HVAC & IAQ article summary
( h ttp ://w ww.a cce ssscie nce .c o m .e zp ro xy2 .lib ra ry .d re xe l. e du/) H id e N atu ra l v e ntila tio n fo r b uild in gs A rtic le b y:
B atta glia , F ra ncin e D epartm ent o f M ech anic a l E ngin eerin g, V ir g in ia P oly te ch nic In stitu te a nd S ta te U niv e rs ity , B la cksb urg , V ir g in ia . P asse, U lr ik e D epartm ent o f A rc h ite ctu re , C olle ge o f D esig n, Io w a S ta te U niv e rs ity , A m es, Io w a. L ast u pdate d: 2 016 D OI: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l.e du/1 0.1 036/1 0978 542.Y B150704 ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l.e du/1 0.1 036/1 097 8 542.Y B150704) C onte nt W hat is n atu ra l v entila tio n, a nd w hy u se it ?
V entila tio n p rin cip le s S patia l c om posit io n B uild in g d esig n s tr a te gie s T o ols a nd n um eric al m odels B enefit s A ddit io nal R eadin gs V en tila tio n is a w ay t o in tro duce f re sh a ir in to a r o om a n d s im ult a n eo usly e xtra ct w arm , s ta le , p ollu te d , o r o doro us a ir . N atu ra l v e ntila tio n h as b eco m e a n im porta nt c o nsid era tio n a s w e s e ek w ays to im pro ve in door a ir q ualit y ( c le an a ir ) in b uild in gs. T he e nerg y r e quir e d to c o ol a nd v e ntila te b uild in gs c o ntin ues to in cre ase , a lo ng w it h a sso cia te d c o sts a nd th e b uild in g c a rb on fo otp rin t. N atu ra l v e ntila tio n c a n b e u tiliz e d to d ecre ase th e a m ount o f e nerg y n eeded to c o ndit io n b uild in gs, a nd d elv in g in to th e p ast fe w c e ntu rie s, w e fin d b uild in gs d esig ned s p ecif ic a lly to e xp lo it n atu ra l v e ntila tio n. H is to ric a l e xa m ple s in clu de th e P alla dia n v illa s ( Ita ly ), th e c o rb elle d d om ed r o ofs o f th e H arra n h ouse s ( T urk e y), a nd th e w in d c a tc h ers o f Y a zd ( Ir a n). T hre e e xtr a ord in ary a nd fa m ous tw entie th c e ntu ry h ouse s th at u tiliz e n atu ra l v e ntila tio n s tr a te gie s a re th e H ow H ouse ( L os A ngele s, C A), th e A ff le ck H ouse ( B lo om fie ld , M I) , a nd th e E sh eric k H ouse ( C hestn ut H ill, P A ). T o r e duce e nerg y r e quir e m ents a nd c o sts to v e ntila te b uild in gs a nd p ro vid e th erm al c o m fo rt ( h ow h um ans p erc e iv e c o m fo rt) , th ese h is to ric a l b uild in gs c a n s e rv e a s a b asis fo r fu tu re d esig ns.
W hat is n atu ra l v en tila tio n, a n d w hy u se it ?
