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International audience; Since its inception in France in 2006, the Energy Efficiency Obligation (EEO) scheme has been subject to a growing obligation in each new period. However, the scheme has experienced different historical phases with low or more recently high prices (a fourfold increase of the price index was observed between January 2017 and December 2019) that show different contexts depending on the year reflecting in a first approximation the ease or otherwise of fulfilling the obligation.In parallel with standardized actions mainly used in the scheme, specific programmes have been set up in a marginal way. Historically, these programmes include actions concerning information, and training of professionals. Today, these programmes are also used to manage the EEO scheme by facilitating the issuance of certificates or to target specific actions (e.g. disappearance of fuel oil or coal space heating).In that way, a new programme concerning the energy renovation of housing allowing for an additional bonus was implemented above expectation at the beginning of the year 2019 with large impact on the retrofit market. This paper reviews the positive outcomes and the unexpected problems and their impacts on the energy renovation market (increase of retrofit market, orientation towards different technical solutions, up-front cost coverage structure, targeted customer, quality problem, lack of a long-term vision, etc.). These impacts show how difficult it is for public bodies to manage a scheme based on an obligation on utilities in connection with a market driven by other economic actors. On the long-term, the main question is how to manage the EEO price between too low incentive and high impact on energy price to transform the building renovation market.

The French EPC (Energy Performance Certificate) was implemented in 2006 to be mandatory for selling or renting a dwelling. From the beginning, the EPC's robustness was questioned. Field tests showed that, for the same building, two different energy labels could be obtained from auditors. Thus in 2012 the EPC was revised to make it more reliable by, among others , doubling the number of inputs in the calculation method. Unfortunately, recent investigations show that the problems persist whereas a law plans to make EPC enforceable against third persons in 2021. In this way, the French government has announced a new rework of the EPC for 2019. In this context we study the part in the dispersion of EPC's results due to the calculation method. In 2011 a first study consisted of an uncertainty propagation (Monte-Carlo method) and a sensitivity analysis in the initial version of the calculation method (2006 method) on the case of a single-family house. Using the same case and the same methodology (and also Sobol method), we are able to compare the differences between the initial and revised calculation methods. The revised version is not more accurate and some main sources of dispersion in the EPC's results are identified: • in all input modes, estimated energy consumption has increased while the EPC is known to overestimate actual consumption , • we observed a doubling of consumption's dispersion, • significant differences in results exist between the input modes ("precise input" vs. "default value" with threshold effects in the value tables), • a large part of discrepancy depends on the uncertainties on transmission coefficients of the thermal insulation and on the surface area. In conclusion, in association with the question of the qualification of diagnosticians, the calculation method must be deeply reworked so that the EPC becomes the main tool of the building stock refurbishment.

The energy performance of a building can be assessed using various indicators that will not give the same score. This study evaluates the performance of the French housing stock using several indicators based either on the energy level at which energy consumption is assessed (primary, final or useful), or on greenhouse gas emissions, or on the energy bill. An indicator calculated at each of the 3 stages of the energy chain allows a sequential approach to building performance: the "useful energy" level measures the performance of the thermal insulation of the envelope, the "final energy" level adds the consideration of the performance of equipment providing energy services, and the "primary energy" level combines the performance of energy sources. The paper focuses on the comparison of French (DPE, Diagnostic de Performance Energétique, French Energy Performance Certificate) and UK (EPC, Energy Performance Certificate) indicators. The European Union has widely disseminated the EPC for housing through the EPBD 2002/91/EC (Energy Performance of Buildings Directive, then revised in 2010 and 2018). Originally, with the exception of the number of seven energy classes, Member States were free to choose the details of the calculations of their "national" EPC. Most European countries including France-have chosen an absolute value scale to define performance ranges and a primary energy indicator for energy performance. The United Kingdom has chosen an indicator related to the energy bill and expressed on a standard scale. The impact of the different approaches proposed for evaluating the performance of the French housing stock is analysed. The relevance of the indicators is discussed according to two criteria: the nature of the actors to whom the evaluation is addressed (households, planners, politicians), and the objectives of the actions that the evaluation should guide (improving housing performance, reducing energy consumption, Green House Gas emissions (GHG), or energy bills). The results are put into perspective with the recent revision of the EPBD directive requiring that the energy performance of a building be expressed by means of a primary energy consumption indicator.

