Session 1 - Montefiore

esidential buildings, a traditional masonry house and a steel frame
house, is carried out in three different climates: Belgium, Portugal
and Sweden. A different life cycle scenario is taken into account for
each location, in which the monthly temperatures, buildings
insulation thicknesses, energy mix, heating and cooling systems are
defined. This study allows us to compare the influence of several
parameters on the LCA of residential buildings: the climate related
to the temperatures and the buildings insulation thicknesses, the
use of different materials, the energy mix and the heating/cooling
systems.
The influence of the energy mix of different countries on their
GHG emissions is a recent research subject found in the literature,
that it is generally studied at national scale, working on demandprofile
changes, varying electricity supply and economic issues
[38e42]. These studies highlight how a shift in the energy mix
toward renewable sources would yield significant reductions in per
capita emissions at the national scale, even without reducing
energy consumptions, but do not give solutions at the local scale. At
the local scale [25], studied the life cycle primary energy analysis of
residential buildings (including low energy buildings) and
concluded that the operational primary energy varied considerable
depending on energy supply systems (cogenerated district heating,
heat pumps, electric space heating, etc.) for all the buildings analysed.
The choice of energy supply system had a greater effect on
the primary energy use than the energy efficiency house envelope
measures. The CO2 emissions from the building operation heavily
depend on the carbon content of the fuel used in the supply
systems.
Studying the influence of the energetic performance of
a building and the influence of occupants’ behaviours on the
environmental impacts of this building, Blom et al. [23] developed
a sensitivity analysis on different electricity mixes. Although each
statement depends greatly on the location and the type of building
that is considered, the conclusions of this study are that:
The fraction of the environmental impact due to electricity
consumption is higher than the proportion of electricity in the
total energy content for all the studied scenarios. Therefore, the
electricity mix used in the analysis widely influences the LCA of
the building.
A comparison between the Dutch electricity mix and an
alternative electricity mix, using 35% renewable sources, based
on European policy goals for 2020, shows that the 35%
renewable sources scenario will not significantly reduce all the
environmental impacts and will result in a maximum reduction
of 14% in the Global warming potential.
All the renewable energies have not the same environmental
impact. The type of sustainable energy sources used to produce
electricity greatly influences the environmental impact of the
energy mix.
While, in the present paper, a basic tool is implemented and
verified against an already validated software, the companion
paper studies the influence of the energy mix on the environmental
impacts of specific houses, at different LCA stages, allowing to
optimize their design. It also shows the complex interactions
between building conception, climate, energy mix, materials and
energy systems into the building.
2. LCA: the basic tool
2.1. Principles, definitions and tools
The present assessment follows the recommendations of the ISO
Standards 14000 series [43] and was made on the basis of a excel
B. Rossi et al. / Building and Environment 51 (2012) 395e401 397
Fig. 1. Operational and embodied energy for the two houses and the two methods.
sheet developed by Pr. Mauritz Glaumann from the University of
Gävle. Amongst other things, the tool was modified to take into
account the climate over one year and more complex designs. For
example, the energy demand for the space heating evaluation takes
into account a scenario including business days and holidays, night
and day demanded comfort temperatures, internal heat gains and
solar passive heating. Two main impacts are calculated: (1) the
Embodied energy/carbon and (2) the Operational energy/carbon
(B6 and B7 of [36]).
Embodied energy is an important concept inasmuch as it allows
energy efficiency, together with operational energy [35]. Embodied
energy represents the energy used for producing building materials
(from the extraction of the raw materials to the manufacture
of the final product, including transportation) and their implementations
in the building. The total embodied energy comprises
a direct component (the energy consumed directly at each phase)
and an indirect component (the energy required indirectly to
support the main processes which is less obvious and more difficult
to measure) [24,31]. Operational energy represents the energy
used in operating the building, that is to say the energy used for
space heating and cooling, hot water, lighting, cooking and others
appliances and equipment operation. Similarly, Embodied carbon
and Operational carbon respectively represent the equivalent CO2
emissions due to the extraction, production and transportation of
the material and the construction of the buildings and the equivalent
CO2 emissions linked to the operation of the building during
its life time.
The procedures and assumptions used herein to evaluate
Embodied energy/carbon and Operational energy/carbon are presented
in Sections 2.2 and 2.3.
Fig. 2. Operational and embodied carbon for the two houses and the two methods.