Good practice

Energy savings by regulating operating times

Energy savings by regulating operating times
© Kuznietsov Dmitriy, image #137673204, source:
Office and administration
Low cost
Annual saving:
Payback time:
0 Year(s)
Resource savings: Energy:
63 000 kWh electricity 39 000 kWh heat network
Co2 emission reduction:
14.7 tonnes CO2 per year
Premises and operation areas:
Office building
Size of company:
Medium (less than 250)
Advancement in applying resource efficiency measures:
One off investment:

Towards real-time room occupany monitoring

  • Hourly programming system saves 63 000 kWh electricity and 39 000 kWh heating annually
  • Zero investment saves € 8 500 per year

The Nantes Conference Centre ('The City') in France carried out an energy audit to better understand what actions it could take in order to have energy and cost savings.

The audit identified a 130 kW fixed power level during The City’s unoccupied periods, which could yield 200 MWh annual savings if remedied. Investigations showed, among other things, that the four air-handling units in the administrative office building were operating continuously, even at night and on weekends, which represented nearly 3 000 'wasted' hours a year.

The City implemented a plan for managing air temperature during office hours, with restart times optimised down to the hour, which ensures comfort levels are maintained when staff are present.

Key benefits

The fine-grained programming of the air-handling units saves The City 63 000 kWh in electricity and 39 000 kWh in heating annually, translating into savings of € 8 500 a year.

Management also plans to instal sensors on the air-handling units to monitor CO2 concentrations as an indication of people being present in the room and the need to adjust fresh air flow. This approach would suit rooms with intermittent and variable occupancy, such as conference and entertainment rooms. 


"Our consumption profile shows that we have a fixed level of electricity consumption of about 15 % that does not depend on our activity and on which we now have simple levers of improvement thanks to our supervision and hourly programming. The idea is therefore to look for equipment and facilities that could be shut down during periods of unoccupied space." - Mr Caille, Deputing Managing Director, The City

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