[a_humean]

The big cost is the upfront cost of insulation and removal the existing heating systems.

Speaking about the UK (article is mostly about he US which will have their own problems), we have very poor quality housing stock with effectively zero insulation. You hold your hand to the exterior walls of your typical 2-3 bedroom terrace house (the most common type of home in the UK) in the winter and its just ice cold. For these homes the exterior wall are just solid brick and plaster with no air gaps. Many homes still don't have double glazing and their windows bleed even more heat. These homes go cold quickly when you turn off a gas boiler, and a heat pump just cannot keep up with the heat loss.

In addition large numbers of households in the UK have migrated to "combiboilers" heating systems that dispensed with hot water tanks for on demand hot water from their gas boiler. In the process many of these properties have converted the space previously designated for hot water storage to loft extensions or other home upgrades. UK homes are pretty small, and going to a heat pump system means going back to hot water storage, which most UK homes have no space for without costly changes to the home layout/structure potentially including sacrificing parts of precious loft conversions.

Frankly we might be better off just knocking down and rebuilding some of our housing stock at higher densities such is the cost of retrofitting and our housing shortages, but there is no political appetite in the UK for any radical solutions like that.

[michaelt]

> Speaking about the UK [...] we have very poor quality housing stock with effectively zero insulation.

To expand upon this, consider an urban street like this: https://maps.app.goo.gl/A4HSZ2TFiJ2PyiAZ8

Beautiful houses with period features, in a great location. Big, traditional sash windows that let in loads of light. An L-shaped layout giving lots of natural light in all rooms. High ceilings. Market price about £2 million https://www.rightmove.co.uk/properties/139018139#/?channel=R... (admittedly being in London pushes prices up a lot - but the point is, these are desirable properties)

The walls are all solid brick, no cavity and no insulation. The L shaped layout means a lot of external wall area, and the big windows don't help either. High ceilings make it even harder to heat. Many of these properties are prone to damp problems if they don't get enough fresh air circulating. You can't add external insulation without covering up the period features. Obviously you can insulate the loft and install double glazing - most of them will already have done so.

It turns out nobody wants a £2000/year heating bill - but also, nobody wants to knock down and rebuild a £2M house over a £2000/year heating bill.

[a_humean]

Exactly, that housing is super desirable by UK standards - probably amoung the most desirable housing in the UK. Pretty much all of those houses will have loft conversions (you can see the loft windows in the roof) made possible in part by removing their hot water tanks.

The reality is that it is actually a bit shit. and would cost tens of thousands to retrofit. The compromises that the owners would have to make in terms of either apperance or internal area make heat pumps very unattractive.

[soco]

When you're sitting on a property valued at a couple millions, I would have thought investing tens of thousands in it would be fair game. Not pleasant, but acceptable...

[a_humean]

Well one thing is there is often a pretty big disconnect between the asset prices of these homes and the incomes of the current owners (these houses have exploded in value over the past 40 years), but setting that aside because you are basically right at least in terms of potential equity:

The main issue is to add insultation you either do exterior insulation which covers up all of the period features that make the property valuable in the first place (and could lead to complaints from neighbours) and for many terrace houses the space between the front of property and the public street is 0, or you give up interior floor space which even at this price point is actually pretty small already. Both lower the value of the home which for most British people is the primary and often only investment (UK financialisation of housing).

[michaelt]

Well, sort of.

The thing is, heat pumps aren't a particularly good deal right now.

Heat pumps generally have less heat output than a gas boiler, so it won't make your house any warmer.

Even taking government subsidies into account, the installation costs are several times higher than a gas boiler, both for the unit and often requiring new radiators and suchlike.

And typical energy prices in the UK might be 6.5p/kWh for gas, 26.0p/kWh for electricity - so even if your heat pump achieves a 3.0 CoP your running costs are still higher. In the UK, the months when you'll want the most heating are the months when domestic solar output will be at its lowest. To make savings you've got to switch to a plan where electricity costs change several times a day, such as https://octopus.energy/smart/cosy-octopus/ and not run your heating between 16:00 - 19:00. This makes a well-insulated home even more important.

And you might think you're going to save money by not paying the gas supply 'standing charge' - but gas suppliers can charge whatever they like to remove your meter. If they say it's £1500 to remove your gas meter and save you 30p/day - you're probably not going to be saving 30p/day

So it's less a case of "investing" in the house, and more a case of "investing" in good karma by helping the environment.

[nerdbert]

How much heat do you need? We've renovated a row house in the Netherlands - very similar climate - with solid foam insulation and triple glazing. Haven't gotten to installing a heating system yet. Even in the current cold period it's perfectly fine indoors with a cheap hoodie on. If I didn't know it would make the place unsaleable, I'd be tempted to move forward without any room heating system at all, only a small on-demand water heater.

