The city of Colombes on the outskirts of Paris wanted to communicate about the challenges of energy upgrades of buildings and identify stimulus measures. As part of this initiative, it commissioned the DRIEA, CEREMA and the CSTB to research specific case examples, the results of which were published in May 2014. The role of the CSTB was to analyze system renovation scenarios in two condominium buildings.
Two buildings were selected from a map of typical locations prepared by the Direction régionale et interdépartementale de l’équipement et de l’aménagement d’Île-de-France DRIEA [Paris Regional and Interdepartmental Infrastructure and Development Agency] in conjunction with the city of Colombes. The CSTB’s mission was to characterize both buildings, assess their initial energy performance, propose alternative renovation scenarios and assess their impacts. The solution packages offered involved improvements to the intrinsic characteristics of each building in terms of envelope thermal performance and energy system efficiency. The post-upgrade assessment was based on energy, environmental and economic criteria.
The two buildings studied were different in many ways, including their dates of construction, external environments and resident profiles; as a result, they required customized solutions. The study demonstrated how the decision-making process for a particular scenario is specific to the building concerned (or family of similar buildings) and cannot be generalized to all building types. The study also underscored the need to set goals for upgrades that address both performance and economic viability, beyond a simple return on investment.
Application of the Paris Region Climate, Air and Energy Scheme (SCRAE)
The study conducted on two buildings in Colombes was the extension of work carried out by the CSTB in 2012 as part of preparing the Paris Region SCRAE. At that time, the CSTB prepared energy upgrade specifications for five building types representative of the Paris Region housing stock, all with substantial energy challenges. For each type of building, it prepared detailed specifications containing remediation solutions and their energy, climate and economic impacts. These specifications were then used to conduct a prospective analysis of Factor 4 for the “Paris Region residential buildings” sector between now and 2050.