chapter six - purdue engineeringyanchen/paper/2006-4.pdf · cfd generally includes large eddy...
Post on 07-Apr-2020
12 Views
Preview:
TRANSCRIPT
CHAP
TER
SIX
WIN
D IN
BU
ILDI
NG
EN
VIRO
NM
ENT
DESI
GN
Qin
gyan
Che
n
INTR
ODU
CTIO
N
Win
d ca
n be
a b
uild
ing’
s “fr
iend
” bec
ause
it c
an n
atur
ally
vent
ilate
the
bui
ldin
g, p
rovi
ding
a c
omfo
rtab
le a
ndhe
alth
y in
door
env
ironm
ent,
as w
ell a
s sa
ving
ene
rgy.
Con
vent
iona
l de
sign
ap
proa
ches
of
ten
igno
reop
port
unit
ies
for
inno
vati
ons
wit
h w
ind
that
cou
ldco
nditi
on b
uild
ings
at
a lo
wer
cos
t, w
hile
pro
vidi
nghi
gher
air
qual
ity a
nd a
n ac
cept
able
the
rmal
-com
fort
leve
l by
mea
ns o
f pas
sive
coo
ling
or n
atur
al v
entil
atio
n.N
atur
al v
entil
atio
n ca
n be
use
d fo
r coo
ling
in th
e sp
ring
and
autu
mn
for a
mod
erat
e cl
imat
e (e
.g.,
Nas
hvill
e, T
N),
the
sprin
g fo
r a
hot
and
dry
clim
ate
(e.g
., Ph
oeni
x, A
Z),
the
sum
mer
for
a c
old
clim
ate
(e.g
., Po
rtla
nd, M
E), a
ndth
e sp
ring
and
sum
mer
for
a m
ild c
limat
e (e
.g.,
Seat
tle,
WA)
. N
atur
al v
enti
lati
on c
an a
lso
be u
sed
to c
ool
envi
ronm
ents
in a
hot
and
hum
id c
limat
e du
ring
part
of
the
year
(e.g
., N
ew O
rlean
s, LA
) (Le
chne
r 200
0).
On
the
othe
r han
d, w
ind
can
be a
bui
ldin
g’s “
enem
y”w
hen
it ca
uses
dis
com
fort
to
pede
stria
ns, u
sual
ly a
s a
resu
lt of
hig
h w
ind
spee
d ar
ound
the
bui
ldin
g. T
able
1su
mm
ariz
es t
he e
ffec
ts o
f w
ind
on p
eopl
e. T
he w
ind
spee
d is
nor
mal
ly re
ferr
ed to
as t
he sp
eed
of w
ind
at te
nm
eter
s ab
ove
an o
pen
terr
ain.
The
win
d sp
eed
atpe
dest
rian
leve
l is
roug
hly
70 p
erce
nt o
f th
e ta
bula
ted
valu
es.
Viss
er (
1980
) pr
opos
ed c
omfo
rt c
riter
ia w
ithdi
ffer
ent
activ
ities
ver
sus
the
freq
uenc
y of
win
d sp
eed
high
er th
an fi
ve m
eter
s per
seco
nd, a
s sho
wn
in T
able
2.
101
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
Tabl
e 1
Effe
cts
of w
ind
on p
eopl
e. B
eauf
ort n
umbe
r cla
ssifi
es w
ind
as 0
(cal
m) t
o 12
(hur
rican
e) (S
ourc
e:Bo
ttem
a 19
93)
For e
xam
ple,
in a
n ar
ea w
here
the
num
ber o
f day
s w
ithan
ave
rage
win
d sp
eed
high
er th
an 5
m/s
is 1
50 d
ays p
erye
ar (o
r the
freq
uenc
y of
win
d w
ith a
spee
d hi
gher
than
5 m
/s is
150
day
s/36
5 da
ys x
100
per
cent
= 4
1 pe
rcen
t),
peop
le w
ho w
alk f
ast w
ould
feel
unp
leas
ant.
Clea
rly, w
ind
spee
ds g
reat
er t
han
five
met
ers
per
seco
nd a
reco
nsid
ered
unc
omfo
rtab
le fo
r mos
t act
iviti
es. T
here
fore
,it
is es
sent
ial t
o re
duce
the
win
d sp
eed
arou
nd b
uild
ings
.In
add
ition
, in
a m
ild, m
oder
ate,
and
col
d cl
imat
e, it
is v
ery
impo
rtan
t to
min
imiz
e in
filtr
atio
n of
col
d ai
r int
oth
e bu
ildin
g du
ring
the
win
ter
to r
educ
e w
ind
spee
dar
ound
bui
ldin
gs. T
he r
educ
tion
of w
ind
spee
d ca
n be
achi
eved
by:
avo
idin
g w
indy
loca
tions
suc
h as
hill
tops
;us
ing
win
d ba
rrie
rs li
ke e
verg
reen
veg
etat
ion;
clu
ster
ing
build
ings
for
mut
ual
win
d pr
otec
tion;
and
des
igni
ngbu
ildin
gs w
ith s
trea
mlin
ed s
hape
s an
d ro
unde
d co
rner
sto
bot
h de
flect
the
win
d an
d m
inim
ize
the
surf
ace-
to-
volu
me
ratio
(Lec
hner
200
0).
For
smal
l-sc
ale
build
ings
, th
ere
are
esta
blis
hed
guid
elin
es f
or p
assi
ve s
olar
hea
ting.
How
ever
, nat
ural
vent
ilatio
n an
d ou
tdoo
r the
rmal
com
fort
are
ver
y di
ffic
ult
to d
esig
n, e
ven
in si
mpl
e ca
ses.
The
purp
ose
of th
e pr
esen
tch
apte
r is
to
dem
onst
rate
, w
ith
the
help
of
the
com
puta
tiona
l flu
id d
ynam
ics
(CFD
) te
chni
que,
how
arch
itect
s ca
n w
ork
with
eng
inee
rs t
o de
sign
nat
ural
lyve
ntila
ted
build
ings
and
com
fort
able
out
door
envi
ronm
ents
aro
und
build
ings
.
WIN
D DA
TA
To d
esig
n na
tura
lly v
enti
late
d bu
ildin
gs a
nd/o
rco
mfo
rtab
le o
utdo
or e
nviro
nmen
ts, t
he f
irst
step
is t
oob
tain
relia
ble
win
d in
form
atio
n, su
ch a
s win
d sp
eed
and
dire
ctio
n. F
or e
xam
ple,
the
Nat
iona
l Ren
ewab
le E
nerg
yLa
bora
tory
der
ived
a s
et o
f ty
pica
l m
eteo
rolo
gica
lw
eath
er d
ata
for
229
stat
ions
thr
ough
out
the
Uni
ted
Tabl
e 2
Com
fort
crit
eria
for d
iffer
ent f
requ
ency
(day
/yea
r) w
hen
win
d sp
eed
is h
ighe
r tha
n 5
m/s
(Sou
rce:
Vis
ser 1
980)
Beau
fort
Num
ber
Win
d Sp
eed
Win
d Ef
fect
Desc
ript
ion
102
Part
Thr
ee -
Tec
hnic
al F
indi
ngs
Figu
re 2
Diu
rnal
and
noc
turn
al a
ir m
ovem
ents
nea
r a la
rge
body
of w
ater
(Sou
rce:
ada
pted
from
Moo
re 1
993)
Stat
es a
nd it
s te
rrito
ries
(Mar
ion
and
Urb
an 1
995)
. The
data
base
pro
vide
s hou
rly w
ind
spee
d an
d di
rect
ions
that
can
be u
sed
dire
ctly
in n
atur
al v
entil
atio
n an
d ou
tdoo
rco
mfo
rt d
esig
n. R
athe
r tha
n ac
coun
ting
for e
very
hou
rin
a f
ull r
efer
ence
yea
r, a
desi
gner
sho
uld
anal
yze
the
data
and
div
ide
it in
to e
ight
dire
ctio
ns (N
, NE,
E, S
E, S
,SW
, W, a
nd N
W) f
or s
ever
al w
ind
spee
ds (e
.g.,
Beau
fort
num
ber
<2,
3-4
, 5-
6, >
7, w
here
Bea
ufor
t nu
mbe
rcl
assi
fies
win
d as
0 f
or c
alm
to
12 f
or h
urric
ane)
. The
wea
ther
dat
a ca
n al
so b
e us
ed t
o de
term
ine
the
perc
enta
ge o
f w
ind
for
each
dir
ecti
on a
nd s
peed
com
bina
tion
(32
in
tota
l). T
he t
otal
num
ber
can
bere
duce
d, e
limin
atin
g th
ose
with
ver
y lo
w p
roba
bilit
ies.
