I moved to the UK nine years ago from Cayman, where AC is everywhere (for obvious reasons) and central AC is built into the designs of homes for many decades now. Water heating used to always be done by immersion heaters (typically well insulated and just left on all the time), though after we had a hurricane in 2004 that flooded the ground floor of many homes, a lot of people now have "instant" water heaters. Still electric (so not like the UK combi boilers), but work well when sized correctly.
Anyway, I was a bit shocked when I bought a "new build" home on the southern edge of London to find how hot it gets. As we all know, the UK almost mandates homes to be designed to soak up and retain heat, but in summer, that meant for me that a 26c day and 16c overnight (pretty common) gave me bedrooms that would not cool below about 27c overnight on a still evening.
So, AC was on my mind right away. My house came with (basic) solar already, so that helps a bit, but I invested £10k in total on two air-to-air heat pump solutions (good news is that all domestic AC is already able to heat as well as cool, so that makes the parts and labour zero-rated for VAT when dual use is spec'd, and that means that this is the default for AC installers in the UK already). This was before the £2500 grant, so now each system would be less.
Each system handles three rooms, so de facto the whole house is cooled. In flat out use this week (with temps yesterday at 34c and only dropping to 25c ovenight), it used only about an additional 10kwh over and above the usual daily summer electricity use.
So far so good, but what about the future?
- when my gas boiler dies (useful life around 10 years, so for me that is a couple of years away), I take it out, turn off the gas, then simply use the hot water tank already in the house. For the bathrooms in winter I remove the (hot water) heated towel rails and put in electric ones. That is all I have to do and then I am using an all electric system for heating and cooling
- I will move to an electric car soon enough and will make sure that one has bidirectional charging, so will charge up the car overnight using cheaper electricity and use it as a battery during the day.
- I may upgrade my solar panels for summer AC use, but with the car as a battery, no need for additional battery installation.
All in all, I will be off carbon-based power (gas) soon enough, and with the inexorable transition to renewables, I can see that within a reasonable time I will be heating and cooling my house efficiently (as you note) with air-to-air heat pumps, devices that will use renewable power.
Oh, and given that I am very familiar with AC compressor units outside homes and businesses in Cayman, I was astonished to find that my 10kw exterior unit runs so silently (55dba). At a distance of over about 3m from the unit, the birdsong is louder. Oh, but my neighbour has a portable AC unit running now next door, it is much louder ;)
Why don’t we have more forward thinking? Every house should have disabled access and facilities. And downstairs! We all get older! They should have specific pipe runs for electricity and gas. Not ad-hoc pathways for pipes underground. Basements to house air to air HVAC systems. Solar panels. If possible ground source heat pumps and air source heat pumps. Back up generators. Car chargers. Great insulation and triple glazing. In fact any modern convenience. Room to park more than two cars comfortably. We have kids who drive! ID card readers at the front door so we know who is knocking on your door. Similar technology to make a phone call so we know who they are!
What that should tell us Nigel is that we are underfunded and underpaid!
There is apparently £19 trillion pounds out there in the aether.
If all that were to be SPENT in just one rotation. Once, not millions of times a day but once in one whole year, we should be able to supply £3.8 trillion pounds to our government from vat alone! One tax only, no other taxes, just one on one spending rotation in one whole year.
Our government gets £1.1 trillion pounds from all taxation from all spending now.
So we could have a surplus each month instead of a deficit. We could have four times our tax take four times!
Now that’s not just our government, it’s also us!
The revenue could increase our incomes by four times easily.
We have had a cash flow problem since the war. Money isn’t the problem we should have sufficient based on population and need. So the key is SPENDING money.
We have had so much money outside our daily economy that we have been underfunded. And the flow is small because the vast sums are unspent! Unused and idle.
What could have been? What could we have now. We just need those holding money to spend it continuously. Earn as much as we can. But spend it is the key to growth.
Well, actually... It should tell us that the UK money is getting pumped away to other countries very rapidly, and the majority of the wealth left behind isn't liquid, but rent seeking.
Thatcher took away exchange control regulations and allowed money to move abroad.
So yes our daily productive economic pot is devoid of freely spent money. Instead it’s full of money resupplied by debt. Loaned by those holding that money here and abroad.
