Kensa announced the launch of its Shoebox NX Ground Source Heat Pump on 29 February 2024. The manufacturer describes it as a small, high-performance unit designed for networked ground source heat pumps, in which individual heat pumps inside each property draw heat from a shared ambient loop rather than a gas network1.
Kensa states the Shoebox NX has a Coefficient of Performance of 4.36 at operating conditions of B0/W35, tested in accordance with EN14511, and that gas boilers typically operate at 0.91. It carries an A+++ energy efficiency rating and a stated 25-year life expectancy, can heat water to over 60oC without an immersion heater, and can provide passive cooling in summer1. Kensa says it is designed to work in flats, apartments, terraced houses, tenements and new build properties, and that factory production can be scaled to 30,000 units a year, with further expansion planned1.
On running costs, Kensa gives figures based on a gas price of 7.42p/kWh and an electricity cap of 28.62p/kWh. It calculates a household would spend 8.24p/kWh to heat a home with gas and could spend 6.56p/kWh with a Shoebox NX, a 20 per cent reduction1. These are the manufacturer's own comparisons; no independent verification is given in the announcement.
Kensa also sets out claims for networked ground source systems against air source heat pumps: up to 20 per cent cheaper to run, upfront costs 8 per cent less when installed at scale as part of a funded heat network, and 40 per cent less electricity consumed for the same heat1. For a typical three-bedroom Victorian terraced house, it says a networked ground source heat pump can cost £900, or 8 per cent, less to install than an air source heat pump because of its smaller size and the lack of external installation work1. Kensa says networked ground source heat pumps are the decarbonisation solution for 60 per cent of UK homes1.
"This is a game-changing heat pump designed for the UK. Until now, achieving mass heat pump rollout has been a complex challenge, but with the launch of our Shoebox NX, we've engineered a small, high-performance heat pump that's ready to replace gas as the main home heating choice."
Under Kensa's networked model, privately funded infrastructure lowers upfront installation costs, with consumers paying a standing charge as part of their energy bill to connect to a shared ambient heat network1. The announcement cites the Climate Change Committee's projection that domestic heat pumps will be needed in at least half, and likely closer to 80 per cent, of homes by 2050, that one third of UK greenhouse gas emissions come from heat, and that 6.5 million homes are estimated to be in fuel poverty1.
| Measure | Kensa figure |
|---|---|
| Shoebox NX Coefficient of Performance | 4.36 (B0/W35, EN14511) |
| Typical gas boiler Coefficient of Performance | 0.9 |
| Heating cost with gas | 8.24p/kWh |
| Heating cost with Shoebox NX | 6.56p/kWh |
| Networked ground source vs air source, running cost | up to 20% lower |
| Networked ground source vs air source, install cost | 8% lower, or £900 on a three-bed Victorian terrace |
Why it matters for households
For a household, the significance lies less in the box itself than in the delivery model around it. A networked ground source system removes the need for a gas connection and for a boiler, and shifts the household's heating onto electricity, which is where the running-cost comparison matters: at the prices Kensa cites, the heat pump figure is lower per kilowatt hour of heat delivered, but that depends on the electricity price holding near the cap and on the unit achieving its rated efficiency in real homes1. The standing charge arrangement means a household on such a network pays for the shared loop through its energy bill rather than upfront, which changes who carries the capital cost of the ground works1. For homes off the gas grid, the comparison set is different again, and the relevant alternatives are covered in heating a home off the gas grid and heat pump vs biomass boiler. The ground array itself, whether boreholes or trenches, is the part that determines whether a property can use this technology at all, as set out in ground loops and boreholes.
What happens next
Kensa says factory production of the NX can be scaled to 30,000 units a year, with further expansion planned, and that the unit can be fitted by most heating and plumbing engineers without extensive training1. The announcement refers to the Future Homes Standard, which it says is set to effectively ban gas boilers in new build homes from 2025, and to a government target of 600,000 heat pumps a year by 20281. No installation dates, customer sites or prices for the Shoebox NX itself are given in the announcement.