V entila tio n is d ependent o n th e m otio n o f a ir , w hic h c a n a ls o a cco m pany h eat tr a nsfe r. C onve ctio n is a fo rm o f e nerg y t r a nsfe r d ue to b oth m ole cu la r m otio n a nd b ulk m otio n ( a dve ctio n). T he o ccu rre nce o f a te m pera tu re g ra die nt in a ddit io n to f lu id m otio n is c o nve ctiv e h eat tr a nsfe r. W hen th e flo w is a r e su lt o f a n e xte rn al s o urc e , s u ch a s a fa n o r a tm osp heric w in d, t h e h eat tr a nsfe r is c la ssif ie d a s fo rc e d c o nve ctio n. N atu ra l ( o r fr e e) c o nve ctio n o ccu rs w hen te m pera tu re d if f e re nce s in th e f lu id c a use d ensit y d if f e re nce s, c re atin g a b uoya ncyd riv e n flo w . If th e b uoya ncy fo rc e is d om in ant, a s tr o nger u pw ard flo w i s p ro duce d a s h ot a ir r is e s a nd c o ld a ir d esce nds, fo rm in g c o nve ctio n c u rre nts . T here fo re , n atu ra l v e ntila tio n is a m eans to p assiv e ly c o ol o r h eat a r o om b y c ir c u la tin g a ir w it h out r e quir in g m ech anic a l s yste m s. T he r e su lt in g e ff e ct m ove s th e a ir in a r e gio n a nd a ssis ts w it h r e m ovin g h eat a nd h um id it y , a nd e xch angin g a ir . S ee a ls o : B uoyan cy ( /c o nte n t/b uoyan cy/0 99500) ; C onvectio n ( h eat) ( /c o nte n t/c o nvectio nh eat/1 60000) ; H eat t ra n sfe r ( /c o nte n t/h eat t ra n sfe r/3 111 00) N atu ra l v e ntila tio n is e ff e ctiv e in im pro vin g a ir q ualit y , p ro vid in g th erm al c o m fo rt, a nd r e ducin g e nerg y c o nsu m ptio n w hen u tiliz e d p ro perly . In th e U nit e d S ta te s, r is in g p ric e s o f n atu ra l g as a nd e le ctr ic it y , a nd c o nce rn s a bout th e d eple tio n o f v a lu able n atu ra l r e so urc e s, m otiv a te r e se arc h to e xp lo re h ow s o cie ty u se s e nerg y. M ore th an 7 0% o f th e e nerg y u se d in t h e U nit e d S ta te s is c o nsu m ed b y h om es, b usin esse s, s ch ools , a nd in dustr ie s. O ne a ppro ach to a ddre ssin g e nerg y c o nce rn s is th e d eve lo pm ent o f a lt e rn ativ e fu els , w hic h s till r e quir e s r e so urc e s. H ow eve r, if a tte ntio n is tu rn ed to a rc h it e ctu ra l b uild in g d esig n, s tr a te gie s c a n b e d eve lo ped to u tiliz e th e b uild in g s tr u ctu re to p ro vid e th erm al c o m fo rt.
I d eally , if n atu ra l v e ntila tio n c o uld a ch ie ve th e s a m e e nvir o nm ent a s m ech anic a l h eatin g, v e ntila tio n, a nd a ir c o ndit io nin g ( H VA C ) s yste m s, th en b uild in g d esig ns u sin g n atu ra l v e ntila tio n w ould n ot c o nsu m e n atu ra l g as a nd e le ctr ic it y fo r e nerg y n eeds to v e ntila te a nd c o ndit io n th e in door e nvir o nm ent. A m ajo r b enefit o f n atu ra l v e ntila tio n is th at it is a fr e e r e so urc e t h at w e c a n u se w it h out h arm in g th e e nvir o nm ent. S ee a ls o : A ir c o ndit io nin g ( /c o nte n t/a ir c o ndit io nin g/0 17000) ; H eatin g s yste m ( /c o nte n t/h eatin gs yste m /7 57298) ; V en tila tio n ( /c o nte n t/v en tila tio n/7 29900) T he u se o f n atu ra l d riv in g fo rc e s is a n u nderu tiliz e d d esig n s tr a te gy to c o ntr o l th e in door e nvir o nm ent. A ir m ove m ent is a ch ie ve d w hen th ere a re p re ssu re d if f e re nce s o r te m pera tu re d if f e re nce