1 Install a Heat Pump part 2

Boiler Phaseout? 1. Install a Heat Pump – Part 2

Details, Details

More on the Government’s Phaseout of Gas and Oil Heating.  In recent decades, the harvesting of gas and oil from the North Sea and elsewhere has brought gas and oil boilers, radiators, and ‘instant-on’ central heating and hot water to most homes in the UK.  The result is that boilers in the UK account for 15-20% of our national carbon footprint, a similar level to that of emissions from motor vehicles.  Following a series of COP and other international meetings, the UK government set a legally-binding target of achieving Net Zero by 2050.  It further kicked off a phase-out of existing gas and oil boilers by banning their installation in new builds from 2025 onwards, and in all buildings from 2030.  Recently, the Prime Minister announced a delay with 2035 as the new date for halting installations in new builds and a reduced goal of 80% reduction in installations in other domestic buildings.  In addition, unlike the previous goal of a total ban after 2025, the new policy will apparently not actually prohibit anyone from installing a new gas or oil boiler even after 2035.  To make this even more confusing, while delaying phaseout of boilers, the UK government has also boosted the incentive to install a heat pump by increasing its lump sum grants to at least £7,500 across the UK, matching the amount already available in Scotland.

In contrast, the Scottish government is planning ‘Heat in Buildings Standards’ law with a much faster timeline for implementing what is termed ‘non-polluting heating’, that is by devices using low carbon electricity (e.g., heat pumps, but also heat networks, storage heaters, and electric boilers).  A public consultation is now in place until March 8, 2024, with the intent that relevant law will be passed shortly thereafter (see https://www.gov.scot/publications/delivering-net-zero-scotlands-buildings-consultation-proposals-heat-buildings-bill/pages/1/).  Proposals under consultation include:

  • A requirement for anyone buying a home with a gas or oil boiler to change it to ‘non-polluting’ heating and comply with defined standards within a designated grace period following purchase (notionally 2-5 years).
  • A requirement for houses within the territory of a heat network to connect to it.  (There is a plan for a heat network in East Lothian, that might also supply North Berwick.  However, this network has not been approved, much less funded or started.  North Berwick would not likely be hooked in until some years after any related work begins.)
  • A target date of 2028 for private landlords to move to non-polluting heating and comply with defined standards.
  • A target date of 2033 for other domestic residences to move to non-polluting heating and comply with defined standards.
  • A target date of 2038 for public buildings to move to non-polluting heating and comply with defined standards.

This new law would provide certain exceptions for buildings unable to comply, and seek to reduce the currently 4 fold higher price of electricity down towards that of gas (see Cost of Electricity below).  Predictably, sceptics will regard this proposed acceleration of phaseout and Net Zero in Scotland as intrusive and unnecessary, whereas those concerned about climate change will view these changes positively.  Regardless, it is unclear at this point how the conflicting plans of the UK and Scottish governments will play out, and specifically how they will affect individual households in Scotland.  The UK government reserves Energy powers (viz Electricity, Oil and Gas, Coal and Nuclear, and Energy Efficiency, but not Heating and Cooling) to Westminster.  In contrast, powers under Health, Environment, Social Welfare, and Town and Country Planning are clearly devolved to the Scottish government in Holyrood.  The complexities of the this very fluid policy landscape are causing considerable confusion and anxiety.   Further, with the vagaries of politics, things will likely change again, especially with upcoming elections in the UK (2024) and in Scotland (2026).

Before we leave this topic, it is instructive to look at the situation in other European countries.  At least eleven, including countries geographically close to the UK – Denmark, France, Germany, Netherlands and Ireland, have comparable government-mandated boiler phaseout schemes, and several of these are moving much faster.  Denmark banned new boilers from 2013, and expects to have them totally eliminated by 2029, six years before the UK’s phaseout even gets going.

