Office building of CAF de Lyon

This building is an office building for the French administration with an area of around 16 500 m². The heating and cooling demand are fulfilled by two reversible heat pumps of 600 kWth. The heat pumps are fed by ground water from an aquifer through an open loop system with one well for extraction of water and another one for the injection.

Project description

Building, overall energy concept

The building was built in 1997. It has an area of 16 633 m², 6 storeys and an energy waste coefficient of 0.42 W/m³/°C, that is to say, less than the requirement of the French thermal regulation of that time (0.54 W/m³/°C for this building). The building is located in the centre of Lyon city. Lyon is the third town of France and is located in the south part with a climate relatively warm. This climate, and the internal thermal loads due to office equipments (computers, copiers, etc.), lead to a need of both heating and cooling.

Photo 1: View of the CAF building

The heating and cooling system is using two heat pumps, fed by ground water through wells.

The well exploiting the water from the aquifer is using two variable-speed pumps of 100 m³/hour.

The distribution for heating and cooling is made through 4 tubes fan coil units.

The hygienic ventilation of the building is made through double flux fan units including a cooling and a heating battery fed by the heat pumps.

A building management system (HONEYWELL) is operating the system, including the lighting of the offices.

Heat pump system

The heat pumps are water to water machines with compressors driven by electricity. The whole system for heating & cooling mode uses the aquifer as heat source or sink.

The heat pumps, called "thermofrigopompe" in French, are able to produce simultaneously both heating and cooling, through the implementation of an additional exchanger as illustrated on the following diagram.

Both heat pumps have a heating capacity of 600 kWth, and a cooling capacity of 600 kWc. They are manufactured by CARRIER and use R134a as refrigerant.

The supply/return temperatures for cooling are 7/12°C in summer and 10/12°C in winter.

The operating points for heating are 35°C for 20°C outside and 45°C for 0°C outside.

Operation experiences

A measurement campaign was done from 1998 to 2006 by the Research and Development department of EDF, the biggest French company for electricity production and distribution.

The system was monitored and operated with very good efficiency and reliability over 8 years.

The yearly average global COP (see diagram), including heating, cooling and pumping have been measured.

The global energy consumption of the building is on average, over the measurement period, of 154 kWh/m²/year. The reversible heat pumps represent 36,5 kWh/m²/year, the wells pumps about 18,8 kWh/m²/year and the ventilation about 12,3 kWh/m²/year. The remaining part covers the offices activities, lighting, hot water, etc.

Costs, economic efficiency, incentives

The investment costs (heating/cooling system, ventilation, building management system) were of 170 Euros/m² in 1996.

The annual heating/cooling costs over the measurement period are of 2,34 Euros/m², plus 0,86 Euros/m² for the wells pumps and 0,73 Euros/m² for ventilation.

The average cost for 1 MWh of heating and cooling is 17 Euros.

With regard to a system using a gas boiler and a traditional cooling system, the economy is of 0,94 Euros/m².

With regard to a system using a gas boiler and a gas absorption cooling system, the economy is of 1,75 Euros/m².

Regulations, guidelines, benchmarking

No information available

References

 "CAF de Lyon : Bilan de 1998 à 2006: Du chaud et du froid à un coût optimal respectueux de l'environnement" (José Naveteur - EDF R&D)

¹ period from 1998 to 2006
² Average over the 1998-2006 period, including the well pumps
³ Average over the 1998-2006 period, including the well pumps
⁴ Average per year over the 1998-2006 period. The average degree days over the period were of 2166.
⁵ Average per year over the 1998-2006 period. The average degree days over the period were of 2166.
⁶ Only direct emissions (thus excluding possible refrigerant leaks). Only for heating, cooling and pumping.