s. F or in sta nce , o penin g a w in dow c re ate s a p re ssu re d if f e re nce b etw een th e in te rio r a nd e xte rio r o f a b uild in g. E ve n if th e a ir te m pera tu re is th e s a m e b etw een th e tw o e nvir o nm ents , a ir c a n s till m ove , a p henom enon k n ow n a s s in gle s id ed v e ntila tio n. O penin g tw o w in dow s c a n e nhance a ir m ove m ent, a nd th e c a se o f o pposin g o pen w in dow s is k n ow n a s c ro ss v e ntila tio n. In c ro ss v e ntila tio n, th e p re ssu re d if f e re nce is o fte n c re ate d b y w in d. A h ig her p re ssu re o n th e w in dw ard s id e o f th e b uild in g a nd a lo w er p re ssu re o n th e l e ew ard s id e d riv e th e a ir flo w fr o m w in dw ard to le ew ard . A te m pera tu re d if f e re nce b etw een th e in door a nd o utd oor e nvir o nm ent c re ate s a p re ssu re d if f e re nce , a nd a ir v e ntila te s th ro ugh a n o penin g, w here s u ch b uoya ncyd riv e n flo w is c a lle d th e s ta ck e ff e ct. M ost flo w s a re a c o m bin atio n o f b uoya ncyd riv e n a nd w in dd riv e n e ff e cts ( F ig . 1 ) . S ee a ls o : P re ssu re ( /c o nte n t/p re ssu re /5 43500) ; T e m pera tu re ( /c o nte n t/t e m pera tu re /6 83500) T a b le 1 In door t h erm al c o m fo rt c o ndit io ns O utd oor a ir t e m pera tu re 1 0°C ( 5 0°F ) 3 3.5 °C ( 9 2.3 °F ) L ow er lim it U pper lim it L ow er lim it U pper lim it 9 0% a cce pta ble 1 7.5 °C ( 6 3.5 °F ) 2 3.5 °C ( 7 4.3 °F ) 2 3°C ( 7 3.4 °F ) 3 0.5 °C ( 8 6.9 °F ) 8 0% a cce pta ble 1 8.5 °C ( 6 5.3 °F ) 2 4.5 °C ( 7 6.1 °F ) 2 6°C ( 7 8.8 °F ) 3 1°C ( 8 7.8 °F ) U se d w ith p erm is sio n fr o m A SH RAE S ta ndard 5 52 013, c o pyrig ht © A SH RAE ( w ww.a sh ra e.o rg ), 2 013. V en tila tio n p rin cip le s F ig . 1 S ketc h o f c ro ss v entila tio n c om bin ed w it h a s ta ck a tr iu m t o in cre ase c ir c ula tio n. ( F ro m U . P asse a nd F . B atta glia , D esig nin g S paces f o r N atu ra l V entila tio n: A n A rc hit e ct's G uid e, R outle dge, T a ylo r & F ra ncis , 2 015 ) * * O ne a sp ect o f n atu ra l v e ntila tio n is th at it c a n c o uple th e b uild in g d esig n a nd e nvir o nm enta l fa cto rs ( s u ch a s w in d) to e xch ange s ta le b uild in g a ir w it h fr e sh a ir . In door a ir q ualit y ( a ls o r e fe rre d to a s in door e nvir o nm enta l q ualit y ) a nd th erm al c o m fo rt a re p re ssin g is su es b eca use , o n a ve ra ge, m ost A m eric a ns s p end a s m uch a s 9 0% o f th eir tim e in doors , a cco rd in g t o th e U .S . E nvir o nm enta l P ro te ctio n A gency's ( E PA 's ) r e port o n in door p ollu tio n to th e U .S . C ongre ss in 1 989, w hic h is s till a b ench m ark s tu dy a lm ost 3 0 y e ars la te r.
T here a re tw o g oals w hen v e ntila tin g b uild in gs: p ro vid in g a c o ole r e nvir o nm ent fo r o ccu pants , a nd e xch angin g a ir to m ain ta in a h ealt h y in door e nvir o nm ent. C ool a ir c a n b e a ch ie ve d b y r e ducin g th e a ir te m pera tu re o r b y in cre asin g th e a ir m ove m ent to in duce e va pora tio n. T he e xch ange o f a ir h elp s to e lim in ate p ollu ta nts a nd v o la tile o rg anic c o m pounds, a nd to r e ple nis h o xyg en. T here h as b een g re at c o nce rn fo r h ealt h is su es, w it h th e fo cu s s h if tin g fr o m o utd oor to in door p ollu tio n.
