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• Bottom-up archetype model for space heating demand of Swiss office building stock. • Archetypes characteristics derived from energy certificates database. • Estimation of current thermal performance and energy retrofit's potential. • Calculation of national heating demand and distribution among archetypes. • Influence of design characteristics and buildings properties on heating demand. Energy efficiency in buildings is a key objective of the European energy strategy. To address the limited knowledge of the thermal performance of the non-domestic building stocks, this paper presents a bottom-up, physics-based, archetypal model derived from a large building stock database and physical characteristics from 2170 building energy performance certificates in Switzerland. The model was validated by measured energy consumption data and national statistics. Results highlight the potential for energy retrofit: most of the stock is still heated with fossil fuels (67% of the total heated area) and 40% of the total envelope surface has a poor thermal performance associated with the period before 1980. We estimate national final energy demand for heating of the office building stock (11.3 PJ/year) and present detailed breakdown of energy by thermal loss element. Significant differences were found between archetypes related to urban settings (specific demand 50% higher in rural than in urban contexts) and age of the buildings (56% of the total demand is due to buildings constructed before 1970). The physical model highlights the impact of architectural design characteristics such as building compactness and glazed surface ratios on thermal performance. The model represents an important step for studies on optimal thermal retrofit pathways. [ABSTRACT FROM AUTHOR]

This paper models scenarios for energy label based retrofit targets for Switzerland's residential building sector for 2050. It takes into account the magnitude and uncertainty in the energy performance gap (EPG) between labelled and actual energy consumption using actual energy performance data, as previous work highlighted that the EPG is not evenly distributed across different building labels. A building stock retrofit model is developed to estimate the potential energy savings from improving building performance through increasing energy label rating. A Monte Carlo analysis is applied using real EPG distribution data. The uncertainty in total energy savings is calculated for business-as-usual case and for three scenarios based on the different retrofit incentive policies of different Swiss Cantons. This allows to quantify the uncertainties in energy and emission outcomes of different policy targets arising from the variable EPG. The results show that with the business-as-usual approach it is impossible to achieve the objectives set (9.7 Mt CO 2 -eq/y vs 0.4 Mt CO 2 -eq/y by 2050). On the other hand, to reach the targets, a more aggressive policy aiming at renovating all buildings to the highest standards is necessary, that translates into a renovation rate that seems unrealistically high (3.4% per year until 2050 vs the proposed 1.4%). The contribution is to inform stakeholders designing new policies (notably the EU Renovation Wave policies) of the risk related to energy policies. [ABSTRACT FROM AUTHOR]