The energy-saving obligation scheme in France launched in 2006 was revised each three-year period. The majority of EEOs issued are based on standardised action valued according to deemed energy savings. These revisions have made it possible to correct errors, to value new actions and to update eligible actions according to changes in the context and regulations. After more than 10 years of operation, and a potential extension of the scheme beyond 2020, it is interesting to look at the lessons of the past. For this purpose, we look at the evolution of the system through the prism of iconic actions. The assessment of a renovation action in the EEO scheme consists of 2 parts: the technical part helps to calculate energy savings (calculation sheet), the second deals with the verification of the eligibility of the works (certificate on honour). Both have evolved over time. The estimation of energy savings have evolved for technical reasons: reduction of the heating-degree-day, decrease of the space heating reference consumption and modifications of other coefficients. If these modifications were made for objective reasons, others have been made to explicit unexplained values. In addition, the EED directive has helped to modify energy saving to value only marginal savings (i.e. beyond the performance of Ecodesign). Recently, the problem of fraud has led to the simplification of modulating energy savings due to the impossibility of verifying certain criteria while adding constraints on the execution of work (proof, on site-visit). Effectiveness of these changes should be studied to ensure this scheme still fosters energy retrofit of the building stock. This study could help to make a relevant trade-off between process simplification and the valuation of accurate energy savings. In summary, the EEO scheme will always be a work in progress and the preparation of the next period will not escape it but lessons from the past should enlight future developments.

International audience; The recent European energy proposals for the revision of the Energy Efficiency and the Energy Performance of Buildings Directives emphasize the importance of driving investments into the renovation of building stocks and stimulating retrofitting demand. Moreover, the ambitious targets on Green House Gas' abatement and energy consumption reduction require refurbishments to a high level of performance. This high level of performance subsequently represents high cost for households. Thus, with the necessity to lead to ambitious renovations, the question about the cost-effectiveness of the relevant level of performance has to be tackled. Unfortunately, the absence of reliable data often makes it difficult to answer this key question. In this paper, we rely on two different regional energy efficiency programmes providing incentives for performing refurbishment with a great importance dedicated to thermal insulation and air tightness. Covering a sample of around 50 households per programme, data on energy consumption and the characteristics of individual dwellings were collected as well as on refurbishment costs. Comparisons between the two programmes and within each programme provide information on the economic relevance of ambitious targets (in terms of energy and carbon). Both programmes pursue similar objectives but the cost associated were different. The first programme presents an average retrofit cost of 290 €/m² compared to an average cost of 415 €/m² for the second one, but both programmes present a large margin of uncertainty. On average the energy savings were 63 kWh/m² (final energy) for the less costly programme compared to 88 kWh/m² for the second programme. Concerning the non-energy impacts, the households express satisfaction about comfort increase and green value of their refurbished real estate property. The findings underline the crucial importance of both financial incentives and extra benefits such as asset value to enhance the accessibility of deep retrofit potential.

International audience; This paper tackles the crucial issue of price structure in the energy retrofit market of the private residential sector. It is based on a quantitative study of retrofit prices in France (1,000+ invoices) and a qualitative sociological survey of installers (25 open-ended interviews). We show a strong dispersion of prices within single retrofit-work categories (e.g. boiler, insulation). Half of the dispersion is explained by technical and economic reasons (brand and quality of product, housing size, type of company, discount…). This means that from a technical standpoint, the price is correct. Other components of the price are revealed by the qualitative survey. On the customer side, the refurbishment market is marked by a strong uncertainty. It is technically complex and there is a concern about poor workmanship, hence the role of reputation and trust. These are factored in the price as a " confidence premium " which makes the price fair from the customers' point of view. On the installer side, the price is formed at the crossroads of three characteristics: the perception of the household willingness to pay, the management practices of the company (profit margin calculation, load plan) and an adjustment to current local market prices. The fair price from the installer point of view is the price that allows his company to survive or make profit and to win new contracts. However, a determining factor of the price lies in the installer's recommendation of exactly which work to do and with which material or equipment. For a given energy performance, several technical solutions exist that impact the final price. To conclude, we note that observed prices may differ from the technically " correct " price but this doesn't mean that prices are inaccurate. Prices incorporate qualitative dimensions such as the accessibility of the site or the work quality of the company (being on-schedule, cleanliness of the work, etc.) that make them " fair " in practice. As a policy consequence, rather than a direct intervention on prices which is complex, governmental action might focus on standardizing the presentation of quotation, craftsmen company management and on assisting customers in their choices.

