The shape of green with biomimicry
[Music]
what is the shape of green
with biomimicry is the title of this
piece
shape by shape i mean form architects
love forms and green of course is the
green movement
is the is um uh green technology
biomimicry really is about copying
that not directly the forms in nature
but what lies behind them in other words
the processes that produce the forms
first i’d like to go back to the famous
phrase that
architects follow the dictum form
follows function
which was said first by louis sullivan
um who built the building you can see on
the left
which is a a an office block
with shops underneath a mixed
development
way back in 1904 and on the left on the
right
you see eastgate 1996 about 100 years
later
after stating form of hollow’s function
louis sullivan said all things in nature
have a shape
which tells us what they are
and it was that that i want to
explore louis sullivan was probably
was educated in paris in the buzzer
tradition and so he might have
uh learnt about in fact inevitably he
would would have
learnt about vitruvius who is a julius
caesar’s architect way back in 18 100.
these sketches show illustrate what he
meant what vitruvius meant
when he said that fire
created society far created
architecture as illustrated
top right
fire gave people warmth and extended
the day with light which is really
the fundamental um
[Music]
stepping as a beginning of architecture
some people call this the third skin the
first skin is the skin you were born
with
the second skin is the clothes you wear
and the third skin is the building
i then go straight into nature and let’s
see let’s test this idea that you should
copy processes
in nature by studying a process
in harare in the uh
late uh september october november
it heats up before the rains
hirari i should remind you is in the
middle of
zimbabwe which is a medium
tropical country about 1 400
metres above the sea clear skies at
night
and it has a long dry season
and a short wet season
when and before the wet season uh you
get
high air temperatures um
our friends termites live underground
in great cities they build and
these towers that i’ve got
pictured here arise rather like
earth fountains the the
space created by the removal of earth
below equals the volume that
that rises up except that this volume
has a hole in the middle
it’s it’s a it’s a chimney
and clearly it’s used like a breathing
apparatus it’s a lung in fact
to enable them to survive they need
oxygen
and so do their symbiotic
fungi that they cultivate
and they need a system that mix that
mixes air in exactly the same way as our
lungs
function and for that you need some
energy
that energy is provided by the
differential
between the air temperature above ground
and the air temperature below ground
below ground it is about 31 degrees
centigrade which i’ve measured
and it has a very high humidity right
through the air
i think the humidity is probably more
important than the variation in
temperature
however when the temperature on above
ground
is lower than the temperature in the
nest
which is most of the year you get
natural buoyancy
and the air rises up through a hole in
the
at the interface between the ground and
and the in the sky
um and you get natural buoyancy which
ventilates
the city below but when the temperature
reaches
almost the same as the temperature
underground about 31
in the heat up they begin to suffocate i
think this is how i think it works
and so they start building the stack the
stack works like any other
chimney that we found it it
channels the hot air hot damp air which
is lighter than the
cold or the even even drier air
it’s it’s it’s uh because it has water
it’s actually lighter
and it with stuck effect
and with the effect of the top of the
chimney being
shaped to create
or aid syphonic action
from winds blowing horizontally over the
top
of the chimneys and they have learnt
to form the top of the chimney to
optimize
this wind energy
it’s it it was absolutely fascinating
when i
discovered this and i realized that they
have a method
of forming
uh or building forms which follow
the movement of air somehow
so in some strange way the architect
is in fact the wind or the sun acting on
it
the other fascinating thing about
termites is that they managed to
maintain a permanent state of
temperature and humidity
without without being able to plug into
the nearest power station
so therefore that that became um
a very important factor when we were
designing eastgate
this gate was inspired
by the termite towers as you can see
from the picture
that was an early version of how i
thought the
termite towers worked east
is made is an office block
and it has shops below it
it is two long slab blocks
running north-south on either side of a
street
which is what we call the atrium it’s a
covered street
but it’s open to the public at both ends
and you can see
chimneys rising up through the building
showing how air is pumped in at the
bottom
and forced up through tapered
ducts all made of masonry up to the
rows and rows of chimneys on the top
there are about
48 chimneys and they’re enormous they’re
two two meters in diameter and about
four meters tall they are really
what we call what we came to call solar
accelerators and they work in the same
way
as the termites towers
there’s a they follow if you’re
relying on nature to ventilate your
building
you follow the cycles the day and night
cycle
in zimbabwe is always about 10 degrees
so the distance the difference between
the night temperature
midnight and the day at noon temperature
is above usually right through the
above 10 degrees difference and that is
enough to drive
an effective buoyancy program
to aid added power to the
to the fans you have to have fans
driving it and what we do
is to have dave fans and night fans the
night fans blow air through the building
at about six air changes between six and
ten actually
and um during the day it’s only about
two uh
changes which is the correct volume
of or or rate of uh ventilation
ventilating air
for breathing
the offices are made um
are surrounded with heat exchangers the
floor
is composed of precast units with
dentals
and the air is blown through them
cooling them down at night and then they
in turn
cool the air coming in through them
during the day
so they just act as batteries or thermal
stores
and we found that we were able to
store about four degrees of cooling
in the in the teeth just by using night
air
we actually made a full-size model
and we tested it out so we knew we were
onto a good thing
on the top right you can see a section
through the office and you can see how
the
the blue is the supply air is blown
under the floors through the teeth comes
out underneath the window
and then rises up with heat of people
and machines
to the ceiling where there are vaults
guiding the air along with the light
fittings
to holes on one side where there are