So the sort of change we need is to reinstate exchange controls. Reintroduce a new currency. You have to swap all sterling here and abroad for a new uk only digital currency.
Then when all money is in the uk we put a spend by date on that new currency.
This would mend our economy overnight.
The tsunami of spending would give that cash flow we all need. Higher wages and so no need to borrow on a daily basis for necessities.
But our politicians don’t have that sort of vision!
You can buy Midea portable split air con units for £1k. They give proper aircon performance because the heat exchanger is outside. Very popular in Germany - good for renters including apartments with balconies. https://www.midea.com/uk/air-treatment/porta-split
The government grant for air-to-air heat pumps, apart from being less generous is entirely wide of the mark. You can only get it if the heat pump entirely replaces your existing heating system. Yet adding an air-to-air unit would provide both air conditioning and a more efficient form of supplementary heating than the existing heating system, allowing reductions in the gas or oil consumed in operating it. Exactly what government policy is intending, yet failing, to do. Associate an air-to-air heat pumps with solar panels to power it, and there is no added load on the grid from the aircon mode because the aircon will mostly be operating in sunny weather.
UK and for that matter all of Europe going “net zero” is a grim joke once you understand that China, India, Africa and the Middle East will *never* embrace the Western obsession with “carbon”. It’s simply not a thing in most of the world, other than participating in fancy conferences and entering into treaties with naive Europeans that confer some advantage. The wealth of a society correlates directly with the availability of cheap, abundant power. The UK will eventually sink below China in per capita wealth, and for what?
They're going from a basic uk medieval level in the 1970s to the leading world superpower in the 2020s, with a population of over a billion. That's not a shock. The average American is ridiculously higher use in every area. What is amazing is how little it has increased per capita in China.
I appreciate the technical descriptions of their systems, now and what could have been, but really what you're talking about is an exponentially, larger facet and belongs in a separate article if not many... Consider France which is mostly nuclear, so should not be an issue.
Ed, I have been looking into this question as I prepare to remodel a house and found a way of using a heat pump based wet underfloor heating system as a cooling solution: https://underfloorheating.info/heat-pump-underfloor-cooling/ Do you have a view on this?
The government grant for air-to-air systems has a pretty significant limitation: you only get the grant if you remove your boiler. So you might get efficient heating and cooling in your living room and bedrooms from your new A2A heat pump, but what about how water and heating bathrooms? A2A indoor units normally come with advice not to be installed in bathrooms.
More thinking is needed about how A2A could work alongside existing boilers as a cheap and convenient way to provide most of the heating, without requiring a full replacement of the central heating system.
The lack of hot water is a real issue with air to air. My daughter wants to upgrade her heating and desperately needs cooling.
But I am not sure instant water heaters are something she would be happy with given our high levels of limescale. Instant water heaters cannot realistically fill baths.
The simplest and cheapest solution for hot water is the trusty unvented direct cylinder (a tank with immersion heater). Fastest way to fill a bath, better shower pressure than electric shower, and can be heated at off-peak times. Or if you want to spend a little more upfront for lower energy costs, there are now standalone heat pump cylinders.
It took the UK government decades to actually introduce sensible thermal standards. It took so much lobbying to achieve that nobody thought about the overheating problem.
More decades will be needed to adapt to hot summers, then the Atlantic currents will fail and we will have horrendous cold winters to deal with.
How does air to air perform in sub zero temperatures with UK humidity levels?? Serious question!!
We are a small wet island and just because a technology works in a dry continental climate doesn’t guarantee success here.
Heat pumps handle the UK's humid winters no problem - based on personal experience and others I know. They may have to defrost more often than in dry climates, but they take care of that themselves without you noticing. Air-to-air will defrost the same as air-to-water does.
I always really enjoy your analysis but want to quibble a little with your recent post on AC options.
I’m in East Yorkshire and renting, so a permanent AC installation isn’t an option.
By being sensible:
-opening all windows overnight when outside is cooler than inside
-closing everything (windows/curtains/etc.) at 6am before the temperature rises
-opening the loft hatch
I’ve been able to keep the house at a reasonably comfortable 23-24C even when it was 32C outside today.
My home office however does get slightly warmer and a bit humid so I was considering a portable AC unit for that room only but I’m struggling to understand why a unit that draws back air from outside, as you are advocating, (which would be hotter and more humid than that inside), would be more efficient in my situation?
