ArticlePDF Available

Abstract and Figures

Stringent limits and reduction strategies paths on greenhouse gas (GHG) emissions are being defined at different levels for long-term temperature stabilization. Given the nearly linear relationship between warming and cumulative net emissions, a carbon budget approach is required to limit global warming, as stated by the IPCC. In this setting, the built environment, as a cross-sectorial and transnational area of activity, plays a crucial role in today’s carbon emissions and future reduction potentials. Previous research showed the need for effective and aligned carbon-targets to support and guide all actors in the construction sector towards these challenging global goals. In this context, previous research compared top-down derived carbon budgets for the Swiss built environment with a preliminary estimation of future cumulative emissions of the sector. Findings showed the misalignment of current best practices and the significant magnitude of effort that would be required to comply with such objectives. Nevertheless, limitations in the preliminary work emerged, such as the lack of dynamicity of the parameters included in the model restricting the representativity of its results. The current paper brings further this previous work by integrating the dynamic evolution of the energy supply, the materials’ production, and the renovation rate. Results are then presented by mean of a parallel coordinate interactive graph. This interactive component allows the parametric exploration of the compliance with limited global budgets by varying the input parameters. This way the influence of macro-level strategies to decarbonize the Swiss building stock can easily be visualized with reference to the IPCC carbon budgets. Ultimately, the available interactive tool might support policy makers in decisions taken at the building stock level.
Content may be subject to copyright.
IOP Conference Series: Earth and Environmental Science
PAPER • OPEN ACCESS
Exploring long-term building stock strategies in
Switzerland in line with IPCC carbon budgets
To cite this article: Y D Priore et al 2022 IOP Conf. Ser.: Earth Environ. Sci. 1078 012023
View the article online for updates and enhancements.
You may also like
Carbon budgets and energy transition
pathways
Detlef P van Vuuren, Heleen van Soest,
Keywan Riahi et al.
-
Impact of short-lived non-CO2 mitigation
on carbon budgets for stabilizing global
warming
Joeri Rogelj, Malte Meinshausen, Michiel
Schaeffer et al.
-
Mitigation of CO2 emissions from
international shipping through national
allocation
Henrik Selin, Yiqi Zhang, Rebecca Dunn et
al.
-
This content was downloaded from IP address 206.204.18.158 on 15/09/2022 at 02:31
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution
of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Published under licence by IOP Publishing Ltd
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
1
Exploring long-term building stock strategies in Switzerland
in line with IPCC carbon budgets
Y D Priore1,2, T Jusselme1 and G Habert2
1 Energy Institute, University of Applied Science of Western Switzerland (HEIA-FR,
HES-SO), Fribourg, Switzerland
2 Chair of Sustainable Construction, ETH Zürich, Zurich, Switzerland
priore@ibi.baug.ethz.ch
Abstract. Stringent limits and reduction strategies paths on greenhouse gas (GHG) emissions
are being defined at different levels for long-term temperature stabilization. Given the nearly
linear relationship between warming and cumulative net emissions, a carbon budget approach is
required to limit global warming, as stated by the IPCC. In this setting, the built environment, as
a cross-sectorial and transnational area of activity, plays a crucial role in today’s carbon
emissions and future reduction potentials. Previous research showed the need for effective and
aligned carbon-targets to support and guide all actors in the construction sector towards these
challenging global goals. In this context, previous research compared top-down derived carbon
budgets for the Swiss built environment with a preliminary estimation of future cumulative
emissions of the sector. Findings showed the misalignment of current best practices and the
significant magnitude of effort that would be required to comply with such objectives.
Nevertheless, limitations in the preliminary work emerged, such as the lack of dynamicity of the
parameters included in the model restricting the representativity of its results. The current paper
brings further this previous work by integrating the dynamic evolution of the energy supply, the
materials’ production, and the renovation rate. Results are then presented by mean of a parallel
coordinate interactive graph. This interactive component allows the parametric exploration of
the compliance with limited global budgets by varying the input parameters. This way the
influence of macro-level strategies to decarbonize the Swiss building stock can easily be
visualized with reference to the IPCC carbon budgets. Ultimately, the available interactive tool
might support policy makers in decisions taken at the building stock level.
Keywords: Carbon Budgets, Building Stock, Carbon targets, Emissions, Mitigation
1. Introduction
To limit global warming and thus achieve the set long-term temperature stabilization (well below 2°C
and pursuing efforts towards a 1.5°C limit) as defined by article 2 of the Paris Agreement [1], countries
must take immediate action to reduce and mitigate emissions. Although reaching a set goal of net-zero
emissions by midcentury (article 4 of the Paris Agreement) is essential to achieve the required balance
for our environment, limiting cumulative emissions over time is not to be forgotten. As stated in the
IPCC Special Report of 2018 [2]: “limiting global warming requires limiting the total cumulative global
anthropogenic emissions of CO2 since pre-industrial period, that is, staying within a total carbon
budget”. The quantification of global carbon budgets is an integral part of the work conducted by the
IPCC [2–4] and the latest values (2021) are used in this work. The concept of a limited remaining carbon
budget and its distribution to countries and sectors is presented in various works in the literature [5–7].
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
2
In this context, buildings and related construction activities contribute to 38% of all energy-related CO2
emissions [8] and urgent reduction strategies are required.