• In 2017, renewable heat used in residential buildings in AT and CH was 48% and 30% • Renewable heat must be increased by 131% in AT by 2040 and 210% in CH by 2050. • Public subsidies contributed to 51% and 36% of total heat savings in AT and CH. • AT relies more on public subsidies and has a lower cost-effectiveness of policies. • CH obtains similar heat savings with eight times lesser public subsidies. Reducing heat demand and decarbonising heat supply are essential if countries have to meet net zero emission targets. This paper presents a comparative assessment of the impact of energy efficiency polices for heat demand reduction and heat decarbonisation in the buildings sector (2000–2017) in Austria (AT) and Switzerland (CH). It assesses the heat demand, heat supply, effect of different factors on changes in total heat consumption, impact of energy policies that provide public subsidies for heating and compares the effectiveness of different policies and measures. The assessment shows that renewable heat supply in residential buildings has to be increased by about 150 PJ (130% increase from 2017) in AT by 2040 and by 120 PJ (210%) in CH by 2050, which is challenging. Energy savings from improvements in energy efficiency from 2000 to 2017 are 83 PJ in AT and 97 PJ in CH, but these are largely offset by increase in activity and wealth effects thereby resulting in small changes in final heat consumption. The average (2014–2017) annual public subsidies for heating were about 2500 million Euros and 310 million CHF and contributed to 51% and 36% share of energy saving in AT and CH respectively. Both countries achieved similar energy savings, albeit following different policy approaches. Public subsidies for heating are an important policy instrument in AT but have lower cost effectiveness. On the other hand, CH minimised the use of public spending by deploying other policies and funding measures that leveraged private investment to achieve similar energy savings. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) strategies can be applied to the coordination of energy hubs to reduce their energy consumption. Despite the effectiveness of these techniques, their potential for energy savings are potentially underutilized due to the fact that energy demands are often assumed to be fixed quantities rather than controlled dynamic variables. The joint optimization of energy hubs and buildings' energy management systems can result in higher energy savings. This paper investigates how different MPC strategies perform on energy management systems in buildings and energy hubs. We first discuss two MPC approaches; centralized and decentralized. While the centralized control strategy offers optimal performance, its implementation is computationally prohibitive and raises privacy concerns. On the other hand, the decentralized control approach, which offers ease of implementation, displays significantly lower performance. We propose a third strategy, distributed control based on dual decomposition, which has the advantages of both approaches. Numerical case studies and comparisons demonstrate that the performance of distributed control is close to the performance of the centralized case, while maintaining a significantly lower computational burden, especially in large-scale scenarios with many agents. Finally, we validate and verify the reliability of the proposed method through an experiment on a full-scale energy hub system in the NEST demonstrator in Dübendorf, Switzerland. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heating system is the most crucial parameter for renovation. • Deep renovation is neither cost-effective nor climate-friendly considering future uncertainties. • Heating system replacement alone has lower overall emissions than solely envelope renovation. Buildings are responsible for a large share of CO 2 emissions in the world. Building renovation is crucial to decrease the environmental impact and meet the United Nations climate action goals. However, due to buildings' long service lives, there are many uncertainties that might cause a deviation in the results of a predicted retrofit outcome. In this paper, we determine climate-friendly and cost-effective renovation scenarios for two typical buildings with low and high energy performance in Switzerland using a methodology of robust optmization. First, we create an integrated model for life cycle assessment (LCA) and life cycle cost analysis (LCCA). Second, we define possible renovation measures and possible levels of renovation. Third, we identify and describe the uncertain parameters related to the production, replacement and dismantling of building elements as well as the operational energy use in LCCA and LCA. Afterwards, we carry out a robust multi-objective optimization to identify optimal renovation solutions. The results show that the replacement of the heating system in the building retrofit process is crucial to decrease the environmental impact. They also show that for a building with already good energy performance, the investments are not paid off by the operational savings. The optimal solution for the building with low energy performance includes the building envelope renovation in combination with the heating system replacement. For both buildings, the optimal robust cost-effective and climate-friendly solution is different from the deep renovation practice promoted to decrease the energy consumption of a building. [ABSTRACT FROM AUTHOR]

• Linking top-down energy efficiency indicator analysis with bottom-up policy analysis. • Explaining the contribution of energy efficiency policies in Germany and Switzerland. • Analysing the counteracting effects to energy policy of rebound and non-compliance. This paper studies the factors underlying the evolution of the energy consumption for space heating in residential buildings by linking top-down analysis, based on meso -indicators, and bottom-up analysis, based on policy evaluations. The top-down analysis (i.e. the perspective from energy statistics) allows one to separate the change in total energy use into activity level, societal factors and energy efficiency gains. The explanatory power of the resulting meso-(statistical) indicators is often limited, if the underlying factors are not examined (e.g. changes in heating levels and patterns, weather effects, cost of energy and policies regarding insulation and heating system standards). We overcome most of these drawbacks by conducting a bottom-up analysis (i.e the perspective from single policy measures), which enables us to discern the contribution of energy efficiency policies to the changes observed with the meso -analysis. We focus on space heating consumption in the residential sectors for Germany and Switzerland. A major aim of this analysis is to show the contribution of energy efficiency policies (such as thermal building regulation, subsidy programmes, fiscal measures etc.) towards the changes in this indicator. The results show that the progress in energy efficiency (both autonomous and policy induced) in both countries had the greatest effect (-776 PJ for Germany, −42 PJ for Switzerland) regarding the change in energy consumption for space heating in the period from 2000 to 2016. However, the impacts of "technical and comfort" rebounds (+436 PJ for Germany, N/A for Switzerland) and other developments such as societal changes (+316 PJ for Germany, +35.5 PJ for Switzerland) were found to compensate for a significant part of the energy efficiency gains. In both countries, it was possible to link physical energy efficiency indicators to policy evaluation, but limitations were also identified which are primarily related to data gaps. [ABSTRACT FROM AUTHOR]