SBE16 Hambu g
In e na ional Con e ence
on Sus ainable Buil En i onmen
S a egies – S akeholde s – Success ac o s
7 h - 11 h Ma ch 2016
Con e ence P oceedings
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In e na ional Con e ence on Sus ainable Buil En i onmen
SBE16 Hambu g
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ISBN 978-3-00-052213-0
DOI: 10.5445/IR/1000051699
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572
In e na ional Con e ence on Sus ainable Buil En i onmen
SBE16 Hambu g
Façade design o nigh cooling by na u al en ila ion in di e en
clima e zones
Ma hias F ied ich, M.Sc., Ha enCi y Uni e si y, Ge many, ma hias. ied ich@hcu-hambu g.de
P o . Lucila Chebel Labaki, S a e Uni e si y o Campinas, B azil, luci[email p o ec ed].b
Luciana Fe nandes, M.Sc., S a e Uni e si y o Campinas, B azil, lu[email p o ec ed]nicamp.b
Abs ac
Depending on he clima e egion, he local com o s anda d and he e iciency o exis ing building
se ices, he sha e o ene gy o cooling, hea ing and a i icial ligh ning o buildings is be ween
30% and 50% o he o e all inal ene gy consump ion o he coun y. The equi ed ene gy o
cooling o buildings can be signi ican ly educed by nigh en ila ion. In his case cool ai is
en ila ed h ough he building o discha ge hea ene gy s o ed in walls, loo slabs, and u ni u e.
The e iciency o his me hod depends mainly on he ai exchange a e be ween he ou doo
en i onmen and he indoo ai olume. D i ing o ces o he ai low h ough açade openings a e
he ou side ai empe a u e d op du ing nigh , wind p essu e dis ibu ions ac ing on he açade due
o local wind and he a ailabili y o c oss wind low h ough he building. Resis ances o he ai
low a e gi en by he size and he geome y o acade openings which can be quan i ied by
discha ge coe icien s. In he acade design phase he ela ion be ween window size and e ec i e
opening a ea mus be conside ed. Wi h p edic ed discha ge coe icien s he o e all ene gy
e iciency and indoo empe a u e o buildings wi h na u al en ila ion can be analyzed in ansien
mul i zone models. Exempla y buildings in Campinas, B azil and Hambu g, Ge many a e analyzed
conce ning hei po en ial o his me hod o sa e ene gy.
Keywo ds: ene gy e iciency, acade opening, discha ge coe icien , nigh cooling, na u al en ila-
ion
Welle sho
F ank
Uni .-P o . D .-Ing.
Ha enCi y Uni e si yHambu g
Ge many
ank.welle sho @hcu-hambu g.de
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S a egies – S akeholde s – Success ac o s
1. Backg ound
The ci y o Campinas is loca ed in he Sou heas o B azil wi h summe a e age empe a u es
exceeding 30°C and high ela i e humidi y le els h oughou he yea . P o ec ion agains o e -
hea ing is one o he mos impo an aspec s o be conside ed in building physics. The ci y o
Hambu g is loca ed in he No h o Ge many. The mode a e clima e zone has s ongly dis inc
seasons wi h cold win e and ho summe days. A he mal insula ed building en elope is as im-
po an as an in elligen concep o a oid o e hea ing. I is aimed o use he empe a u e ampli ude
be ween day and nigh in bo h coun ies o nigh en ila ion o educe he cooling loads. Massi e
conc e e elemen s a e hea s o ages du ing he day ime. Fo nigh cooling he hea con ec ion
om inside o ou side shall be maximized, bu i is limi ed by he ai exchange a e.
2. Me hods
The ene gy e iciency and indoo empe a u es a e analyzed wi h ansien mul i zone simula ions.