The building stock is a complex dynamic system that evolves over time and needs, amongst others,
to accommodate a constantly increasing population. Although new buildings are becoming increasingly
energy efficient, the impact of the existing stock and the increasing impact of embodied emissions [9]
are still an unsolved long-term problem. Furthermore, building stock strategies often focus on only one
aspect of buildings’ emissions and forget the cross-impact that, for example, increasing deep renovations
can have on embodied emissions [10]. Especially, countries’ initiatives and incentives to tackle
renovations often lack this level of understanding and tend to focus on the reduction of operational
energy without considering the impact of the materials put in place. For example, the 110% superbonus
[11] in Italy requires renovations to pass at least two energy-efficiency categories but does not mention
the embodied impact of the work. Similarly, in Switzerland the “Programme Batiments”, regulated by
the Cantons, defines a framework of incentives to increase the energy efficiency of buildings but no
weight is given to the choice of materials. An urgent need to understand these relations, especially at a
policy making level, is identified and thus, the present work presents a way to explore the impact of
building stock strategies, enabling the possibility to set more informed long-term policies for our built
environment. This contribution builds upon previous work, presented in section 2.
2. State of the art
Previous work from the same authors [12] attempted a first static estimation of future cumulative
emissions of the Swiss building stock, highlighting the great misalignment of current best practices in
Swiss constructions with limited budgets. The first part of the previous research established a
methodology to allocate the IPCC global carbon budget to the operation and construction of Swiss
buildings. This methodology is retained in the current paper but updated with most recent global carbon
budgets [3]. The second part of the previous work estimated future cumulative emissions with static
parameters such as a constant 1% renovation rate till 2050. The static nature of the previous model
presented shortcomings in its representative value. A more realistic evolution of the parameters used in
the model, such as a gradual increase of the renovation rate, is needed to fully represent the possible
pathways of the building stock and its compliance with climate goals. Furthermore, the initial state of
the stock, in the previous work, was assessed as a best case scenario following the SIA 2040 targets
[13]. In this work, the initial impact of the stock is assessed in more depth to better represent the current
level of emissions.
The contribution presented in this paper builds upon this previous work and further develops a usable
final interactive graph to enable the simple exploration of the results. Cumulative emissions of the Swiss
building stock are calculated considering the gradual evolution of the renovation rate, the operational
emissions as well as the embodied emissions of construction works. The main aim of the current work
is to explore which macro strategies would allow the compliance with limited budgets until 2050. The
graphical and interactive representation, by means of a parallel coordinate graph, further allows the
exploration of the sensitivity of the parameters put in place, giving insight on the parameters we should
focus on to reach the challenging climate goals.
In conclusion, this paper focuses on building stocks emissions and their ability to comply, or not,
with a limited carbon budget allowance for the sector till 2050. Furthermore, it allows the exploration
of various long-term building stock strategies in Switzerland in line with climate goals. The estimation
of cumulative emissions of buildings is made possible through a building stock model. As the scope of
this work was to create a simple model with easily accessible data, the level of detail of the model is
limited to its purpose.
3. Methodology
This section presents the methodology used to, initially build a simplified model with few input
parameters, then estimate emissions till 2050 and finally automatically explore different scenarios. The
construction of the graphical final output is presented in subsection 3.3.
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
3
3.1. Model components and structure
A simplified top-down and statistical building stock model was built using the programming language
Python [14]. As presented in Figure 1 the model can be separated in three main “blocks”. The first one
incorporates the development of surfaces composing the stock in terms of square meters. The second
one includes greenhouse gas emissions related to every square meter of the stock in kgCO2-eq./m2. The
changes in surfaces and related emissions are calculated yearly and finally added up in the last block of
the model in terms of cumulative emissions over the studied period in Mt.CO2-eq. The outputs of one
block feed the other block through predefined relations as shown in Figure 1. The model is further
composed of two main elements with varying functions. First, input data, mainly retrieved by national
statistics or literature, are mainly used to characterize the initial state of the building stock. Secondly,
variable and dynamic parameters, defined as possible targets to be explored by the model. The number
of possible values (limited for computational reasons) for each variable parameter is shown in Figure 1
with the value “n” under each parameter. Further details on these parameters are found in section 3.2. .
All blocks are explained in more details in the following subsections, where input data, assumptions,
relations, and sources are presented.
Figure 1. Graphical representation of the model (“n” represents the number of possible values).
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
4
3.1.1. Surfaces. The Swiss building stock in this work is represented in terms of existing (non-
renovated), renovated, and newly built surfaces. Considering surfaces instead of buildings makes the
model easier to manage as no distinction is made between different typologies but is limited in terms of
level of detail. The main assumptions behind these surfaces and their evolution are shown in the previous
research [12] and are here summarized in Table 1. Table 1 further presents the dependency on variable
and dynamic parameters used in this contribution. In summary, every year of the studied period, a part
of the existing stock is renovated while a part stays untouched and new surfaces are added. Renovated
and non-renovated surfaces are calculated with a renovation rate that varies every year depending on the
renovation rate target and goal year chosen for the scenario. Newly built surfaces are, instead,
independent of variable parameters and calculated based on the increasing population over the studied
period.
Table 1. Definition of surfaces in the model, input data, sources, and variable relations.