Air conditioning has two sets of air input and output. The first set draws air in, chills it and blows it back out. At the same time, the second set draws air in, heats it, and blows it out. It can only cool air by heating other air at the same time.
Ideally the hot part is all outdoors. This is how a permanently installed "split" system works. The box outdoors pulls in outdoor air, dumps the heat into it and blows it out hot. Meanwhile the indoor unit pulls in indoor air, chills it, and blows it out cold.
Portable units are a compromise. Ideally the hot part uses outdoor air so as not to waste cool indoor air. But to make the product cheaper and simpler to set up, the hot side can also draw in indoor air, dump heat into it, and blow it out through a single hose. But that means that cool air is being pulled out of the building, working against the efforts of the air conditioner. By bringing in a second hose, you can avoid needing to use indoor air to dump heat into, keeping the building more sealed and using outdoor air instead.
Sorry but thermodynamics and basic principles of physics: how can drawing in warmer more humid air from outside when the temperature differential is 10C be more efficient?
From the US but explains how 2 hose option works! Basically one hose cools the unit mechanics which makes it more efficient while the other extracts the room hot air!
I used to live in a house built in 1830s - solid stone walls almost 30 inches thick - never needed the house cooled down in summer and house heated up great in winter . Is some of the issue not to do with the materials that are used in house building now ?
I moved to the UK nine years ago from Cayman, where AC is everywhere (for obvious reasons) and central AC is built into the designs of homes for many decades now. Water heating used to always be done by immersion heaters (typically well insulated and just left on all the time), though after we had a hurricane in 2004 that flooded the ground floor of many homes, a lot of people now have "instant" water heaters. Still electric (so not like the UK combi boilers), but work well when sized correctly.
Anyway, I was a bit shocked when I bought a "new build" home on the southern edge of London to find how hot it gets. As we all know, the UK almost mandates homes to be designed to soak up and retain heat, but in summer, that meant for me that a 26c day and 16c overnight (pretty common) gave me bedrooms that would not cool below about 27c overnight on a still evening.
So, AC was on my mind right away. My house came with (basic) solar already, so that helps a bit, but I invested £10k in total on two air-to-air heat pump solutions (good news is that all domestic AC is already able to heat as well as cool, so that makes the parts and labour zero-rated for VAT when dual use is spec'd, and that means that this is the default for AC installers in the UK already). This was before the £2500 grant, so now each system would be less.
Each system handles three rooms, so de facto the whole house is cooled. In flat out use this week (with temps yesterday at 34c and only dropping to 25c ovenight), it used only about an additional 10kwh over and above the usual daily summer electricity use.
So far so good, but what about the future?
- when my gas boiler dies (useful life around 10 years, so for me that is a couple of years away), I take it out, turn off the gas, then simply use the hot water tank already in the house. For the bathrooms in winter I remove the (hot water) heated towel rails and put in electric ones. That is all I have to do and then I am using an all electric system for heating and cooling
- I will move to an electric car soon enough and will make sure that one has bidirectional charging, so will charge up the car overnight using cheaper electricity and use it as a battery during the day.
- I may upgrade my solar panels for summer AC use, but with the car as a battery, no need for additional battery installation.
All in all, I will be off carbon-based power (gas) soon enough, and with the inexorable transition to renewables, I can see that within a reasonable time I will be heating and cooling my house efficiently (as you note) with air-to-air heat pumps, devices that will use renewable power.
Oh, and given that I am very familiar with AC compressor units outside homes and businesses in Cayman, I was astonished to find that my 10kw exterior unit runs so silently (55dba). At a distance of over about 3m from the unit, the birdsong is louder. Oh, but my neighbour has a portable AC unit running now next door, it is much louder ;)
Why don’t we have more forward thinking? Every house should have disabled access and facilities. And downstairs! We all get older! They should have specific pipe runs for electricity and gas. Not ad-hoc pathways for pipes underground. Basements to house air to air HVAC systems. Solar panels. If possible ground source heat pumps and air source heat pumps. Back up generators. Car chargers. Great insulation and triple glazing. In fact any modern convenience. Room to park more than two cars comfortably. We have kids who drive! ID card readers at the front door so we know who is knocking on your door. Similar technology to make a phone call so we know who they are!