More on the Upsides of Heat Pumps:  The scientific principle behind heat pumps is similar to that of a fridge (see Further Reading – A Fridge but in Reverse.  This has a helpful schematic).  In the UK, most heat pumps extract heat from air, ground or water outside, and bring it inside for wet (hydronic) heating using radiators or UFH, and hot water.  There is an air-to-air version, which provides domestic heating by means of warm air blown through ducts, rather than hydronically.  This is not often used in the UK since it is not suitable for retrofitting to existing boiler-driven hydronic heating with radiators, and systems with a central blower require major renovation to fit the ducts needed.  Air-to-air versions also have no provision for supply of hot water, but these models are sometimes used in new builds, to provide air conditioning.

Picture:  A Typical Heat Pump for a three-bedroom house

Modern heat pumps  are quite small (see picture), and extremely efficient.  During summer months, some achieve efficiencies of up to 600-700%, meaning that they produce 6-7 kWh of heat for every 1 kWh of electricity used.  In winter, efficiency drops to the 300-400% range (3-4 kWh heat per kWh electricity), with relatively more energy being used to extract each kWh of heat during colder weather.  However, there is still something almost magical in their ability to muscle large amounts of heat inside, even in the depths of winter.  Water-source and ground-source models work particularly well in the UK, since water temperatures (including the sea) and in the ground 2 meters or more down, rarely drop below 5oC during our winters, whereas air temperature may be well below 0oC.  Theoretically, some heat is available for capture all the way down to absolute zero at -273.15oC (-460oF, or 0o Kelvin).  In contrast, as noted above, even the most efficient gas or oil boiler can only produce around 0.95 kWh of heat for every kWh of energy used – equivalent to 95% efficiency.  The high efficiency of heat pumps means that they only use a third to a quarter of the energy consumed by boilers to generate a given amount of heat.  This makes heat pumps an attractive green replacement for boilers.

The other potential green bonus of heat pumps is that they can be run on ‘clean’ low carbon electricity, which is rapidly replacing ‘dirty’ electricity generated from hydrocarbons.  Moreover, although low carbon technologies embody some carbon from hydrocarbons used in their manufacture and set-up, they are responsible for little or no greenhouse gases once in operation.  This is very different from the situation with the gas or oil used in current boilers (see also below), not to mention the reality that the UK is now much more dependent on increasingly unreliable supplies of gas and oil from other countries (Energy Issues. 4. The Cost and Supply of Hydrocarbons).

If we install a heat pump and use low carbon electricity, we can be gratified that we are making a significant contribution to reducing greenhouse gases and atmospheric pollutants by not burning any fossil fuels.  Moreover, there are already signs that installing a heat pump, even without other modification, increases equity and resale value.  This is because the purchaser does not have to take on the risks, costs and inconvenience of replacing a gas or oil boiler.

More on the Downsides of Heat Pumps:  It is important to dig deeper into some of the very confusing misconceptions and frank FUD (fear, uncertainty and doubt) pumped out in the media about heat pumps. There are legions of ‘experts’ pushing mind experiments that definitively conclude that heat pumps can never work.  The reason cited is that they circulate water at generally lower temperatures than do gas or oil boilers.  (This is the reason that high temperature cycles need to be run periodically using an immersion heater, to prevent the growth of Legionella bacteria).  This ignores the fact that heat pumps supply heating for much longer periods of time that the constant on-off supply from boilers.  However, dour prognostications from boiler engineers, and graphic ‘told you so’ reports from some dissatisfied adopters (see Further Reading) have stoked much scepticism about giving up proven boilers and relying on heat pumps ‘that just won’t heat adequately’.  Some homeowners have therefore installed heat pumps, while leaving their boilers in place as backups for cold days (so-called hybrid or dual fuel heat pumps).

A more balanced view is that despite all the scepticism, an increasing number of people have successfully installed heat pumps, and are satisfied with the results (see Are Users Satisfied with their Heat Pumps? below).  It has also been pointed out that, on very cold days, a thicker jumper can be worn, and/or temperatures can be supplemented in the main living spaces by quick bursts from electric heaters, just as happens today in many households with boilers.