For
coun
trie
s w
here
typ
ical
met
eoro
logi
cal w
eath
erda
ta a
re n
ot a
vaila
ble,
win
d ro
ses
can
be u
sed.
Fig
ure
1sh
ows
a pa
rt o
f th
e w
ind
rose
map
for
nor
thea
ster
nU
nite
d St
ates
in J
anua
ry. T
he w
ind
rose
s gi
ve t
he w
ind
dire
ctio
n an
d pe
rcen
tage
. The
num
ber
insi
de t
he w
ind
rose
sta
nds
for
the
perc
enta
ge o
f ca
lm p
erio
d. N
OAA
(198
3) u
ses
anot
her
figu
re t
o pr
ovid
e th
e m
onth
lyav
erag
e w
ind
spee
d ov
er a
yea
r.N
ote
that
the
win
d da
ta f
rom
wea
ther
dat
abas
es,
win
d ro
ses,
or a
wea
ther
sta
tion
is f
or a
n op
en t
erra
in.
Num
erou
s fa
ctor
s co
uld
have
a s
igni
fican
t im
pact
on
the
loca
l clim
actic
con
ditio
ns. F
or e
xam
ple,
a la
rge
wat
erbo
dy, s
uch
as a
lake
, can
cre
ate
a lo
cal w
ind
from
the
wat
er b
ody
to th
e la
nd d
urin
g th
e da
y an
d a
loca
l win
dfr
om th
e la
nd to
wat
er d
urin
g th
e ni
ght (
Figu
re 2
). Th
isis
bec
ause
wat
er h
as a
hig
her
effe
ctiv
e th
erm
al m
ass
than
tha
t of
land
. Und
er t
he s
un, t
he s
urfa
ce o
f lan
d is
heat
ed m
uch
fast
er t
han
wat
er. T
he w
arm
er a
ir ab
ove
the
land
goe
s up
due
to
the
buoy
ancy
eff
ect,
crea
ting
an a
ir pr
essu
re d
iffer
entia
l fro
m th
e w
ater
to la
nd. D
urin
gth
e ni
ght,
land
coo
ls f
aste
r th
an w
ater
due
to
ther
mal
radi
atio
n. It
is a
gain
the
ther
mal
buo
yanc
y in
the
air t
hat
form
s a la
nd-t
o-w
ater
win
d. O
ther
fact
ors i
nclu
de v
alle
ys,
mou
ntai
n ra
nges
, and
eve
n la
rge
build
ing
bloc
ks.
DESI
GN
TO
OLS
Trad
ition
ally
, man
y ar
chite
cts
pred
ict t
he a
irflo
w in
and
arou
nd b
uild
ings
by
usin
g “s
mar
t ar
row
s,” a
s sh
own
inFi
gure
3. D
raw
ing
the
airf
low
cor
rect
ly r
equi
res
a ric
hkn
owle
dge
of f
luid
mec
hani
cs. U
nfor
tuna
tely
in m
any
case
s, th
e “p
redi
cted
” airf
low
pat
tern
can
be
com
plet
ely
diff
eren
t fr
om t
hat
in r
ealit
y. F
urth
erm
ore,
the
sm
art
arro
ws c
anno
t giv
e th
e w
ind
spee
d, o
r at l
east
the
relia
ble
air s
peed
, whi
ch is
an
impo
rtan
t par
amet
er fo
r eva
luat
ing
the
bene
fits o
f nat
ural
ven
tilat
ion
and
outd
oor c
omfo
rt.
Chan
dra,
Fai
rey
and
Hou
ston
(198
3) d
evel
oped
a si
mpl
em
odel
for
cal
cula
ting
the
air
exch
ange
rat
e fo
r na
tura
lcr
oss v
entil
atio
n. H
owev
er, i
t is l
imite
d in
that
it c
an o
nly
be a
pplie
d to
bui
ldin
gs w
ith
sim
ple
geom
etry
and
surr
ound
ings
.M
any
empi
rical
and
ana
lytic
al t
ools
hav
e al
so b
een
deve
lope
d fo
r m
anua
l pre
dict
ion
of n
atur
al v
entil
atio
nin
bui
ldin
gs a
nd o
utdo
or t
herm
al c
omfo
rt,
asdo
cum
ente
d by
Alla
rd (1
998)
, Aw
bi (1
996)
, CIB
SE (1
997)
,an
d Li
nden
(199
9). T
hese
man
ual m
etho
ds a
re g
ener
ally
very
sim
ple
and
can
be e
xpre
ssed
by
alge
brai
c eq
uatio
nsan
d sp
read
shee
ts. D
espi
te b
eing
use
ful,
thes
e em
piric
alan
d an
alyt
ical
tool
s hav
e gr
eat u
ncer
tain
ties w
hen
used
for c
ompl
ex b
uild
ings
.As
a re
sult,
mos
t tra
ditio
nal s
tudi
es u
se w
ind
tunn
els
to s
imul
ate
and
mea
sure
the
airf
low
aro
und
build
ings
for
outd
oor
ther
mal
com
fort
and
a f
ull-
scal
e m
ock-
upro
om to
det
erm
ine
natu
ral v
entil
atio
n. F
igur
e 4
show
s asi
te m
odel
pla
ced
in a
win
d tu
nnel
. By
rota
ting
the
site
mod
el d
isc a
nd b
y ch
angi
ng th
e fa
n sp
eed,
diff
eren
t win
ddi
rect
ions
and
spe
eds
can
be s
imul
ated
.W
hen
the
buoy
ancy
eff
ect
is n
ot s
tron
g, s
uch
asdu
ring
nat
ural
cro
ss v
enti
lati
on,
the
win
d tu
nnel
,to
geth
er w
ith m
odel
ing
theo
ry, c
an a
lso b
e us
ed to
stud
yna
tura
l ve
ntila
tion
. Fo
r bu
oyan
cy-d
omin
ant
natu
ral
Figu
re 1
Surf
ace
win
d ro
ses
in Ja
nuar
y fo
r nor
thea
ster
n U
.S.
(Sou
rce:
ada
pted
from
NO
AA 1
983)
103
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
vent
ilatio
n, s
uch
as s
ingl
e-si
ded
natu
ral
vent
ilatio
n,id
eally
a fu
ll-sc
ale
moc
kup
is n
eede
d in
ord
er t
o sa
tisfy
both
the
Reyn
olds
num
ber t
hat r
epre
sent
s ine
rtia
l for
cefr
om th
e w
ind
and
the
Gra
shov
num
ber t
hat r
epre
sent
sth
e bu
oyan
cy f
orce
. The
exp
erim
ent
usua
lly m
easu
res
win
d sp
eed
in t
he w
ind
tunn
el, a
nd w
ind
spee
d an
dte
mpe
ratu
re i
n th
e m
ocku
p ro
om. R
arel
y is
the
win
ddi
rect
ion
also
mea
sure
d. A
lthou
gh t
he e
xper
imen
tal
appr
oach
es p
rovi
de r
elia
ble
info
rmat
ion
conc
erni
ngai
rflo
w i
n an
d ar
ound
bui
ldin
gs, t
he a
vaila
ble
data
is
gene
rally
lim
ited
due
to th
e ex
pens
ive
expe
rimen
tal r
igs
and
proc
esse
s. M
oreo
ver,
the
appr
oach
is n
ot p
ract
ical
for a
des
igne
r who
wis
hes t
o op
timiz
e hi
s or h
er d
esig
nsbe
caus
e th
e ex
peri
men
tal
met
hod
is v
ery
tim
e-co
nsum
ing.
Alte
rnat
ely,
ano
ther
flu
id s
uch
as h
eavy
refr
iger
ant
vapo
r (O
lson
, Glic
ksm
an a
nd F
erm
199
0) o
rw
ater
(Li
nden
199
9) c
an b
e us
ed f
or m
odel
ing.
The
seflu
ids
allo
w t
he m
odel
siz
e to
be
subs
tant
ially
red
uced
.W
hole
bui
ldin
gs c
an b
e sim
ulat
ed w
ith th
e w
ater
mod
els.
