DIREN building in Guadeloupe

country : France	collector area : 61 m²
location : Basse Terre, Guadeloupe (Carib. area)	collector type : Evacuated tube collectors
building : DIREN	cooling capacity : 35 kW
technology : absorption	In operation since : October 2003
main positive points : First solar cooling system working in France, overseas (tropical climate) Cooling campaign all year long. Specific climatic conditions with high humidity rate : interest on the behaviour of the absorption chiller in term of performance

The regional environment authority (DIREN) in Guadeloupe has built a new office building at Basse Terre. The high environmental quality of this building includes a cooling technique that
uses chilled water produced from solar energy as a demonstration project. The project was initiated in 1998 and the offices will be operational in 2003.

This project concerns a two-floor office building, built in length and slightly curved (see photos). The main axis runs North-East/South-West. The total floor area is 1.000 m², but only 570 m² are cooled by the solar system, that is about 36 offices.

View of the building

The local climate is a wet tropical one.

	jan	feb	mar	apr	may	jun	jul	aug	sept	oct	nov	dec
external temperature (°c)	24,3	24,1	25,5	26,1	27,1	28	28	27,9	27,7	27	25,9	24,5
horizontal solar irradiation (kw/h/m² ; day)	4,4	5,2	5,6	5,7	5,1	5,9	5,1	5,4	5,2	5,3	4,6	3,8

The instructions for the desired indoor conditions are as follows:
Dry bulb temperature: 26 °C
Relative humidity: 50%
The air-conditioning should be operational during office hours, that are from 7:00 to 17:00, from Monday to Friday.

Ventilation: the total fresh air flow is 1470 m3/h

The maximum cooling load is 79 kW with:
57 kW without ventilation
22 kW due to the fresh air intake.

Design of air conditioning equipment/concept

Cooling is distributed by means of a chilled water circuit, produced according to the following principle (see diagram):
Pre-cooling of the chilled water loop (nominal temperatures: 7 – 12 °C) by the absorption machine (30 kW), supplied by the solar vacuum tube collectors, and connected to a water based open cooling tower.
The back-up energy is supplied by a liquid based cooling plant (55 kW), with air condensation. Without the absorption machine, this plant would have required a power input of 90 kW.

This system was chosen for several reasons:

The DIREN, is responsible for environmental protection and was obliged to build an exemplary building.
The building should provide an excellent demonstration project, without too much risk: it should function and offer comfortable working conditions.
The cooling system and its regulation should not be too sophisticated, in order to avoid the risk of frequent breakdowns. The reliability should be similar to traditional systems,
The system in series, that was chosen, is an answer to the need for simplicity, reliability and security.

Collector + solar system design

The required temperature levels needed for the good working order of the absorption machine (85 – 95°C) called for the choice of vacuum tube collectors from the beginning of the project.
A call for tender was made for the complete system: Caraïb’ Froid Systems, were selected amongst the three companies that replied, and he proposed the CORTEC solar collectors manufactured by J. Giordano Industries, in his offer.

The pre-sizing is simple:

Cooling output: 30 kW
Average COP: 0.70
Input needed for the generator: 42.8 kW
Reference solar energy supply: 700 W/m²
Useful solar collector area needed: 61.2 m²

There isn't an intermediary storage tank (see diagram). The collectors are connected to the generator of the machine by means of a very small capacity buffer tank (<100 litres). The cooling output (30 kW) was established so that it would be always slightly less than the load at all times during sunny periods. In this way the machine can operate directly with the sun, and use all the energy supplied by the solar collectors for cooling. When the load is higher, the compressor makes up the difference

Technical premices

System operating since October 2003. Test phase.No results available yet.

Expected results:

This system should make it possible to save a third of the electricity billed for air-conditioning every year, if this is compared with a traditional compression system (for which the output is 90 kW):
Cooling load: 68 681 kWh/y (68 kWh/m².year)
Solar cooling supply: 32 700 kWh/y
Electricity saved: 10 900 kWh/y
Primary energy saved: about 3 TOE/y
Financial savings: 1 500 €/y
Environmental impact: 8 tonnes of avoided annual CO2 emissions to the atmosphere.

The solar cooling system has just started working so the users cannot really measure the impact on the comfort conditions.

TECSOL S.A
105, av. Alfred Kastler – BP 434
TECNOSUD
66000 PERPIGNAN Cedex
FRANCE
E-mail : info@tecsol.fr

The first data must be recorded before giving any conclusions.