I t h as b een s h ow n th at v e ntila tio n r a te s lo w er th an 3 6 m / h ( 1 271 ft / h ) c a n a dve rs e ly a ff e ct o ccu pants , e sp ecia lly c h ild re n a nd th e e ld erly . S ee a ls o : I n door a ir p ollu tio n ( /c o nte n t/in doora ir p ollu tio n/7 57411 ) A p ara m ete r to in dic a te q ualit y v e ntila tio n is th e a ir c h ange r a te ( A C H), d efin ed a s th e v o lu m e flo w r a te in to a r o om d iv id ed b y th e r o om v o lu m e. A C H s im ply m eans th e m ove m ent o f a v o lu m e o f a ir in a 1 h p erio d. T o m ain ta in m in im um a ir q ualit y , t h e r e co m mended A C H is 1 to 2 , a nd to r e m ove h eat o r p ollu ta nts , A C H s h ould r a nge fr o m 2 to 1 5. T he A m eric a n S ocie ty o f H eatin g, R efr ig era tin g, a nd A ir C ondit io nin g E ngin eers ( A SH RAE) h as s e t fo rth r e co m mendatio ns fo r th erm al c o m fo rt ( T a b le 1 ) , p ro vid in g lo w er a nd u pper lim it s a s a fu nctio n o f o utd oor te m pera tu re . T herm al c o m fo rt is d ete rm in ed fr o m th e c o ndit io ns in w hic h 8 0% o f th e o ccu pants p erc e iv e th at th e e nvir o nm ent is a cce pta ble . If th e in door te m pera tu re s a re l o w er, 9 0% o f th e o ccu pants a re s a tis fie d. A ir flo w v e lo cit ie s a re r e co m mended b ase d o n p erc e iv e d c o m fo rt le ve ls w it h t e m pera tu re c h anges ( T a b le 2 ) . T a b le 2 A ccep ta b le t e m pera tu re in cre ase d ue t o m ovin g a ir A ir s peed, m /s ( ft/s ) T e m pera tu re in cre ase, ° C ( ° F ) 0 .6 ( 2 .0 ) 1 .2 ( 2 .1 6) 0 .9 ( 3 .0 ) 1 .8 ( 3 .2 4) 1 .2 ( 3 .9 ) 2 .2 ( 3 .9 6) U se d w ith p erm is sio n fr o m A SH RAE S ta ndard 5 52 013, c o pyrig ht © A SH RAE ( w ww.a sh ra e.o rg ), 2 013. S patia l c o m posit io n T o u tiliz e n atu ra l v e ntila tio n e ff e ctiv e ly , th e d esig n o f a b uild in g m ust a llo w a ir to flo w fr e ely . S patia l la yo ut c o nsid ers h ow a re as a nd r o om s a re in te rc o nnecte d in a b uild in g. T he u tiliz a tio n o f b uild in g s p ace m ust b e c o nduciv e to d eve lo p p re ssu re d if f e re nce s fr o m o ne e nd o f th e b uild in g to th e o th er to fa cilit a te a ir flo w . T he a m ount o f flo w c a n b e c o ntr o lle d b y th e s iz e a nd o rie nta tio n o f th e s p ace s. T hus, th e p rin cip le s o f n atu ra l v e ntila tio n m ust b e c o nsid ere d in th e d esig n o f th e b uild in g a nd n ot s im ply b e a n a fte rth ought.
T hre e s p atia l c o nce pts th at e nhance n atu ra l v e ntila tio n a re th e s ta ck e ff e ct, th e w in d c a tc h er, a nd c ro ss v e ntila tio n. A ta ll s p ace c a n a ct a s e it h er a w in d c a tc h er o r a s ta ck c h im ney, d ependin g o n th e p re ssu re d if f e re nce . W hen th e a m bie nt p re ssu re is h ig her th an th e in te rio r b uild in g p re ssu re , th e v e rtic a l s p ace b ehave s lik e a w in d c a tc h er, d ra w in g a ir d ow nw ard i n to th e b uild in g. O th erw is e , w hen a m bie nt p re ssu re is lo w er th an th e in te rio r, a ir m ove s u p th e s ta ck. T hese s p atia l 3 3 * * a ttr ib ute s a re fo und in th e th re e p re vio usly m entio ned “ b re ath in g” b uild in gs: th e H ow H ouse d esig ned b y R udolp h M .
S ch in dle r ( 1 925), th e A ff le ck H ouse d esig ned b y F ra nk L lo yd W rig ht ( 1 940), a nd th e E sh eric k H ouse d esig ned b y L ouis I.