Input data Sources Dependency on variable and
dynamic parameter
Non-renovated
surfaces
Initial stock 2018
= 392 945 800 m2
[15]
Renovation rate target
Goal year
Renovated
surfaces
Initial stock 2018
= 392 945 800 m2
Renovation rate target
Goal year
Newly built
surfaces
Population 2018 = 8 525 611
Population 2050 = 10 440 600
Average new dwellings per
1000 inhabitant = 6
Average surface per dwelling =
99m
2
[15]
/
3.1.2. Emissions. Emissions from the building stock are subdivided into operational emissions and
embodied emissions. Each set of surfaces, outputted from the previous block, is related to each type of
emissions according to the methodology presented in previous work [12] and updated values that are
summarized in Table 2. Input data in this case represent the current emissions of buildings and
construction works in Switzerland. Most values are derived with a top-down approach from total
national territorial emissions and imported emissions for materials in construction in relation to surfaces
affected from it. Consequently, the average values presented do not refer to a specific new or renovated
construction. Operational emissions of new buildings are instead estimated analysing consumption
levels and energy carriers for buildings built in the last year in the cantonal energy certification scheme
database [16]. Operational emissions of renovated buildings are adapted by using the same ratio used
by the SIA 2040 [13]. Although the operational emissions of renovated buildings do not directly refer
to a specific strategy, they do refer to a representative average renovation work as presented in the
literature [17]. Average operational emissions of the existing stock remain unchanged and are not
affected by a variable parameter. It was here assumed that, although buildings are being renovated, no
order is defined (ex: renovating first buildings with highest impact), therefore the average emissions of
the stock will not be affected. The initial inputs estimate a current share of embodied and operational
emissions of 77%/23% and 56%/44% for new and renovated buildings respectively. These shares are
very close to the current targets proposed by the SIA 2040 [13] in Switzerland as well as shares found
in the literature [17].
Table 2. Definition of emissions in the model, input data, sources, and variable relations.
Input data
Dependency on variable and
dynamic parameter
Operation of non-
renovated surfaces
Average operational emissions
of existing stock
= 28 kgCO2eq/m
2
.year
/
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
5
Operation of
renovated surfaces
Current average operational
emissions of renovated buildings
= 5.8 kgCO2eq/m
2
.year
Operation renovated
target
Goal year
Embodied of
renovated surfaces
Current average embodied
emissions of renovated buildings
= 440 kgCO2eq/m
2
Embodied renovated
target
Goal year
Operation of new
surfaces
Current average operational
emissions of new buildings
= 3.5 kgCO2eq/m
2
.year
Operation new target
Goal year
Embodied of new
surfaces
Current average embodied
emissions of new buildings
= 696 kgCO2eq/m
2
Embodied new target
Goal year
3.1.3. Results. The final block, as illustrated in Figure 1, produces the results by cumulating, over each
year, emissions stemming from the stock for each possible combination of the variable parameters
(348 480 combinations in total). Results are subdivided into operational cumulative emissions,
embodied cumulative emissions, and total cumulative emissions. This subdivision gives a better
understanding of the influence of each parameter on final emissions over time. The final output of the
Python model is a csv file compiling all combinations of variable parameters and respective results.
3.2. Variable and dynamic parameters
Variable parameters are characterized in this work as the clue elements defining long-term strategies at
the stock level. Their variability stands in the possible “target” value to be achieved in the chosen goal
year. Each variable parameter in the model has predefined sets of values it can reach in the goal year as
well as initial values as presented in Table 3 and graphically shown in Figure 2. The list of possible
values was limited for computational reasons but can easily be changed, increased, or decreased in the
Python model to generate different scenarios. The goal year definition was kept separate as it has a
different level of relation compared to the other parameters. The choice of the goal year complements
the other target choices by defining the length of the x-axis and not the y-axis in Figure 2. For all
parameters, the choice of minimal, maximal, and steps of possible values was chosen to represent both
acceptable and extreme scenarios. The renovation rate was assumed to remain constant or increase
according to Swiss and European commitments [18,19] and 10% is considered a drastic value.
Table 3. Variable parameters definition.
Initial value (2018)
List of possible values
Renovation rate
1% [20]
[1%, 3%, 5%, 10%]
Operational emissions of new
buildings (in kgCO2-eq/m
2
.year)
3.5
[0 to 10]
Operational emissions of renovated
buildings (in kgCO2-eq/m
2
.year)
5.8
[0 to 10]
Embodied emissions of new buildings
(in kgCO2-eq/m
2
)
696
[-540 to 1140] steps of 120
Embodied emissions of renovations
(in kgCO2-eq/m
2
)
440
[-300 to - 600] steps of 60
Goal year
/
[2040, 2045, 2050]
3.2.1. Dynamic evolution over time of parameters. The dynamic aspect applied in this work refers to
the non-static behaviour of the parameters in the model. The variable parameters presented in the
previous chapter are characterized by an initial value and a possible target (variable) to be reached in a
certain year (goal year). The assumption is here made that each parameter evolves linearly from its
starting point till its target value in the time frame defined by the goal year chosen as presented in Figure
2.
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
6
Figure 2. Linear evolution of variable parameters.
3.3. Graphical representation
Finally, the model output feeds a parallel coordinate graph [21], outlining all variable parameters and
related outcomes in terms of cumulative emissions in Mt.CO2eq. The graph is also created in python,
using the pandas and plotly libraries [22,23]. The graph is interactive, and strategies can be explored to
compare results with defined limited carbon budgets. The same graph can be used as well to test the
sensitivity of the different parameters by choosing the cumulative emissions goal and visualizing instead
the span of possible combinations.
3.3.1. Climate goals reference. The final graphical tool makes a reference to temperature limit targets
as seen in Figure 3 (coloured scale bar on the right). Those are derived by calculating the limited carbon
budgets (to be spent during the time frame of the study) for the operation and construction of buildings
in Switzerland. The methodology used to derive a 1.5°C and a 2°C budget is presented in previous work
[12], where global carbon budgets are first allocated to Switzerland with an equal per capita method and
then further distributed to the relevant sectors with a grandfathering method, considering future
estimations of negative emissions technologies. Furthermore, the Swiss climate strategy goal was added
as reference, taken from the Energy Perspective 2050+ [24].
4. Results
This section presents the main outcomes of this work by showing first, results in a business-as-usual
scenario, secondly a commonly accepted strategy of increased renovation rate and finally the sensitivity
of parameters to achieve specific climate goals. The final output of this research, the interactive graph,
is meant to be used to explore different solutions and this can be done only by actively using the said
graph on https://github.com/YasminePriore/Exploring-long-term-building-stock-strategies. The results
presented here are just part of the possible conclusions and outcomes of this output.
