The ranked list in this dataset covers 27 companies, with a single leading assignee holding 28 of the 114 records in scope — roughly a quarter of everything filed. The next four assignees combined bring the top-5 total to 78 records, or 68.4% of all filings. Below tenth place, filing counts fall to single digits and then to one-off filers, so due diligence should focus first on the handful of names at the top rather than the full list.

Filing activity was close to zero before 2021 and climbed sharply afterward: from 2 records in 2021 to 14 in 2024, a +600% increase over that three-year span, which is the peak filing year recorded so far. Because patent publication typically lags actual filing by around 18 months, the 2025 and 2026 counts in the same dataset are still incomplete and should not be read as the trend cooling off. Anyone tracking this space should expect the 2024 wave to keep filling in for another year or two of published records.

Core refrigeration and heat-pump engineering (IPC class F25B) is the largest single category at 34.2% of the 114 records, covering compressor cycles and cascade configurations. Materials claims (C09K) follow at 26.3%, and printed circuit or control assemblies (H05K) at 19.3%. Because a single patent can carry several IPC classes, these percentages overlap rather than sum to 100%, which reflects how heat-pump claims are increasingly bundled with materials chemistry and control electronics rather than filed as pure mechanical claims.