Les prix des travaux de rénovation énergétique du secteur résidentiel privé présentent une forte dispersion en France. Cette dispersion est inhérente à la nonstandardisation des chantiers du résidentiel privé. Elle s’explique par : des raisons techniques propres aux travaux, des raisons liées à la gestion des entreprises et le coût de la coordination entre l’offre et la demande. Cette situation n’est pas exceptionnelle en Europe. Les prix ne sont pas plus transparents ailleurs et pas systématiquement moins élevés. Partout, la question de la qualité se trouve au coeur des difficultés de massification de la rénovation énergétique performante. En conséquence, le levier de massification de la rénovation énergétique est moins le prix .même s’il demeure un levier6 que la coordination de la rencontre entre l’offre et la demande, ce qui suppose de traiter deux sujets majeurs :· La définition des travaux à mener et la maturation de la demande, aujourd’hui largement opérés par les artisans et entreprises lors de la réalisation du devis, ce qui a un coût significatif.· La garantie de qualité des travaux, alors que les malfaçons et insatisfactions freinent le lancement de travaux par les ménages ou conduisent ces derniers à accepter des prix élevés.

Les prix des travaux de rénovation énergétique du secteur résidentiel privé présentent une forte dispersion en France. Cette dispersion est inhérente à la nonstandardisation des chantiers du résidentiel privé. Elle s’explique par : des raisons techniques propres aux travaux, des raisons liées à la gestion des entreprises et le coût de la coordination entre l’offre et la demande. Cette situation n’est pas exceptionnelle en Europe. Les prix ne sont pas plus transparents ailleurs et pas systématiquement moins élevés. Partout, la question de la qualité se trouve au coeur des difficultés de massification de la rénovation énergétique performante. En conséquence, le levier de massification de la rénovation énergétique est moins le prix .même s’il demeure un levier6 que la coordination de la rencontre entre l’offre et la demande, ce qui suppose de traiter deux sujets majeurs :· La définition des travaux à mener et la maturation de la demande, aujourd’hui largement opérés par les artisans et entreprises lors de la réalisation du devis, ce qui a un coût significatif.· La garantie de qualité des travaux, alors que les malfaçons et insatisfactions freinent le lancement de travaux par les ménages ou conduisent ces derniers à accepter des prix élevés.

Evaluation of energy savings of retrofitting programmes are relativized due to the rebound effect. Moreover, their economic relevance (i.e. NPV calculation) is questioned because of the discouraging paybacks. The underlining question of both problems is missing consideration of comfort improvement, often hidden behind the concept of rebound effect. Yet, it can be considered that some potential energy savings in an initially uncomfortable dwelling are assigned to achieving decent comfort. In this case, the household sets aside some of the potential savings to improving thermal comfort and thus part of the rebound effect is simply to catch up. It therefore imports to distinguish within the so-called rebound effect between the share of legitimate comfort improvement and the energy "wastage". We propose an approach embodied in a formula to monetize the comfort catch-up relying on the comparison of ex-ante and ex-post energy savings. This approach has been applied to regional energy efficiency programmes consisting for each participant to the realisation of one to two energy efficiency measures concerning insulation and/or heating equipment of his housing. These cases study are located in 3 different regions with different climates (oceanic, continental and Mediterranean). After refur-bishment, we evaluate the level of comfort catch up according to the set-temperature and the difference between the real consumption and its potential value at a conventional set-temperature. The methodology turned out to be quite easily applicable providing that some essential data are available (energy consump-tions and set-temperatures before and after retrofit). Quantitative results of comfort catch up are in the same order of magnitude of energy savings.