K ahn ( 1 961).
B uild in g d esig n s tr a te g ie s S urv e ys h ave s h ow n th at o ccu pants h ave a p re fe re nce fo r o pen w in dow s a nd n atu ra l lig ht. C urre ntly , s o cie ty r e adily u se s H VA C s yste m s to c o ndit io n in te rio r e nvir o nm ents , w here by th e b uild in g to polo gy h as b een d eco uple d fr o m th e H VA C r e quir e m ents in th e b uild in g d esig n. C ountle ss b eautif u l b uild in gs w it h e xce ssiv e H VA C r e quir e m ents a re w astin g e nerg y b eca use it is n ot e asy o r e ff ic ie nt to c o ndit io n th e in te rio r th erm ally .
N atu ra l v e ntila tio n m ust b e in co rp ora te d in to th e d esig n o f th e b uild in g a nd s h ould b e a n im porta nt c o nsid era tio n a lo ngsid e t h e b uild in g e nve lo pe, e nerg y u se , o ccu pancy h abit s , h um an h ealt h , a nd c o m fo rt. P ro per u se o f n atu ra l v e ntila tio n w ill p ro vid e e nerg y a t n o c o st a nd w it h n o a dve rs e e nvir o nm enta l e ff e cts . H ow eve r, b uild in gs th at u tiliz e n atu ra l v e ntila tio n m ust b e d esig ned d if f e re ntly , k e epin g in m in d th at th eir c o ntr o l a nd o pera tio n a re d if f e re nt fr o m th at o f th ose th at u se tr a dit io nal H VA C s yste m s. T he c a ve at is k n ow in g w hen a nd h ow o fte n to o pen w in dow s, a nd th e a ppro pria te s iz e s o f th e o penin gs. A c h alle nge is th at n atu ra l v e ntila tio n r e lie s o n e nvir o nm enta l fa cto rs s u ch a s a tm osp heric w in d a nd te m pera tu re , w hic h c h ange d aily . T hus, c o ntr o l o f n atu ra l v e ntila tio n b eco m es th e r e sp onsib ilit y o f th e o ccu pants .
I n th e d esig n o f b uild in gs th at u tiliz e n atu ra l v e ntila tio n, a rc h it e cts e m plo y c e rta in r u le s o f th um b b ase d o n r e co m mendatio ns b y th e C harte re d In stit u tio n o f B uild in gs S erv ic e s E ngin eers . T he r u le s o f th um b in clu de r e co m mendatio ns fo r c ro ss v e ntila tio n a nd s in gle s id ed v e ntila tio n. C ro ss v e ntila tio n is e xp ecte d to b e e ff e ctiv e if th e s p ace d epth to h eig ht r a tio is 5 :1 w it h a n u nre str ic te d flo w p ath . F or s in gle s id ed v e ntila tio n w it h o nly o ne o penin g, th e d epth to h eig ht r a tio is 2 :1 , a nd fo r tw o o penin gs, th e r a tio is 2 .5 :1 . W it h in cre asin g flo orto c e ilin g h eig ht, th e r o om te m pera tu re s a re m ore s tr a tif ie d a nd p ollu ta nts r is e a bove th e o ccu pie d s p ace .
I n tu it io n a nd e xp erie nce h ave b een th e d ecid in g fa cto rs in b uild in g d esig ns, b ut s o ftw are to ols a re b ein g d eve lo ped a nd u se d to a ssis t a rc h it e cts a nd e ngin eers . T hese to ols c a n b e c o uple d w it h w eath er d ata to p re dic t te m pera tu re d is tr ib utio ns a nd a ir flo w p atte rn s w it h in a b uild in g. S pecif ic s ce nario s c a n b e c o nsid ere d s o th at th e d esig ner c a n tr y to o ptim iz e th e b est s p atia l c o m posit io n a nd s p atia l p rin cip le s to c re ate a w ell fu nctio nin g, n atu ra lly v e ntila tin g b uild in g.