Also
, by
rela
som
e of
the
mod
elin
g cr
iteria
, suc
h as
mat
chin
g th
e Re
ynol
ds n
umbe
r, sm
all-
scal
e ai
r m
odel
sca
n al
so b
e em
ploy
ed.
Num
eric
al s
imul
atio
n ha
s be
com
e a
new
tre
nd f
orde
term
inin
g na
tura
l ve
ntila
tion
and
outd
oor
ther
mal
com
fort
. Tw
o nu
mer
ical
met
hods
are
ava
ilabl
e fo
rpr
edic
ting
natu
ral v
entil
atio
n. T
he fi
rst o
ne is
the
zona
lm
etho
d, w
hich
cal
cula
tes
inte
r-zo
nal a
irflo
w u
sing
the
Bern
oulli
equ
atio
n al
ong
with
exp
erim
enta
l cor
rela
tions
of fl
ow re
sista
nce
thro
ugh
door
way
s, w
indo
ws,
and
othe
ror
ifice
s.Th
e pr
edic
tion
of th
e in
ter-
zona
l airf
low
relie
s on
the
exte
rnal
pre
ssur
e di
strib
utio
n ca
used
eith
er b
y w
ind
orth
e bu
oyan
cy e
ffec
t. H
owev
er, t
he d
eter
min
atio
n of
the
exte
rnal
pre
ssur
e is
ver
y co
mpl
ex, s
ince
the
pre
ssur
edi
stri
buti
on d
epen
ds o
n in
com
ing
win
d sp
eed
and
dire
ctio
n, b
uild
ing
size
and
sha
pe,
and
the
size
and
loca
tion
of t
he b
uild
ing’
s in
terio
r op
enin
g (V
icke
ry a
nd
Kara
kats
anis
198
7). T
here
fore
, the
acc
urac
y of
the
zona
lm
etho
d de
pend
s on
the
acc
urac
y of
the
pre
ssur
edi
strib
utio
n. F
urth
erm
ore,
the
zon
al m
odel
is in
capa
ble
of d
eter
min
ing
ther
mal
com
fort
aro
und
a bu
ildin
g,be
caus
e it
does
not
pro
vide
win
d ve
loci
ty in
form
atio
n.H
owev
er, s
uch
a m
etho
d ca
n su
pply
goo
d pr
elim
inar
yes
timat
es o
f ai
r flo
w a
nd t
empe
ratu
re le
vels
with
in a
build
ing
if re
ason
able
est
imat
es o
f ext
erna
l win
d pr
essu
redi
strib
utio
ns c
an b
e m
ade.
The
othe
r nu
mer
ical
met
hod,
CFD
, cal
cula
tes
the
airf
low
dist
ribut
ion
for b
oth
indo
or a
nd o
utdo
or th
erm
alco
mfo
rt. T
he C
FD t
echn
ique
num
eric
ally
sol
ves
a se
t of
part
ial
diff
eren
tial
equa
tions
for
the
con
serv
atio
n of
mas
s, m
omen
tum
(N
avie
r-St
okes
equ
atio
ns),
ener
gy,
spec
ies
conc
entr
atio
ns, a
nd t
urbu
lenc
e qu
antit
ies.
The
solu
tion
prov
ides
the
fie
ld d
istr
ibut
ion
of p
ress
ure,
air
velo
city
, tem
pera
ture
, con
cent
ratio
ns o
f w
ater
vap
or(r
elat
ive
hum
idity
), an
d co
ntam
inan
ts, a
nd t
urbu
lenc
e.Re
fer t
o Ch
en a
nd G
licks
man
(200
0) fo
r a m
ore
deta
iled
desc
riptio
n of
the
CFD
tec
hniq
ue. D
espi
te h
avin
g so
me
unce
rtai
ntie
s an
d re
quiri
ng a
n en
gine
er w
ith s
uffic
ient
know
ledg
e of
flu
id m
echa
nics
and
a h
igh-
capa
city
com
pute
r, th
e CF
D m
etho
d ha
s be
en s
ucce
ssfu
lly u
sed
to p
redi
ct a
irflo
w in
and
aro
und
build
ings
(Che
n 19
97,
Mur
akam
i 199
8). W
ith t
he r
apid
incr
ease
in c
ompu
ter
capa
city
and
the
dev
elop
men
t of
new
CFD
pro
gram
inte
rfac
es, t
he C
FD te
chni
que
is b
ecom
ing
very
pop
ular
.Th
e fo
llow
ing
sect
ions
will
dis
cuss
the
app
licat
ions
of C
FD t
o ou
tdoo
r th
erm
al c
omfo
rt a
nd n
atur
alve
ntila
tion
desi
gn. C
FD g
ener
ally
inc
lude
s la
rge
eddy
sim
ulat
ion
and
Rey
nold
s av
erag
ed N
avie
r-St
okes
equa
tion
mod
elin
g. L
arge
edd
y si
mul
atio
n, a
s re
view
edby
Mur
akam
i (19
98),
can
give
mor
e de
taile
d re
sults
, suc
has
an
inst
anta
neou
s ai
rflo
w f
ield
, but
it r
equi
res
mor
eco
mpu
ting
time
than
tha
t of
the
Rey
nold
s av
erag
edN
avie
r-St
okes
equ
atio
n m
odel
ing.
Larg
e ed
dy si
mul
atio
nha
s sta
rted
app
earin
g in
bui
ldin
g en
viro
nmen
t res
earc
h,
Figu
re 4
A b
uild
ing
site
mod
el w
ithin
a w
ind
tunn
el
Figu
re 3
Smar
t arr
ows
used
by
arch
itect
s to
pre
dict
airf
low
inan
d ar
ound
bui
ldin
gs (S
ourc
e: a
dapt
ed fr
om M
oore
199
3)
104
Part
Thr
ee -
Tec
hnic
al F
indi
ngs
but h
as y
et to
be
appl
ied
as a
des
ign
tool
. The
refo
re, t
his
chap
ter
focu
ses
on R
eyno
lds
aver
aged
Nav
ier-
Stok
eseq
uatio
n m
odel
ing.
Man
y co
mm
erci
al C
FD p
rogr
ams
base
d on
the
Reyn
olds
ave
rage
d N
avie
r-St
okes
equ
atio
nm
odel
ing
are
avai
labl
e on
mar
ket a
nd a
re ra
ther
sim
ilar
to e
ach
othe
r. Th
is i
nves
tigat
ion
uses
the
PH
OEN
ICS
prog
ram
(CH
AM 2
000)
.
OU
TDO
OR
THER
MAL
CO
MFO
RT S
TUDI
ES
Out
door
the
rmal
com
fort
des
ign
will
be
illus
trat
ed b
ytw
o ap
plic
atio
n ex
ampl
es. T
he f
irst
exam
ple
conc
erns
the
desi
gn o
f th
e St
ata
Cent
er a
t th
e M
assa
chus
etts
Inst
itute
of
Tech
nolo
gy, a
nd t
he s
econ
d is
a h
igh-
rise
resi
dent
ial b
uild
ing
com
plex
in B
eijin
g.
Stat
a Ce
nter
Figu
re 5
a sh
ows
a m
odel
of
the
Stat
a Ce
nter
and
its
surr
ound
ings
des
igne
d by
Fran
k O.
Geh
ry a
nd A
ssoc
iate
s.Si
nce
this
cam
pus b
uild
ing
has w
indy
surr
ound
ings
, the
arch
itect
was
con
cern
ed a
bout
the
out
door
the
rmal
com
fort
in th
e pl
aza
(the
fron
t par
t of F
igur
e 5a
). At
one
time,
the
arch
itect
wan
ted
to a
dd a
gla
ss ro
of th
at w
ould
prov
ide
a w
ind
shie
ld o
ver
the
plaz
a. S
ince
the
gla
zed
roof
wou
ld c
ost
seve
ral
mill
ion
dolla
rs, t
he a
rchi
tect
initi
ated
a st
udy
of th
e w
ind
dist
ribut
ion
arou
nd th
e St
ata
Cent
er, w
hich
was
rese
arch
ed b
y th
e au
thor
.Th
is in
vest
igat
ion
used
a c
omm
erci
al C
FD p
rogr
am(C
HAM
200
0) fo
r the
stud
y. Th
e CF
D p
rogr
am a
llow
s one
to r
ead
data
fro
m a
n Au
toCA
D f
ile. T
his
feat
ure
is v
ery
impo
rtan
t be
caus
e of
the
com
plic
ated
geo
met
ry o
f the
build
ings
. Sim
ilar t
o a
win
d tu
nnel
, CFD
requ
ires d
etai
led
info
rmat
ion
on th
e su
rrou
ndin
gs o
f the
Sta
ta C
ente
r in
orde
r to
calc
ulat
e th
e ai
rflo
w. T
he su
rrou
ndin
g bu
ildin
gsca
n ei
ther
blo
ck o
r enh
ance
the
win
d sp
eed
arou
nd th
ece
nter
. The
com
puta
tiona
l dom
ain
for t
he b
uild
ing
and
surr
ound
ings
is s
how
n in
Fig
ure
5b. T
he d
omai
n le
ngth
is a
bout
fiv
e tim
es t
hat
of S
tata
Cen
ter
in t
he f
our
horiz
onta
l dire
ctio
ns (o
r 100
tim
es th
e St
ata
Cent
er a
rea
size
). Th
e w
ind
dist
ribut
ions
aro
und
Stat
a Ce
nter
wer
eca
lcul
ated
for
the
nor
th, e
ast,
sout
h, a
nd w
est
win
ddi
rect
ions
with
a t
ypic
al w
ind
spee
d fo
r ea
ch d
irect
ion.