4.1. Business as usual
The business-as-usual scenario represents a path till 2050 that keeps current targets and practices
unchanged in this time span. In this case the renovation rate stays constant at 1% until 2050 and operation
of new and renovated buildings as well as their embodied emissions keep current values, as presented
in Table 3. As shown in Figure 3 this scenario exceeds the 2°C budget reaching a 2.1°C temperature
limit. Total cumulative emissions are here clearly driven by cumulative operational emissions. These
results are explained by the relatively low renovation rate, resulting in a high number of existing
buildings that keep a high operational impact until 2050.
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
7
Figure 3. Illustration of cumulative emissions results for the Business-as-usual scenario.
4.2. Renovation+ scenario
Following up on the previous results, the renovation+ scenario follows a commonly agreed pathway
where renovation rate is gradually increased to reduce the operational impact of the existing stock. In
this case, presented in Figure 4, renovation rate linearly reaches 10% in 2050. However, it must be noted
that this rate influences only the existing stock of 2018 and by circa 2040 all buildings are renovated;
thus, renovation works stop. All other parameters are kept the same as in the BAU scenario. As shown
in Figure 4, although cumulative operational emissions are strongly reduced by this measure, embodied
emissions increase due to the strong renovation activities, resulting in the same total cumulative
emissions in 2050 as in the BAU scenario. This result clearly demonstrates that just renovating more,
without considering the carbon content of the materials, will not help the end result for our climate
change goals.
Figure 4. Illustration of cumulative emissions results for the Renovation+ scenario.
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
8
4.3. Sensitivity to reach climate goals
As mentioned before, the interactive graph can also be used to test the sensitivity of the parameters in
reaching specific climate goals. Previously presented scenarios were constraining the variable
parameters to explicit values in order to get results. In the following sections, instead, results are
constrained to a precise goal to visualize the range of possible parameters.
4.3.1. 1.5°C limited budget. Figure 5 represents the possible range of values to achieve a 1.5°C limited
budget and in Table 4 the minimal and maximum values possible to achieve this goal are listed. It must
be noted that each line of the graph represents a specific scenario and that not every combination of
values in the range will reach the 1.5°C goal.
Figure 5. Illustration of variable parameters’ range to comply with a 1.5°C budget.
Although operation of new and renovated buildings can span through all possible values, they are not
compatible with all possible values of embodied targets and renovation rate. What is most evident in
Figure 5 are the excluded values such as 2050 as a goal year or 1% renovation rate and the very limited
embodied targets. These values are, in no scenario, a possibility to achieve a 1.5°C target. One can also
immediately visualize the high sensitivity of the embodied targets, where the only possible values are
negative targets to be achieved to compensate emissions.
Table 4. Range of possible values for a 1.5°C goal.
Goal year
Operation
new
Operation
ren
Embodied
ren
Embodied
new
Renovation
rate
Max
2040
10
10
-120
-180
10%
Min
2040
0
0
-300
-540
3%
4.3.2. Swiss climate strategy. Achieving the goals set by the Swiss climate strategy will leave more
freedom in terms of long-term strategies. Important to notice in Figure 6 is the high sensitivity of the
embodied targets. Although relatively high embodied targets are possible, they are only compatible if
all other parameters are drastically decreased (grey lines starting from high embodied targets). From
the result part of the graph one can also notice how the reduction of cumulative embodied emissions is
effectively essential in achieving the goal.
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
9
Figure 6. Illustration of variable parameters’ range to comply with the Swiss climate strategy.
Table 5. Range of possible values for the Swiss climate strategy.
Goal year
Operation
new
Operation
ren
Embodied
ren
Embodied
new
Renovation
rate
Max
2050
10
10
420
780
10%
Min
2040
0
0
-300
-540
1%
5. Discussion
The model used in this paper was simplified, to reduce the level of complexity, to six main variables
and dynamic parameters, defined as the most impactful long-term strategies on cumulative emissions.
Further parameters could be implemented to increase the level of detail such as a more precise
renovation rate of heating systems or the operational-embodied trade-off of renewable production on
site or, again, the dynamic emission factors for electricity production. The top-down approach applied
to the whole Swiss building stock used in this work has a main limitation of feasibility/representability
of the strategies on single building solutions. The building stock is here generalized, and strategies are
applied to every square meter without distinction of real design feasibility. This low level of detail is
useful to understand overall dynamics in the stock but fails to propose concrete design solutions.
Nevertheless, results can help policy makers to set high ranked national strategies to decarbonize the
building sector without compromising the design intelligence required at a higher level of detail.
Furthermore, the range in which each parameter was allowed to be explored was defined and limited
for computational reasons. Minimal and maximal values are meant to represent a realistic span in which
each parameter could fall in the design of buildings but do not claim to be exhaustive. The limits chosen
have an influence, not on the overall final result but mainly on the amplitude of possible results,
especially in the comparison between the amplitude of cumulative operational emissions and cumulative
embodied emissions. This contrast in the presented range of results should not be considered as an
absolute reality but is dependent on the values the model is exploring. The flexibility to change these
limits in the model is open and further investigations are possible.