T o ols a n d n um eric al m odels T he U .S . E nvir o nm enta l P ro te ctio n A gency h as c re ate d to ols to a ssis t d esig ners a nd p ro vid e g uid ance fo r in door a ir q ualit y w it h th e c o nstr u ctio n o f n ew b uild in gs. O ne to ol is th e In door A ir Q ualit y B uild in g E duca tio n a nd A sse ssm ent M odel ( I B EAM ), a nd a noth er p opula r to ol is In door a ir P LU S. T here a re a ls o to ols th at h elp d ete rm in e th erm al c o m fo rt o f th e b uild in g o ccu pants . S oftw are to ols a ls o e xis t th at e va lu ate e nerg y r e quir e m ents to m ain ta in a c o m fo rta ble b uild in g e nvir o nm ent. T he U .S . D epartm ent o f E nerg y d eve lo ped E nerg yP lu s, w hic h p ro vid es in fo rm atio n r e la te d to e nerg y c o nsu m ptio n o f a b uild in g, a nd th e N atio nal In stit u te o f S ta ndard s a nd T e ch nolo gy ( N IS T) to ol is C O NTA M , w hic h p ro vid es a ir q ualit y , in clu din g th e tr a nsp ort o f c o nta m in ants . A noth er to ol d eve lo ped b y N IS T is L oopD A, w hic h c a n d ete rm in e th e s iz e s o f n atu ra l v e ntila tio n o penin gs. T hese to ols a re v e ry u se fu l to p ro vid e g uid elin es fo r d esig nin g b uild in gs a s w ell a s a naly ze e xis tin g b uild in gs s o th at im pro ve m ents c a n b e m ade to r e duce e nerg y c o sts .
V entila tio n c a n b e a sse sse d u sin g e xp erim enta l m eth ods s u ch a s w in d tu nnel a nd fie ld m easu re m ents , e m pir ic a l a nd a naly tic a l m eth ods, m ult iz o ne a nd z o nal m eth ods, a nd c o m puta tio nal flu id d yn am ic s ( C FD ). E xp erim ents c a n b e c o stly d ue t o e quip m ent a nd r e so urc e r e quir e m ents . E m pir ic a l m odels u se e xp erim enta l d ata to d eve lo p s im ple r e la tio nsh ip s.
A naly tic a l m odels a re d eve lo ped b y s im plif y in g e quatio ns th at g ove rn th e m otio n o f m ass, m om entu m , a nd e nerg y. A m ore i n clu siv e a nd p ow erfu l to ol is C FD , w hic h c a n p re dic t p re ssu re , te m pera tu re , a nd flu id m otio n, a s w ell a s p ro vid e a w ay to v is u aliz e a ir flo w . E xa m ple s o f C FD c o m pute r p ro gra m to ols in clu de A N SYS F lu ent, C FX, a nd O penF O AM . S ee a ls o : C om puta tio nal f lu id d yn am ic s ( /c o nte n t/c o m puta tio nal flu id d yn am ic s/7 57259) ; W in d t u nnel ( /c o nte n t/w in d t u nnel/7 46800) A m odel o f th e E sh eric k H ouse w as s im ula te d u sin g F lu ent. U niq ue fe atu re s o f th e h ouse a re th e w in dow s a nd w ooden s h utte rs , w here by th e s h utte rs h elp c o ntr o l a ir flo w ( F ig . 2 ) . T he fr o nt o f th e h ouse h as s m all w in dow s, w hile th e r e ar s id e h as la rg er w in dow s. D if f e re nt s ce nario s w ere s im ula te d u sin g C FD fo r c o olin g ( F ig . 3 ) , a ssu m in g th e fr o nt s h utte rs a nd b alc o ny d oors w ere o pen. S im ula tio ns n ot o nly p re dic t te m pera tu re c h anges th ro ugh th e h ouse , b ut h ow w in d is e ntr a in ed a nd m ove s th ro ugh th e o pen flo or la yo ut. C FD c a n b e u se d to p re dic t a nd v is u aliz e m any s ce nario s u sin g a th re e d im ensio nal b lu eprin t o f a b uild in g to d ete rm in e e ff e ctiv e v e ntila tio n.