Figu
re 6
show
s the
win
d di
strib
utio
n ar
ound
Sta
ta C
ente
rw
ith a
n ea
st w
ind.
Thi
s st
udy
used
abo
ut o
ne m
illio
ngr
id p
oint
s; th
e st
udy
requ
ired
thre
e da
ys o
f com
putin
gtim
e on
a P
entiu
m II
450
PC
with
512
MB
of m
emor
y.Th
at P
C w
as c
onsi
dere
d to
be
high
-end
in
1999
.O
bvio
usly
, the
grid
num
ber w
as t
oo c
oars
e so
the
win
din
form
atio
n w
as n
ot s
uffic
ient
ly d
etai
led.
Ther
efor
e, th
e in
vest
igat
ion
used
a zo
om-i
n ap
proa
chto
stu
dy th
e de
tails
of t
he w
ind
dist
ribut
ion.
The
zoo
m-
in a
ppro
ach
used
the
win
d in
form
atio
n co
mpu
ted
(Fig
ure
6) a
s bou
ndar
y co
nditi
ons i
n ca
lcul
atin
g th
e w
ind
spee
ddi
strib
utio
n ju
st a
roun
d St
ata
Cent
er, a
s sho
wn
in Fi
gure
7. W
ith th
e zo
om-i
n ap
proa
ch, t
he C
FD re
sults
pro
vide
dve
ry d
etai
led
win
d sp
eed
info
rmat
ion.
For
exa
mpl
e, t
hew
ind
spee
d w
as fo
und
to b
e al
mos
t ide
ntic
al a
roun
d St
ata
Cent
er w
ith o
r w
ithou
t th
e gl
ass
roof
. Hen
ce, t
he g
lass
roof
was
not
nec
essa
ry.
A H
igh-
Rise
Res
iden
tial B
uild
ing
Com
plex
in B
eijin
gIn
the
past
, a g
ood
livin
g en
viro
nmen
t in
Chin
a im
plie
dam
ple
spac
e be
twee
n bu
ildin
gs fi
lled
with
tree
s and
gra
ss.
Hig
h-ris
e bu
ildin
gs h
ave
been
reg
arde
d as
a s
ymbo
l of
mod
erni
ty a
nd lu
xury
. A t
ypic
al b
uild
ing
cons
istin
g of
such
res
iden
tial u
nits
is s
how
n in
Fig
ure
8. J
iang
et
al(1
999)
mad
e a
deta
iled
anal
ysis
on th
e de
sign
and
foun
dth
at s
uch
a de
sign
is n
ot s
usta
inab
le in
term
s of
ene
rgy
effic
ienc
y an
d Ch
ines
e cu
lture
. The
stu
dy s
how
ed t
hat
the
best
des
ign
wou
ld b
e m
ade
up o
f low
-ris
e bu
ildin
gsw
ith v
aryi
ng-s
ized
cou
rtya
rds.
This
wou
ld a
void
a h
arsh
win
ter w
ind,
let t
he w
inte
r sun
in, a
nd p
rom
ote
the
use
of n
atur
al v
entil
atio
n.
Figu
re 5
Stat
a Ce
nter
: (a)
mod
el s
how
n w
ithou
t gla
ss ro
of a
nd(b
) sur
roun
ding
s
(a)
(b)
Stat
a Ce
nter
105
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
Figu
re 7
Win
d di
strib
utio
n ar
ound
Sta
ta C
ente
r (zo
om-i
n): (
a)w
ith a
gla
ss ro
of a
nd (b
) with
out a
gla
ss ro
of (d
ark
- lo
w v
eloc
ityan
d lig
ht -
hig
h ve
loci
ty)
Figu
re 6
Win
d di
strib
utio
n ar
ound
Sta
ta C
ente
r at t
he g
roun
d le
vel (
dark
- lo
w v
eloc
ity a
nd li
ght -
hig
h ve
loci
ty)
(a)
(b)
106
Part
Thr
ee -
Tec
hnic
al F
indi
ngs
As i
s th
e ca
se w
ith
man
y do
wnt
own
area
s w
ith
skys
crap
ers,
high
-rise
bui
ldin
gs so
met
imes
cre
ate
a w
ind
tunn
el e
ffec
t tha
t is
very
unc
omfo
rtab
le to
ped
estr
ians
.Th
e pr
opos
ed d
esig
n fo
r Bei
jing
Star
Gar
den
form
s a w
ind
tunn
el e
ffec
t on
the
site
with
pre
vaili
ng w
inte
r w
inds
from
the
nor
th. F
igur
e 9a
sho
ws
the
win
d di
strib
utio
non
the
site
with
a n
orth
win
d fr
om th
e rig
ht. T
here
are
afe
w p
lace
s th
at h
ave
very
hig
h w
ind
spee
ds (
see
red
arro
ws
in F
igur
e 9a
). Th
e de
velo
pers
did
not
ado
pt o
ursu
gges
tion
of lo
wer
ing
the
build
ing
heig
ht a
nd c
reat
ing
cour
ts to
elim
inat
e “w
ind
tunn
el” p
robl
ems a
nd e
nhan
ceco
ntac
t be
twee
n ne
ighb
ors.
Inst
ead,
the
y so
ught
to
chan
ge t
he s
hape
of
the
four
tow
ers
in t
he n
orth
to
elim
inat
e hi
gh w
ind
spot
s. T
he n
ew d
esig
n us
ed a
diff
eren
t bu
ildin
g sh
ape
to d
efle
ct t
he w
ind
to t
hew
estw
ard
dire
ctio
n. F
igur
e 9b
sho
ws
the
airf
low
dist
ribut
ion
with
a n
orth
win
d un
der t
he n
ew d
esig
n of
the
four
tow
ers
that
redu
ces
area
s of
hig
h w
inds
.O
f co
urse
, win
d is
not
the
onl
y fa
ctor
in p
rodu
cing
an e
nerg
y-ef
ficie
nt b
uild
ing
desig
n. C
hang
ing
the
tow
ersh
ape
may
hav
e an
impa
ct o
n th
e de
sire
to h
ave
sout
h-fa
cing
win
dow
s. T
his
can
be a
chie
ved
thro
ugh
arch
itect
ural
des
ign,
as
show
n in
Fig
ure
10. T
he t
hin
stru
ctur
e al
so a
llow
s th
e us
e of
nat
ural
ven
tilat
ion
inth
e su
mm
er. S
ee C
hapt
er 1
1, C
ase
Stud
y Tw
o –
Beiji
ngSt
ar G
arde
n fo
r mor
e in
form
atio
n.
NAT
URA
L VE
NTI
LATI
ON
STU
DIES
The
last
ten
yea
rs h
ave
seen
a s
igni
fican
t sh
ift in
the
deve
lopm
ent
and
inte
grat
ion
of e
nvir
onm
enta
l,ec
olog
ical
, and
ene
rgy
issue
s int
o th
e ar
chite
ctur
al d
esig
nof
bui
ldin
gs. E
nerg
y-ef
ficie
nt b
uild
ings
add
ress
not
onl
yth
e is
sues
of
cons
umpt
ion
and
perf
orm
ance
, but
als
oth
e de
velo
pmen
t an
d in
tegr
atio
n of
a s
erie
s of
des
ign
and
syst
em t
echn
olog
ies.