Important to discuss is the fact that operational emissions, both for new and renovated buildings,
were limited to 0kgCO2eq/m2 as a best solution in contrast to embodied emissions that reach negative
values. This choice was made by considering negative emissions as a true sequestration effect and not a
balance in limited system boundaries. It could be argued that producing more energy on site than the
building’s demand would result in negative operational emissions for that specific building, but should
this effect be accounted for on cumulative building stock emissions? On the other hand, the
implementation of materials with a carbon capture potential (ex: fast growing biobased materials) was
deemed as a possible contribution to reduce cumulative stock’s emissions. Current building calculation
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
10
methods in Switzerland [25] do not consider biogenic materials as potential negative emissions, so there
are no possibilities of producing a carbon negative building, although other methods would allow it [26].
The model and the tool are built on easily accessible building stock data and can, in a way, be adapted
to different building stocks (in other countries for instance). The simplistic nature of the model and the
relatively few inputs make it a very adaptable tool.
The next step would be to make the tool available in an online format, allowing its access to the
responsible entities for long-term strategies of decarbonization of buildings. Future works are envisioned
to investigate the feasibility of single strategies on detailed archetypes of buildings to prove the viability
of the targets.
6. Conclusions
The main objective of this contribution was to investigate and visually represent the influence of
building stock parameters on cumulative greenhouse gas emissions until 2050. An initial static model,
presented in previous work, was enhanced by the dynamic evolution of the parameters over time
allowing a gradual improvement of the building stock based on set long-term goals. Six parameters have
been identified and scenarios for each one of them are defined to explore multiple combinations of them.
The initial business-as-usual state of the building stock is identified with average current values.
Results highlight the urgent need to change the way we build and operate buildings, demonstrating
that by continuing with a business-as-usual scenario we would surpass a 2°C budget, far from the goals
set nationally and internationally. Another important result presented in this paper is the importance of
accounting for interactions between different strategies as, for example, increased renovation rate
without decreasing embodied impact of said renovations. Cumulative emissions until 2050 in such a
scenario would result in the same 2.1°C budget as in the BAU scenario. Although renovating the existing
stock remains essential to reach challenging goals, the link with the materials’ impact we put into these
renovations plays an essential role. Furthermore, 2050 seems already a very challenging target but it is
not enough to reach a 1.5°C limit in temperature.
Finally, the visually attractive final visualization is a promising solution to easily explore different
scenarios and combinations of targets and strategies. The graph further allows a simple way to test the
sensitivity of each parameter in achieving set goals. At the policy making level there is a need to easily
understand interactions of parameters without analysing complex construction details and high-level
exploration tools can fill this gap.
Acknowledgments
The authors would like to thank the collaborators (Radu Florinel, Jonathan Parrat, Julie Runser
Transform Institute at the University of Applied Science of Western Switzerland) and partners (Emilie
Nault CSD Ingénieurs; Igor Andersen Urbaplan; Philippe Jemmely Bluefactory SA; Werner Halter
Climate Services; Francois Guisan One Planet Living) of the research project SETUP PRO for the
constructive discussions held around the topics presented in this article. Financial support is gratefully
acknowledged from the HEIA-FR Smart Living Lab research program.
References
[1] United Nations 2015 Paris agreement
[2] IPCC 2018 IPCC Special Report
[3] IPCC 2021 Climate Change 2021, The Physical Science Basis
[4] IPCC 2014 Climate change 2014: mitigation of climate change: Working Group III contribution
to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (New York,
NY: Cambridge University Press)
[5] Alcaraz O, Buenestado P, Escribano B, Sureda B, Turon A and Xercavins J 2018 Distributing
the Global Carbon Budget with climate justice criteria Climatic Change 149 131–45
[6] Rodríguez-Fernández L, Fernández Carvajal A B and Bujidos-Casado M 2020 Allocation of
Greenhouse Gas Emissions Using the Fairness Principle: A Multi-Country Analysis
Sustainability 12 5839
[7] Vieli B, Fussen D and Müller M 2017 CO2-Budget der Schweiz (EBP)
[8] United Nations Environment Programme 2020 2020 Global Status Report for Buildings and
Construciton (Nairobi)
SBE-BERLIN-2022
IOP Conf. Series: Earth and Environmental Science 1078 (2022) 012023
IOP Publishing
doi:10.1088/1755-1315/1078/1/012023
11
[9] Röck M, Balouktsi M, Mendes Saade M R, Rasmussen F N, Hoxha E, Birgisdottir H,
Frischknecht R, Habert G, Passer A and Lützkendorf T 2020 Embodied GHG emissions of
buildings – Critical reflection of benchmark comparison and in-depth analysis of drivers IOP
Conf. Ser.: Earth Environ. Sci. 588 032048
[10] Göswein V, Silvestre J D, Sousa Monteiro C, Habert G, Freire F and Pittau F 2021 Influence of
material choice, renovation rate, and electricity grid to achieve a Paris Agreement-compatible
building stock: A Portuguese case study Building and Environment 195 107773
[11] Presidenza del consiglio dei ministri Art. 119 (Incentivi per l’efficienza energetica, sisma bonus,
fotovoltaico e colonnine di ricarica di veicoli elettrici). - Decreto-Legge 19 maggio 2020, n. 34
[12] Priore Y D, Jusselme T and Habert G 2021 Deriving Global Carbon Budgets for the Swiss Built
Environment J. Phys.: Conf. Ser. 2042 012172
[13] S. suisse des ingénieurs et des architectes 2017 SIA 2040 - SIA Energy Efficiency Path
[14] van Rossum G 1995 Python tutorial, Technical Report CS-R9526 vol 620 (Centrum voor
Wiskunde en Informatica (CWI), Amsterdam)
[15] O. fédéral de la Statistique
[16] Swiss Cantonal Energy Certificate for Buildings (GEAK-CECB-CECE)
[17] Lasvaux S, Favre D, Périsset B, Bony J, Hildbrand C and Citherlet S 2015 Life Cycle
Assessment of Energy Related Building Renovation: Methodology and Case Study Energy
Procedia 78 3496–501
[18] Conseil fédéral à l’Assemblée fédérale 2016 Efficacite des aides financieres accordees pour la
reduction des emissions de CO2 des batiments conformément à l’art. 34 de la loi sur le CO2.
