Cooll tests thermally driven heat pump at extreme low temperatures in GTI Energy Lab in the United States
This summer, Cooll took an important step forward in its Canadian NGIF project. In August 2025, our team traveled to Chicago to test our thermally driven heat pump (TDHP) under extreme cold conditions at GTI Energy’s laboratory. The goal: to see how the system performs at extreme cold outdoor temperatures that are common in North America but rarely encountered in Western Europe.
Putting the heat pump to the test
The testing campaign was carried out in line with U.S. standards and marked the first time that Cooll’s heat pump was operated at such extreme temperatures. Over the course of two weeks, two of our engineers worked closely with GTI Energy’s team to set up the installation and conduct a full range of performance measurements.
Beyond the technical tests, we also had the opportunity to present our technology to GTl Energy’s end use research team. The presentation sparked a lot of interest, and many researchers visited the lab to see the system in action. One aspect that stood out immediately: just how quietly the Cooll heat pump runs.
Key findings low temperature testing
- Stable performance – The system delivered consistent results across all baseline measurements;
- Integration with air handling units – In North America, most homes rely on air heating systems rather than radiators. We tested our heat pump with an air handling unit, and these tests showed minimal degradation in performance compared to radiator-based systems;
- Operation at –17 °C – We successfully operated the heat pump at -17 °C for the first time. Mechanically, the unit performed well. The team did identify a limitation in one of the control strategies, which we will optimize in the next project phase.
Next steps in extreme conditions
The test campaign was a major milestone in the NGIF project and an associated project funded by Utilization Technology Development, NFP (UTD). Reporting and analysis are now underway, and we are already preparing for the next test round. In Spring 2026, Cooll will return to GTI Energy to apply the lessons learned and further validate performance improvements under extreme conditions.