International audience; In the residential sector it is often observed that savings linked to energy efficiency actions are smaller than estimated inter alia especially due to the rebound effect. Thus, according to the sole energy viewpoint, outcomes of actions can seem low or even negative whereas in taking into account Multiple Benefits (MBs) the conclusion tends to be more positive. Nevertheless, these conclusions are more complex to obtain. To include the MBs in the analysis, we use the functional economy model that focuses on the performance of a response to a functional need instead of the material production. This theory has other specific key features: the incorporation of external factors in meeting functional needs and a deep interaction with local economic development. Thereby, in such a framework, some of the MBs can be taken into account via an estimation of the monetized value of:  Impact on household's welfare:  Set-temperature increase (willingness to pay for comfort).  Green value (building market value linked to energy labelling).  Health impacts.  Economic development:  Disposable income fed back into economy (propensity to consume).  Added value created from the local installers.  Value creation for utilities (loss margin, Energy Efficiency Obligation if existing).  Social welfare:  GHG mitigation (carbon price) and other externalities.  Social expenditure decrease. To investigate this large field of study, we rely on a French regional energy efficiency programme providing incentive for a wood stove in case of an existing electric space heating system. 45 households were surveyed regarding their energy consumption and their characteristics. Likewise, the survey highlights household behaviours concerning both space heating before and after refurbishment (e.g. declared set-temperature). A three years billing is used to calculate the energy savings. Beyond the electricity savings, we give a monetary value of the MBs considered on a progressively extended assessment scope, starting from a household perspective towards a societal perspective: adding step by step the value of MBs, we explicit the increase of energy efficiency value even if the figures include large uncertainties. We show the interest of such an approach by ranking the MBs and showing that the green value could be the largest MB of the studied programme.

International audience; Before the first oil crisis, the majority of new buildings in Euro-pean countries were constructed without any energy efficiency obligation. In those times, Space Heating (SH) consumptions accounted for more than 80 % of the total energy consumption of residential sector. In France, SH in dwellings was rated at 300 kWh fe /(year.m²), final energy. 40 years later, SH is only 60 % of total consumptions and the unitary SH consumptions have been cut by almost 50 %. Unitary decrease has been sufficiently strong to decrease the total SH consumptions despite increases of numbers and size of dwellings and standards of comfort. This paper studies the causes of this spectacular decrease: what are the respective responsibilities of demolition, refur-bishment of existing housing stock, efficiency of new dwellings and daily behaviour? A particular attention is given to pre-1975 dwelling stock. The pre-1975 French dwelling stock still represents more than 50 % of Primary Residences (PR) in France and 2/3 of SH con-sumptions. Due to slow renewal of the stock, it will constitute almost 40 % of PR by 2050 in a Business as Usual Scenario. Understanding the past benefits of retrofitting of this specific stock is important to forecast future consumptions as well as to design future policies. Our analysis is based on SH energy consumptions time-series from 1973 to 2012 of dwelling's; different vintages and various building census. In our paper, behavioural evolutions are quantified with the calculation of Space Heating Intensity Factors (SHIF). This indicator is the ratio between observed SH consumptions and EPC (Energy Performance Certificate) normative ones. SHIF is used in literature and considered as a proxy of households' behaviour regarding SH consumptions and thermal comfort. SHIF has been estimated for the pre-1975 dwelling stock by 1975 and by 2009 to determine if the increase of efficiency has been partly transformed in "increased" comfort or not. Quantifications of these four main identified drivers (demo-lition, refurbishment, new dwellings efficiency and behaviour) are proposed. Quite surprising results like evolutions of SHIF are discussed.

The initial idea of the French White Certificate (WC) scheme, which entered into force in 2006, was to rely on a tradable WC on the basis of market development leading to save energy at the lowest cost. However, the WC market lacks of liquidity and the majority of the trading is done over-the-counter 1. Thus the question of the energy savings cost arise, especially to better understand where are the "low hanging fruits" and the highest ones. Given the dominance of the residential building sector in the scheme (about 80 % of total WC have been issued in this area since the beginning of the program), we confine our study to the energy refurbishment market for residential buildings in this paper. An economic model, based on standardized operations' monotonic functions of abatement costs (on the same model as Marginal Abatement Cost curve), is designed to estimate the distribution of energy saving costs (Euro per saved kWh). At the opposite of what is usually available in the literature, the costs are described using log-normal distributions, and not mean values, to take into account the scattering of retrofitting prices for the same operation. So we can take in account for each type of action the mean and marginal costs of refurbish-ment. This more realistic approach gives results that are significantly different from using mean values.