F ig . 2 F ro nt v ie w o f t h e E sheric k H ouse w it h s hutte rs c lo sed. [ P hoto gra ph b y S m allb ones ( p ublic d om ain ) v ia W ik im edia C om mons ] B en efit s V entila tin g b uild in gs u sin g n atu ra l d riv in g fo rc e s is a c o m ple x b ut w orth w hile e ndeavo r. T he p ush fo r g re en d esig n s tr a te gie s to s a ve e nerg y a nd n atu ra l r e so urc e s s u pports th e u se o f n atu ra l v e ntila tio n in fu tu re a rc h it e ctu ra l d esig ns. It is w orth n otin g th at e ve n H VA C s yste m s h ave th eir d ra w backs. A lt h ough th erm osta ts c a n b e p ro gra m med to c o ntr o l in te rio r h eatin g a nd c o olin g, o ccu pants a re n ot n ece ssa rily s a tis fie d w it h th e th erm al c o m fo rt, a nd th ey m ay fe el th at th e e nvir o nm ent is d ra fty o r s tu ff y , to o c o ld o r to o h ot. N atu ra l v e ntila tio n is a n e co nom ic a l w ay to p ro vid e d esir a ble fr e sh ( c o ol) a ir , a lb eit c o ntr o lle d b y th e o ccu pants . B earin g in m in d th e p ro s a nd c o ns, n atu ra l v e ntila tio n h as g re at p ote ntia l to b e a s ta ndard in co rp ora te d in to n ew c o nstr u ctio n to c re ate a n ew g enera tio n o f h ealt h y, e nerg ye ff ic ie nt b uild in gs. F ra ncin e B atta glia U lr ik e P asse A ddit io nal R ead in gs F ig . 3 C FD s im ula tio ns o f t h e E sheric k H ouse, s how in g t e m pera tu re d is tr ib utio n ( c olo r) a nd a ir flo w p atte rn s ( w hit e lin es). T = t e m pera tu re . T ( ° F ) = 1 .8 T ( ° C ) + 3 2. ( I m age c ourte sy o f P . J . S to akes, S im ula tio n o f A ir flo w a nd H eat T ra nsfe r in B uild in gs, M .S . t h esis , V ir g in ia T e ch, B la cksburg , V A , 2 009 ) A m eric a n S ocie ty o f H eatin g, R efr ig era tin g, a nd A ir C ondit io nin g E ngin eers ( A SH RAE), A SH RAE S ta ndard 5 52 013: T herm al E nvir o nm enta l C ondit io ns fo r H um an O ccu pancy , A tla nta , G A, 2 013 D . E th erid ge, N atu ra l V entila tio n o f B uild in gs: T heory , M easu re m ent a nd D esig n , W ile y, 2 012 D . E th erid ge a nd M . S andberg , B uild in g V entila tio n: T heory a nd M easu re m ent , W ile y, 1 996 U . P asse a nd F . B atta glia , D esig nin g S pace s fo r N atu ra l V entila tio n: A n A rc h it e ct's G uid e , R outle dge, T a ylo r & F ra ncis , 2 015 P . J . S to ake s, S im ula tio n o f A ir flo w a nd H eat T ra nsfe r in B uild in gs , M .S . th esis , V ir g in ia T e ch , B la cksb urg , V A , 2 009 B re ath in g B uild in gs ( h ttp ://w ww.b re ath in gbuild in gs.c o m /h om e) M assa ch use tts In stit u te o f T e ch nolo gy: C oolV ent ( h ttp ://c o olv e nt.m it .e du) U niv e rs it y o f C alif o rn ia –B erk e le y, C ente r fo r th e B uilt E nvir o nm ent: C BE T herm al C om fo rt T o ol ( h ttp ://w ww.c b e.b erk e le y.e du/r e se arc h /th erm al to ol. h tm ) U niv e rs it y o f S id ney, P ro fe sso r R ic h ard d e D ear: H um an H eat B ala nce ( c a lc u la to r) ( h ttp ://w eb.a rc h .u syd .e du.a u/~ rd edear) U .S . E PA : A n O ff ic e B uild in g O ccu pants G uid e to In door A ir Q ualit y : W hy is In door A ir Q ualit y Im porta nt?
( h ttp ://w ww.e pa.g ov/in doora ir q ualit y ia q/o ff ic e b uild in go ccu pants g uid ein doora ir q ualit y # w hyin door)