[michaelt]

The estimates in that terraced house's energy performance certificate [1] are 15,992 kWh per year for heating, 2,324 kWh per year for hot water.

Of course these figures depend on how much of the day the house is occupied, how high the thermostat is set, and how cold the weather is.

[1] https://find-energy-certificate.service.gov.uk/energy-certif...

[time4tea]

(I have a heat pump)

You can get electricity at 7.5pkWh. With a battery, I get 12h of cheap electricity per day, and the rest at higher prices.

At the coldest time of the year, I'm getting an average of 20pkWh.

This is just a fraction above break even gas/electric.

The rest of the year its no contest, heat pump wins.

My energy usage for heating is down by 60% year on year

My bills are the same as they were 3 years ago.

[michaelt]

Nice. Who's your supplier and what do you have to do to get those rates? The 6.5p/kWh for gas, 26.0p/kWh for electricity figures are from my Ovo bill for this month.

[Symbiote]

> The walls are all solid brick, no cavity and no insulation.

How do you know that? Perhaps just from "Victorian", but I think it would help if estate agents were required to list some basic facts about the house — the year it was built, the basic materials for the walls and roof, the type of heating installed.

Statistics on insulation for British dwellings:

- double glazing in 87.5%

- wall insulation of some sort 49%

- loft insulation 39%

https://www.statista.com/statistics/292265/insulation-in-dwe...

[a_humean]

He knows that in the same way that all British people know that - we have lived in or know people that have lived in houses that look exactly like that house. The amount of uniformity to British housing stock can be surprising as much as their general shoddiness. Try playing UK geoguesser - every UK residential street looks the same.

There are actually very few enforced rules about house listings. The market is pretty unregulated. However that house has an epc of C which would suggest its not insulated beyond maybe roof insulation or else isn't well insulated. To get a B or above you need to have a reasonable amount of insulation that you mostly only see in new build properties.

[michaelt]

> How do you know that?

Glad you asked! For a start, as you say, it's Victorian.

For further confirmation, zoom in on the buildings with exposed red bricks and you'll see they're in a Flemish bond pattern, which only appears on solid walls. It's not new enough to have a fake Flemish bond pattern for decorative purposes.

You can also see at roof level, the party wall extends above the slates. Where it's unpainted, it's visibly two bricks thick.

If you can get into the house, you can usually tell from how thick the walls are. On houses with cavity walls, sometimes you can remove the skirting board going through an external door and look into the cavity.

You can also check externally for weep holes, the telltale signs of cavity insulation having been installed, and whether there's a damp proof course.

If you have friends in the area, they'll probably be able to tell you. If you get a survey done (which might be reasonable on a house of this age) they'll probably also be able to tell you. Often the homeowner will know too.

If you get cavity wall insulation installed, they'll drill a hole in the wall to check the cavity with a borescope and take a photo. It's a condition for getting the government grant that they confirm you don't already have cavity wall insulation.

> I think it would help if estate agents were required to list some basic facts about the house — the year it was built, the basic materials for the walls and roof, the type of heating installed.

If you check the 'energy performance certificate' (EPC) it should tell you about the insulation and heating. Of course, the qualifications to do EPCs are minimal so they don't really tell you any more than you can figure out from a house viewing. And estate agents often don't deign to produce the EPC until the house is already sold.

For this house, the EPC is https://find-energy-certificate.service.gov.uk/energy-certif... and states the walls are "Solid brick, as built, no insulation (assumed)"

The land registry's title plan will tell you when it was built for about three quid.

[Symbiote]

Thanks for the detailed explanation!

The EPC has the overview I was expecting. I had expected this to be linked from the estate agent's site, and didn't realise there was a place to search for them. (I no longer live in Britain.)

[PaulDavisThe1st]

Two small things there - not trying to take away from your main point.

(1) This is what Americans would call a "row house", and IIRC in the UK is called "terraced housing", which has the huge benefits for all but the ends of the rows that your side walls (the longest walls of the house) are insulated by ... your neighbor's house. So, although the architectural features you mention are indeed drawbacks, their impact is significantly reduced by being in a row of connected houses. It's the single-family/full-detached houses that suffer from these problems more fully.

(2) I don't see the L-shape at all.

[pm215]

For this specific case it's a bit less clear because the house has been extended significantly and so the ground floor floor plan is no longer L-shaped, but if you check the floor plan for the first floor (UK terminology) you can see that the rear-facing square-shaped bedroom has a window facing into the garden, making the overall floor plan an L. The shared walls with the neighbours match up about with the second floor floor plan's extreme left and right edges.