Recent European energy policies like the Energy Efficiency Directive (EED) and the EcoDesign Directive (EDD) set new targets to increase energy efficiency. Article 7 of EED implies that EU Member States set up energy savings amounting to 1.5 % of the annual energy sales to final customers from 2014 to 2020. To comply with this requirement the level of French White Certificate (WC) obligation should double in the next period. Moreover, the EDD directive sets the minimum energy efficiency level only for a limited number of equipment such as boilers, heat pumps and water heater. In this regard, the WC scheme deemed savings must be revised in order to comply with the European calculation rules of EED's Annex 5. Certain adjustments must be made to the French WC which has been enforced since 2006 and is entering its third period (2015-2017) to be in tune with these directives. Thus, the WC scheme undergoes a revision of unitary savings differentiating between devices already covered by EDD (e.g. boilers) and appliances which are not (e.g. windows). The outcome is a blend of different references (stock, market) and savings (total, marginal) depending on the considered unitary action. Consequences could be a lack of clarity especially for non-specialists of energy policy. This paper addresses the question of a possible conflict of interests between the European system, allocating savings by directive, and the overall customer savings. Scenarios embedded impacts of the new European rules on the WC market are quantified in order to answer the question: will the third period of WC give a positive signal to the refurbishment market? The overall revising process of the third period of WC and its consequences will be presented concerning the building sector. More precisely, calculations to quantify impacts on unitary action savings, on WC costs and on the retrofitting market structure are detailed. Finally, suggestions are proposed that enable both the enhancement of energy efficiency at the European level as well as the sustaining of the dynamics of the French WC market by providing clear and explicit information.

Energy retrofits are an important leverage to reduce energy consumption in dwellings, especially for space heating. In this paper, we use a discrete choice experiment on space heating for both detached houses and apartments in France. In our choice experiment, we asked 1,820 respondents, both owners and tenants, to imagine that their current space heating system had broken down and that they had to choose a new one to replace it. A multinomial logit model was used to analyze the households preferences and willingness to pay for various space heating system attributes. We found that in general households prefer renewable sources and systems, but avoid wood. Preferences for familiar technologies have a considerable impact on the probabilities of choice and could represent a significant obstacle to the development of energy-efficient equipment. Willingness to pay for attributes that control energy consumption depends on thermal comfort preferences. The more cold-sensitive the household, the more willing it is to invest to renewable energy sources and to set temperature management.

International audience; The thermal comfort in winter is ensured by the capacity of space heating to maintain the desired indoor temperature. This temperature is chosen by household, subject to two limits. On the one hand, the indoor temperature must be high enough to prevent adverse effects on human health due to increase in the risk of diseases. On the other hand, it would be preferable to limit the level of indoor temperature in order to reduce energy consumption for environmental and economic reasons. Given the importance of thermal comfort, it may play a major role in the decision to undertake or not the retrofits works. The discomfort encourages the household to improve thermal characteristics of dwelling and to install more efficient equipment. In this study we propose first the formulation of household utility function from energy retrofits which takes into account the thermal comfort. After that, we estimate Multinomial and Mixed Logits to understand the household behavior the role of thermal comfort in the household’s energy decisions.In January 2015 a sample of 2000 respondents is collected by internet from a panel of 600,000 French Households. The survey consists of two parts (revealed preferences data and two choice experiments) and contains questions about socio-economic and demographic information, dwelling conditions, energy attitudes, space heating system and thermal comfort. In the first choice experiment, the respondent must take a choice between three offers of space heating systems in order to replace the old system which is broken down. The offers are characterized by the following attributes: investment cost, expected energy-savings potential, energy used, type of space heating system, guarantee period, control system to manage set temperature, financial grant and bank loan. In the second choice experiment, we propose to improve energy efficiency of respondent’s dwelling. The respondent must choose between three offers: install new space heating system, insulate walls and roof, to do both. The offers’ attributes are the same as in the first choice experiment.