Ah, that's only for the super rich, and those with expense accounts and fat pensions (MPs) don't care about the running costs of their homes!
What that should tell us Nigel is that we are underfunded and underpaid!
There is apparently £19 trillion pounds out there in the aether.
If all that were to be SPENT in just one rotation. Once, not millions of times a day but once in one whole year, we should be able to supply £3.8 trillion pounds to our government from vat alone! One tax only, no other taxes, just one on one spending rotation in one whole year.
Our government gets £1.1 trillion pounds from all taxation from all spending now.
So we could have a surplus each month instead of a deficit. We could have four times our tax take four times!
Now that’s not just our government, it’s also us!
The revenue could increase our incomes by four times easily.
We have had a cash flow problem since the war. Money isn’t the problem we should have sufficient based on population and need. So the key is SPENDING money.
We have had so much money outside our daily economy that we have been underfunded. And the flow is small because the vast sums are unspent! Unused and idle.
What could have been? What could we have now. We just need those holding money to spend it continuously. Earn as much as we can. But spend it is the key to growth.
Well, actually... It should tell us that the UK money is getting pumped away to other countries very rapidly, and the majority of the wealth left behind isn't liquid, but rent seeking.
Cashflow is the issue in the UK.
Spot on Nigel.
Thatcher took away exchange control regulations and allowed money to move abroad.
So yes our daily productive economic pot is devoid of freely spent money. Instead it’s full of money resupplied by debt. Loaned by those holding that money here and abroad.
So the sort of change we need is to reinstate exchange controls. Reintroduce a new currency. You have to swap all sterling here and abroad for a new uk only digital currency.
Then when all money is in the uk we put a spend by date on that new currency.
This would mend our economy overnight.
The tsunami of spending would give that cash flow we all need. Higher wages and so no need to borrow on a daily basis for necessities.
But our politicians don’t have that sort of vision!
You can buy Midea portable split air con units for £1k. They give proper aircon performance because the heat exchanger is outside. Very popular in Germany - good for renters including apartments with balconies. https://www.midea.com/uk/air-treatment/porta-split
The government grant for air-to-air heat pumps, apart from being less generous is entirely wide of the mark. You can only get it if the heat pump entirely replaces your existing heating system. Yet adding an air-to-air unit would provide both air conditioning and a more efficient form of supplementary heating than the existing heating system, allowing reductions in the gas or oil consumed in operating it. Exactly what government policy is intending, yet failing, to do. Associate an air-to-air heat pumps with solar panels to power it, and there is no added load on the grid from the aircon mode because the aircon will mostly be operating in sunny weather.
UK and for that matter all of Europe going “net zero” is a grim joke once you understand that China, India, Africa and the Middle East will *never* embrace the Western obsession with “carbon”. It’s simply not a thing in most of the world, other than participating in fancy conferences and entering into treaties with naive Europeans that confer some advantage. The wealth of a society correlates directly with the availability of cheap, abundant power. The UK will eventually sink below China in per capita wealth, and for what?
All those places are deploying renewables faster than the west, China in particular.
A large part of that is about resiliance though. About reducing vulnerability to an oil shock.
It’s win-win-win-win! Cheaper to install, resilient to oil-price shocks, lower running costs, and lower carbon.
China’s carbon emissions are rising massively at the same time though
They may have peaked, still need to fall rapidly though. https://www.carbonbrief.org/analysis-chinas-co2-emissions-have-now-been-flat-or-falling-for-21-months/
They're going from a basic uk medieval level in the 1970s to the leading world superpower in the 2020s, with a population of over a billion. That's not a shock. The average American is ridiculously higher use in every area. What is amazing is how little it has increased per capita in China.
India is also going solar at an incredible rate. I think you are regurgitating oil company propaganda.
Net zero is cheaper. How have you missed that? It's also generally better against price shocks and less affected by international saber rattling!
I moved from Scotland to NZ over 20 years ago. Left a house with full gas central heating
I thought Material World (your book) was absolutely fabulous.
And the Meaco is out of stock. Same as most everything else around the country. I can’t wrap my head around the opportunity to
Print money that’s been passed by so often.
Environmental concerns, perhaps?
Why not mention that?
