Dr. Lars Schernikau: Energy Economist, Commodity Trader, Author (recent book “The Unpopular Truth… about Electricity and the Future of Energy”)
Details inc the full Blog are available at www.unpopular-truth.com
Heat pumps are having a moment. Governments promote them, utilities love them, and they are, now more often than ever, described as an obvious replacement for fossil fuels (oil, coal, gas), fueled heating. The basic idea sounds great…a heat pump works like a reverse refrigerator. Instead of “pushing heat out, it pulls heat in”. That heat can come from the air outside your house or from the ground below it.
The International Energy Agency (IEA) sums up the enthusiasm nicely. “Heat pumps, powered by low‐emissions electricity, are the central technology in the global transition to secure and sustainable heating. Heat pumps currently available on the market are three‐to‐five times more energy efficient than natural gas boilers. That statement contains three big claims:
(1) heat pumps are three to five times more efficient,
(2) they run on “low-emission” electricity, and
(3) they are secure and sustainable
All three deserve a closer look, so here we go…
1. Why heat pumps really are efficient… at the device level
There is a solid reason, rooted in physics, behind why heat pumps are attractive. Transferring heat from one place to another takes much less energy than generating heat from scratch by burning fuel. Under favorable conditions, a heat pump might use one unit of electricity to move three units of heat. This is where the famous “three to five times more efficiency” number comes from.
But here is the catch! That number is not efficiency in the everyday sense. It’s called the Coefficient of Performance (COP), and COP is not the same thing as system efficiency. To start with, a heat pump relies on electricity, while a gas or oil boiler mostly relies on chemical energy and needs very little electricity to operate. You can keep a boiler running with a small backup battery… but you cannot do that with a heat pump… the three to one number forgets the (in)efficiency of the electricity required from the grid… and you and I know how complex that grid is.
2.Electricity doesn’t just “arrive” for free
The “three to five times more efficiency” claim, quietly assumes that electricity arrives at your home with no losses. But in reality, electricity available 24/7/365 has to be generated, transmitted, balanced, and backed up.
On average, roughly 2.5 to 3 units of primary energy are needed to deliver one unit of electricity to your socket when thermal power plants are involved, as they mostly are.
That means using electricity “100% efficiently” at home starts, at the system level, at only 30 to 40% efficiency. Wind and solar changes the accounting by introducing their own challenges, among them being the need for overbuild, short duration storage, long duration storage, thermal backup and larger and more complex network integration and transmission infrastructure. Once these are considered, wind and solar dominant systems do not outperform coal, gas, or nuclear in net energy efficiency but actually underperform. Think about energy density, intermittency, and the short operational lifetime.
3.Heat pumps struggle when you need them most
Another unpopular truth that raises the temperature… or does it?…
The colder it gets, the more the performance of heat pumps decline.
When winter hits and heating demand peaks, the heat pump performance COP drops. This is especially true for air-source heat pumps as ground-source systems tend to perform a bit better, even though they are more expensive, slow to install, and often impractical in densely populated cities.
This creates a nasty feedback loop… because just as heat pumps need more electricity during cold spells, solar output tends to be low, wind can be unreliable, and grids are already under pressure on top of the dropping COP. In winters coal and gas plants are usually ramped up to secure the electricity supply. So even if your annual electricity mix looks “green,” the marginal power that keeps your heat pump running during a cold snap is more often than not fossil-based… do you see the feedback loop?
4.Peak power is the real bottleneck
Electrifying heating doesn’t just increase electricity consumption, it increases peak power demand in winters when power system are already strained. Grids must be built for the coldest, darkest, calmest winter evenings, not for yearly averages. The IEA projects that peak electricity demand grows far faster than total electricity demand due to heat pumps, electric vehicles, data canters, and AI. When demand spikes, coal, oil, gas and nuclear fill the gap. That is why the idea of heat pumps running on wind and solar often collapses under real winter conditions.
5. Security and sustainability depend on where you live
If you are in rural Scandinavia with abundant hydropower and a very secure grid, heat pumps could make more sense, but in large cities with fragile grids, the picture changes completely. In urban areas, air-source “monoblock” heat pumps are popular because they are cost-effective and easy to install. However, they are noisier, lose efficiency in winter, and are vulnerable during power outages. When the power goes out during freezing weather, circulation stops, water freezes, pipes burst, and systems can be a complete write-off. After some recent winter blackouts (Berlin end December 2025), many heat pumps didn’t come back online even after electricity was restored.
Now imagine there is an armed conflict or cyber-attack? Do you feel safer with a heat pump or with a standard gas- or oil-based boiler?