[19] European Commission Directive of the European Parliament and of the Council on the energy
performance of buildings. (2021)
[20] International Energy Agency 2018 Energy Policies of IEA Countries: Switzerland 2018 Review
178
[21] Inselberg A and Dimsdale B 1990 Parallel coordinates: a tool for visualizing multi-dimensional
geometry Proceedings of the First IEEE Conference on Visualization: Visualization `90
Proceedings of the First IEEE Conference on Visualization: Visualization `90 pp 361–78
[22] McKinney W and others 2010 Data structures for statistical computing in python Proceedings of
the 9th Python in Science Conference vol 445 pp 51–6
[23] Plotly Technologies Inc. 2015 Collaborative data science (Montreal, QC)
[24] Swiss Federal Office of Energy 2020 Energy Perspectives 2050+
[25] Conférence de coordination des services de la construction et des immeubles des maitres
d’ouvrage publics 2009 Données des écobilans dans la construction - KBOB
[26] Hoxha E, Passer A, Saade M R M, Trigaux D, Shuttleworth A, Pittau F, Allacker K and Habert
G 2020 Biogenic carbon in buildings: a critical overview of LCA methods Buildings and Cities 1
504–24
... Buildings and the construction sector represent more than 40% of greenhouse gas (GHG) emissions globally [1][2][3] . As the energy consumption of residential buildings in Switzerland is, on average, closely aligned with that of Northern European countries 4,5 , it makes Switzerland an informative case study for exploring energy retrofitting scenarios in Europe. ...
... Decarbonization of the building stock is usually only seen through decarbonization of energy systems combined with increased energy efficiency 10,11 . However, a growing number of studies point out that a high renovation rate can worsen the life-cycle climate impact if the embodied GHG emissions linked with the materials used for the renovation are not considered 3,12 . A fine line has then to be found between the necessary renovation of an energy-inefficient and fossil fuel-powered building stock and a deep renovation which will increase upfront GHG emissions 13 at the crucial moment where they need to drastically be reduced to avoid overshooting and overstepping planetary tipping points 14 . ...
Article
Full-text available
Building renovation is urgently required to reduce the environmental impact associated with the building stock. Typically, building renovation is performed by envelope insulation and/or changing the fossil-based heating system. The goal of this paper is to provide strategies for robust renovation considering uncertainties on the future evolution of climate, energy grid, and user behaviors, amongst others by applying life cycle assessment and life cycle cost analysis. The study includes identifying optimal renovation options for the envelope and heating systems for building representatives from all construction periods that are currently in need of renovation in Switzerland. The findings emphasize the paramount importance of heating system replacements across all construction periods. Notably, when incorporating bio-based insulation materials, a balance emerges between environmental impact reduction and low energy operation costs. This facilitates robust, equitable, and low-carbon transformations in Switzerland and similar Northern European contexts while avoiding a carbon spike due to the embodied carbon of the renovation.
... Studies emphasize the importance of including embodied emissions when evaluating renovation strategies Ferreira, 2015, 2017;Lasvaux et al., 2015Lasvaux et al., , 2017Almeida, Ferreira and Barbosa, 2018). If the renovation rate increases without addressing embodied emissions, cumulative national GHG emissions could rise until 2050 (Priore, Jusselme and Habert, 2022). The literature emphasizes that the key component of energyrelated renovations is the energy source of the heating system (Galimshina, Moustapha, Hollberg, Padey, et al., 2021) and adding fossil-derived insulation once the heating source is decarbonized might be counterproductive (Mosquini, Tappy and Jusselme, 2022). ...
Technical Report
Can be downloaded fore free from https://www.aramis.admin.ch/Texte/?ProjectID=53407
... Studies highlight the importance to have a life cycle perspective on emissions for such renovations. If renovation rate is increased without looking at embodied emissions, cumulative national emissions will increase until 2050 [7]. Adding fossil derived insulation when the heating system is decarbonized has a negative effect on life cycle emissions [8]. ...
Article
Full-text available
To tackle the upcoming renovation wave, this work evaluates renovation strategies with a life cycle GHG emissions perspective and includes time and sequencing in the decision-making process. A case study is used to conduct a full life cycle assessment of renovation strategies in line with the Swiss normative context. Improvements in the operational energy consumption are evaluated with an energy model using the software Lesosai and considering the normative limits from the SIA 380/1. GHG emissions are calculated using the Swiss KBOB data inventory and in line with the SIA 2032 methodology. The renovation measures are then examined individually with the carbon payback time indicator and strategies with cumulative emissions over time in contrast to carbon budgets. Results show that the sequence of the refurbishment steps can increase or decrease cumulative GHG emissions of ca. 30% over the lifetime of the building. Changing a fossil-fuel based heating system is the most impactful measure and must happen as soon as possible. Switching to decarbonized heating systems reduces the carbon effectiveness of subsequent renovation measures but poses the question of energy availability. Fully renovating a building but delaying the change of heating system by only 7 years can compromise the achievement of the carbon targets.
... It has been shown that renovation rate needs to be increased in order to decarbonize the building stock and decrease the operational impact (Camarasa et al., 2022). However, other studies showed that a high renovation rate can worsen the GHG impact due to embodied emissions of materials (Galimshina et al., 2021;Priore et al., 2022). ...
