How to air-condition outdoor spaces

During the hot summer months, watching an outdoor sports match or concert can be tantamount to baking uncomfortably in the sun -- but it doesn’t have to be. At the TEDxSummit in Doha, physicist Wolfgang Kessling reveals sustainable design innovations that cool us from above and below, and even collects solar energy for later use.

Good evening.

We are in this wonderful

open-air amphitheater

and we are enjoying ourselves

in that mild evening

temperature tonight,

but when Qatar will host

the football World Cup

10 years from now,

2022,

we already heard it will be

in the hot, very hot and sunny

summer months of June and July.

And when Qatar has been assigned

to the World Cup all, many

people around the world have been

wondering, how would it be

possible that football players

show spectacular football,

run around in this desert

climate? How would it be

possible that spectators sit,

enjoy themselves in open-air

stadia in this hot environment?

Together with the architects of

Albert Speer & Partner, our engineers

from Transsolar have been

supporting, have been developing

open-air stadia based on 100 percent

solar power, on 100 percent solar cooling.

Let me tell you about that,

but let me start with comfort.

Let me start with the aspect

of comfort, because many people

are confusing

ambient temperature

with thermal comfort.

We are used to looking at charts like

that, and you see this red line

showing the air temperature

in June and July, and yes, that's right,

it's picking up to 45 degrees C.

It's actually very hot.

But air temperature is not

the full set of climatic

parameters which define comfort.

Let me show you analysis

a colleague of mine did looking

on different football, World Cups,

Olympic Games around the world,

looking on the comfort

and analyzing the comfort

people have perceived at these

different sport activities,

and let me start with Mexico.

Mexico temperature has been, air

temperature has been something between

15, up to 30 degrees C, and people

enjoyed themselves.

It was a very comfortable game

in Mexico City. Have a look.

Orlando, same kind of stadium,

open-air stadium. People have

been sitting in the strong sun,

in the very high humidity

in the afternoon, and they

did not enjoy. It was not comfortable.

The air temperature was not too high, but it was not

comfortable during these games.

What about Seoul? Seoul, because

of broadcast rights, all the

games have been in the late

afternoon. Sun has already been

set, so the games have been

perceived as comfortable.

What about Athens? Mediterranean

climate, but in the sun it was

not comfortable. They didn't perceive comfort.

And we know that from Spain,

we know that "sol y sombra."

If you have a ticket, and you

get a ticket for the shade,

you pay more, because you're

in a more comfortable environment.

What about Beijing?

It's again, sun in the day

and high humidity,

and it was not comfortable.

So if I overlay, and if you

overlay all these comfort

envelopes, what we see is,

in all these places, air temperature has

been ranging something from 25

to 35, and if you go on

the line, 30, of 30 degrees C

ambient temperatures. If you

go along that line you see

there has been all kind of

comfort, all kinds of perceived

outdoor comfort, ranging from

very comfortable

to very uncomfortable.

So why is that?

This is because there are

more parameters influencing

our thermal comfort, which is

the sun, the direct sun,

the diffuse sun, which is wind,

strong wind, mild wind, which is

air humidity, which is

the radiant temperature of the

surroundings where we are in.

And this is air temperature.

All these parameters go into

the comfort feeling of our

human body, and scientists

have developed a parameter,

which is the perceived

temperature, where all these

parameters go in and help

designers to understand

which is the driving parameter

that I feel comfort or that

I don't feel comfort.

Which is the driving parameter

which gives me a perceived

temperature? And these parameters,

these climatic parameters are

related to the human metabolism.

Because of our metabolism,

we as human beings,

we produce heat.

I'm excited, I'm talking to you,

I'm probably producing

150 watts

at the moment. You are sitting,

you are relaxed, you're looking

at me. It's probably 100

watts each person is producing,

and we need to get rid of that

energy. I need, with my body,

to get rid of the energy, and

the harder it is for myself,

for my body, to get rid of the

energy, the less comfort I feel.

That's it. And if I don't

get rid of the energy,

I will die.

If we overlay what happens

during the football World Cup,

what will happen in June, July,

we will see, yes, air

temperature will be much higher,

but because the games and

the plays will be in the afternoon,

it's probably the same comfort

rating we've found in other

places which has perceived

as non-comfortable.