International audience; The modelling of long-term energy demand dynamics is of prime interest for energy policy design and energy infrastructure planning. The two main modelling approaches (bottom-up and top-down) of dynamics demand simulation have well-known drawbacks: a lack of behavioural realism for the first and a lack of technological explicitness for the second. The main challenge of our work is to build a simulation model of residential energy demand dynamics that is both realistic regarding household behaviour and the overall housing refur-bishment market while ensuring a sufficient level of technological precision. The following elements of realism have been implemented in our bottom-up model, ranging from end-users to the provision chain: • Household energy use: people do not use energy as it is usually described in engineering models, rather they adopt energy saving practices when the energy service price is high (prebound effect), and relax their efforts when energy efficiency is improved (rebound effect). • Household investment in energy efficient technologies: investment decisions are not solely based on techno-economic analyses but also on non-energy benefits (e.g. comfort or estate value), capital constraints and individual preferences. • Refurbishment markets: information problems lead to energy-efficiency barriers, including the low visibility of energy efficient equipment prices (which are notoriously heterogeneous within the market). Moreover, price and efficiency dynamics depend on technology diffusion (techno-logical learning). This model has been applied to two "Factor 4" scenarios-one that is technologically driven (diffusion of energy efficient and low-carbon technologies) while the other is economically driven (high carbon tax)-to analyse how an enhanced integration of realism influences simulated energy dynamics. Results highlight the fact that it can dramatically change the dynamics of consumption, making it a crucial point for policy makers and utilities.

International audience

The paper presents the evaluation of a regional energy efficiency programme in France dedicated to space heating in the residential sector. The large French energy company EDF provides refurbishment advice and financial incentives to the end-users as well as training courses and certification to local installation contractors and building firms. Due to the pilot character of the programme the evaluation is particularly important, both in terms of saved energy and programme costs. Such data were monitored right from the beginning of the programme. In this study, heat pumps for space heating that replace inefficient fossil fuel boilers are analyzed. A billing analysis with temperature normalisation is used to calculate the savings attributed to the programme. Around 90 households were interviewed regarding their individual energy consumption and building as well as household characteristics. Actual data of installation and equipment costs as well as financial incentive payments to customers are provided by EDF. The cost-effectiveness is determined from the perspective of the participant and society as well as EDF. All cost and benefit components are calculated in Euro/kWh, which allows a direct comparison of levelized costs of conserved energy with the avoidable costs of the energy supply system. Results are also expressed in benefit-cost ratios. Critical parameters like the future energy and carbon price development are considered to achieve the most accurate and reliable estimates. Uncertainties are assessed using Monte Carlo simulations. Energy savings and cost distributions are crossed with random probability distributions of the underlying assumption parameters such as the growth rates of future energy and carbon prices. The results indicate how reliable the cost-effectiveness of the programme is from each of the three evaluated perspectives.

National audience; RESUME : La modélisation thermique d'un logement est aujourd'hui usuelle avec un ensemble d'outils de complexité variable. En revanche l'utilisation de ces outils pour simuler les consommations de chauffage réelles d'un logement particulier et de ses habitants, en dehors d'un calcul normatif, reste difficile. Par ailleurs cette étude montre que même avec des outils très simplifiés, l'estimation de la consommation de chauffage d'un parc de logements (plusieurs dizaines de millions) est réalisable avec une erreur acceptable (moins 10%). Entre ces deux échelles (de 10 à quelques milliers de logements), il est beaucoup plus difficile, d'atteindre un résultat correct en l'absence de données détaillées. Différents types de simulations simplifiées (modèle thermique, régression multilinéaire) ont été utilisés pour estimer la consommation de chauffage d'un ensemble de logements. Ce travail se base sur des données réelles notamment issues d'une enquête spécifique auprès des ménages. Les simulations sont réalisées à partir de données techniques, socio-économiques et comportementales. Les erreurs issues de la modélisation et leur évolution en fonction du nombre de logements simulés ont été étudiées. L'analyse des résultats montre que l'ensemble des modèles est capable, sur la base d'un échantillon représentatif minimal (>250), d'estimer la consommation de chauffage d'un parc de logements à l'échelle nationale avec une erreur limitée (

This paper presents the evaluation of a regional energy efficiency program implemented in two "départements" of France. EDF provides refurbishment advices and financial incentives to end-users in the residential sector as well as specific training courses and certification to local installation contractors and building firms. Refurbishment actions analysed in this paper are efficient space heating equipment (condensing boilers, heat pumps and wood stoves or boilers), solar domestic water heating and the installation of new windows. A billing analysis based on a survey of program participants' energy consumption is used to calculate the energy savings attributed to the program. In order to receive an economic feedback of this demonstration program, the evaluation of both saved energy and program costs is of importance. The detailed knowledge of the program's cost effectiveness is essential for EDF to achieve the saving obligations imposed by the French White Certificate scheme at the lowest cost. Results of this evaluation can support the development and implementation of further energy efficiency programs with similar characteristics in other regions of France. The cost-effectiveness is determined from the perspective of the program participant and society as well as the energy company in charge of the program. Results are expressed in levelized costs of conserved energy in Euro/kWh, which allow a direct comparison with the avoidable costs of the energy supply system.