The other point to emphasise is that if calculations pre-installation, or performance post-installation, show that a heat pump will not provide sufficient heat, it can be supplemented by several effective heat-enhancing, especially in the main living areas:

  • Increasing extraction of heat by
    • upsizing to thicker radiators.  This can be combined with upsizing the smallest microbore (10mm) feed tubes
    • installing under-floor heating (UFH), to provide a bigger array of pipes emitting heat, and
  • Reducing heat loss by
    • installing or upgrading insulation in floor, walls and ceiling
    • installing double, triple, or secondary glazing, and
  • Raising circulating water temperature.

There will be more to say about these ‘fixes’ in other pieces.  For now, several high level points should be noted.  Upsizing radiators is generally straightforward.  UFH and insulation are more disruptive and add more cost, but can always be added later if heating after installation is found to be insufficient.  They will also likely increase home equity and resale value, as well as reducing the costs of heating.  UFH provides radiant heat, which feels much more comfortable even at lower temperatures than the primarily convection heat of radiators.  It’s also worth noting that some or all of these measures might be included as required standards in Scotland’s proposed Heat in Buildings Bill.  One other expense to mention is the hot water storage cylinder that will be required, if a combi-boiler providing instant-on hot water is being replaced.  This also means finding a space to put it in.

Why is the Installation of Heat Pumps in the UK so Slow?  Another prominent ‘proof’ that heat pumps won’t work in the UK, is the fact that our housing stock is often older, draughtier and more poorly-insulated than the rest of Northern Europe.  The installation of heat pumps has certainly been much slower in the UK than in some other parts of Europe.  Currently, in round numbers, only around 2% of UK homes have heat pumps installed, as compared with 40-45% in Finland, Sweden, and Estonia, and up to 60% in Norway.  Clearly, these countries have much colder winters than does the UK.  This suggests the hand of other factors in the sluggish rate of installation here in the UK.  One is the persistently higher price of electricity as compared with gas (see below); prices in the UK are currently the third highest in Europe, behind Belgium and Germany.  There could also be a bottle neck in terms of trained heat-pump installers, of which the UK only has about 4,000 currently. Estimates suggest that we need many more, perhaps 30,000 by 2028.

Another problem is the massive gas infrastructure that has been built out in the UK.  The sunk capital and political costs of this are huge, and act as a powerful impediment to junking this in favour of heat pumps running on electricity.  Moreover, the UK Government’s indecision on whether or not to support the use of this gas infrastructure for hydrogen gas for domestic heating, despite current indications of its unsuitability, is not helping.  These factors seem to be encouraging a powerful push from holdout industry proponents to stick with boilers and use our gas infrastructure for distribution of hydrogen.  Germany seems to be in a similar quandary, with an electricity: gas price differential even higher (closer to 5), an extensive national gas grid, and a heat pump installation rate about the same as the UK.

It is also the case that an extensive network of gas and boilers means a strong focus in the UK on hydronic heating.  Consistent with this, the current Boiler Upgrade Scheme (BUS) in the UK offers grant for air-to-water, but not air-to-air heat pumps.  In contrast, in much of Europe, the heat pumps installed are more likely to be air-to-air, rather than air-to-water.  These are often used for air conditioning in Southern countries during the summer.  In colder Scandinavian homes without existing hydronic heating, air-to-air units offer simplicity and cheaper installation of smaller individual units room-by-room.

As part of an attempt to boost sales of heat pumps, energy suppliers in the UK have recently set up the Clean Heat Market Mechanism.  This requires manufacturers to sell a minimum percentage of heating appliances as heat pumps (4% in 2024/25 and 6% in 2025/2026), with non-trivial penalties if these goals are missed. This is designed to increase manufacturing economies of scale, and reduce prices.  Together with £7,500 grants and bringing down artificially high electricity prices towards those of gas, it is hoped that this will incentivise sales, and bring the number up from just 55,000 in 2022 to the 600,000 annually that the government has called for.  For context, France had sales of 620,000 in 2022.

