Cllr David Evans is a councillor on East Hampshire District Council.
The National Audit Office March 2024 Report on decarbonising home heating informed us that “Low heat pump uptake slowing progress on decarbonising home heating”
Gareth Davies, the head of the NAO said:
“Government needs to engage every household to achieve its objective to decarbonise home heating as part of the transition to net zero. DESNZ’s progress in making households aware and encouraging them to switch to low-carbon alternatives has been slower than expected.”
The NAO report notes on page 16:
Cost: In 2020, the Climate Change Committee estimated that £162 billion of additional investment would be required from 2020 to 2050 to install low‑carbon heating in existing UK homes, compared to the cost of like‑for‑like replacement of boilers as they reach the end of their lifetime.
As there are about 30 million homes in the UK, £162 billion is only £5,400 per home
Even with a £7,500 subsidy, they are not flying off the shelves.
But the messages are out there – good and loud – about how wonderful Heat Pumps are, how much money we would all save if we replaced our gas boilers and how other European Countries are way ahead of us and we Neanderthals are missing out on such a slam-dunk obviously great advance. So why are we slow to change?
Of course, people are not stupid, they will look at the messages being pumped out by the Government, manufacturers, installers and any number of environmentalist groups and then make their decision – that’s how markets work. The products work, they reduce CO2 emissions and the designs are mature and proven.
So, if the product is OK and the marketing messages are not cutting through, maybe it’s the messages!
So, let’s look at some of the messages.
Message 1 – Heat Pumps reduce energy usage
This Government’s energy efficiency website tells us
“Heat pumps use proven technology to provide homes with cleaner electricity and are significantly more efficient than traditional boilers so will reduce your home’s energy usage.”
And the same statement from the Government is made here
About heat pumps
Heat pumps are highly efficient electric appliances that transfer and intensify heat from the outside air or ground into a building. They can produce around 3 units of heat for every unit of electricity they use. They significantly reduce a property’s energy demand when replacing technologies such as gas boilers
And heat pump companies push out the same message. iHeat says here
Key takeaways
Heat pumps boast superior efficiency levels compared to traditional boilers, potentially offering significant energy savings.
The Energy Saving Trust says under:
What is a heat pump?
This makes it a more energy efficient way to heat your home than a traditional gas or oil boiler.
The problem is that these highlighted phrases are simply not true. The energy needed to heat your home is a function of outside temperature, the temperature you decide to heat you home to and the thermal properties of the building such as the amount of insulation. That’s just simple physics and thermodynamics. Where that energy comes from does not affect the amount of energy that you need to heat your home.
So that’s marketing problem No 1 – don’t tell fibs!
Message 2 Heat Pumps are three times more efficient than gas boilers
The oft repeated message is that Heat Pumps are three times more efficient than gas boilers. Is this correct and is this message intended to suggest that if you replaced a gas boiler with a Heat Pump your heating costs would be only one third of what they were?
The problem stems from what is meant by efficiency of a gas boiler and efficiency of a heat pump.
The efficiency of a gas boiler is explained here. Put simply, a modern gas boiler converts about 94 per cent of the chemical energy held in the gas to heat energy delivered to your home. This is much better than boiler efficiencies of 30 years ago – that’s technological advances for you. It’s also obvious that the maximum possible would be a hundred per cent – you cannot get more energy by burning gas than is in there!
Heat pumps, on the other hand, do not convert one type of energy to another. They take heat from the air (or ground) and, effectively, concentrate it to keep your home warm using electrically powered pumps. This is explained in a July 2023 report here:
“Heat pump efficiency is measured by the coefficient of performance (COP), which is the ratio of heat produced to electricity consumed. More heat energy is produced than electrical energy is consumed (COP > 1).”
The figure of about 3x for the COP of heat pumps is seen in Table 1 on page 5 where it is referred to as efficiency.
The Energy Saving Trust says in their In Depth Guide asserts:
“Heat pumps are more efficient than other heating systems and generally produce around three times more energy than they take in – 300 per cent efficient. They’re more efficient as the heat they provide is harvested from the environment rather than coming directly from an energy source, such as natural gas.”