Preprint
Full-text available
Building renovation is urgently required to reduce the environmental impact associated with the building stock. Typically, building renovation is performed by envelope insulation and/or changing the fossil-based heating system. Life cycle assessment and life cycle cost analysis are seen as suitable methods to evaluate the performance of a building in terms of environmental impacts and cost. However, the results are highly affected by uncertainty. The goal of this paper is to provide recommendations for robust renovation strategies considering uncertainties on future evolution of climate, energy grid, user behaviors. The method includes identifying optimal renovation options for the envelope and heating systems for building-representatives from all construction periods that are currently in need of retrofit in Switzerland. Conventional and bio-based materials are examined with inclusion of dynamic carbon storage potential. The results of the analysis show that heating system is a priority for building renovation for all the considered construction periods. The results also show that if only conventional materials are considered for building renovation, optimal solution does not prescribe deep renovation and higher energy consumption during life time is favored. However, when bio-based insulation materials can be used, the opposite conclusion is drawn and synergies between low environmental impact and low energy costs during life cycle are identified. Such renovation strategies pave the way for a just and low carbon transformation of the Swiss building stock.
... Embodied targets refer to newly and renovated surfaces each year. These surfaces are calculated through a previously developed building stock model [47]. The model can be accessed online (link in Supplementary Data) and the background assumptions for this study are mentioned in the Supplementary Data section 4. Embodied targets in this paper are directly derived from the industry's production of materials at national scale; thus, the impact of disposal at the end of life is not accounted in the same sectoral budget and should be reported in the waste management sector. ...
Article
Full-text available
Challenging climate goals demand immediate greenhouse gas emissions reductions for long-term temperature stabilization. Given the nearly linear relationship between warming and cumulative net emissions, the carbon budget approach is a useful tool to quantify remaining carbon allowances for countries, sectors, and even buildings. The built environment plays a crucial role in today’s carbon emissions and future reduction potentials. Although much progress has been achieved towards energy efficient buildings, less attention has been given to the impact of materials put in place. Furthermore, the construction sector lacks of quantified reduction efforts and time horizon limits to clearly define a climate neutrality pathway. This article proposes a definition of yearly targets until 2050 for the operational and embodied carbon of buildings in line with a global 1.5°C carbon budget and the Swiss climate strategy. The proposed targets are then compared with the impact of current practices and future technical developments. Gaps between targets and practices are quantified and discussed to better understand the upcoming challenges of the Swiss construction sector.
Article
Full-text available
In order to limit global warming, remaining carbon budgets have been defined by the IPCC in 2018. In this context translating global goals to local realities implicates a set of different challenges. Standardized methodologies of allocation can support a target-cascading process. On the other hand, local strategies and norms are not currently designed to directly respond to limited carbon budgets in a 2050 horizon. The life cycle assessment of buildings implicates an intricate cross-industry and cross-border carbon accounting. For these reasons, effective and aligned carbon targets are needed to support and guide all actors in the construction sector. This research aims at addressing these challenges by developing a new methodology of allocation of a global carbon budget at different scales using the Swiss built environment as a case study. This approach allows the assessment of current best practices in regards to limited carbon budgets. Results show misalignment of global goals with current practices at all levels and present the magnitude of effort that would be required to have a chance to limit global warming to 1.5°C.
Article
Full-text available
Building thermal retrofit plays a key role to limit global warming. However, the spatial and temporal dynamics of urban-scale renovation are not well understood. We propose a new methodology that is based on a bottom-up building stock model and links dynamic Material Flow Analysis with dynamic Life Cycle Assessment to include the temporal dynamics of emissions and renovation activity, and the spatial dynamics of the building stock. Alternative renovation scenarios for a Lisbon neighborhood are analyzed over the next 100 years. This includes renovation rates, electricity grid transformation and material choice: Conventional renovation systems are compared to bio-systems (using cork, wood and straw). A need-based prioritization of poorly insulated buildings is suggested and the effect of different energy grid transitions analyzed. It was found that bio-systems, especially made with fast-rotation biomass, are beneficial regarding radiative forcing. The straw- and wood-based system (TES), combined with an increased renovation rate, results in a cumulative radiative forcing of −45.4 * 10⁻⁸ kW/m² for embodied impacts in 2050, compared to 3.5* 10⁻⁸ kW/m² with a conventional system and a business-as-usual renovation rate. A fast and radical transition of the energy grid is crucial to meet the downscaled carbon budget to limit global warming to 2 °C.
Conference Paper
Full-text available
In the face of the unfolding climate crisis, the role and importance of reducing Greenhouse gas (GHG) emissions from the building sector is increasing. This study investigates the global trends of GHG emissions occurring across the life cycle of buildings by systematically compiling life cycle assessment (LCA) studies and analysing more than 650 building cases. Based on the data extracted from these LCA studies, the influence of features related to LCA methodology and building design is analysed. Results show that embodied GHG emissions, which mainly arise from manufacturing and processing of building materials, are dominating life cycle emissions of new, advanced buildings. Analysis of GHG emissions at the time of occurrence, shows the upfront 'carbon spike' and emphasises the need to address and reduce the GHG 'investment' for new buildings. Comparing the results with existing life cycle-related benchmarks, we find only a small number of cases meeting the benchmark. Critically reflecting on the benchmark comparison, an in-depth analysis reveals different reasons for cases achieving the benchmark. While one would expect that different building design strategies and material choices lead to high or low embodied GHG emissions, the results mainly correlate with decisions related to LCA methodology, i.e. the scope of the assessments. The results emphasize the strong need for transparency in the reporting of LCA studies as well as need for consistency when applying environmental benchmarks. Furthermore, the paper opens up the discussion on the potential of utilizing big data and machine learning for analysis and prediction of environmental performance of buildings.
