Octopus Energy has put one of the heat pump industry’s biggest arguments to a live public test. Its new Cosy Heat Pump Fleet Performance dashboard publishes fleet-wide data from thousands of homes across Great Britain. According to the supplier, this data shows that four in five customers paid less to heat their homes over the past year than they would have with a gas boiler.
For households on Octopus’s Cosy Octopus tariff, the supplier says the average saving was £219 a year.
Octopus says the dashboard uses actual energy consumption from Cosy heat pump customers between 19 March 2025 and 18 March 2026 – comparing the cost of running those systems with the estimated cost of producing the same amount of heat from a gas boiler assumed to run at 85 per cent efficiency.
At the time of writing, the dashboard shows a last 30 days average coefficient of performance (COP) of 4.15, a last 90 days average COP of 3.87 and a full-year seasonal performance factor (SPF) of 3.68. In simple terms, that means the fleet produced just over four units of heat for each unit of electricity used over the past month, and 3.68 units of heat per unit of electricity over the course of the year.
That matters because a heat pump’s economics depend not just on the price of electricity compared to gas, but on how efficiently the system turns electricity into usable heat. Octopus argues that when a heat pump is running efficiently enough, especially on a smart tariff designed around lower cost off-peak electricity, it can undercut a conventional gas boiler on running costs.
The dashboard also breaks performance down by season and outside temperature. Even at temperatures between -5C and 0C, the median COP range it shows is 2.72 to 3.10. In milder conditions, performance improves markedly, rising to a median COP range of 4.22 to 4.36 between 12C and 15.5C.
For Octopus, the dashboard is an attempt to shift the terms of the heat pump debate from theory to monitored performance in occupied homes. In the company’s announcement, Octopus founder and chief executive Greg Jackson describes the data as proof “in perpetuity that heat pumps cost less to run than a gas boiler.”
Still, the claim comes with some important conditions. The £219 annual saving figure is based on Cosy customers using Octopus’s Cosy Octopus tariff and compares that with the cost of running a gas boiler on Octopus’s Flexible standard variable tariff. The company also says gas standing charge savings were included only for customers who had removed their gas supply entirely. And as Octopus notes on the dashboard, actual savings will vary depending on system design, tariff choice, insulation levels and household energy use.
For households weighing up the cost of switching from gas, the dashboard may not settle every question around installation cost, radiator upgrades or payback periods. But it does add a more concrete set of numbers to a debate that has often been driven by assumptions.