Heat pumps are clearly more efficient than using electric heaters which convert electrical energy directly to heat energy – virtually a hundred per cent is converted. Gas heating that converts only 94 per cent of its source energy (the chemical energy in gas) to heat is clearly (slightly) less efficient than electric heaters, but that is not the comparison that the Energy Saving Trust and others are inviting you to make. Again, the 300 per cent efficiency is wheeled out to invite you to infer that two thirds of your heating costs can be saved if you change from a gas boiler to a heat pump.
The statement that “Heat Pumps are three times more efficient than gas boilers” comes from dividing a typical COP of 3 by the energy conversion efficiency of a modern gas boiler of fractionally less then 1 (the modern performance of about 94 per cent).
But this is a ratio of two numbers that mean different things. It therefore has no scientific or engineering meaning and is misleading.
Thus the claim that “Heat Pumps are three times more efficient than gas boilers” is not particularly helpful and is probably intended to deceive. Get a person to “buy in” to the idea of Heat Pumps and hope that when they find out that the costs are much higher than they were expecting they are so committed to the transition they will continue.
Message 3 The rest of Europe is doing much better than us – we need to speed up Heat Pump adoption
We are told that we have to speed up our installation of heat pumps but so far “The UK is losing the Heat Pump race!” and Norway, Sweden, Finland and Estonia are way ahead of us!
Leaving aside the fatuous “Heat Pump Race” tag, is it a cause for national shame or simply a matter, primarily, of geography?
Obviously, Scandinavia has much colder and longer winters than we do, but does that explain why they have been able to switch from fossil fuels heat pumps more quickly than the UK?
Actually, yes it does, for these reasons. Their homes have always been built with much higher levels of insulation than ours for the simple reason that it was necessary. Therefore, one of the major impediments to installing heat pumps in the UK, that of the cost and complexity of upgrading the insulation of our homes to the standard needed to make heat pumps work satisfactorily, is just not needed in Scandinavia.
Why are our homes less well insulated? In part it’s the same reason – we have a much warmer climate with warmer and shorter winters than most of continental Europe courtesy of the Gulf stream. (don’t forget – it’s only in winter that we need to heat our homes). And if you’re looking for confirmation of this, consider the emerging issue of highly insulated UK homes needing air conditioning in the summer to be habitable.
Then there’s the cost of energy to heat our homes. Ever since central heating began to become commonplace in the UK (remember that coal fires heated most houses up to the 1970’s?) we have enjoyed our own supply of cheap gas from the North Sea which now heats some 85 per cent of UK homes.
Message 4 Converting from Gas to Heat Pumps will save you money
This is very complicated but perhaps the most honest estimate is from e-on Next
We’ve listed some potential annual savings of installing a standard air source heat pump in a three-bedroom semi-detached home, calculated over one year:
Gas boiler Carbon savings (kg/year) Cost saving
New gas boiler 1,900 kg No significant
– energy rating A (78-82 per cent) savings
Old gas boiler – energy rating G (60-40 per cent) 2,900 kg £340
Note, though, that a new gas boiler will have an efficiency greater than 90 per cent and if your gas boiler is only 60 per cent efficient it must be at least 20 or 30 years old and well overdue for end-of-life replacement!
Let’s summarise these messages
Heat pumps will reduce your CO2 emissions, although 30 per cent or our electricity still comes from gas, so if saving CO2 is your key driver, and you’re willing to invest in more insulation and the remodelling of your central heating system and possibly pay more for heating then it may be for you.
Otherwise, it does seem rather that the reluctance to switch from gas to Heat Pumps is probably, for most people, a rational decision that no amount of extra marketing and encouragement by Government will change. People will be aware, also, that even at 18 per cent of the UK’s one per cent of global greenhouse gas emissions, it’s not going to make a useful contribution to combating climate change globally.
The $64,000 question: Will we be able to convert every UK house to heat pumps by 2050? And can we afford it?
My guess is no, and by a significant margin. And if that’s the reality, it begs the question just how much time and effort and taxpayer’s money should the Government be spending today to try to achieve the impossible?
To conclude, maybe what the Government should be doing is encouraging people to replace old gas boilers that may be only 60-70 per cent efficient with modern gas boilers with efficiencies of greater than 90 per cent which could cut your heating cost, and CO2 emissions by 30 per cent.