roof span of six metres was as wide as it
25
Transcript of roof span of six metres was as wide as it
CAPE TOWN
Cape Town is the m o t h e r - c i t y of the
Re pub lic of South Africa situated in the
Cape Province on the shores of Table Bay
with a latitude of 33°54,S and 18 0 32'E of
longitude.
H is t o r y
It was in January 1488 that the
''ortuguese navi gat or B a rto lom eu Dias de
Novaes rounded for the first time the tip
of southern Africa, known until then as
the Cape of Storms where t r e ac her ous
c u rr e n t s and winds were the cause of many
sh i pwrec k s .
from then on the p rom ont ory which guarded
the sea route to India would be called
the Cape of Good Hope.
Tor European seafarers this a ch ie ve men t
mar ke d the b e g i n n i n g1 of a new era of
e x pl or at i o n and trade; for the i n d i g
enous Khoikhoi and San it was the
be gi nn i n g of great dis tre ss for their
social and political e x i s t e n c e . 1
The Portugu ese navigat ors were frequent
ca ll er s in South African waters, mos t l y
on their way to India, thus their
In terests in Africa lay elsewhere.
It was the Dutch who c o n s t r u c t e d the
first fort in the Cape of Good Hope.
In 1650 a for tif ied r e f r e s h m e n t station
was est ab li sh e d at the Cape and seven
years iater the first f ar mer s settled
there permanently.
The main purpose of the Cape s ett lem ent
to the Dutch Co m p a n y was to provid e
adeq ua te f aci lit ies for its shipping.
Dutch ships were always in the m a j o r i t y
at the Tape - until 1772 when the Co mp a n y
slid into a rapid decline.
The British c on que red the Cape in 1795,
but it wojld change hands three times
until the London C o n v en t i o n in August
1814 when the Dutch p e r m a n e n t l y ceded the
Cape to Great Britain.
Ihe Dutch o ff i c i a l l y d i s a p p e a r e d from the
Cape, but the d e ve lo p m e n t which had taken
place under its rule left a legacy which
is still present today.^
C ape Dutch A rc h i t e c t u r e
The ea rli est houses of the set tl e m e n t at
the Cape c on sis ted of two or three rooms
in a row about six met e r s along the
street front.
B ec aus e of c on s t r u c t i o n li mit ati ons the
©
roof span of six metr es was as wide as it
cou Id be built.
t r e m e n d o u s l y the local a r c h i t e c t u r e
the years to come.
i n
To o v e r c o m e this limitation " dominoes" or
" l e t t e r - o f - t h e - a l p h a b e t " plans were
i mp lem ent ed and they remai ned c u s t om a r y
until the mid dle of the 19th century.
By m ea n s of wings of standard width, and
ridges of unif orm height, any number of
rooms could be added to the e arl ie st two
or three. Thus the plan d e v e l o p ed to a
“I" shaped or a U-shaped plan and later
T -s hap ed and H-s haped plans became also
very c omm o n . ^
The houses were built with clay brick
pl as te r e d and limewashed with m a g n i f i c e n t
sash wind ows with fine outsid e shutters.
The roof was of thatch and gabled .
The need to define the front e n tr an c e and
to admit light into the house made the
front gable the most prominent feature of
the house.
It is int ere sti ng to see how the front
gable d e ve lop ed showing in its dec or at i o n
and co nto urs the d i f fere nt Eu rop ean
styles from a m i x tu re of R e n a i s s a n c e and
Gothic to Neo -Cl ass ic pil ast er gables.
With the British o ccu p a t io n in 1814,
di ff er e n t taste and manne rs were brought
to Cape Town. They w ould in fluence
Today Cape Town is a beautiful cit y
c o n cer ned with the p r es e rv at io n of its
history, m eet ing an unusual b alan ce
between new d e v e l o p m e n t s and c o ns e r v a t i o n
of the old.
©
*
R e f e r e n c e s :
1. An I llustrated Histo ry of So ,th
Africa.
by e d ito rs Tre wh el l a n Cameron and S B
Spies.
2. The Old Bui ldi ngs of the Cape,
by Hans Fransen and Mary A Cook.
3. E i g h t e e n t h Centi'ry A r c h i te ct u r e in
South Africa.
by G E Pearse.
4. E arl y N i n e te en t h Century A r c h i t e c t u r e
in South Africa.
by Ronald Dewcock.
Project
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A C o mp u t e r Program, " Q u i c kTe mp" is used
to test the Thermal P er f o m a n c e of the
four houses at desi gn stage, ("Method"
d e sc r i b e d at the end of Chapter)
A typical South A fr ica n "Standard House"
D w g . 1 4 , is t e s t e d in p a r a l l e l . R e s u l t s
are shown in G r aph form.
U 1
f . . . .
D w q .14.
When d esigning an energy ef fi c i e n t house,
a c omp rom ise some tim es must be made
betw een the r e q u i re me nt s to meet a
comf ort abl e e n v i r o n m e n t in both hot and
cold seasons. In this case the longer
season should have a more d e t er m i n i ng
influence on the d e c i s io ns to be made.
