INETI building in Lisbon, Portugal

Description of the application

The objective is to have air conditioning of 12 office rooms, located in the first floor of Building G of INETI Campus and belonging to the Renewable Energy Department.
The design chosen for the system optimizes users comfort in office rooms whom are well satisfied with system operation along the years.

General description of the system

The air conditioning system is an air handling unit of DEC type incorporating a heat pump and assisted by 24 CPC type solar collectors located in the flat cover of the building. A gas boiler is used as backup for the solar thermal system in winter.
Cooling is provided in summer months (between April-May and September-October) and heating in winter months (between October and March).

Central air-conditioning unit


open cycle (DEC)

Nominal air volume flow rate

5,000 m3/h

Minimum air volume flow rate

2,000 m3/h

Desiccant cooling system type

solid desiccant

Desiccant type

lithium chloride,

Cooling capacity

36 kW

Brand of desiccant unit


Solar thermal

Collector type


Brand of collector

Ao Sol

Collector area

46.1 m2 aperture

Tilt angle, orientation

30, 0 west/east

Collector fluid


Typical operation temperature

4560 C driving temperature for chiller operation


Heat storage

2 m3 water

Cold storage


Auxiliary heating support

gas boiler

Use of auxiliary heating system

space heating in winter

Auxiliary chiller


- type

heat pump

- capacity

16.4 kWcold

System performance

The standard design of the solar assisted desiccant evaporative technology incorporates two humidifiers: one for the process air, after heat recovery wheel, and another for the exhausted air, before heat recovery wheel.
The system that is installed at INETI was modified to incorporate a heat pump in the process air path (incoming new air path), substituting the humidifier in this path. The reason of this modification relies on the limited size of the air distribution system, which obliged to reduce the air flow rate in the design conditions and at the same time to introduce air in the rooms at lower temperature, to be able to cover the cooling load.
The analysis of system behaviour showed the need to introduce again a humidifier in the incoming air duct. This change was made (2007) but it is not yet operational and monitored.

General information

Type of building  office building
Location  INETI Campus, Lisbon
In operation since  1999
System operated by  -
Air-conditioned area  117 m2
Capacity  597 m


Air handling unit with DEC technology
Caption 1
Solar field in the cover of DER building
Air handling unit with DEC technology
Scheme of the system
Solar field in the cover of DER building

Clicking an image opens the gallery view.

Specific information

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


848 K


For more information on the project please feel free to contact:

Maria Joo Carvalho