Challenge
Schiphol Airport in the Netherlands aimed to achieve sustainable heating and cooling for its office buildings, terminals, and piers. The airport uses Thermal Energy Storage (TES) systems, which store thermal energy underground. New buildings are equipped with TES, and existing buildings are transitioning away from gas, leading to significant reductions in CO₂ emissions.
A collective TES was designed for the Schiphol Building (SHG), Outlook 1 and 2, and Avioport. This required connecting heat pumps and dry coolers to the three buildings via underground pipes, with each building having its own heat pump station. A solution was needed for two nearby buildings without their own TES. The Outlook office building still relied on gas-fired boilers and chillers for heating and cooling
Solution
In preparation for the central TES project, four Trane City RTSF heat pumps were installed in the Schiphol building a few years ago, initially operating with the old sources.
For The Outlook's heat pump system, Trane was also selected: five Trane City RTSF 110 heat pumps with refrigerant R1234ze (<1 GWP) were installed. These heat pumps are compact and modular, making sustainability possible in challenging locations.
Paul Varekamp, project leader at technical service provider Equans stated: " At the entrance of The Outlook's parking basement, we only had a few centimeters of clearance. A larger size unit than the Trane City RTSF would not have been possible.”
City™ RTSF water/water heat pump highlights:
• 99.5% reliability thanks to screw compressor technology and standard Adaptive Frequency™ Drive
• Fully optimized for HFO R1234ze refrigerant (<1 GWP). Available with R515B as an alternative
• Minimized refrigerant charge
In addition to the five Trane RTSFs, one Trane Exergy P30 industrial heat pump was also installed in the parking basement.
Paul Varekamp explained: "Some installations in The Outlook buildings needed 70°C water. Replacement would have caused too much disruption for tenants. Therefore, we installed a small Trane Exergy to boost the water from the RTSFs to 70°C where needed. It's an economical solution."
Exergy RE, P, and S series industrial heat pumps highlights:
• Suitable for heating and cooling applications, either as a specific cooling/heating solution or as a combined solution
• Multiple compressor technologies: scroll, piston, and screw
• Multiple refrigerants: standard to near-zero GWP
The new sustainable themal system of The Outlook can simultaneously provide heating and cooling in different parts of the building if desired.
The old chillers In the parking basement were replaced by heat pumps, with existing gas boilers remaining on standby to assist if needed.
Paul Varekamp noted: "If you consider weather extremes when selecting a thermal energy storage system, you get an unnecessarily large and expensive system. How often does it get below -10°C in the Netherlands? The heat pumps will likely always meet the heat demand.”
Results
At the end of January 2025, in the middle of winter, The Outlook office building switched to the renewed source system and its own heat pump solution.
With the collective TES for three buildings, Schiphol saves approximately 625,000 m3 of natural gas per year. The airport aims to have all of their buildings off the gas grid by 2030, using thermal energy storage systems in new constructions and phasing out gas in existing premises.
