Suchergebnisse

International audience ; 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 ...

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.