The he mo-ene ge ic pe o mance using nigh en ila ion in exempla y o ice ooms o non-
esiden ial buildings is simula ed wi h Ene gyPlus. Ene gyPlus is a building ene gy simula ion
p og am o model ene gy consump ion and wa e use in buildings. I is a ee and open-sou ce
so wa e unded by he U.S. Depa men o Ene gy (DOE) Building Technologies O ice (BTO) and
managed by he Na ional Renewable Ene gy Labo a o y (NREL) [1]. The s udied ooms a e loca -
ed in B azil (Campinas) and Ge many (Hambu g) in uni e si y acili ies wi h ypical o ice ac i i y.
Fig. 1: Wea he p o ile o Campinas, B azil (le ) and Hambu g, Ge many ( igh )
Fi
g
. 2: Sou hwes iew o he campus buildin
g
IFCH Campinas
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In e na ional Con e ence on Sus ainable Buil En i onmen
SBE16 Hambu g
The analyzed oom in he ho B azil clima e demands he use o ai condi ioning sys ems du ing
mos hou s o he day o p o ide com o o he use s. Na u al nigh en ila ion can be used o
educe he cooling loads. The o ice oom in Ge many is na u ally en ila ed and has no mechani-
cal en ila ion. The ex e nal shading by he balcony cons uc ion shown in igu e 3 and 4 in he
a ea o he es oom is no conside ed in he simula ions o esea ch pu poses. To ensu e he
use com o , he hou s o o e hea ing shall be minimized. Acco ding o na ional Ge man s and-
a ds [2], he maximum com o empe a u e is 26°C. Gene ally he amoun o o e hea ing can be
quan i ied by di e en me hods. Jus coun ing he numbe o hou s abo e 26°C would be insu i-
cien o he eason ha he use com o dec eases wi h aising empe a u e. The e o e i is
common o conside he del a o he maximum com o empe a u e. An app op ia e and simple
me hod o use is o de e mine he ene gy consump ion o an imagina y ai condi ioning sys em
ha cools he oom empe a u e o 26°C i equi ed. Hou ly local wea he da a a e used o bo h
en i e yea simula ions. The he mal loads a e gi en by in e nal gains om occupancy, equipmen
and ligh ing sys ems. Ai low esis ances by openings o passi e en ila ion modes a e aken
om he li e a u e and adjus ed o use in each açade. De ails abou each oom as well as model-
ing se ings a e p esen ed in Table 1.
Table 1 - De ails abou he ooms
Unicamp - IFCH
Campinas/SP, B azil Ha enCi y Uni e si y
Hambu g, Ge many
Use O ice
Mo - F 9 a.m. – 5 p.m. O ice
Mo - F 8 a.m. – 7 p.m.
Floo A ea 29.4 m² 40.1 m²
In e nal Gains
People
numbe 3 4
ac i i y le el [3] 130 W 130 W
hea gain 13.3 W/m² 13.0 W/m²
ac ion adian [3] 0.58 0.58
sensible hea ac ion [3] 0.58 0.58
Ligh s 13.0 W/m² 7.4 W/m²
Equipmen 12.1 W/m² 15.0 W/m²
Fig. 3: Sou h iew o he campus building Ha enCi y Uni e si y, Hambu g

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S a egies – S akeholde s – Success ac o s
Tempe a u e Limi s 25°C HVAC (PTAC)
COP 2.11W/W
du ing wo king hou s
26°C
Na u al en ila ion only
Window Glass A ea
(see also able 2) 5.14 m² single glazing 15.44 m² iple glazing
Openable A ea 2.68 m²
Ho izon ally pi o ed 2.30 m²
Bo om pi o ed
Discha ge Coe icien cd 0.61 0.61
Opening Fac o 0.12 0.458
O ien a ion No h-Eas Sou h
Shading Blinds and
ex e nal ixed side
elemen s
Blinds max. 180°
close abo e 300 W/m²
Na u al
Ven ila ion
modes
Base “No Na u al Ven ila ion” “No Na u al Ven ila ion”
Ven 1 “S a ic Nigh Cooling”
Nigh Ven ila ion
om 9 p.m. un il 9 a.m.
