e 14 clea ly shows he maximum and minimum ansmission alues o Glass
H (ex a clea ) and glazing 04, espec i ely. Glass B (g een sola con ol) enables good
illumina ion and weakens he in a ed adia ion in he in e al analyzed, educing he
hea ing in his egion. G een glasses a e known o always end o dec ease ansmission in
longe wa eleng hs.
Sus ainabili y 2021, 13, x FOR PEER REVIEW 17 o 20
Figu e 13. To al T ansmission o Simple and Double Glazings.
Besides he Glass H, which can be indica ed o use in T ombe walls, Glass G and
Glass C mus be highligh ed, as hey ha e shown he highes alues o o al ansmission
in he cha ac e is ic in e als. The o al ansmission o glass 07 (Glass C-sel -cleaning in
he ou e pane and Glass G-clea loa annealed, in he inne pane), mainly in he in a ed
egion, has also p o en i s e iciency ega ding he dec ease in he hea ene gy needs. The
da a o ansmission o sola adia ion a e di ec ly ela ed o he he mal com o condi-
ions, mainly in ela ion o he esul s o he in a ed in e al.
Figu e 14 clea ly shows he maximum and minimum ansmission alues o Glass
H (ex a clea ) and glazing 04, espec i ely. Glass B (g een sola con ol) enables good
illumina ion and weakens he in a ed adia ion in he in e al analyzed, educing he
hea ing in his egion. G een glasses a e known o always end o dec ease ansmission
in longe wa eleng hs.
Figu e 14. T ansmission cu es o all glazings.
Ano he ac o ha mus be highligh ed is he di e si y o beha io s ega ding he
ansmission shown by he glasses (see abo e g aph), e en o ma e ials o simila cha -
ac e is ics in e ms o composi ion.
Figu e 14. T ansmission cu es o all glazings.
Ano he ac o ha mus be highligh ed is he di e si y o beha io s ega ding he
ansmission shown by he glasses (see abo e g aph), e en o ma e ials o simila cha ac-
e is ics in e ms o composi ion.

Sus ainabili y 2021,13, 5437 17 o 19
Acco ding o he esul s, he sola con ol glasses (colo less, g een, Glass F-clea loa -
sola con ol and Glass A- sola con ol) ha e shown li le anspa ency o he ul a iole ,
he e o e hey can be adequa e o shop windows, comme cial cen e s, museums, and e en
esidences. Glazing 04 can be highligh ed in e ms o con ol o ul a iole sola adia ion,
wi h he lowes ansmission o his egion. This spec um band has high ene ge ic powe ,
which de e io a es and discolo s he ma e ials and may e en cause skin diseases. Howe e ,
in some si ua ions, i s incidence can be impo an , as in eco e y a eas in hospi als, as i is
esponsible o he syn hesis o some i amins.
Glass C, which has a sel -cleaning coa ing, exhibi ed good he mal beha io , based on
he esul s o he mal pe o mance simula ions o o he esea ch s ages [
14
]. Such esul s
show he pe o mance o his glass is good, ega ding he dec ease in he hea ene gy needs.
Figu e 14 also shows a cu e o he possible beha io o an ideal glass in e ms o
adia ion ansmission, which a ies in unc ion o he clima e o which he ma e ial will
be indica ed. Fo ins ance, he glass conside ed ideal o açades in ho egions and exposed
o sola adia ion daily should p esen a good ansmission in he isible egion and ligh
ansmission in he in a ed. The ma e ial mus allow he en y o ligh and a oid he en y
o hea om he p edominan clima ic condi ions. As he clima e in Po ugal is empe a e,
he ideal glazing should wo k as a ba ie agains ul a iole adia ion, enable he passage
o he isible ligh o a o dayligh ing, and enable a pa o In a ed ligh o p omo e
passi e hea ing, hus he low-e glass use is a good indica ion.
Al hough he s udy was done o he clima e o Po ugal, i is emphasized ha
i can be consul ed o applica ion in o he loca ions, acco ding o he needs ha a e
sough in he applica ion o glazing sui able o he clima e. Fo example, i an applica ion
in a chi ec u e equi es minimizing issues ela ed o he ading o su aces, glass wi h
he g ea e ansmission in he ul a iole egion should be a oided. I he applica ion
objec i es o he glazing a e o imp o e he condi ions o dayligh , g ea e alues o
ansmi ance should be sough in he isible egion and, inally, i he main cha ac e is ic
o he applica ion o he glass is o minimize he hea ansmi ed o he in e io , glass
wi h high ansmi ance in he in a ed egion should be a oided. The e o e, his analysis
o wha is necessa y in e ms o speci ying he glazing acco ding o he clima e (mo e o
less dayligh ing; mo e o less ansmission o hea ) mus be done i s and, knowing he
ansmi ance o he glass o be applied in he h ee egions o he spec um, i is possible
o make he speci ica ion mo e app op ia e o he clima e.
