Refurbishing 17 Millions of thermal insufficient “prior-to-1975” dwellings in France
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Author : Olivier SIDLER - ENERTECH
This report (in French) starts with an analysis of the energy stakes at the begining of the 21st century. The main threats are global warming and exhaustion of the ressources.
The carbon balance indicates that we have to divide by four our energy consumptions. This effort in the building sector is analysed here, in order to determine the rules that should be implemented as soon as possible in this sector. From now on, the objective should be to renovate buildings so that their energy consumption for space heating does not exceed 50 kWh/mē/year, and that their consumption for domestic hot water (DHW) remains lower than 10 kWh/mē/year.
We therefore study what national strategy should be to go with and support this ambitious objective. It first appears that it is essential to renovate all of the dwellings that were built prior to 1975, before 2050. And we also have to renovate these dwellings up to 50 kWh/mē/year maximum, if we want to reach the objective we set.
But how can we reach such a high performance, and by which technical means ? Many dynamic thermal simulations have shown that the best way is to rationalize renovations, and to propose a unique technical solution France-wide. This would lead to noticeable differences between the consumption of the dwellings in different French regions (between 20 and 80 kWh/mē/year), but the average value for the whole country would reach the expected 50 kWh/mē/year. This report therefore suggests a "package" of technical solutions that would greatly simplify these operations, especially for the renovation of detached houses.
The economic analysis over 20 years shows that in most cases of thermal renovations, the savings in energy costs are greater than the yearly repayment of renovation costs. At the end, savings become earnings.
This study then examines the strategical advantages of a national program for renovation, as well as the strategy that the relevant actors should adopt.
Finally,we explain in detail the German experience of dwellings renovation.
In conclusion, we present the first French projects to renovate dwellings to very low energy consumption levels.