“S a ic Nigh Cooling”
Nigh en ila ion
om 7 p.m. un il 8 a.m.
Ven 2 “Selec i e Ven ila ion”
Na u al Ven ila ion when
Tin > Tou and Tin > 24°C
“Selec i e Ven ila ion”
Na u al en ila ion when
Tin > Tou and Tin > Tse
Tse = 21°C when
occupancy, else 18°C
3. Na u al Ven ila ion Simula ion in Ene gyPlus
This esea ch add esses a me hod o quan i y ele an cha ac e is ics o açade design ela i e o
i s sui abili y o na u al noc u nal en ila ion. Hence, wo di e en en ila ion s a egies a e ana-
lyzed o bo h ooms desc ibed in Table 1. The s a ic nigh cooling allows na u al en ila ion du ing
he nigh independen ly o he ou doo ai empe a u e. This me hod is easy o implemen in exis -
ing, mo o ized windows and he e is no need o complex açade con ol so wa e. Addi ionally, a
selec i e en ila ion mode is simula ed. This mode allows na u al en ila ion du ing he day, espe-
cially du ing ea ly day ime, as well as du ing he nigh , i he oom ai empe a u e is abo e he
ou doo ai empe a u e and he oom empe a u e is abo e a empe a u e se poin . This se poin
will be chosen by local clima e condi ions (Table 1).
Beside he en ila ion s a egy, he pe o mance o na u al en ila ion depends on he design o
he ai low pa h. Changes in geome y and ic ion among he ai low pa h a e he mos signi ican
low esis ances. In ene gy simula ion ools (e.g. Ene gyPlus) hese esis ances a e o en summa-
ized o discha ge coe icien s cd which indica e he e ec i eness o ai low hough openings. Fo
ec angula openings, e.g. 90 deg ees open windows, he esis ance coe icien ȗ = 1/cd is in a
small ange be ween 2.7 and 2.8 [4] and he e o e he discha ge coe icien is 0.61. Fo common
used window cons uc ions he obs uc ion o he pane in pi o ed cases mus also be conside ed.
The il ed pane educes he e ec i e a ea Ae which is a ailable o he ai low. Consequen ly i is
no su icien o use he discha ge coe icien cd = 0.61 o desc ibe all impac s. Bo om pi o ed
windows a e used a he Ha enCi y Uni e si y in Ge many (Figu e 4, igh ). Hul e al. [5] s udied
he algo i hm used by Ene gyPlus o pi o ed windows and modi ied he exp ession in o de o
achie e be e esul s o op pi o ed windows. Fo his s udy he exp ession is ans o med o he
calcula ion o Ae o bo om pi o ed windows o ake he di e en posi ion o he o a ing axis in o
accoun . W/H is he window wid h/heigh , Į is he opening angle and z is he e ical coo dina e
576
In e na ional Con e ence on Sus ainable Buil En i onmen
SBE16 Hambu g
s a ing om he pi o ing axis. The e ec i e window a ea o he window sys em in Hambu g is
calcula ed acco ding o he equa ions (1) and (2):
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ܹ௣௜௩௢௧ ൌቆͳ
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ሺʹݖሺߙሻ൅ሺߙሻܹሻ;ቇି଴Ǥହ
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The IFCH building in B azil has ho izon ally pi o ed windows whe e he o a ion axis is eccen ical-
ly placed (Figu e 4, le ). The e is no eliable e e ence a ailable o his window cons uc ion.
Geome ic analysis p o ides opening ac o s equi alen o he a io o e ec i e and geome ic
opening a ea. The e ec i e a ea o en ila ion is he ec angula a ea which emains open when
he pane is il ed (Figu e 5). The la e al a eas o en ila ion o he windows a e no conside ed as
hey a e obs uc ed by shading elemen s. The a io be ween he e ec i e a ea and he opening
a ea esul ed in an opening ac o o 0.12 (Table 1).