5. Conclusions
Acco ding o he esul s o he spec opho ome ic es s, he double Glass B (g een
sola con ol)—Glass E (ex emely low-e) (glazing 04) has shown a subs an ial ansmission
dec ease in all egions o he spec um, especially in he isible egions (25.2%). On he
o he hand, he double Glass C (sel -cleaning)—Glass G (clea loa annealed) (glazing 07)
ansmi s 70.3% o he isible ligh , which gua an ees be e condi ions o dayligh .
The g een double Glass B—Glass E (glazing 04) led o he lowes ansmission alue in
he in a ed (2.6%) ega ding hea . The e o e, such glazing can be e icien in he dec ease
o he nominal needs o cooling. Double Glass C—Glass G (glazing 07) led o a ansmission
simila o ha o low-e (47.9%) in e ms o in a ed adia ion, which indica es i s use will
cause s onge hea ing in an indoo habi able space.
As he clima e in Po ugal is empe a e, he ideal glazing should wo k as a ba ie
agains ul a iole adia ion and enable he passage o he isible ligh o a o dayligh ing.
In o he wo ds, such glazing should enable good ansmission in he isible egion and
a small amoun o hea om he nea -in a ed so as o help he hea ing o he indoo
en i onmen . Low-emissi i y glazings display hose cha ac e is ics as hey usually show
good he mal pe o mance o empe a e clima es. The esul s o high ansmission in
he in a ed o some ma e ials analyzed show hei adequacy o use in coun ies o
p edominan ly cold wea he .
Sus ainabili y 2021,13, 5437 18 o 19
Each ype o glazing has led o dis inc ansmissions o each band o he sola
spec um. The concep ion o a good dayligh ing sys em and he mal com o equi es
a en ion ega ding he localiza ion and o ien a ion o he building, bu also he a ia ions
o he dayligh in unc ion o he seasons o he yea , ime, and wea he condi ions.
The esul s o he spec opho ome ic es s show de ining ansmission as adequa e
only in unc ion o he luminous ansmission (in he isible egion) o he glazing may
no be co ec , as he ansmission in he o he in e als will also in luence he he mal
com o . The dimension o he glazed a ea, i s geog aphic o ien a ion, la i ude, and ime o
he yea mus also be aken in o accoun . In he e alua ion o he dayligh ing condi ions,
o ins ance, he le els o illuminance o an en i onmen can be adequa ed by he use
o glazings o di e en pe cen ages o isible ansmission h ough he esizing o he
windows. The le el o illuminance o an en i onmen is ela ed o no only he ype o
glazing bu also o he sola o ien a ion, dimension, and disposi ion o he opening and he
ex e nal obs acles, colo s o he in e nal su ace, among o he ac o s.
Au ho Con ibu ions:
Concep ualiza ion, H.M.S. and R.C.; Me hodology, H.M.S. and R.C.; Fo -
mal analysis, L.B. and M.A.; In es iga ion, H.M.S.; Da a cu a ion, H.M.S.; W i ing—o iginal d a
p epa a ion, e iew and edi ing, H.M.S.; Supe ision, L.B. and M.A.; P ojec adminis a ion, L.B.
and M.A.; Funding acquisi ion, H.M.S. All au ho s ha e ead and ag eed o he published e sion o
he manusc ip .
Funding:
This esea ch was unded by E asmus Mundus Ex e nal Coope a ion Window–ISAC:
Imp o ing Skills Ac oss Con inen s (F amewo k Pa ne ship Ag eemen 2008-1021/001 FRAMEECW
L16 Coimb a, Speci ic G an Ag eemen 2008-3628/001-001-MUN-ECW).
Ins i u ional Re iew Boa d S a emen : No applicable.
In o med Consen S a emen : No applicable.
Da a A ailabili y S a emen :
Da a suppo ing epo ed esul s can be ound a ailable online in:
h ps:// eposi o ium.sdum.uminho.p /.
Con lic s o In e es : The au ho s decla e no con lic o in e es .
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