So we sat together with a team

which prepared the Bid Book, or goal,

that we said, let's aim

for perceived temperature,

for outdoor comfort in this range,

which is perceived with a

temperature of 32 degrees

Celsius perceived temperature,

which is extremely comfortable.

People would feel really fine

in an open outdoor environment.

But what does it mean?

If we just look on what happens,

we see, temperature's too high.

If we apply the best architectural design,

climate engineering design,

we won't get much better.

So we need to do something active.

We need, for instance, to bring

in radiant cooling technology,

and we need to combine this

with so-called soft conditioning.

And how does it look like in a stadium?

So the stadium has a few

elements which create that

outdoor comfort. First of all,

it's shading. It needs

to protect where the people

are sitting against strong

and warm wind.

But that's not all what we need

to do. We need to use

active systems.

Instead of blowing a hurricane

of chilled air through the stadium,

we can use radiant

cooling technologies, like a

floor heating system where water

pipes are embedded in the floor.

And just by using cold water

going through the water pipes,

you can release the heat

which is absorbed during the day

in the stadium, so you can

create that comfort, and then by

adding dry air instead of

down-chilled air, the spectators

and the football players can

adjust to their individual

comfort needs, to their

individual energy balance.

They can adjust and find

their comfort they need to find.

There are 12 stadia probably

to come, but there are

32 training pitches where

all the individual countries

are going to train.

We applied the same concept:

shading of the training pitch,

using a shelter against wind,

then using the grass.

Natural-watered lawn is a

very good cooling source

stabilizing temperature,

and using dehumidified air to

create comfort.

But even the best passive design

wouldn't help.

We need active system.

And how do we do that?

Our idea for the bid was

100 percent solar cooling,

based on the idea that we use

the roof of the stadia,

we cover the roofs of the stadia

with PV systems.

We don't borrow any energy

from history.

We are not using fossil energies.

We are not borrowing energy

from our neighbors.

We're using energy we can harvest

on our roofs, and also on the

training pitches, which will be

covered with large, flexible

membranes, and we will see

in the next years an industry

coming up with flexible

photovoltaics, giving

the possibilities of shading

against strong sun and producing

electric energy in the same time.

And this energy now is

harvested throughout the year,

sent into the grid,

is replacing fossils

in the grid, and when I need it

for the cooling, I take it

back from the grid and I

use the solar energy

which I have brought to the grid

back when I need

it for the solar cooling.

And I can do that in the first

year and I can balance that

in the next 10, and the next

20 years, this energy,

which is necessary to condition

a World Cup in Qatar,

the next 20 years, this energy

goes into the grid of Qatar.

So this -- (Applause)

Thank you very much. (Applause)

This is not only useful

for stadia. We can use that also

in open-air places and streets,

and we've been working on

the City of the Future

in Masdar, which is in the

United Emirates, Abu Dhabi.

And I had the pleasure to work

on the central plaza.

And the same idea to use there,

to create outdoor conditions

which are perceived

as comfortable. People enjoy

going there instead of going

into a shopping mall, which is

chilled down and which is

cooled. We wanted to create

an outdoor space

which is so comfortable that

people can go there in the

early afternoon, even in these

sunny and hot summer months,

and they can enjoy and meet there

with their families. (Applause)

And the same concept:

shade against the sun,

shade against the wind,

and use, use and take advantage

of the sun you can harvest

on your footprint.

And these beautiful umbrellas.

So I'd like to encourage you

to pay attention to your

thermal comfort, to your

thermal environment,

tonight and tomorrow,

and if you'd like to learn more

about that, I invite you

to go to our website.

We uploaded a very simple

perceived temperature calculator

where you can check out

about your outdoor comfort.

And I also hope that you

share the idea that

if engineers and designers

can use all these different

climatic parameters,

it will be possible to create

really good and comfortable

outdoor conditions,

to change our thermal perception

that we feel comfortable

in an outdoor environment,

and we can do that

with the best passive design,

but also using the energy source

of the site in Qatar which is

the sun.

(Applause)

Thank you very much. (Applause)

Shukran. (Applause)