CO2 heat pumps for the Rocksresort Laax
Using resources responsibly is a core part of Rocksresort’s DNA. As part of its efforts to further reduce its use of fossil fuels, air-conditioning and heating at the resort now rely on two efficient and climate-friendly CO2 heat pumps from CTA.
A bespoke solution for tight spaces
Due to space constraints in Rocksresort’s existing energy centre, CTA delivered two compact, custom CO2 heat pumps that can generate both heat and cooling. Each heat pump has a cooling output of 160 kW and a heat output of 240 kW. Cooling is stored in a cold storage tank and used for air-conditioning, dehumidifying the air and cooling hotel rooms and apartments. Heat is fed into the local heat network at 73 °C for around 1,100 guest bedrooms. Efficiency is increased even further by recovering waste heat from wastewater used in both the most recently constructed buildings and the three-storey car park.
The heat pumps on site
2x CTAexklusiv industrial heat pumps
Cooling output: 163 kW
Heat output: 240 kW
Refrigerant: R-744 (CO2)
Continuous output control with frequency inverter: 50–100%
CO2 refrigerant shows its strengths
CTA suggested a CO system based on Rocksresort’s requirements, including the need for a natural refrigerant, warm water heated to more than 70 °C and the layout of the machine room. The refrigerant offers clear advantages for this use case, particularly in terms of safety requirements (Class A1). CO is non-flammable, which means the machines are easy to integrate with relatively little work required to meet safety standards. As CO is heavier than air, the resort only needed to install additional gas detectors and a reliable ventilation system to protect people and equipment in the event of a leak.New control software for transcritical operation
Precise high-pressure control is vital for both efficiency and operational safety in transcritical CO2 systems. For this reason, CTA developed its own control software for its CO2 machines. All key control components – from the flooded evaporator and low-lift ejector technology to high-pressure control in transcritical operation – were developed in-house and brought together in a proprietary control system. This delivers direct benefits in terms of efficiency over the product’s entire service life.The CTA control system also includes peripheral devices such as pumps, valves, evaporators and gas coolers. Clear interfaces with building automation, which handles load and storage management, guarantee reliable and safe operation.
Christoph Brechbühler,Systems Engineer and Head of Sales
A convincing integrated system
“Combining heat and cooling led to an integrated system that is highly energy-efficient, compact and perfectly tailored to Rocksresort’s requirements.”
Successful performance test
Prior to delivery, engineers at CTA put the system to the test in our quality assurance facility in Münsingen. The control architecture was put through its paces, and the design was tested with the same space constraints it would have in the machine room in Laax. This ensured that both machines could be installed without any issues and put seamlessly into operation in May 2026.
Contributors
Building owner: Rocksresort Laax
Planning: enavant AG, Malans
Construction and project management: domenig architekten, Chur
Heat pump and system supplier: CTA AG
Comprehensive range of services
Once your CTA chiller, air conditioning unit or industrial heat pump has been installed and commissioned, our service team will ensure it runs perfectly and smoothly for years to come. Find out more about our choice of service contracts, from direct labour maintenance via flat-rate service contracts to CTAprotect, our all-inclusive service with warranty extension.
