Résidence du Lac, Maclas, France

Description of the application

The targeted building welcoming the solar cooling application is the Résidence du Lac, a building dedicated to retired people. This building is sitted in the village of Maclas in the Rhône Alpes area, close to Lyon. The village is in altitude, nearly 450 m high.
The building was created in the seventies and is of an average quality level for the energy efficiency. Only one small part of the building is cooled, the leisure space/restaurant which is compulsory since summer 2003 in retired buildings. This area is of 210 m² and includes a veranda oriented in the Southern direction. Efforts were made to increase the solar protection level in the veranda by adding dark thin protection films. Till 2007, the building owner used electric compression chillers (3 monosplits). Two of them were out of order in 2007 and the management took the decision with the help of the SIEL (Syndicat Intercommunal d’Energie de la Loire) to go for a solar cooling system. The owner of the system is the SIEL itself.   

General description of the system

The system is based on an absorption chiller of 10 kW coupled with evacuated tube collectors. The system is in configuration of a quasi solar autonomous cooling system because only a small electric compression chiller (splite type) is used in case of failure of the solar system. The load of a part of the entire building is based on the following scenario: cooling demand from June to mid September and heating demand from mid October to end of May. The solar system is using fan coils for the cooling and heating modes but thanks to a buffer storage, it can be valorized as well in the heating mode through the central heating network of the Résidence du Lac. The heat rejection system is done by a drycooler sitted in the Northern facade of the building.

Central air-conditioning unit


closed cycle

Nominal capacity

10 kWcold

Type of closed system


Brand of chiller unit


Chilled water application

fan coils



Heat rejection system


Solar thermal

Collector type

evacuated tube

Brand of collector

Thermomax Mazdon 20

Collector area

24 m2 absorber area

Tilt angle, orientation

30 °, 15 ° west

Collector fluid


Typical operation temperature

75 °C driving temperature for chiller operation


Heat storage

0.5 m3 water

Cold storage

buffer water (80 litres)

Auxiliary heating support


Use of auxiliary heating system


Auxiliary chiller


- type

el. compression chiller

- capacity

3 kWcold

System performance

Energy production expectations:

  • Cooling : 4,300 kWh/year (4 months)
  • Heating : 8,300 kWh/year (8 months)

TOTAL = 12 600 kWh/year

Energy savings:

  • Cooling: 5 c€/kWh (EER = 2; bad quality split)
  • Heating: 6 c€/kWh (fuel burner; 85 %)
  • Electricity consumption : 845 kWh = 42 €/year

TOTAL = 1,150 €/year
(on the basis of an average increase of energy price of 5 %/year)

General information

Type of building  Retired people residence
Location  Maclas, France
Auxiliary heating support  fuel (central heating system)
In operation since  2007
System operated by  SIEL
Air-conditioned area  210 m2


Dry cooler

Cooled area: the leisure space/restaurant
Dry cooler
Schema of the application
Cooled area: the leisure space/restaurant
24 m² of evacuated tube collectors
Schema of the application

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Specific information

Further specific information about the system are included in the filled in technical questionnaire.


285 K