So let’s be honest…from an energy security standpoint, heat pumps seem flaky. From a sustainability standpoint, powered by energy systems that require massive overbuilding, short lifetimes, and heavy material use it is questionable at best and deserves some skepticism and allot of discussion.
Summary – So where do heat pumps actually fit?
Heat pumps are neither a universal solution nor a dead end. They work best, out in the country, where grids are reliable, electricity is reliable, or where winter temperatures are moderate. But in a city setting, district heating combined with large ground- or water-source heat pumps and thermal storage is likely more appropriate than widespread deployment of individual units.
One last reality check we should consider is that… adoption closely follows subsidies. When subsidies drop, sales drop. That doesn’t make heat pumps bad, but it does suggest they are not the obvious, no-brainer solution they are often made out to be.
Heat pumps are efficient machines, sure, but whether they actually contribute to an efficient, secure, and sustainable energy system depends on too many elements around them. One thing is for sure, heat pumps cannot make oil and gas boilers go extinct… and anyone telling you otherwise is disingenuous.
Read the full analysis here:
https://unpopular-truth.com/2026/02/14/heat-pumps-for-all/
“Grids must be built for the coldest, darkest, calmest winter evenings, not for yearly averages.”
I worked for a manufacturing company who did an expansion and had an out of state engineering company do up the plans. Result? We did not have enough cooling available during the summer and first hard freeze led to burst pipes everywhere. Yes they used the yearly averages of 40’s in the winter and 80’s in the summer.
Heat pumps are air conditioners running backwards. Heat pump good, A/C bad. Please explain
Yes, the UK will subsidise Heating only capable heat pumps but the more useful Air To Air heat and cold heat pumps are not. Odd as they say we will burn due to global warming and air conditions would be then useful. But you would be using energy which is really what they want you not to do and get back to cave dwelling instead.
Here in the Puget Sound area, where it rarely gets below freezing, heat pumps work pretty well, and they also provide AC in the summer. I still decided against it for my finished basement because that space requires very little heat (being very well insulated, and having a heated house above), and it does not get hot in the summer. A few wall electrics are all I need.
But I did look into the pumps, and found that in parts of the country where it actually gets cold, heat pumps are only used for heat in spring and fall, when temperatures don’t get much below freezing.
Those areas (the upper mid-west to eastern Washington) spend so much on heating that a less expensive sometimes option can be worth adding, especially given the added AC capacity.
Unfortunately, pumps do nothing at all when it gets really cold. Even special expensive cold-weather heat pumps only work (and not very efficiently) down to about +15F, which is nothing in Minnesota.
In colder conditions, they don’t reduce at all the need for un-pumped fossil, electric, or wood-stove heating, making them a secondary luxury for non-critical situations only.
Requiring that heat pumps REPLACE oil and gas furnaces, instead of supplementing them, as England is doing, is definitely nuts. A good zero Fahrenheit cold snap and people will be dying all over.
I find it difficult to compare cost between our heat pump and the backup propane furnace at various temperatures. What I did find (but am not confident of, given the unfamiliar terminology) suggests that, at the temperatures where I live and the electricity cost here, the heat pump costs about 25% as much per BTU than propane.
Where we live, 89% of our electricity comes from hydro, 8% from nuke, and 3% from, I dunno, raccoons on treadmills for all I know. I like the heat pump because it’s both a heater and an air conditioner. The propane furnace is a backup. We use propane for the on-demand water heater, a gas fireplace, and a cooktop.
We have a new heat pump with COP=6.6 nameplate value used for a pool in south Florida.
But that COP is measured under ideal AHRI test conditions (80°F air / 80°F water / 80% RH). When air temp is 55F the COP=3 and below 48F the unit shuts down during defrost cycles. So COP might even be below 1.
The nameplate values are often what is quoted when attempting to pitch how great heat pumps are. But, in real world conditions, the benefit is less. Kinda reminds me of RCP8.5…
Grids must be built for the coldest, darkest, calmest winter evenings, not for yearly averages? Say rather they should be built for the most extreme conditions rather than mildest yearly averages.
In some parts of the world extreme cold is the big challenge. In other parts – not so much Scandinavia, heat and humidity are the big issues. And while I’ve heard that you shouldn’t run your AC more than 10 degrees different to what’s outside, should and can’t are slightly different. When the thermometer hits 0 you’d be limited to heating to 10 degrees, while conversely when it hits 40 you’d be limited to cooling to 30. That’s fine in many parts of the world, but not where it hits sub-zero, or above 40! Unfortunately AC units aren’t clearly labelled with minimum or maximum operating temperatures, just preference settings.
