Widely considered a fundamental benchmark of Italian and European rationalism, Grattacielo Pirelli was designed by Arch. Gio Ponti and Ing. Pier Luigi Nervi and built in the late 1950’s as the new Pirelli headquarter. In 1978, Grattacielo Pirelli was acquired by Regione Lombardia and refurbished by Arch. Bob Noorda.

In 1997, Regione Lombardia established a public tender for the refurbishment of all building services of Grattacielo Pirelli. Regione Lombardia also requested the following constraints to be kept into account:

  • Daily operations of the office floors to be guaranteed during the refurbishment works, expect for a maximum of two floors at a time
  • No additional temporary plant room space allowed

Although the use of Groundwater as heat source for mechanical services was strongly prohibited by all laws and regulations in force in Lombardy at that time, ARIATTA proposed for the public tender to use Groundwater for several uses in the refurbishment, highlighting the huge advantages in terms of energy efficiency and cost effectiveness.
The design strength points of ARIATTA were such convincing and clearly beneficial not just for this particular refurbishment, but also as a strategic way of designing new urban developments in general, that Regione Lombardia changed Building Regulations and current laws, in order to allow the use of Groundwater as heat source for building services.

The following points outline ARIATTA’s design and strategy for the refurbishment of Grattacielo Pirelli in 1997, which won the public tender and contributed to change the way new buildings are designed nowadays in Italy.

  • Replacement of existing floor standing fan coil units with new water source reversible heat pumps, two floors at a time (condensing water routed to the new units inside the ceiling void of the floor below)
  • New risers for condensing water loop, connected to on-floor water source reversible heat pumps
  • Condensing water discharges heat into the Groundwater loop via plate heat exchanger with no need of mechanical refrigeration (reverse cycle for heating); much lower condensing water operating temperatures than in traditional cooling tower systems, resulting in higher efficiencies of the water source heat pumps (20% cooling energy saving is calculated)
  • Condensing water loop recovers heat from the east facing offices to the west facing offices during partial load operations
  • Groundwater is also used to pre-cool primary air for the office floors (estimated 50% cooling energy saving compared to traditional air handling unit systems)
  • Existing cooling towers located on the last floor removed and existing plant room replaced with new top floor terrace; high commercial value improvement of the building
  • Existing plant rooms on Basement level used during the refurbishment to maintain the office daily operations, fully re-designed after the last office floor was completed; large quantity of asbestos removed during the refurbishment
Performed Activities
MEP Design for plants refurbishment
Eleca spa
End user
Regione Lombardia
High Rise, Office, Headquarter
25.000 m² (Tower) + 11.000 m² (Auditorium + Low Rise Buildings)
127 m - 31 floors
Electric power from network: 8 MW / Cooling Capacity installed : 5,5 MW / BMS Structure: 5400 points controlled
1997 (Design), 2005 (Completed after airplane crash in 2002)
Photo Credits