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