Build
ings
sho
uld
prov
ide
the
Figu
re 8
Beiji
ng S
tar G
arde
n -
a hi
gh-r
ise
resi
dent
ial
deve
lopm
ent
(a)
Figu
re 9
Win
d di
strib
utio
n on
the
build
ing
site
: (a)
orig
inal
des
ign,
and
(b) d
esig
n w
ith fo
ur p
ropo
sed
tow
ers
to th
e no
rth
(to
the
right
)(r
ed in
dica
tes
high
vel
ocity
, yel
low
- m
oder
ate
velo
city
, and
blu
e -
low
vel
ocity
)
(b)
Figu
re 1
0Th
e un
it la
yout
in th
e fo
ur n
ew to
wer
s al
low
s m
ore
effe
ctiv
e na
tura
l ven
tilat
ion
in th
e su
mm
er (n
orth
is u
p)
107
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
basi
c am
eniti
es o
f sh
elte
r an
d ye
t pr
actic
e re
spon
sibl
eus
e of
res
ourc
es. W
hate
ver
the
clim
ate
zone
, ene
rgy-
cons
ciou
s de
sign
util
izes
str
ateg
ies
that
opt
imiz
e th
epa
ssiv
e en
viro
nmen
tal
syst
ems
in r
efer
ence
to
activ
e“s
eale
d sy
stem
” str
ateg
ies.
This
lead
s to
the
use
of n
atur
alve
ntila
tion
and
the
max
imiz
atio
n of
day
light
ing
whe
reve
rre
ason
able
. Eve
n un
der
unfa
vora
ble
outd
oor
clim
ate
cond
ition
s, pa
ssiv
e-ba
sed
tech
nolo
gy c
an b
e co
mbi
ned
wit
h ac
tive
sys
tem
s du
ring
sho
ulde
r se
ason
s an
dso
met
imes
for
nig
ht c
oolin
g in
con
junc
tion
wit
had
equa
te t
herm
al m
ass.
Lead
ing
arch
itect
s of
thi
s ge
nera
tion
in t
he U
nite
dKi
ngdo
m, G
erm
any,
Fran
ce, S
witz
erla
nd, a
nd S
cand
inav
iaha
ve tu
rned
thei
r att
entio
n to
a m
ore
sust
aina
ble
form
of p
ract
ice
in b
oth
build
ing
syst
em t
echn
olog
ies
and
build
ing
typo
logi
es. T
his
appr
oach
can
be
witn
esse
d in
the
wor
k of
arc
hite
cts s
uch
as Fo
ster
and
Par
tner
s, Re
nzo
Pian
o, A
lan
Shor
t, Th
omas
Her
zog,
Mic
hael
Hop
kins
,Ed
war
d Cu
llina
n, a
nd K
iess
ler
and
Part
ners
. In
the
irde
sign
s, th
e is
sue
of r
esou
rces
and
the
env
ironm
ent
isat
the
hea
rt o
f m
akin
g in
telli
gent
and
wel
l-cr
afte
dar
chit
ectu
re.
Thei
r bu
ildin
gs p
rovi
de a
n in
tera
ctio
nbe
twee
n th
e en
clos
ure
syst
ems
and
the
envi
ronm
enta
lan
d m
echa
nica
l st
rate
gies
for
the
int
erna
l sp
ace.
The
build
ings
are
repu
ted
to s
ave
a co
nsid
erab
le a
mou
nt o
fen
ergy
whi
le im
prov
ing
indo
or a
ir qu
ality
and
com
fort
.Ta
ble
3 sh
ows
the
pote
ntia
l of
usi
ng n
atur
alve
ntila
tion
in th
e U
nite
d St
ates
for r
esid
entia
l bui
ldin
gs.
With
pro
per
desi
gn o
f bu
ildin
g or
ient
atio
n, l
ocat
ion,
shap
e, a
nd o
peni
ngs,
dayt
ime
natu
ral v
entil
atio
n an
d/or
nigh
t coo
ling
can
prov
ide
a th
erm
ally
com
fort
able
indo
oren
viro
nmen
t for
a lo
ng p
erio
d in
mos
t all
U.S
. clim
ates
.Ev
en i
f it
is
not
poss
ible
to
avoi
d th
e us
e of
air
-co
nditi
onin
g in
the
sum
mer
, air-
cond
ition
ing
units
can
be m
uch
smal
ler w
ith n
atur
al v
entil
atio
n, re
duci
ng fi
rst
and
oper
atin
g co
sts.
Tabl
e 3
The
pot
entia
l for
nat
ural
ven
tilat
ion
in th
e U
.S. (
Sour
ce: L
echn
er 2
000)
Tabl
e 4
A s
urve
y co
nduc
ted
in B
eijin
g w
ith re
spec
t to
the
use
of a
ir-co
nditi
onin
g in
hom
es(S
ourc
e: Ji
ang
1999
)
Age
< 1
9 2
0-40
40-
60 >
60
Sex
MF
MF
MF
MF
Like
AC
(%)
4352
4835
3837
2230
Neu
tral
(%)
4332
4353
3737
3733
Dis
like
AC (%
)14
169
1225
2641
37
Mon
thJa
nFe
bM
arAp
rM
ayJu
nJu
lAu
gSe
pO
ctN
ovD
ec1.
Har
tfor
d, C
TH
HH
HN
VN
VN
VN
VN
VH
HH
2. M
adis
on, W
IH
HH
HN
VN
VN
VN
VN
VH
HH
3. In
dian
apol
is, I
NH
HH
NV
NV
NV
ACAC
NV
NV
HH
4. S
alt L
ake
City
, UT
HH
HH
NV
NV
ACAC
NV
NV
HH
5. E
ly, N
VH
HH
HN
VN
VN
VN
VN
VN
VH
H6.
Med
ford
, OR
HH
HN
VN
VN
VN
VN
VN
VN
VH
H7.
Fre
sno,
CA
HH
NV
NV
NV
NV
NV
NV
NV
NV
HH
8. C
harle
ston
, SC
HH
NV
NV
NV
ACAC
ACAC
NV
NV
H9.
Litt
le R
ock,
AR
HH
HN
VN
VAC
ACAC
NV
NV
NV
H10
. Kno
xvill
e, T
NH
HH
NV
NV
ACAC
ACN
VN
VN
VH
11. P
hoen
ix, A
ZH
NV
NV
NV
ACAC
ACAC
ACN
VN
VH
12. M
idla
nd, T
XH
HN
VN
VN
VAC
ACAC
ACN
VN
VH
13. F
ort W
orth
, TX
HN
VN
VN
VAC
ACAC
ACAC
NV
NV
H14
. New
Orle
ans,
LAH
HN
VN
VN
VAC
ACAC
ACN
VN
VH
15. H
oust
on, T
XH
NV
NV
NV
ACAC
ACAC
ACN
VN
VH
16. M
iam
i, FL
NV
NV
NV
NV
ACAC
ACAC
ACAC
NV
NV
17. L
os A
ngel
es, C
AH
HN
VN
VN
VN
VAC
NV
NV
NV
NV
H
Furt
herm
ore,
it is
ver
y in
tere
stin
g to
see
the
sur
vey
cond
ucte
d in
Bei
jing
by J
iang
(19
99)
rega
rdin
g th
eac
cept
abili
ty o
f air-
cond
ition
ing
syst
ems.
Tabl
e 4
show
sth
e su
rvey
res
ults
sep
arat
ed in
to c
ateg
orie
s ac
cord
ing
to a
ge a
nd s
ex. P
eopl
e w
ho li
ke a
ir-co
nditi
onin
g th
ink
that
it
prov
ides
a c
ool
tem
pera
ture
(40
per
cent
),re
pres
ents
a m
oder
n te
chno
logy
(34
perc
ent)
, and
off
ers
an a
bilit
y to
con
trol
the
clim
ate
(23
perc
ent)
. On
the
Peri
ods
Suit
able
for
Nat
ural
Ven
tila
tion
(NV)
and
whe
n Ai
r-Co
ndit
ioni
ng (A
C) o
r H
eati
ng (H
) is
Nee
ded
for
Resi
dent
ial B
uild
ings
Clim
ate
Regi
onan
d Re
fere
nce
City
othe
r ha
nd, t
hose
who
dis
like
air-
cond
ition
ing
belie
veth
at a
ir-c
ondi
tion
ing
sepa
rate
s th
em f
rom
nat
ure
(47
perc
ent),
lead
s to
draf
t and
a h
igh-
noise
env
ironm
ent
(26
perc
ent)
, and
cau
ses
high
ele
ctric
ity a
nd f
irst
cost
s(2
3 pe
rcen
t). I
n ge
nera
l, yo
unge
r peo
ple
tend
to li
ke a
ir-co
nditi
onin
g m
ore
than
eld
erly
peo
ple
do. T
he r
esul
tssh
ow a
gre
at p
oten
tial f
or u
sing
nat
ural
ven
tilat
ion
inBe
ijing
.