I appreciate the technical descriptions of their systems, now and what could have been, but really what you're talking about is an exponentially, larger facet and belongs in a separate article if not many... Consider France which is mostly nuclear, so should not be an issue.
Ed, I have been looking into this question as I prepare to remodel a house and found a way of using a heat pump based wet underfloor heating system as a cooling solution: https://underfloorheating.info/heat-pump-underfloor-cooling/ Do you have a view on this?
Big fan of Material World.
Simon
The government grant for air-to-air systems has a pretty significant limitation: you only get the grant if you remove your boiler. So you might get efficient heating and cooling in your living room and bedrooms from your new A2A heat pump, but what about how water and heating bathrooms? A2A indoor units normally come with advice not to be installed in bathrooms.
More thinking is needed about how A2A could work alongside existing boilers as a cheap and convenient way to provide most of the heating, without requiring a full replacement of the central heating system.
The lack of hot water is a real issue with air to air. My daughter wants to upgrade her heating and desperately needs cooling.
But I am not sure instant water heaters are something she would be happy with given our high levels of limescale. Instant water heaters cannot realistically fill baths.
The simplest and cheapest solution for hot water is the trusty unvented direct cylinder (a tank with immersion heater). Fastest way to fill a bath, better shower pressure than electric shower, and can be heated at off-peak times. Or if you want to spend a little more upfront for lower energy costs, there are now standalone heat pump cylinders.
It took the UK government decades to actually introduce sensible thermal standards. It took so much lobbying to achieve that nobody thought about the overheating problem.
More decades will be needed to adapt to hot summers, then the Atlantic currents will fail and we will have horrendous cold winters to deal with.
How does air to air perform in sub zero temperatures with UK humidity levels?? Serious question!!
We are a small wet island and just because a technology works in a dry continental climate doesn’t guarantee success here.
Heat pumps handle the UK's humid winters no problem - based on personal experience and others I know. They may have to defrost more often than in dry climates, but they take care of that themselves without you noticing. Air-to-air will defrost the same as air-to-water does.
Hi Ed
I always really enjoy your analysis but want to quibble a little with your recent post on AC options.
I’m in East Yorkshire and renting, so a permanent AC installation isn’t an option.
By being sensible:
-opening all windows overnight when outside is cooler than inside
-closing everything (windows/curtains/etc.) at 6am before the temperature rises
-opening the loft hatch
I’ve been able to keep the house at a reasonably comfortable 23-24C even when it was 32C outside today.
My home office however does get slightly warmer and a bit humid so I was considering a portable AC unit for that room only but I’m struggling to understand why a unit that draws back air from outside, as you are advocating, (which would be hotter and more humid than that inside), would be more efficient in my situation?
Air conditioning has two sets of air input and output. The first set draws air in, chills it and blows it back out. At the same time, the second set draws air in, heats it, and blows it out. It can only cool air by heating other air at the same time.
Ideally the hot part is all outdoors. This is how a permanently installed "split" system works. The box outdoors pulls in outdoor air, dumps the heat into it and blows it out hot. Meanwhile the indoor unit pulls in indoor air, chills it, and blows it out cold.
Portable units are a compromise. Ideally the hot part uses outdoor air so as not to waste cool indoor air. But to make the product cheaper and simpler to set up, the hot side can also draw in indoor air, dump heat into it, and blow it out through a single hose. But that means that cool air is being pulled out of the building, working against the efforts of the air conditioner. By bringing in a second hose, you can avoid needing to use indoor air to dump heat into, keeping the building more sealed and using outdoor air instead.
Sorry but thermodynamics and basic principles of physics: how can drawing in warmer more humid air from outside when the temperature differential is 10C be more efficient?
From the US but explains how 2 hose option works! Basically one hose cools the unit mechanics which makes it more efficient while the other extracts the room hot air!
https://www.forbes.com/sites/forbes-personal-shopper/article/dual-hose-vs-single-hose-portable-ac/
I used to live in a house built in 1830s - solid stone walls almost 30 inches thick - never needed the house cooled down in summer and house heated up great in winter . Is some of the issue not to do with the materials that are used in house building now ?
fascinating! Thank you very much.
You are quite right, I have been investigating this myself and have been appalled by how basic the UK technology seems to be.