The original design on these Victorian terraces is typically an L shape, where the upright of the L had the kitchen in it, and the base of the L is the main block of the house. This allows the room at the back of the main block to have a window facing back into the garden for light. Many have subsequently been extended for extra space and to add bathrooms, which were not originally present. Partially or completely filling in the corner of the L is popular.

[PaulDavisThe1st]

OK, I see what you mean now. It's a very subtle L :)

I am extremely familiar with this shape - my sister lives in one just like this in Walthamstow (prolly not worth 2M yet though).

[michaelt]

It's subtle - but it's an extra 7m of exposed wall on a house that would otherwise only have 10m of exposed wall (the plots being about 5m wide)

[andrewaylett]

The L comes at the back of the property -- most visible on the first floor of the floor plan linked. Someone's roofed over the side passage on the ground floor to make a bigger kitchen and knocked the two main rooms together to make a larger living room.

That design of terrace is exceptionally common in the UK, where each pair of houses is mirrored, with a kitchen out the back and a side passage letting light into the middle room on each level.

[switch007]

(Brits, don't look at the sale history of that house. You'll get depressed)

[badpun]

In Poland, some of the houses where historical exterior by law needs to be preserved are insulated from the inside. Of course this eats into the square footage of the building.

[dkjaudyeqooe]

I run a building with 5 apartments with central water based wood fire heating, ie a furnace and radiators in various rooms. It's brick construction with no insulation. It's absolutely stupidly constructed.

The central heating is still there and used sometimes, but I installed mini-split reverse cycle air conditioners in each apartment and they work great, you just have to size them (power wise) correctly. They were 550-700 euros each installed. It's much much cheaper to pay for electricity than the equivalent amount of wood, even after the cost of the units. There are various additional benefits like being able to use the aircons when it's briefly cold, or you just want to warm up the space a bit. You also get cooling for no additional charge of course.

Mini split systems are not always the best solution, but they are another useful option to be weighed against larger central heat pump systems. All depends on the situation, but heat pumps are the present and future, nothing else makes sense.

[DrScientist]

> Frankly we might be better off just knocking down and rebuilding some of our housing stock at higher densities such is the cost of retrofitting and our housing shortages, but there is no political appetite in the UK for any radical solutions like that

Indeed. However a first step would be to put in decent building regs so that sub par new houses aren't being built! Still waiting for the new regs that were originally started in the planning back in 2006 or so.

[a_humean]

The fact that new builds are still installing gas boilers and without ventilation systems in 2024 is insanity. A family member just bought a brand new flat that has a gas boiler in it with zero space for a hot water tank and no ventilation. A brand new flat that will need retrofitting within the next 10 years.

I cannot find the source atm, but I recall that the government advice to builders is against installing ventilation systems to discourage retrofitting them in future for air conidtioning, which is makes it even harder to retrofit for heat pumps.

Insanity!

[pjc50]

> government advice to builders is against installing ventilation systems to discourage retrofitting them in future for air conidtioning

WTF? We're going to need air conditioning! We definitely need heat recovery ventilation if we're going to have proper insulation.

Not to mention that it's starting to look like "minisplit" reverse aircon might be one of the more economical forms of heatpump.

[a_humean]

Their thinking is basically if we have mass aircon then our residential energy consumption will skyrocket. New purpose built offices and retail pretty much always have aircon though because they have obvious productivity benefits.

However they also don't encourage passive cooling or low cost active solutions either such have making sure building have pass throughs for airflow, shading of windows, or fan systems. Government seems to be forgetting that current projections have us with Madrid style weather in the next 30 years and we will all be waving our fists.

[DrScientist]

Don't have to wait 30 years - the problem is here today.

https://www.thebureauinvestigates.com/stories/2023-12-05/sti...

Partly through poor design of new builds.

[rcxdude]

Yeah, the gov is doing its best to discourage aircon. For example the subsidy on heat pumps can only be claimed if the heat pump can't act as aircon, which is just the problem the US has but in reverse.

[brailsafe]

Seeing how expensive and drawn-out it seems to be just to get through the permitting process for new construction where I live, I would not favor increased regulation as a first step, but I suppose it would depend on how much of a burden the current standards are in any given area. Some places go as far as to regulate duration of shadows cast upon opposing sidewalks, and some others only seem to see development where sidewalks aren't required, so it seems like various countrys' systems suck all around. Sub-par houses now were not necessarily sub-par houses when they were built, and I'm sure they performed a hell of a lot better than had they not been at all.

[pastage]

What is so special about insulation for heatpumps? You need that insulation anyways.