108
Part
Thr
ee -
Tec
hnic
al F
indi
ngs
It sh
ould
als
o be
not
ed t
hat
natu
ral v
entil
atio
n ha
sits
shor
tcom
ings
; the
se in
clud
e iss
ues o
f hum
idity
cont
rol,
nois
e co
ntro
l (1
0 dB
ded
uctio
n fo
r an
ope
n w
indo
wve
rsus
30
dB d
educ
tion
for
a s
eale
d w
indo
w),
heat
reco
very
, sec
urity
con
cern
s, an
d ra
in. I
n ad
ditio
n, in
are
asw
ith h
igh
outd
oor
pollu
tion,
nat
ural
ven
tilat
ion
has
diff
icul
ty in
con
trol
ling
air
qual
ity. O
ne s
olut
ion
coul
dbe
the
use
of n
ight
cool
ing
that
clos
es th
e w
indo
w d
urin
gda
ytim
e, a
s ill
ustr
ated
by
Carr
ilho
da G
raça
et a
l (20
02)
and
as d
escr
ibed
in c
hapt
er 5
.Ac
cord
ing
to C
IBSE
(19
97),
natu
ral v
entil
atio
n ca
nbe
cla
ssifi
ed a
s:
•cr
oss
vent
ilatio
n;•
sing
le-s
ided
ven
tilat
ion;
•st
ack
vent
ilatio
n; a
nd•
mec
hani
cally
ass
iste
d ve
ntila
tion.
Cros
s ve
ntila
tion
occu
rs w
here
an
indo
or s
pace
has
vent
ilatio
n op
enin
gs o
n bo
th s
ides
. Air
flow
s fr
om o
nesi
de o
f th
e bu
ildin
g to
the
oth
er d
ue t
o a
pres
sure
diff
eren
ce b
uilt
up b
y w
ind.
Sin
gle-
side
d ve
ntila
tion
impl
ies
that
an
indo
or s
pace
has
all
of t
he o
peni
ngs
onon
e si
de.
Stac
k ve
ntila
tion
mak
es u
se o
f de
nsit
ydi
ffer
ence
s du
e to
buo
yanc
y in
pro
mot
ing
an o
utflo
wfr
om a
par
t of a
bui
ldin
g (e
.g., r
oof)
and
draw
ing
in fr
esh
and
cool
air
from
ano
ther
par
t of
the
bui
ldin
g (e
.g.,
win
dow
s an
d do
ors)
. Mec
hani
cally
ass
iste
d ve
ntila
tion
uses
mec
hani
cal v
entil
atio
n to
incr
ease
the
airf
low
inan
y of
the
abo
ve-m
entio
ned
syst
ems.
A bu
ildin
g m
ayha
ve m
ore
than
one
of t
he v
entil
atio
n sy
stem
s des
crib
edab
ove. This
sec
tion
will
des
crib
e th
e ap
plic
atio
ns o
f CF
D t
ode
sign
cro
ss v
entil
atio
n an
d si
ngle
-sid
ed v
entil
atio
n in
build
ings
. The
met
hod
can
be u
sed
for o
ther
ven
tilat
ion
syst
ems
as w
ell.
Cros
s Ve
ntila
tion
in a
Bui
ldin
gTh
e de
sign
team
was
requ
este
d to
des
ign
thre
e m
id-r
ise
build
ings
for
a r
esid
enti
al b
uild
ing
deve
lopm
ent
inSh
angh
ai (F
igur
e 11
).Si
nce
win
d ar
ound
the
build
ings
is th
e dr
ivin
g fo
rce
in c
ross
ven
tila
tion
, th
is i
nves
tiga
tion
inv
olve
s th
esim
ulat
ion
of in
door
and
out
door
airf
low
by
CFD.
In o
rder
to s
tudy
the
im
pact
of
surr
ound
ing
build
ings
, th
eco
mpu
tatio
nal
dom
ain
for
outd
oor
airf
low
sho
uld
besu
ffic
ient
ly la
rge
(e.g
., an
are
a of
tens
of t
hous
ands
to a
mill
ion
squa
re m
eter
s). D
ue t
o th
e lim
itatio
n in
cur
rent
com
pute
r cap
acity
and
spe
ed, t
he g
rid s
ize
used
can
not
be v
ery
smal
l (it
can
be a
few
met
ers)
. On
the
othe
r han
d,th
e gr
id si
ze fo
r ind
oor a
irflo
w si
mul
atio
n sh
ould
be
smal
len
ough
(in
term
s of
a f
ew c
entim
eter
s) f
or o
ne t
o se
eth
e de
tails
. The
refo
re, t
he in
door
and
out
door
airf
low
shou
ld b
e se
para
tely
sim
ulat
ed. F
or n
atur
al v
entil
atio
nde
sign
, the
out
door
airf
low
sim
ulat
ion
can
prov
ide
flow
info
rmat
ion
as b
ound
ary
cond
itio
ns f
or t
he i
ndoo
rai
rflo
w s
imul
atio
n. Z
hai e
t al
(20
00)
have
dis
cuss
ed a
few
met
hods
to p
rovi
de th
e flo
w in
form
atio
n.Fo
r sim
plic
ity, t
his i
nves
tigat
ion
used
a C
FD p
rogr
amto
cal
cula
te th
e pr
essu
re d
iffer
ence
aro
und
the
build
ings
and
uses
it a
s the
bou
ndar
y co
nditi
ons f
or in
door
airf
low
sim
ulat
ion.
Idea
lly, t
he c
alcu
latio
n sh
ould
be
perf
orm
edfo
r diff
eren
t win
d di
rect
ions
und
er v
ario
us w
ind
spee
dsin
a p
erio
d su
itab
le f
or n
atur
al v
enti
lati
on,
such
as
sum
mer
. Fig
ure
12 il
lust
rate
s th
e pr
essu
re d
istr
ibut
ion
unde
r the
pre
vaili
ng w
ind
dire
ctio
n (s
outh
east
) and
spee
d(3
m/s
). In
ord
er t
o co
rrec
tly t
ake
the
impa
ct o
f th
esu
rrou
ndin
g bu
ildin
gs in
to a
ccou
nt, t
he c
ompu
tatio
nal
dom
ain
is m
uch
larg
er th
an th
e on
e sh
own
in th
e fig
ure.
Clea
rly, t
he p
ress
ure
diff
eren
ce is
the
hig
hest
bet
wee
nth
e no
rthe
rn a
nd so
uthe
rn fa
çade
s. It
is a
lso
inte
rest
ing
to n
ote
that
the
high
est p
ress
ure
diff
eren
ce is
nei
ther
at
the
top
floor
nor
at
the
bott
om f
loor
, but
som
ewhe
rene
ar th
e to
p, a
s sh
own
in F
igur
e 12
b.
