One activity of the French company "La Française Asset Management" is the management of real estate assets and services. The company manages over 1,000 buildings and 150 hotels with a total area greater than 2.1 million square meters. An energy audit was operated on 42 commercial buildings for a total area of 153,254 m² between March and December 2010. The objectives were to develop a methodology and to assess the amount of work to be done for an energy efficiency improvement.
The energy audit, with a cost of 251 k€, has been partly funded (110 k€) by ADEME.
The 42 audited real estate assets were selected and classified into nine typologies acoording to their period of construction (some of them dating from the 19th century) and their use (offices, shops, warehouses). An energy audit and an energy action plan with costs were established for each building. Synthesis reports called "Greenbooks" were developed for each asset typology, presenting a technical description (structure, envelope, technical equipment), energy and environmental performance figures and the energy efficiency action plan.
The lessons learnt are:
- It is essential to distinguish between commercial buildings according to the date of construction. Old buildings renovated before 1988 offer the highest energy savings potential, even if offices from the period 2000-2005 can also reduce their energy consumption by 15 to 30%.
- The type of renovation (light, full renovation, restructuring) is strongly influenced by the choices made during construction. This is particularly true for the heating system that accounts for between 30 and 40% of consumption, or for lighting (20% of consumption).
- The financial impact of compliance is not insurmountable.
These conclusions led the company to start the renovation of 2 buildings from the 1960s.
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