When looking at the graphs, Summer and
Wint er c ond i t i o ns should be analys ed in
conjunction, so that we can have a
g e n e r a l id ea o f how the h o u s e p e r f o r m s
all year round.
As we can s e e f r o m the g r a p h s (1n thi s
c h a p t e r ) the c u r v e s r e p r e s e n t i n g the
t h e r m a l p e r f o m a n c e o f t h e " S t a n d a r d
House" show overall wor se values than the
curves rep res en ti n g the "Pro pos ed Houses"
w here concern for c lim ati c c on di ti o n s was
taken into the design.
In fact, we can see that the said
"Standard House" p e r f o r m s poor ly In most
of the c l i m a t e s , h a v i n g u n c o m f o r t a b l y
hi g h t e m p e r a t u r e s in S u m m e r an d as bad
low t em p e r a t u r e s 1p Winter.
If the testing of the thermal per fo rm a n c e
of this house had taken place at the
design stage, a lt era tio ns to its basic
concept could have been s uggested
ac cording to a sp ecific c li mat e and a
more c o m fo rt a b l e house would have evol ved
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Shell Area ~ 3 2 5 . SO
Therrr. Csp = 97 5. 95 (windows closed)
T h e r m Cap = S04.B1 (windows open)
Pr o j e c t : J H B G .H O U S E .SUM ME R
G R A P H .8 .
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U - v a . l u s = 1 . 8 3
S h e l l A r e a = 3 2 5 . 5 0
T h e r m C a p = 1 0 1 2 . 0 6 ( w i n d o w s c l o s e d )
Ther^i C a p = 8 3 6 . 6 3 ( w i n d o w s o p e n )
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• I H O U D R A I R T E M P E R A T U R E
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O U T D O O R A I R T E H ? I R A T U R E
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C e p i n d o w s c l o s e d )
i o p e n )
0G R A P H . 11 .
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COMP *RATIVE STUDY OF BUILDING MA TE RI AL S AND ITS AREAS IN m2
C a p e-T own Durban J oh a n n e s bu rg Keetman " St and ard
shoop House"
Shell A r e a ............ . . . 4 3 7 ____ ____ 304 . ____ 325 ,5 ....... . . .261 ,5. .. ..... 261 ,5
Net External Wall A r e a ....... ____ 110. ____1 4 0 .......... ____8 2 ...... ..... 124,75
Total W i n d o w Area... ____ 5 0 _____ ..... 64. ..... 7 1 , 5 ........ ____ 16,5. . . .......23,75
Net Internal Wall A r e a ....... ...217,5.. ____ 157. ..... 7 5 .......... . . .237 ..... .......72
R oo f / C e i 1 i nq Area
- Type A ..... ..... 9 8 , 5 ....... ____ 110- Type B ..... ... 165
- Type C ..... ____ 106
- Type D ..... . , ,145
F loor Area
" - Type A. .. ... 1 65____ ..... 29. ..... 9 8 , 5 ....... . . . 1 4 5 ..... ..... 110H - Type B. . . ..... 77
" - Type C
W i n do w Area in North W a l l .. ____ 14,5. . ..... 17. ..... 3 7 , 5 ....... ____ 10...... ........ 5,75
in South Wall.. ..... 13,5.. ..... 17. .......6 .......... ..... 6,5.. .......11,5
in East Wall.. ____ 11_____ ..... 25. .......6 .......... ........ 2in West Wall ..... 11_____ .......5. ..... 22....... . . ........ 4,5
External North Wall Area
M M M
- Type A ..... 41,5.. ..... 27
M II II
- Type B
M II II
- Type r. ..... 10, 5 ................. .......30,25
N 11 II
- Type D ..... 21, 75
M II II
- Type E . .27,5
External South Wall 'irea
N II II
- Type A ____ 43.5..
M II II
- Type B
f ABI. t . 7 .
©
C O M P AR A T I V E STUDY OF BUILDING M A T E RI AL S AND ITS AREAS IN m2 (cont.)