109
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
Figu
re 1
1 A
rchi
tect
ural
ele
vatio
n an
d pl
ans
of fi
nal d
esig
n fo
r Sha
ngha
i Tai
dong
Res
iden
tial Q
uart
er
Figu
re 1
2 P
ress
ure
dist
ribut
ion
arou
nd th
e bu
ildin
gs p
ropo
sed
(sho
wn
circ
led)
for S
hang
hai T
aido
ng R
esid
entia
l Qua
rter
, due
to p
reva
iling
win
ds, f
rom
the
sout
heas
t at 3
m/s
(da
rk g
ray
- hi
gh p
ress
ure,
ligh
t gra
y -
low
pre
ssur
e): (
a) is
the
plan
(nor
th is
up)
and
(b) i
s th
e se
ctio
nlo
okin
g w
est (
see
colo
r ver
sion
of F
igur
e 12
b in
cha
pter
12,
Fig
ure
34)
(b)
(a)
110
Part
Thr
ee -
Tec
hnic
al F
indi
ngs
By w
orki
ng t
oget
her w
ith t
he a
rchi
tect
s, th
e de
sign
team
eva
luat
ed t
he v
entil
atio
n pe
rfor
man
ce f
or t
hebu
ildin
gs. U
nit G
in th
e m
iddl
e bu
ildin
g w
as u
sed
(Fig
ure
13) a
s an
exa
mpl
e to
illu
stra
te t
he e
valu
atio
n of
cro
ss-
vent
ilatio
n de
sign
.W
ith t
he u
nit
layo
ut in
Fig
ure
13, a
CFD
mod
el c
anbe
est
ablis
hed,
as s
how
n in
Figu
re 1
4a. W
ith th
e pr
essu
redi
stri
buti
on f
rom
Fig
ure
12,
the
CFD
pro
gram
can
calc
ulat
e th
e di
strib
utio
ns o
f ai
rflo
w, a
ir te
mpe
ratu
re,
rela
tive
hum
idity
, pre
dict
ed p
erce
ntag
e di
ssat
isfie
d (P
PD),
and
the
mea
n ag
e of
air,
as s
how
n in
Fig
ure
14. C
FD u
ses
the
hum
idity
ratio
and
air
tem
pera
ture
to d
eter
min
e th
ere
lativ
e hu
mid
ity. T
he P
PD is
det
erm
ined
by
usin
g th
eai
r ve
loci
ty,
tem
pera
ture
, hu
mid
ity
rati
o, a
nden
viro
nmen
tal t
empe
ratu
re. T
he re
sults
show
n in
Fig
ure
14 a
re w
ith a
n ou
tsid
e ai
r te
mpe
ratu
re o
f 24
°C a
nd a
rela
tive
hum
idity
of 7
0 pe
rcen
t.Th
e co
mpu
ted
resu
lts
by C
FD i
ndic
ate
that
the
max
imum
air
velo
city
in th
e un
it is
less
than
one
met
erpe
r se
cond
– a
com
fort
able
val
ue f
or c
ross
ven
tilat
ion.
The
air
exch
ange
rat
e va
ries
from
16
ACH
on
the
first
floor
to
a m
axim
um o
f 40
air
chan
ges
per
hour
(ACH
)tw
o-th
irds
up t
he h
eigh
t of
the
bui
ldin
g. W
ith t
he a
irex
chan
ge r
ate
of 1
6 AC
H, t
he i
ndoo
r ai
r te
mpe
ratu
rein
crea
ses l
ess t
han
1°K,
alth
ough
ther
e ar
e he
at so
urce
sin
the
uni
t. Th
e re
lati
ve h
umid
ity
is a
roun
d 65
to
70 p
erce
nt, a
val
ue c
lose
to
that
of t
he o
utdo
ors.
Sinc
eth
e ai
r exc
hang
e ra
te is
hig
h, th
e m
ean
age
of a
ir is
less
than
120
sec
onds
. The
refo
re, t
he a
ir qu
ality
wou
ld b
eve
ry g
ood
whe
n ou
tdoo
r air
qual
ity is
hig
h.Si
nce
the
air
exch
ange
rat
e is
a v
ery
impo
rtan
tpa
ram
eter
in c
ross
ven
tilat
ion
desi
gn, t
his
inve
stig
atio
nin
dica
tes
the
desi
gn to
be
very
suc
cess
ful.
How
ever
, the
win
d is
not
alw
ays a
t the
pre
vaili
ng sp
eed
and
dire
ctio
n,an
d th
e ou
tdoo
r air
tem
pera
ture
var
ies o
ver t
ime.
A m
ore
com
plet
e ev
alua
tion
of t
he d
esig
n sh
ould
be
com
bine
dw
ith a
n en
ergy
ana
lysi
s of
the
bui
ldin
g, a
s de
scrib
ed in
chap
ter
5. C
arril
ho d
a G
raça
et
al (
2002
) ha
ve s
how
nho
w to
com
bine
the
info
rmat
ion
from
flow
and
ene
rgy
anal
ysis
for
suc
h a
build
ing.
The
pap
er a
lso
emph
asiz
esth
e im
port
ance
in u
sing
diff
eren
t con
trol
stra
tegi
es. F
orex
ampl
e, in
Sha
ngha
i it i
s mor
e ap
prop
riate
to u
se n
ight
cool
ing
and
min
imum
day
time
vent
ilatio
n to
ach
ieve
an
indo
or a
ir te
mpe
ratu
re lo
wer
than
that
of t
he o
utdo
ors.
This
is su
perio
r to
vent
ilatin
g bu
ildin
gs tw
enty
-fou
r hou
rsa
day.
See
Cha
pter
12,
Cas
e St
udy
Thre
e– S
hang
hai
Taid
ong
Resi
dent
ial Q
uart
er fo
r mor
e in
form
atio
n.
Sing
le-S
ided
Ven
tilat
ion
in a
Bui
ldin
gTh
e bu
ildin
g st
udie
d is
a st
uden
t dor
mito
ry in
Cam
brid
ge,
Mas
sach
uset
ts. S
ingl
e-si
ded
vent
ilatio
n w
as e
valu
ated
for
a ty
pica
l roo
m t
hat
is 4
.7 m
eter
s lo
ng, 2
.9 m
eter
sw
ide,
and
2.8
met
ers h
igh.
The
gen
eral
room
mod
el u
sed
thro
ugho
ut th
e st
udy
is sh
own
in Fi
gure
15.
The
furn
iture
with
in t
his
room
con
sist
ed o
f a
bed,
des
k, c
lose
t, an
dbo
okca
se. T
he h
eat s
ourc
es w
ere
a co
mpu
ter (
300
W),
aTV
set
(300
W),
and
one
occu
pant
(100
W).
For
each
of
the
heat
sour
ces,
conv
ectiv
e an
d ra
diat
ive
heat
tran
sfer
was
app
roxi
mat
ely
equa
l. Th
e su
rrou
ndin
g w
alls
, cei
ling,
and
floor
abs
orbe
d th
e ra
diat
ive
com
pone
nt a
nd re
leas
edit
back
to
the
room
air
by c
onve
ctio
n. S
olar
gai
ns w
ere
not
incl
uded
for
pur
pose
s of
the
tim
e-av
erag
edve
ntila
tion
stud
y. T
he w
indo
w d
esig
ned
for
the
room
cons
iste
d of
an
uppe
r and
low
er w
indo
w (0
.4 m
2 eac
h),
as sh
own
in F
igur
e 15
. The
out
door
air
tem
pera
ture
was
mai
ntai
ned
cons
tant
at
25.5
°C,
the
aver
age
noon
tem
pera
ture
for
Bos
ton
in J
uly.