Article
Full-text available
The increasing pressure to reduce greenhouse gas emissions from buildings has motivated specialists to develop low-carbon products incorporating bio-based materials. The impact of these materials is often evaluated through life-cycle assessment (LCA), but there is no clear consensus on how to model the biogenic carbon released or absorbed during their life-cycle. This study investigates and compares existing methods used for biogenic carbon assessment. The most common approaches were identified through an extensive literature review. The possible discrepancies between the results obtained when adopting different methods are made evident through an LCA study of a timber building. Results identified that land-use and land-use-change (LULUC) impacts and carbon-storage credits are not included in most existing methods. In addition, when limiting the system boundary to certain life-cycle stages, methods using the –1/+1 criterion can lead to net negative results for the global warming (GW) score, failing to provide accurate data to inform decision-making. Deviation between the results obtained from different methods was 16% at the building scale and between 35% and 200% at the component scale. Of all the methods studied, the dynamic approach of evaluating biogenic carbon uptake is the most robust and transparent. 'Practice relevance' This critical review identified key methodological differences between the most commonly used methods and recommended standards for biogenic carbon accounting in buildings. This indicates a lack of consensus and guidance for conducting LCAs of bio-based construction products and buildings using bio-based materials. A case study applying four different LCA approaches on a timber building identified the inability to compare results and create proper benchmarks. Moreover, different methods lead designers to pursue different strategies to reduce a building’s carbon footprint. Regulators, the construction industry and the construction products industry are directly affected by this lack of comparability. This research highlights the flaws and benefits of commonly used methods. A clear and grounded recommendation is for practitioners to adopt dynamic biogenic carbon accounting for future assessments of bio-based materials and buildings.
Article
Full-text available
This study presents an analysis of the allocation of greenhouse gas emissions based on a comparison of criteria for 66 countries and fairness-based indicators. The academic literature contains very few broad multi-country studies. The large sample of countries included in our analysis has allowed us to make a more comprehensive, holistic comparison than other studies with similar characteristics. The United States and China must make the greatest effort to fight climate change worldwide, but all countries have a responsibility, including some that are not usually analyzed in this type of research.
Article
Full-text available
In this paper, a model for the distribution of the Global Carbon Budget between the countries of the world is presented. The model is based on the criteria of equity while also taking into account the different historical responsibilities. The Global Carbon Budget corresponds to the quantity of carbon dioxide emissions that can still be released into the atmosphere while maintaining the increase in the average earth surface temperature below 2 °C, and it is therefore compatible with the long-term objective defined in the Paris Agreement. The results of applying the model are shown both for the 15 emitters that currently top the ranking for world emissions as well as for the other countries, which are grouped together in three main groups: Other African, Other Latin American and Caribbean, and the Rest of the World. Mitigation curves compatible with the carbon budget allocated to the different countries are presented. When comparing each emitter’s historical emissions for the period 1971–2010 with the proposed distribution for the period 2011–2050 obtained using the model, it can be seen that developed countries must face the future with a greatly reduced carbon budget, whereas developing countries can make use of a carbon budget that is higher than their cumulative historical emissions. Finally, there is a discussion about how a model with these characteristics could be useful when implementing the Paris Agreement.
Article
Full-text available
The building sector contributes up to 40% of energy consumption and 30% of greenhouse gases emissions (GHG) worldwide [1]. One of the main driver to mitigate these energy and GHG emissions is the renovation of existing buildings. While the energy demand is reduced during an energy related renovation, investment costs and environmental impacts increase due to the materials and building integrated technical systems (BITS) replaced or added to improve its energy performance. To address these trade-offs, there is a need to consider a life cycle approach to avoid impacts’ transfer between the operational and embodied energy and impacts. In this paper, we present a pragmatic Life Cycle Assessment (LCA) methodology for energy related renovation measures of building developed in the framework of the IEA annex 56 “Cost effective energy and carbon emissions optimization in building renovation”. The approach is consistent with the existing building LCA's state-of-the-art but goes into a more applicable methodology by focusing only on the significant life cycle stages for energy related building renovation i.e. the production, transportation, replacement and end of life of new materials for the thermal envelope and building integrated technical systems (BITS) and the operational energy demand. In this paper, the methodology is applied on a Swiss multi-family residential building built in 1965 which was renovated in 2010. The LCA is presented using three indicators: the total and non-renewable cumulative energy demand (CED) and the global warming potential (GWP). Results show that embodied CED and GWP remain negligible in the renovated building compared to the energy savings. Further studies are needed to further apply this LCA methodology.
Article
Full-text available
—In this paper we are concerned with the practical issues of working with data sets common to finance, statistics, and other related fields. pandas is a new library which aims to facilitate working with these data sets and to provide a set of fundamental building blocks for implementing statistical models. We will discuss specific design issues encountered in the course of developing pandas with relevant examples and some comparisons with the R language. We conclude by discussing possible future directions for statistical computing and data analysis using Python.
Conference Paper
Full-text available
By means of parallel coordinates a mapping R N → R 2, which is not a projection is obtained. Relations among N variables, for any positive integer N, are “represented” by their planar images. These planar diagrams have geometrical properties corresponding to certain properties of the relation they represent. Starting from a point ← → line duality when N = 2, the representation of lines in R N is given and illustrated by an application to Air Traffic Control (i.e. for R 4). It is followed by the representation of hyperplanes, polytopes and more general convex and some nonconvex (i.e. “pretsels” in R N ) hypersurfaces. An algorithm for constructing and exhibiting any interior point to such a hypersurface is shown. Such a display shows some local (i.e. near the point) properties of the hypersurface and information on the point’s proximity to the boundary. Graphics from the computer implementation of the representations and algorithms are included.
CO2-Budget der Schweiz (EBP)
  • Vieli