then horizontal ducts carrying the
exhaust air
out to the chimneys
the other thing we we did
was to worry about the outside of the
building
observing the cacti in the desert
we knew there was something about
surface area that affects
the efficiency of absorbing
day heat from the sun and getting rid of
it
to back radiation at night so
you need to see when you’re looking at
the outside of the building in fact
any part of the building it there’s a
day mode and a night mode
the night mode is is to to
harvest cough the day mode is to protect
against direct heat from the sun
if you make a an architecture with
smooth surfaces
it’s far more efficient at absorbing
solar heat and far less efficient at
getting rid of it
at night you need a prickly building
like the cactus
prickles have a huge surface area
and they have you can see they have
shadows because the sun
falling on them comes from one direction
at a time
and then at night um the black space
is all around the the uh
the building and therefore radiant heat
can
escape in many directions so that again
large surface area is of enormous
importance for efficiency
so there you are that explains the
fingers
the architecture is prickly um
the west and the east is even more
prickly this is an east end
and because that gets the morning sun
on one side and the afternoon sun on the
other
the north and south elevations are
um are covered in
prickles and plants plants
um uh have another speciality
in nature they have many leaves the
leaves
are very efficient at dispersing heat
they not only absorb the heat from the
sun in the form of
photons light which they need for
photosynthesis but that’s a small amount
compared with the
heat loss or heat dispersal
of many surfaces picking up very small
surfaces picking up solar heat and
and it runs the heat runs to the edge of
the leaf and out so the smaller the leaf
in fact is more efficient at heat
dispersal
which is why you find that the hotter
the climate the smaller the leaf
generally with trees um in fact if you
sit under a tree
in the middle of the day with the sun
beating down
you’ll find it’s about seven degrees
cooler
than sitting under the same area of a
parasol
where you just have a canvas between you
in the sun
seven degrees difference and that is all
about
surface area and the rate at which heat
is dispersed from the center of the
of the surface to the edge and into the
air
so that’s a an an
important addition to increasing surface
area on the outside
in order to make the building
modify the climate inside
inside between the two blocks and
describe the street
this street has corridors and lifts
hanging over it it’s a public
through fair but by putting
getting permission to hang things over
the street you
can remove those spaces from the
buildings on either side
which there are spaces which volumes
which don’t have to be
air conditioned again increasing the
efficiency of the building
it’s a sort of intermediate zone also a
narrow street
running from the east to the west always
has one
side because of the movement of the sun
in shadow
and that absorbs the heat from the
from the street as you will find when
you’re walking through
the heat of the day in an italian city
when the
sun is overhead uh in italy
people go to sleep they have a siesta
but in the morning in the evening you
get that lovely
cool absorption
from one side of the street which is in
shadow
so there we have eastgate this huge
building with 48 chimneys
low rise the building behind it top
on the right i’m sorry on the left is
a building with aluminium and windows
and
a lot of glass uh eastgate has only 25
of the wind of the area facing the sun
on the north of the south and that makes
a huge difference for heat
absorption it reduces natural light but
night is heat the other thing is that
um the lower the building
the and the more spread out it is
you can actually save energy save energy
in building
and energy in running with lifts
um now we did this was
a building designed with engineers very
good engineers
of arab and i had the london office
working on it as well as
the zimbabwe office um and we
we actually
had data loggers logging the performance
of the building
for three years after it was finished
and
fully occupied and the graph on the left
here shows
the diagonal swing and the different
behaviors of the internal temperatures
on different surfaces
in an office generally
there are all sorts of oddities
monday tended to be cooler than tuesday
and so on so towards the end of the week
the building was getting too hot
or losing the advantage of night cooling
and that we were able to adjust by by
the timing of the fans
and we we knew that eventually
uh to take this principle further
forward
you would need to control both services
with the external temperature using
thermostats
we didn’t do that in this case it’s
absolutely
simple it’s just two fans and we relied
entirely on the timing of turning them
off and turning them on
and changing the velocity of the air
running through the building
and it took nearly two years to get this
building
tuned properly with the weather so any
any uh building which in which
passive um uh ventilation
or systems are used um
you have to tune them in with the
with the weather cycles of at sight
um and as you can hear me
i’m talking about two systems one is
active
and one is passive the active system is
where you’re adding power
to the system and passive is where
you’re using nature
it’s responding to the forces of nature
in order to achieve the comfort levels
you need
other levels you need are very very well
illustrated on the study we did
comparing eastgate with other buildings
in harare
some of them naturally one of them the
green one naturally ventilated
and all the others are with normal
conventional
air conditioning systems you can see the
red column on the far right
is the building behind this gate
compared
with east gate which is in yellow and it
proves that
following this system of design
with passive inactive you can actually
reduce the energy
use energy consumption by at least 50
without any difficulty now bowlings and
cities use about
um 50 of total energy
consumption on the planet so you’re
talking about
reducing the 50 by another 50.
so it’s a huge advantage changing the
design
to green now we go
back to the two buildings that i started
with
on the right now is louis sullivan’s
form follows function building in which
he was really celebrating the
use of steel frame and glass
he loved glass but instant louie
there’s a lot of sun and there’s a cold
winter very
cold winter or in chicago this one
actually is
and chicago has a particularly nasty
winter
so um you need to add to that facade in
some way
and you know in a way uh what i’ve done
at eastgate
is it’s the same exactly the same
function it’s an office block with shops
below
but look at all the greenery the at
added pieces which
which change the shape