EDIT: ok so the best interpretation I have is that it has just been so cheap with gas that people have not bothered insulating their houses.

[sokoloff]

A building’s heat loss (the rate of energy needing to be re-added to maintain thermal equilibrium) increases with decreasing outside temperatures and decreases with better insulation.

A heat pump’s max output in heating mode decreases when the outside temperatures are low enough (whereas a gas boiler has a roughly constant max output and it’s quite inexpensive to size a wall-hung combi for 150K BTU/hr [44 kW] if needed).

Buildings that are fine on the coldest design day with a gas boiler may need more output than a heat pump can provide on that day.

Adding insulation can reduce this gap, which is why you’ll often find a heat pump project needs insulation, while a boiler replacement like-for-like would merely benefit from additional insulation.

[a_humean]

Yes, gas has been so cheap, until recently, that nobody has invested into insulation, and our housing stock is so poor quality and small in average size that insulation has lots of detractions in terms of property appearance and internal area.

The UK government back in 2010 actually had major plans for nation wide insulation, but famously the prime minster at the time, David Cameron, ordered the cutting of "the green crap" (widely reported to be his words) to help resolve some short term political problems with the budget in the early 2010s.

[sandworm101]

Heat pumps have a solid max heat output that cannot scale as easily as gas heating. So without insulation they can quickly hit a limit. The upper limit for gas system is limited by how much gas can flow through a pipe, which is a huge amount of energy. The upper limit for a heat pump aystem is set by the compressor capacity, which is in turn set by the electrical circuit, and relative temperatures.

[mmaurizi]

The piece you're missing, beyond just "gas is cheap", is that increasing the heating capacity of a heat pump costs lots of money when installing it, whereas increasing the capacity of a gas boiler isn't much more expensive during installation, but costs loads more when running it.

So technically it would be possible to install a heat pump with the same capacity as the existing gas boiler, but it would costs a ton more and it would all be upfront.

[wizardwes]

Another detail I think others might have missed, heat pumps need to defrost sometimes, during which time you effectively can't provide heat. In other words, you need to trust the house to be a good enough thermal battery so that you aren't having to continually heat it

[nsteel]

When operating efficiently, an ASHP's max flow temp is far lower than a gas boiler. Reducing heat loss is the solution.

[nsteel]

The bulk of the cost in the UK seems to be the actual unit. I don't understand why, other than boiler manufacturers trying to maintain the status quo (oversized boilers that can be badly installed by one of the many gas-safe "engineers" already out there).

The split of cavity to solid walls is pretty even in the UK. There are gov grants available for insulation, both for walls and loft. It is true that many houses have moved to a combi-boiler and lost their hot water cylinder but cylinders are smaller than they used to be and personally I would guess the number of converted lofts in these cases is relatively small.

https://www.checkatrade.com/blog/cost-guides/air-source-heat...

https://www.gov.uk/apply-great-british-insulation-scheme

The main problem with an ASHP for your typical 2-3 bedroom terrace house is there is very limited outside space to put the thing.

[throw0101d]

> You hold your hand to the exterior walls of your typical 2-3 bedroom terrace house (the most common type of home in the UK) in the winter and its just ice cold.

The opposite is now becoming more true: with heat waves that seem to occur more often, you want to keep the heat out and the cold in in the summer.

[masklinn]

Thankfully insulation tends to work both ways, it keeps warmth in and out.

One of my neighbours redid all the insulation of their house and lowered the high point of the south-facing living room by 10-15C (and made the house much easier to heat in the winter, they can now get by on just the fireplace).

An other good option if you have the space (and money), especially with a south-facing living room, is to add a "sacrificial" sunroom (/ enclosed patio): at the cost of a bit of light, you get extra living space in spring and autumn, and the sunroom will insulate the living room in winter and summer (for the latter especially if it has an opaque roof e.g. tiling).

[a_humean]

Yep, now our wall act as raidators in the summers - our homes do not cool down during heat waves because they are radaiting heat collected during the day.

[BobaFloutist]

I mean it doesn't matter that much, excluding sunshine insulation is insulation.

[usefulcat]

> UK homes are pretty small, and going to a heat pump system means going back to hot water storage

Why not a tankless water heater? They are quite compact, and can be powered by gas or electricity. Are they just not really a thing in the UK?

[Symbiote]

An electric heater is up to 100% efficient, the idea is to go beyond that with a heat pump — 200%, 300% or more.

[AniseAbyss]

In my country builders didn't seriously start to consider "insulation" until the 1990s.

Gas was cheap so nobody cared. Just turn up that dial!

Modern houses and apartments are marvels of engineering though.