C a p e - T ow n Durban J oh a n n e s b u r g Keetman "Standard
shoop House"
External South W a 11 Area
N M II
- Type C ................. 1 0 , 5 ................................ ........ 32
M II II
- Type D ................. 21,75
N M It
- Type E ... 16,5
E xt ernal West Wall Area
M M M
- Type A . . . 2 5 , 5 .................... 22
M M M
- Type B
M II II
- Type r ...................3 .................................. ........ 31,5
M N II
- Type D ................. 45,5
N H N
- Type E ... 19,5
External East Wall Area
M M M
- Typo A . . . 2 5 , 5 .................... 27
M M M
- Type B
M II M
- Type r ........ 31
M M M
- Type D ................. 15
M M M
- Type E ... 18,5
Trom be Wall on the North Side ............................. 1 2; 5 ............. 13,5
Interna 1 W a 11 Area
M M M
- Type A . . 1 2 0 ...........1 0 1 ....... 97
M M M
- Type B
m r M
- Type C ...................30
M M M
- Type D
External Door Area. .... 3 ............. 3 _________3 ______ 3
©
I
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/4
B U IL D I N G C ON S T R U C T I O N DETAILS
Type B .............................. . . 230mm Brick
ROOF (cavi ty w a l 1 50mm Glass Wool
underground (with f o i 1 both
Type A ............. ...2mm Corrugated iron plastered on the s i d e s )
sheet inside) 230mm Brick
50mm Glass Wool
(with Alu minium Foil Type C ............... . 230mm Brick
both sides) (one brick w a l 1200mm Airgap plastered on
25mm Gypsum Plaster both sides )
Board
Type D ............... ..2x25mm Wood
Type B ............. (timber wall) 50mm Glass Wool
200mm Airgap (with foil on both
25mm Gypsum Plaster sides)
Board 2x25mm Wood
Type C ............. Type E ............... ..200mm Thatch
corruga ted iron sheet (Thatch 45° 200mm Airgap
shading it 200mm Wal 1 ) 25mm Gy p s u m Board
above
Type 0 ............. INTERNAL WALL
200mm Concrete slab
Type A ............... ,.230mm Brick
(one brick wall)
EXTERNA! MALI plastered on
both sides)
Type A .............
(cavity wall 50mm Glass Wool Type B ............... ,,115mm Brick
p l a st er e d both (with foil on both (half brick wall
sides) sides) plastered on
115mm Brick both s i d e s )
TABI E .8 .
I
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B U I L DI N G CON STR UC TI O N DETAILS (cont.)
Type C ..............................
{timber wall)
. .2x25mm Wood
50mm Glass Wool
(with f o i 1 on both
sides)
2x25mm Wood
Type D ...............
(under ground
wal 1 )
. . 230mm Brick
50mm Glass Wool
230mm Brick
FLOOR
Type A ...............
(in contact
with soil)
. . 25mm Clay Tile
100mm Concrete
Type B ...............
(s u s p e n d e d )
.. '/x?5 Wood
Type C ...............
(suspended)
. . 150mm Concrete
m i R N A I 100RS
T i m b b e r ............. . . .40mm
WI ND OW S
G l a s s ................ .... 3mm
mmu
m
!
£ ■'
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E T 1 •' t
QUICK TEMP
THE "METHOD", ITS L I M I T ATIO NS AND
P RA C T I C A L USES
( ex t r a ct ed from the paper:
"AN A C C E S S I B L E METHOD TO PREDICT THF.
THERMAL P E R F O R M AN CE OF BUILDINGS AT THE
DESIGN STAGE" (Topic Code: PA 16 and 17)
by E.H. Mathews, P.H. Joubert and P.G.
R ic har ds, Dep ar t m e n t of Mechanical
E n gi n ee ri n g , U ni ve r s i ty of Pretoria, S.A.
P r es e n t e d at the National Bu ilding
R e se a r c h Institute, Council for
| S c i e n t i f i c and Industrial Research,
Preto ria , S .A .
I Quick Temp is a s e m i - e m p i r i c a 1 me tho d for
i the thermal analys is of buildings at the
sketch desi gn stage.
The m e t ho d is based on theory, but
em p l o ys c e rta in empirical const ant s to
acco unt for typical rates of natural
v e nt i l a t i o n or infiltration in
c o nv e n t i on al buildings.
The m et h o d was verified e x t en s i v e l y and a
goofl ag re e m e nt between pr edi cti ons and
m e a s u r e m e n t s for 39 cases was found; for
90* of the time the a ccu rac y of
p re d i c t i o n s was within 2 degrees Celsius.
Results were the 24 hour a veraged values
for m e as u r e m e n t s of a period of 5 to 7
d a y s .
The 24-hou r period is t h e ref ore a design
day r e pr es e n t a t i o n of the me as ur e d data.
The pr og ra mm e is based on a desi gn day
due to the fact that the design day data
for di ff er en t locations are usuall y
read ily a va ila ble to b uil di ng d e s ig ne rs
[ 1].
The meth od can however analyse the
thermal p er fo r m a n c e of b u il din gs for any
period of time [2 ].
THEORY
The met hod is based on a s im pli fie d
electrical a nalogue model of the
buil d i n g 's thermal properties.
The fol low ing thermal p ro pe rt i e s can be
identified in the ana logue model in
Fig. 15:
(a) Two forcing tempe rat ure s: the outdo or
cir t e mp er at ur e (TQ ) and the sol-air
te m p e ra tu re (T„„). The sol-air
5 u
t em p e r a tu re a ccounts for the colour
of and rad iat ion on e xte r i o r
s u r f a c e s .
©
Author De Almeida D M M Name of thesis Passive solar systems for domestic architecture in Southern Africa 1988
PUBLISHER: University of the Witwatersrand, Johannesburg
©2013
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