Financial efficiency of retrofitting actions of dwelling stock is always difficult to evaluate. Even if retrofitting market is not driven by financial profitability, evaluation of any efficiency programme is necessary and relies primarily on energy saving calculations and costs assumptions. The main question is the accuracy of chosen assessments that depend to a large extent on available data and sources. In this paper, we discuss how arguable is an evaluation with 5 different methods of energy savings evaluation and 5 different sources of cost data. For each considered retrofitting action (3 for dwelling envelope, 2 for space heating system, and 1 for domestic hot water generation) 5 different financial indicators are calculated. Large number of results (900 data) allows discussion on data, sources and methods accuracy. Ranking of retrofitting actions and influence of chosen indicators are also discussed. Finally, the impact of energy saving evaluation methods and cost data on the cost and energy savings variability of retrofitting program is calculated.

Implementing effective energy policies in the residential sector requires better understanding of the sources for the dispersion of energy consumption amongst households. Bottom-up statistical models have been identified as one major modelling technique, particularly accounting for the diversity of inhabitants behaviours. In the various statistical models of the literature, behaviour characteristics are seldom incorporated in the data set but socioeconomic data are most often used as " proxy " of occupant behaviour. The present study is based on a detailed survey, combining energy billing data with technical, geographical, socioeconomic and behavioural variables. The corresponding sample, despite of its limited size (420 individuals), is representative of French households. A statistical model relating energy consumption to the other variables has been applied, enabling simultaneous use of quantitative and qualitative explanatory factors (ANCOVA, analysis of covariance). The main determinants found for energy consumption in the sector of single-family dwellings in France are, by decreasing order of weights, surface area, type of main heating system, age of the household head and climate zone. We detected that the most influential behaviour variable is night temperature setting reduction. Explanation and prediction capacities of the model as the accuracy of the model coefficients are studied and some possibilities of improvement are proposed.

The potential of energy savings in the EU has been evaluated in the recent years. On a technical basis, it is frequently said that the amount of energy services delivered could increase by a factor two while using 50 % less energy. The EU green paper for energy efficiency published in June 2005 and the resulting European Action Plan for Energy Efficiency indicate that the economic energy saving potential is higher than 20 % of the total energy consumption in the EU. On the same time, markets face barriers to fill the gap between this economic energy savings potential and the actual observed energy consumption. An investigation of the evaluation methods for assessing the energy savings potential at a global level introduces many assumptions. The paper reports the different issues to be addressed in order to evaluate the energy savings potential at a regional or national level. Results obtained at EDF/R&D on technical potentials of individual energy end uses in France are given. The aggregation and the accessibility of these potentials are discussed but not quantified, while it is considered at the present time that the uncertainty is still too high to enable a consistent quantification.

National audience; Deux des objectifs importants des politiques énergétiques européennes et françaises sont la réduction de la dépendance énergétique et des émissions de gaz à effet de serre. La « MDE » (maîtrise des consommations d'énergie) fait partie des actions incontournables pour atteindre ces deux objectifs. Les bâtiments sont le premier secteur de la demande en énergie en France. Il est désormais reconnu que les objectifs de réduction drastique de leur consommation d'énergie et des émissions de CO 2 passent par une rénovation intensive du parc de logements existants. Une estimation des coûts techniques (investissements) liés aux scénarios étudiés est proposée. A horizon 2030, ce travail explore différents scénarios de rénovation du parc de logements [rythmes tendanciels et accélérés, techniques « standard » ou « MTD » (meilleures technologies disponibles)] en introduisant, en complément des solutions actuelles, quelques techniques encore peu développées qui pourraient jouer un rôle important pour atteindre un objectif « facteur 4 » à 2050. Les scénarios sont modélisés à l'aide du logiciel MIeL « Modélisation de l'Impact de mesures Energétiques sur les Logements », développé par EDF et construit sur une démarche bottom-up. Mots-clés : MIeL, MDE, Modélisation.