The
int
entio
n w
as t
oan
alyz
e th
e re
sults
for
thi
s fix
ed o
utdo
or t
empe
ratu
re,
and
then
app
ly th
em to
a ra
nge
of o
utdo
or te
mpe
ratu
reco
nditi
ons
to d
evel
op tr
ends
.Th
is s
tudy
sta
cked
thr
ee id
entic
al d
orm
itory
roo
ms
vert
ical
ly a
bove
one
ano
ther
to e
valu
ate
the
effe
ct a
long
a bu
ildin
g’s
heig
ht. T
his
thre
e-st
ory
setu
p w
as p
lace
dw
ithin
a la
rger
out
side
dom
ain
(Fig
ure
15b)
. The
ext
ensio
n
Figu
re 1
3Bu
ildin
g flo
or p
lan
- un
it G
(the
uni
t far
thes
t to
the
right
) was
ana
lyze
d fo
r int
erio
r CFD
stu
dies
111
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
Figu
re 1
5 T
he C
FD m
odel
use
d to
stu
dy s
ingl
e-si
ded
vent
ilatio
nin
an
MIT
dor
mito
ry ro
om: (
a) th
e ro
om m
odel
and
(b) t
hebu
ildin
g an
d en
viro
nmen
t mod
el
Figu
re 1
4Cr
oss
vent
ilatio
n pe
rfor
man
ce a
naly
sis
of B
eijin
g un
it in
terio
r (re
d –
high
, yel
low
– m
oder
ate
high
, gre
en –
mod
erat
e lo
w,
blue
– lo
w):
(a) u
nit m
odel
, (b)
air
tem
pera
ture
, (c)
pre
dict
ed p
erce
ntag
e of
dis
satis
fied
peop
le (P
PD) d
ue to
ther
mal
com
fort
, (d)
air
velo
city
, (e)
rela
tive
hum
idity
, and
(f) m
ean
age
of a
ir
(a)
(d)
(b)
(e)
(c)
(f)
(a)
(b)
book
case
clos
et
desk
bed
win
dow
s
112
Part
Thr
ee -
Tec
hnic
al F
indi
ngs
Figu
re 1
7U
ncer
tain
eff
ects
of c
ombi
ned
win
d an
d st
ack
forc
es: (
a) re
info
rcin
g vs
. cou
nter
actin
g ef
fect
and
(b)
depi
ctio
n of
cou
nter
actin
g w
ind
and
stac
k ef
fect
s ov
er a
pro
gres
sion
of w
ind
spee
ds
Figu
re 1
6 CF
D re
sults
in th
e ce
nter
of t
he ro
oms
with
sta
ckef
fect
(red
– h
igh,
yel
low
– m
oder
ate
high
, gre
en –
mod
erat
elo
w, b
lue
– lo
w ):
(a) a
ir ve
loci
ty d
istr
ibut
ion
and
(b) a
irte
mpe
ratu
re d
istr
ibut
ion
Figu
re 1
8CF
D re
sults
in th
e ce
nter
of t
he ro
oms
with
the
com
bine
d w
ind
and
stac
k ef
fect
s (r
ed –
hig
h, y
ello
w –
mod
erat
e hi
gh, g
reen
– m
oder
ate
low
, blu
e –
low
): (a
) air
velo
city
dis
trib
utio
n an
d (b
) air
tem
pera
ture
dis
trib
utio
n
(a) (b)
(a)
(b)
(b)
(a)
T inT ou
t
win
d-
win
d+
1 m
/s2
m/s
3 m
/s4
m/s
STAC
KST
ACK
> W
IND
WIN
D >
STAC
KW
IND
>> S
TACK
113
Chap
ter S
ix -
Win
d in
Bui
ldin
g En
viro
nmen
t Des
ign
of th
e flo
w d
omai
n to
the
outd
oors
allo
ws u
s to
cons
ider
the
vert
ical
(hyd
rost
atic
) pre
ssur
e di
strib
utio
n.U
nder
a b
uoya
ncy-
driv
en s
cena
rio
(win
dles
sco
nditi
on),
the
tem
pera
ture
s in
each
spac
e in
crea
sed
with
heig
ht d
ue to
the
outs
ide
ther
mal
plu
me
from
one
room
ente
ring
the
room
abo
ve (a
s sho
wn
in F
igur
e 16
) des
pite
the
fact
tha
t th
e sp
aces
wer
e ph
ysic
ally
and
the
rmal
lyis
olat
ed fr
om o
ne a
noth
er. T
his c
an c
lear
ly b
e se
en fr
omth
e sh
ifts
in t
he g
raph
of
indo
or t
empe
ratu
re v
ersu
she
ight
, as
sho
wn
in F
igur
e 16
b (A
llocc
a, C
hen
and
Glic
ksm
an 2
003)
. Thi
s typ
e of
eff
ect s
eem
s pla
usib
le d
ueto
the
sm
all
dist
ance
bet
wee
n th
e up
per
open
ings
of
one
spac
e an
d th
e lo
wer
ope
ning
s of
the
spa
ce a
bove
.An
alyt
ical
sol
utio
ns o
r ex
perim
enta
l mea
sure
men
ts d
ono
t eas
ily d
iscov
er su
ch a
phe
nom
enon
foun
d in
the
CFD
sim
ulat
ion.
Alth
ough
the
stu
dy o
f pu
re b
uoya
ncy
effe
cts
onsi
ngle
-sid
ed v
entil
atio
n is
inte
rest
ing,
it is
mor
e us
eful
to e
xam
ine
the
effe
cts o
f com
bine
d w
ind
and
buoy
ancy
on t
he v
entil
atio
n. T
he e
xper
imen
ts (
Phaf
f et
al 1
980)
show
ed th
at, f
or a
par
ticul
ar te
sted
room
, win
d an
d st
ack
flow
rei
nfor
ced
each
oth
er. O
ur s
tudy
fou
nd t
hat
win
dan
d st
ack
forc
es d
id n
ot a
lway
s re
info
rce
each
oth
er. I
nfa
ct, t
hey
oppo
sed
each
oth
er in
som
e in
stan
ces.
This
ambi
guity
is il
lust
rate
d in
Fig
ure
17a.
An
exam
ple
of th
eco
unte
ract
ing
win
d an
d st
ack
effe
ct d
urin
g an
incr
easin
gpr
ogre
ssio
n of
win
d sp
eeds
is a
lso
show
n in
Fig
ure
17b.
A co
unte
ract
ing
win
d an
d st
ack
flow
too
k pl
ace
inth
e m
iddl
e un
it. Fi
gure
18a
show
s the
airf
low
at t
he m
id-
sect
ion
in th
e ro
om. T
he w
ind
forc
e at
the
uppe
r ope
ning
was
stro
nger
than
the
buoy
ancy
forc
e, th
ereb
y fo
rcin
g a
cloc
kwis
e flo
w in
to th
e un
it th
roug
h th
e up
per o
peni
ngan
d ou
t thr
ough
the
low
er o
peni
ng. S
ince
the
two
forc
esop
pose
d ea
ch o
ther
, the
ven
tilat
ion
was
red
uced
. As
are
sult
, th
e te
mpe
ratu
re i
n th
e m
iddl
e un
it w
as t
hehi
ghes
t, as
sho
wn
in F
igur
e 18
b. H
owev
er, i
n th
e up
per
unit,
the
win
d ai
ded
the
buoy
ancy
eff
ects
by
driv
ing
air
in th
roug
h th
e lo
wer
ope
ning
and
out
thro
ugh
the
uppe
rop
enin
g. T
he r
oom
air
tem
pera
ture
was
the
low
est
inth
e bu
ildin
g. In
the
low
er u
nit,
the
buoy
ancy
eff
ects
wer
est
rong
er t
han
the
oppo
sing
win
d ef
fect
s. Th
e ai
r st
illflo
wed
in fr
om t
he lo
wer
ope
ning
and
out
thr
ough
the
uppe
r op
enin
g. T
he c
orre
spon
ding
tem
pera
ture
in t
heun
it w
as m
oder
ate
sinc
e th
e w
ind
velo
city
was
low
erne
ar th
e ba
se o
f the
bui
ldin
g.Th
ere
are
no g
uidi
ng r
ules
to
dete
rmin
e w
here
coun
tera
ctin
g w
ind
and
stac
k ef
fect
will
occ
ur. O
rdin
ary
desig
n gu
ides
may
not
pro
vide
use
ful i
nfor
mat
ion,
unl
ess
deta
iled
air v
eloc
ity d
istr
ibut
ions
nea
r the
ope
ning
s ar
ekn
own.
It s
eem
s th
at C
FD a
naly
sis
can
prov
ide
deta
iled
info
rmat
ion
to a
des
igne
r, en
surin
g a
succ
essf
ul d
esig
nof
nat
ural
ven
tilat
ion
syst
ems.
SUM
MAR
Y
The
resu
lts in
this
chap
ter s
how
that
win
d ca
n ha
ve m
any
posi
tive
attr
ibut
es in
an
arch
itect
ural
env
ironm
ent s
uch
as p
rovi
ding
a c
omfo
rtab
le a
nd h
ealt
hy i
ndoo
ren
viro
nmen
t th
at c
an a
lso
save
ene
rgy
by m
eans
of
pass
ive
cool
ing
or n
atur
al v
entil
atio
n. H
owev
er, t
his
chap
ter
illus
trat
es t
hat
win
d ca
n al
so c
ause
dis
com
fort
to p
edes
tria
ns if
its
spee
d ar
ound
a b
uild
ing
is to
o hi
gh,
and
it ca
n al
so in
crea
se e
nerg
y lo
ss in
the
win
ter.
This
chap
ter h
as d
iscus
sed
diff
eren
t met
hods
ava
ilabl
efo
r win
d de
sign.
Am
ong
the
met
hods
stud
ied,
CFD
seem
sto
be
attr
activ
e fo
r bu
ildin
g en
viro
nmen
t de
sign
, sin
ceit
is th
e m
ost a
ffor
dabl
e, a
ccur
ate,
and
info
rmat
ive
whe
nit
is p
rope
rly a
pplie
d. T
his
chap
ter
has
also
illu
stra
ted
anu
mbe
r of a
rchi
tect
ural
indo
or a
nd o
utdo
or e
nviro
nmen
tde
sign
s th
at h
ave
utili
zed
CFD
. The
se in
clud
e:
top related