Façade design for night cooling by natural ventilation in different climate zones

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 O ganised by )$6 )BGFO$JUZ6OJWFSTJUÊ U )BNCVSH 4 In e na ional Con e ence on Sus ainable Buil En i onmen SBE16 Hambu g Imp in Con e ence o ganise s In coope a ion wi h ZEBAU – Cen e o Ene gy, Cons uc ion, A chi ec u e and he En i onmen GmbH www.zebau.de )$6 )BGFO$JUZ6OJWFSTJUÊ U )BNCVSH Edi ed by: ZEBAU – Cen e o Ene gy, Cons uc ion, A chi ec u e and he En i onmen GmbH, G oße Elbs aße 146, 22767 Hambu g, Ge many This P oceedings a e published unde he ollowing C ea i e Commons license: h p://c ea i ecommons.o g/licenses/by-sa/4.0/ This booN was p epa ed om he inpu ¾les supplied by he au ho s. The publishe is no esponsible o he use which migh be made o he ollowing in o ma ion. 2016 P in ed on 100% ecycled pape . D ucke ei in S . Pauli, G oße F eihei 70, 22767 Hambu g, Ge many ISBN 978-3-00-052213-0 DOI: 10.5445/IR/1000051699 Suppo ed by 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 573 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 574 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 575 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): ܣ௘௙௙ ൌනܹ ௣௜௩௢௧ሺݖሻ݀ݖ ுୡ୭ୱሺఈሻ ଴൅ න ܹ݀ݖ ு ுୡ୭ୱሺఈሻ  ;ϭͿ ܹ௣௜௩௢௧ ൌቆͳ ܹ;൅ͳ ሺʹݖሺߙሻ൅ሺߙሻܹሻ;ቇି଴Ǥହ  ;ϮͿ 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