International audience; Determinants of Household Energy Consumption in France : Behavior Approach

International audience; The European energy and political context suggests that households will have to face up to making significant reductions of their energy consumption over the coming decades. Indeed European Union has adopted a 20 % reduction in energy consumption by 2020 in its climate energy package. The aim of this paper is not only to study the refurbishment and technological changes implied by such targets but also to show its impact on household budget as this ambitious target may imply strong efforts from households. Studies that deal with efficiency of policy tools generally adopt a global economic point of view and rarely consider dis-tributional impacts on final consumers and if so, do not consider possible differences in consumer behavior patterns regarding energy use. How can we therefore assess the suitability of such policies without clearly anticipating their repercussions on households, whose behavior is obviously heterogeneous? In order to provide useful insights about the impact of such policies on residential sector, it appears crucial to capture both household heterogeneity and household behaviour in long-term planning models. Our analysis relies on the TIMES-Households model which is a bottom-up optimization model from the MARKAL/TIMES family of energy models that allows for a very significant disag-gregation of demand and technological processes. The building stock and its inhabitants are then represented in a very detailed manner considering both technical and socio-demographic characteristics. Moreover, thanks to analyses picked from a detailed household survey we are then able to differentiate access to technologies, level of energy demand and equipment purchasing behaviour according to household characteristics (income, size, type of housing, occupation status). We show the impact on household budget of the 38 % reduction target of primary energy consumption in residential building stock by 2020 adopted by the French government.

International audience; Residential buildings sector encompasses increasing energy demand projections and large technical potentials for energy savings [Levine et al., 2007] that are mainly more cost-effective than in sectors like transportation or industry. However, the decline of main residential energy uses in France (space and water heating) is limited by market and behavioural failures, making the reach of ambitious reductions targets very unlikely without the implementation of dedicated public policies [Giraudet et al., 2009]. Moreover, prospective studies have also shown that only major technological change scenarios on heating usages for existing buildings meet overall national long-term target (carbon emissions reduction by a factor of 4 in 2050 comparing to current level) [CLIP, 2011]. On one hand, current political context is characterized by increasing public finances constraints (leading recently to the reduction of efficient refurbishment tax credit in France). One the other hand, it has been shown that residential energy savings potentials are very diverse in cost-effectiveness [Laurent et al., 2009] and technological learning potential [Weiss et al., 2008]. Finally, recent work highlighted the importance of energy demand heterogeneity representation when studying the diffusion of energy efficient equipments [Cayla, 2009]. Previous elements draw a need for a realistic and technology rich modelling of energy efficiency potentials and related households investment decisions in response to various types of policy instruments. Such model aims at providing an efficient and realistic support for national energy policymakers, better adapted to their financial constraints and energy reduction targets than classical normative and aggregated models.

International audience

International audience

International audience

International audience

This paper presents the evaluation of a regional energy efficiency programme implemented in two “departements” of France. Electricite de France (EDF), a French energy company, provides refurbishment advice and financial incentives to end-users in the residential sector as well as specific training courses and certification to local installation contractors and building firms. Refurbishment measures analysed in this paper are efficient space heating equipment (condensing boilers, heat pumps and wood stoves or boilers), solar water heating systems and the installation of double-glazed windows. A billing analysis based on a survey of programme participants’ energy consumption is used to calculate the energy savings attributed to the programme. In order to receive an economic feedback of this demonstration programme, the evaluation of both saved energy and programme costs is of importance. Detailed knowledge of the programme’s cost-effectiveness is essential for EDF to achieve the saving obligations imposed by the French White Certificate scheme at the lowest cost. Results of this evaluation can support the development and implementation of further energy efficiency programmes with similar characteristics in other regions of France. The cost-effectiveness is determined from the perspective of the programme participant and the society as well as the energy company in charge of the programme. All cost and benefit components are calculated in Euro per kilowatt-hour, which allows a direct comparison of levelized costs of conserved energy with the avoidable costs of the energy supply system.

International audience