One aspect that Schernikau does overlook is that while grid efficiency may make even 100% efficient AC far less efficient, households relying on independent solar (or other form of power generation) are in a different position. IF sunshine is producing electricity on your roof then it’s free power for your AC. If you have batteries then being cold and dark doesn’t matter, unless it’s Day 1 of a multiday cold and dark winter storm, your solar isn’t generating, and your battery is almost flat – then you need a generator. On the other hand if it’s too hot, and your solar panels are overheating, while you’ll generate power, it’ll be far less than optimal, especially given extreme demand by some AC units. There are no perfect answers, only some that work better or worse in different contexts.
Outstanding post, bring on more like this. Let us all understand heat pumps are not a substitute for traditional heating so in that regard they are a bad idea. The dishonesty by those pushing this idea is disgraceful.
The efficiency comparison isn’t VS gas, oil, coal, or wood burning, it’s VS electric resistance heating. Dr. Lars Schernikau rather conveniently left out any mention of that. Current generation heat pumps can extract usable amounts of heat from outside temperatures below 0F, though efficiency falls off quite a bit down there. Manufacturers of modern variable speed heat pumps offer supplemental resistance heating for areas that experience very cold temperatures.
Heat pump naysayers constantly ignore 21st century technology, repeatedly using comparisons to technology that conked out before outside temps got down to freezing. The oldschool models (which are still sold, with minor improvements over decades old ones) cycle between full on and off. The temperature it either on full heat or full chill. Temperature is controlled by the cycle time and a multi-speed fan, which is one of those minor improvements.
The modern ones use a variable speed compressor and fans to directly control the temperature of the air so that the overall temperature of the heated space stays more consistent.
The electric grid going down will also shut down all but the most ancient of gas and oil furnaces since their control systems rely on external electricity supply to operate, including igniting the burners on demand.
But even really old ones that worked without any external power to light the main burner (they had a pilot flame constantly burning) and operate the main fuel valve, still need power to run a blower motor.
The only non-solid fuel heating systems that can work without a supply of electricity are the “gravity furnace” style that used convection to circulate air through ducts and a large central grate directly above the furnace. Those are only found in really old houses that haven’t had that antique system taken out and replaced with a forced air system. Coal or wood burning fireplaces or heating stoves are far more common now than old gravity furnaces.
Side note. Vancouver, British Columbia recently required all coal and wood burning fireplaces and other heaters to be registered. Any that were removed, blocked up, or otherwise disabled were not allowed to be restored to use. And (no) surprise, last year the city banned all wood and coal burning heating. If you want to keep your fireplace or heating stove it must be converted to gas.
I own five. They work very well when you don’t really need them. They struggle poorly in severe cold.
Repair cost is very high. The warranty usually is parts only. Service calls are very costly.
In 2021, I installed a new heating system in my home; 120,000 btu 96% efficiency NG furnace, an high efficiency a/c at 5 tons, 3 tons of which is an air-exchange heat pump – that is – an a/c with one extra valve. The price was slightly higher -so what the heck
In ground heat exchangers work better, in principle, since the extraction of heat occurs at ~10C, IF you have a large enough heat exchange volume. Research showed me that the sufficient in-ground heat exchange would easily triple the cost of the heat pump and would never repay itself. The ground is a poor heat conductor, so the exchanger needs to be seriously over-sized to not freeze the ground in our extended cold spells (-15 to -20C).
Five years on, the furnace is wonderful, inexpensive to run and reliable.The 5 tons of a/c works very well on the hottest periods in summer, where we can reach 37-38C for weeks and keeps the home comfortable at 21C.
Of course, proper insulation helps both winter and summer.
In our hot summers, an in-ground heat exchanger a/c – heat pump would unfreeze the ground frozen during our cold winters. That is the best of all worlds, according to Voltaire.
BUT, and there is always a but… ‘BUT’, Europe/Britain have mild summers in most areas, so the summer heat input does not equal the winter take-out and one creates permafrost under the property.
The graph above is what one gets for a Carnot cycle efficiency, not practically realizable. The cross-over point is typically near 0C when the heat pump can no longer meet the heating demand – works fine at +5C but fails at -5C. It is downhill from there and then, the heat pump freeze-up happens (photo). The COP also drops to near unity. The electric furnace, COP = 1, works at any temperature, giving 100,000 BTU always.
Why do we even need heat pumps.
After all, adding CO2 to air makes it hotter, right?
So just pump in CO2 to higher levels and your house warms to a toasty level.
Right?
Right?
Direct heat from a local nuclear reactor, without generating electricity, would be more efficient for district heating.
Story tip:
One of my friends built a house with a heat pump on San Juan Island in the Puget Sound. He had no heat during cold winter days because the heat pump couldn’t vaporize Freon below 23°F. He had to spend a lot more to convert it to Earth coupling instead of air coupling.