Our planet is feverish. 
Global warming is threatening our future.
In this lecture causes, effects and remedies 
will be shortly described,
and the role of the building sector, 
especially in the EAC countries, will be examined.
Since the beginning of last century, changes 
have been observed throughout the climate system:
the atmosphere and the ocean have warmed, 
the extent and volume of snow and ice have diminished, and the sea level has risen.
Temperature is going to reach unprecedented values 
in the last 5 million years.
The main cause of the temperature rise is the increase in the atmospheric concentration of CO_2,
whose concentration skyrocketed 
from 1950 onwards.
In 2013, CO_2 levels surpassed 400 ppm for the first time in recorded history.
This rise in CO_2 shows a remarkably constant relationship with fossil fuel burning.
The consequences of the global warming are more 
and more frequently experienced:
hurricanes, floods, landslides, draught, and fires.
Extreme climatic events are expression of climate change, but they are only one aspect of the problem.
At global temperature increase between 1 and 2 °C, significant global impacts on ecosystems and water resources are likely,
and from 2.5 °C upwards negative impacts 
on global food production are also likely,
with dramatic consequences on the increasing 
world population.
The picture shows some of the impacts related
to specific and increasing temperature.
In December 2015, to cope with global warming
was signed, by almost all the countries in the world,
the Paris agreement, committing all these countries 
to hold the global average temperature
to well below 2 °C above pre-industrial levels 
and to pursue efforts
to limit the temperature increase to 1.5 °C 
above pre-industrial levels.
To reach the 2 °C target the emissions in 2050 should 
be reduced by 50% with reference to those in 1990.
Developed countries will have to reduce them by 85% and developing countries should not increase them,
in spite of their hopefully expected development.
Developing countries are going to play a decisive role 
in the future world CO_2 emissions scenario,
as a consequence of their economic development.
Putting it in another way, to achieve 
the 2 °C target,
world GHG emissions should be reduced to 2 tons CO_2eq per capita in 2050 (with 2 billion people more).
For East African Community countries the challenge is: economic growth with GHG reduction.
In 2010 the building sector of the whole world was responsible for 25% of total GHG emissions
deriving from fossil fuel combustion, second
only to the industrial sector.
In East African Community countries, the building
sector takes the highest share of energy consumption,
65% in Kenya, 74% in Tanzania, 83% in Uganda.
This is due mainly to the inefficient use of energy
for cooking, lighting, hot water production 
and air conditioning,
air conditioning, of course, only in wealthy homes 
and in commercial buildings.
Improving the quality of life, this share will diminish, approaching to that of developed countries,
but the absolute value of the GHG emissions 
will increase.
This increase will be enhanced by the fact that 
the expected improvement of living conditions
will lead to a shift from biomass, 
which is carbon neutral, to fossil fuels.
But this does not tell the full story.
We have to consider also the energy needed 
for production of building materials,
the so-called embodied energy, 
which becomes embodied emissions
if the CO_2 produced is taken into account.
The impact on world emissions of construction materials is not negligible:
it weights for more than 12%, mainly due to cement 
and steel.
The picture is exacerbated by a worrying trend: modern buildings in EAC countries are replicas
of buildings designed for the western world 
(where climate is cold or temperate)
and do not take into consideration the differences 
in climate, so becoming energy voracious.
But the main reason of the expected increase of energy consumption, and thus of CO_2 emissions in EAC
is due to the population increase, which 
will almost double from now to 2050.
This increase, combined with economic growth,
will cause a sharp increase of the number of buildings.
If all these new buildings will be as energy
consuming as present ones,
it will be impossible to meet the 2 °C target.
While in Europe it is expected that, in the year 2050, some 25-30% of the building stock
will have been built between now and that date,
in developing countries the figure 
can be estimated close to 75%.
The challenge is unprecedented and will require
(it requires it by now)
a radical transformation of the ways to design 
and build.
The reduction of CO_2 emissions by reducing
energy consumption is the top priority
that the construction industry has to face.
Especially the construction industry of EAC, 
with the large amount of buildings that are being built
and will be built in the next years, is in the front row.
