By George Mirams

14 May 2024

In parallel with The Guardian's mini-series Heat Pump Mythbusters, we’ll be sharing a running commentary on each article and our additional thoughts on the opportunities and challenges of electrifying heat in the UK. 

Article 1: 'Are heat pumps more expensive to run than gas boilers?' 

Article summary

1. Burning gas for space heating and hot water is a significant source of carbon emissions in the UK and Europe.

2. The cost of installing a heat pump can be high, even with the grants currently available, however during operation heat pumps can be as cheap, if not cheaper to run than gas boilers.

3. The efficiency of a heat pump is strongly linked to the design of the whole heating system.

4. The current disparity between gas and electricity prices, where gas is subsidised and electricity is penalised with green levies, is likely to close over time, further increasing running cost savings from switching from a gas boiler to a heat pump.

Read the full article here.

Commentary by George Mirams, Senior Engineer, Max Fordham

This week's commentary is by Senior Engineer, George Mirams. Working from our Bristol office, George has worked on a wide variety of projects, including new builds, refurbishments and extensions, and installed a heat pump at his own home in 2023, providing both heating and hot water. 

1. What’s not stated in the article is why heat pumps can have such an impact on reducing carbon emissions. In addition to being three to five times as efficient as a gas boiler, heat pumps use electricity to generate this heat and the UK electricity grid is far cleaner than the gas grid and will continue decarbonising into the future as more renewables come online. The gas grid is not feasible to decarbonise and even the government is realising that replacing natural gas with hydrogen for domestic heating is a non-starter, having recently cancelled several hydrogen trials.

2. One aspect the Guardian article does not cover is standing charges. These are the charges levied by utility providers to customers for connecting to the gas and electricity networks and managing billing. These are charged at a fixed rate, typically around 30p per day. This might not sound much but once the need for gas is omitted completely from a property, by providing heating, hot water and cooking through electricity, then the gas meter can be removed (typically free of charge) and the gas meter standing charge removed. This would save over £100 per year.

3. Domestic gas boilers are typically massively oversized, usually to provide instantaneous hot water to baths, showers and sinks. Oversizing a heat pump is a surefire way of creating an inefficient heating system, therefore customers should not expect that their 30 kW boiler will be replaced with a 30 kW heat pump.

4. Although the article mentions “eye-watering costs to upgrade their radiators or improve their home insulation” to make a heat pump viable, what is not mentioned is that every year millions of kilowatt hours of energy and associated costs are wasted through keeping these existing homes warm using gas boilers. In other words, improvements to people’s homes are required regardless of the heat source. One reason these improvements are currently not prioritised is due to the relatively low cost of gas. This is likely to change as subsidies and levies switch between gas and electricity. However, it must be asserted that heat pumps can work efficiently, even in poorly insulated homes.

5. To allow for the electrification of heat and transport, the capacity of the UK electricity grid is going to need to be increased several-fold over a very short timescale. The existing electricity grid is already creaking, with limitations on new renewables in multiple regions and waiting lists of 10+ years in some areas for a new connection. This is a national-scale problem that requires a national-scale solution – one which to date has not been forthcoming.

George's cat Pickle inspects the new heat pump