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Abstract:
In 2015, the international community committed to limiting global warming well below
2°C. Since 2015, however, and before the coronavirus pandemic stroke, GHG emissions
have continued on their growing track and the achievement of ambitious climate targets
has become even more arduous. In order to rein in global warming well below 2°C, energy
systems must reach net-zero emissions by mid-century. The energy supply, in particular
the electricity sector, offers a great potential for reducing emissions. But in the absence
of large transformations on the energy demand side, achieving the Paris Agreement’s
target would necessitate an extensive recourse to debated negative emission technologies.
The interest in demand-side solutions has therefore risen over the last few years. Today,
buildings account for 28% of CO2 emissions in the energy system. This sector is therefore
an essential building block of any successful mitigation strategy. The aim of this thesis is
to investigate the contribution of buildings to limit climate change.
The widespread view on the role of buildings is that there is a large and cost-effective
potential for energy demand reductions, and that this potential remains unexploited due
to some barriers, which policies should remove.
This thesis relies on energy modeling to shed a new light on that widespread view. It
uses the strengths of both an energy simulation model and of an integrated assessment
model representing the energy, economy and climate systems. In order to assess the
role of buildings in climate policies, the thesis addresses the following complementary
questions: How will buildings energy consumption evolve in the future? What is the
technological and behavioral potential for demand reductions? What are optimal climate
change mitigation pathways for the buildings sector in the context of the overall energy
system, and when the energy efficiency gap is taken into account?
This thesis shows that the landscape of buildings energy demand will undergo major
changes in the 21st century: while cooking and other heating purposes account for the
bulk of the demand today; space cooling, appliances and lighting will represent the lion’s
share tomorrow. Similarly, despite its current weight in demand, traditional biomass will
gradually leave the stage. Against this background, radical changes in technologies and
behaviors could lead to a halving of energy demand. The decarbonization of the sector
however does not only pass through energy demand reductions. In the scenarios presented
in this thesis, most of the decarbonization is attributed to the decline in the emissions per
unit of energy consumed — a topic under-represented in the literature dealing with build-
ings energy demand.
In light of the thesis’ results, and supported by the literature, we challenge the widespread
view on the role of buildings in climate change mitigation. Indeed, the widespread narrative focuses mostly on energy demand reductions and does not embrace the strategy
consisting in decreasing the amount of emissions per unit of energy — in particular via
electrification and fuel switching. This strategy accounts however for a substantial part of
the sector’s decarbonization. We therefore propose an alternative narrative:
Two complementary and interacting strategies can lead to a deep decarbonization of
buildings energy demand: reducing energy demand and decreasing the carbon content
of energy demand through energy supply decarbonization and fuel switching. Virtually
all energy services in buildings could be provided by carbon-free energy carriers. How-
ever market incentives as well as barriers do not allow for a widespread uptake of clean
energy carriers and efficient technologies. Policies should remove barriers to the uptake
of efficient and low-carbon technologies, and design markets to give the right incentives
in favor of these options.
