Dr. Matthew Trewhella, Managing Director at Kensa Contracting, explains why short-term, ‘sticky plaster’ solutions are not the answer for helping the UK reaches its zero-carbon goals.

It is widely accepted that for the country to meet the government target of becoming zero carbon by 2050, emissions will have to be almost entirely eliminated from the UK’s housing stock.

The figures speak for themselves: heating accounts for 47% of all energy consumption in the UK; 55% of which is used by domestic homes, mostly for space heating, but also for hot water. Currently, over 80% of domestic heating is provided by gas boilers. The combustion of this fossil fuel releases particulates, NOx, and SOx into the atmosphere that contribute to global warming and air pollution. Shockingly, domestic heat accounts for 13% of the UK’s annual emissions footprint – comparable to the contribution of all petrol and diesel cars.

Switching domestic properties to non-combustion heating systems would significantly reduce these harmful emissions and move the UK closer to its net-zero target. According to the Committee on Climate Change, electrification of heating is the most effective route for reducing carbon in housing. But how can this be achieved on a scale large enough to realistically meet the 2050 deadline, and what effect will the rapid electrification of heat have on the grid?
Short-term thinking

In an effort to reduce carbon emissions as quickly as possible, it might initially seem logical to fit an air source heat pump into every property with a gas boiler to create a hybrid system, with 50% of the heating and hot water load being handled by each appliance.

However, firstly this commits every property to live with twice the service and maintenance regimes every year, twice the costs of replacing these relatively short-lived appliances (typically every 10 years), and twice the grid connection standing charges. So, while it would achieve some rapid decarbonisation, it would be a short-term approach with very little effective legacy created by the capital expenditure.

Investing the same capital amount in the phased retrofitting of ground source heat pumps across local communities would achieve higher carbon savings and lower running costs. Homeowners would be left with a single, low maintenance, long life appliance, and the ground array infrastructure would be in place for a century or more, leaving a highly beneficial long-term legacy.

Studies have shown that ground source heat pumps, in particular, are the only renewable heating solution capable of delivering domestic heating and hot water at a lower running cost than a traditional gas boiler, with no local emissions and the lowest carbon intensity of any heating. They also have the lowest grid impact because they can be run flexibly at any time of day or night without loss of efficiency.

Kensa has pioneered the use of ground source heat pumps connected to ambient temperature loops linked to shared ground arrays. This system architecture acts as a thermal energy supply grid, which circulates low-grade heat sourced from the ground, water, or waste heat processes around a network of pipes to individual heat pumps in separate dwellings. The heat pumps then upgrade this heat to deliver low cost and low carbon heating; the system can also work in reverse and provide cooling.
A scalable solution 

This scalable low carbon heating solution enables community-wide ground source heat pump initiatives to be rolled out quickly and effectively, as evidenced by the Energy Superhub Oxford (ESO) project which Kensa is a part of. Under ESO, hundreds of Kensa Shoebox heat pumps are being retrofitted within properties across the city and run on flexible time-of-use tariffs to optimise heat production for cost and carbon savings. 

Coupled with Switchee smart heating controls, the system constantly senses, learns, and responds to the inhabitant’s behaviour. Synchronising with Kensa’s heat optimisation software, it takes a day-ahead forecast of half-hourly electricity costs to automatically shift the ground source heat pumps operating times to enable occupants to make savings from dynamic tariffs without adjusting their usage patterns. By decarbonising heat, power, and transport, ESO is predicted to save 10,000 tons of CO2 per year, the equivalent of taking 2,000 cars off the road.

With this combination of smart controls, remote grid balancing, and time of use tariffs, ground source heat pumps can have a positive effect on the grid, turning on when there is overgeneration and turning off when the grid is under strain. Because their source temperature is more stable, they can be run overnight when the grid generally has the most excess capacity without loss of efficiency. 

If properly synchronised, smart control of millions of devices, such as ground source heat pumps and electric vehicles, will bring the grid stability. Combined with the low electricity consumption of ground source heat pumps, this will save billions of pounds of capital investment in future generating capacity.