The he mal p ope ies o he en elope a e also impo an o he e ec i eness o he na u al
en ila ion, as an addi ional he mal load is ansmi ed h ough he en elope and needs o be
emo ed by na u al o a i icial ways. Table 2 shows he he mal p ope ies o he en elope o
bo h buildings.
Fig. 4: Illus a ion o he openings o en ila ion o IFCH Campinas (le ) and Ha enCi y
Uni e si y, Hambu g ( igh )
Fig. 5: E ec i e a ea o en ila ion ha is conside ed in IFCH building
577
S a egies – S akeholde s – Success ac o s
Table 2 - The mal p ope ies o he componen s o he model
Componen U- ac o
(W/(m².K)) SHGC [-]
IFCH Campinas
Ex e nal wall 1 2.65
Ex e nal wall 2 3.09
Slab 2.04
Roo 1.74
Single glazing 3.84 0.818
Ha enCi y Uni e si y T iple glazing 0.60 0.450
In e nal walls and slabs adiaba ic
4. Resul s and Discussion
4.1 Ene gy consump ion
An o e iew o he mon hly ene gy consump ion o cooling o bo h ooms is p esen ed and dis-
cussed o u he analysis. F om igu e 6 i is possible o no e ha nigh en ila ion o he B azili-
an building (IFCH) is no ha e icien om ene gy aspec s conside ing he whole yea . E alua ing
he peak o cooling in Oc obe , na u al en ila ion allows educ ions o he cooling load up o 14%
(Table 3). Fu he mo e in win e , he s a egy was mo e e icien educing up o 29% o he cooling
ene gy in July. The consump ion du ing his season is no exp essi e; he e o e i gi es no big
con ibu ion o he annual ene gy demand ( educ ions a ound 6%). On he opposi e, signi ican
educ ions a e possible o he oom in Hambu g (HCU), mainly wi h selec i e en ila ion. The
po en ial educ ion eaches up o 87% pe cen in July h ough selec i e en ila ion and 23% in
imes wi h peak cooling loads. Yea ly i is possible o educe 76% o he cooling demand wi h nigh
en ila ion and 93% wi h selec i e en ila ion (Figu e 7).
In gene al i is ound ha na u al en ila ion is an e ec i e me hod o educe he ene gy consump-
ion o cooling as well as he peak loads. In mode a e clima e wi h coole nigh ime ai empe a-
u es he e iciency is also d i en by he en ila ion s a egy. An adap i e opening con ol allows
he usage o empe a u e di e ence be ween indoo and ou doo o passi e cooling bu i can
also p e en he oom agains o e hea ing, while he s a ic en ila ion does no conside he ou -
doo empe a u e. In ho clima es he posi i e e ec o na u al en ila ion is less no iceable. Fo
he case o s a ic nigh cooling an ene gy conse a ion o 6% is calcula ed. Fo he lexible en ila-
ion s a egy based on he empe a u e di e ence he same ene gy conse a ion pe cen age o 6
%
is calcula ed. A highe bene i o a lexible en ila ion s a egy canno be de e mined because he
windows a e open less equen ly.
578
In e na ional Con e ence on Sus ainable Buil En i onmen
SBE16 Hambu g
Table 3 - Peak cooling sensible hea gain.
HVAC inpu sensible ai cooling (kW) and da e + ime o he peak load
Room Base-case Nigh en ila ion Selec i e en ila ion
HCU -1.87 08/03 15:00 -1.60 08/03 15:10 -1.45 08/07 15:10
IFCH -4.87 10/13 09:03 -4.20 10/12 09:03 -4.21 10/12 09:03
Fig. 6: Mon hly ai condi ioning use o he oom in Campinas
Fig. 7: Mon hly ai condi ioning use o he oom in Hambu g