Are Users Satisfied with their Heat Pumps?  Hard data is still rather limited, but encouraging despite the loud predictions of doom. The recent Nesta survey (see Further Reading) found that:

  • Three quarters of heat pumps users were satisfied, particularly if they had previously used more expensive electric boilers.
  • Heat pump users were also happier than boiler users with their running costs, despite the higher prices for electricity than for gas.
  • Some installations included heat-enhancing measures.  Regardless, satisfaction was just as high in Victorian as in more modern houses.

The Cost of Electricity.  The dramatically lower energy requirements of heat pumps should theoretically provide a powerful incentive for us to take the plunge and replace their boilers.  Yet electricity prices have been set 3-4 times higher than gas, regardless of the method of generation.  This electricity price premium pretty much cancels out the 3-4 fold energy efficiency advantage of heat pumps, and therefore the large savings in running costs that would otherwise be realised.  This price differential is currently the third highest in Europe behind Belgium and Germany, and across Europe the price differential seems to correlate somewhat with low rates of installation.  More worrying still is that this price differential has risen above 4 in the UK over recent years.

If people are to be encouraged to replace their boilers with heat pumps, further reducing electricity prices to a level closer to that of gas seems like a no-brainer, given the massive FUD in the media and any possible added costs and inconvenience of installing a heat pump (see above). This issue will be discussed in more detail elsewhere (Energy Issues. 2. Why is Electricity So Expensive?).

The Supply of Electricity.  This is another potentially gnarly problem.  In short, if everybody in the UK with a boiler goes ahead and installs a heat pump, will the supply of extra electricity required keep pace?  Current estimates are that we will need to at least double the available supply of electricity by 2035.  This may be an underestimate if we also factor in the growth of EVs, and possibly the electrolytic generation of green hydrogen and more carbon capture, all of which will predictably consume quantities of electricity.  It’s also worth stressing that any expansion in the supply of electricity must be generated from other than the usual hydrocarbon suspects, if we are to avoid adding to the national carbon footprint that we are trying to shrink. This issue, and our national grid infrastructure, will be considered in further detail in the companion series (Energy Issues. 3. Will We Have Enough Electricity?).

Health Issues:  The addition of new high voltage lines to beef up the grid will itself predictably cause resistance.  This is often based on aesthetic objections.  However, there are also concerns that the electromagnetic radiation emitted by high voltage pylon lines can cause a variety of health issues, and specifically cancer.  In fact, the relevant data for this is rather weak, and sometimes tinged by strong opinions.  In fact, electromagnetic radiation diminishes rapidly with increasing distance away from the lines, and further than about 100 metres away is undetectable.  What is clear however is that if we continue our current ravenous hydrocarbon habit unabated, gross pollution of the atmosphere with greenhouse gases and a myriad of associated chemicals will be unavoidably more widespread, pervasive, and potentially hazardous to health, especially in our small, densely-populated island.

A Note on Timing:  The big question remains, when to replace our boiler with a heat pump?   For some people, consideration of the issues outlined above may prompt a ‘wait and see’ approach, especially if the UK government’s leisurely phaseout position is maintained and takes precedence over Scotland’s more ambitious timeline.  Remember, new boiler installations are no longer apparently being banned by the current UK government after 2035 (see Burning Issues. 2. Keep Your Current Boiler).  However, if phaseout is faster, along current Scottish government’s lines, there will be a predictable rush to install heat pumps over the next decade.  Will there be enough trained and certified technicians available?  Will government grants of £7,500 or more still be available?  Or, as the installation of heat pumps gathers momentum will they quietly disappear, in a fashion reminiscent of solar panel incentives and feed-in tariffs, and swallows in autumn?  All this suggests that for those of us with a 12-15 year-old boiler, looking seriously into replacing it with a heat pump now might be wise, especially if additional heating-enhancing measures needed are minimal or affordable.

Further Reading