UK energy

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[XAP]Bob
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Joined: 26 Sep 2008, 4:12pm

Re: UK energy

Post by [XAP]Bob »

Astonish: I don't have a heat pump (though I am likely to get one once this boiler packs in). Ok - technically I have four heat pumps in the house, but one is called a fridge, one is called a freezer, then I have a portable A/C unit which is mostly used as a dehumidifier and a dedicated dehumidifier.

I do have a small (six panel) solar array and a home battery, as well as an EV. Those combine to make the best use of a time of day tariff.
I am considering getting a hot water tank before the heat pump, partly because my off peak electricity costs are already substantially lower than my gas cost and partly to get a stratified tank with data about the amount of hot water available for when the heat pump is installed (HP installers only seem interested in installing the most basic tanks).

Is your boiler 90% efficient, or is that the sticker efficiency?
Are you actually measuring the heat output and comparing with the oil in? I've got a flow meter to put on my cold feed into the boiler in order to measure the actual DHW heat output, I just haven't actually hooked it up yet (and I'm a massive data geek).
A fairly wide study of condensing boilers in 2009 found that combi boilers on average ran at 82% and system boilers at 85%.
I'd be fairly confident that because of the optimisations I have made that my heating is on the efficient end of the range, but my hot water is probably not.

The current profit guarantee has electricity at 30-33p and gas at 10p.
Efficiency -> Required SCOP [33p/(10p/eff%)]:
100% -> 3.3
90% -> 3.0
85% -> 2.8 (likely real world)
80% -> 2.6
75% -> 2.5 (A good non-condensing boiler)
65% -> 2.1

A correctly sized and installed heat pump should get a scop (seasonal coefficient of performance) of 3.5-4 (see real world data from http://heatpumpmonitor.org), which is well above the 2.8 needed to make it cost effective. I've also completely ignored the electrical consumption of the boiler - which can be quite significant.

However, cost is not the only factor here. You have the opportunity to remove a significant safety risk from your house as well.

When I do get a HP installed then I don't expect my heating bills to drop massively, though the amount of fuel used will - because even accounting for the <10% losses in electricity transmission I only need a SCOP of ~2.2 to use less gas (assuming *all* of my energy needs come from a gas power station, which won't be the case).
They will probably drop, but that's not the primary reason I'd be making the change.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
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[XAP]Bob
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Joined: 26 Sep 2008, 4:12pm

Re: UK energy

Post by [XAP]Bob »

Biospace wrote: 11 May 2023, 4:56pmYes, too right. I've a feeling we've high Grid energy prices for decades to come.
Unfortunately I think that until we have a substantially greener grid, you're going to be correct in that prediction.
Well insulated homes which make good use of solar radiation when the sun is lower in the southern sky, solar hot water and PV panels, bicycles for short trips and home grown food would all seem to make sense.
Changing the fabric of houses, and in particular their orientation and glazing, is quite difficult.
Solar thermal is cheap... but a PV system with a heat pump hot water tank will get you more hot water for the same incoming radiation.
But if you can't fit PV (probably for cost reasons) then go for it... it's not a technology I'm all that familiar with.

I'm not growing my own food though... I'm quite happy leaving that to those better equipped than I.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
ANTONISH
Posts: 2958
Joined: 26 Mar 2009, 9:49am

Re: UK energy

Post by ANTONISH »

[XAP]Bob wrote: 11 May 2023, 11:23pm Astonish: I don't have a heat pump (though I am likely to get one once this boiler packs in). Ok - technically I have four heat pumps in the house, but one is called a fridge, one is called a freezer, then I have a portable A/C unit which is mostly used as a dehumidifier and a dedicated dehumidifier.

I do have a small (six panel) solar array and a home battery, as well as an EV. Those combine to make the best use of a time of day tariff.
I am considering getting a hot water tank before the heat pump, partly because my off peak electricity costs are already substantially lower than my gas cost and partly to get a stratified tank with data about the amount of hot water available for when the heat pump is installed (HP installers only seem interested in installing the most basic tanks).

Is your boiler 90% efficient, or is that the sticker efficiency?
Are you actually measuring the heat output and comparing with the oil in? I've got a flow meter to put on my cold feed into the boiler in order to measure the actual DHW heat output, I just haven't actually hooked it up yet (and I'm a massive data geek).
A fairly wide study of condensing boilers in 2009 found that combi boilers on average ran at 82% and system boilers at 85%.
I'd be fairly confident that because of the optimisations I have made that my heating is on the efficient end of the range, but my hot water is probably not.

The current profit guarantee has electricity at 30-33p and gas at 10p.
Efficiency -> Required SCOP [33p/(10p/eff%)]:
100% -> 3.3
90% -> 3.0
85% -> 2.8 (likely real world)
80% -> 2.6
75% -> 2.5 (A good non-condensing boiler)
65% -> 2.1

A correctly sized and installed heat pump should get a scop (seasonal coefficient of performance) of 3.5-4 (see real world data from http://heatpumpmonitor.org), which is well above the 2.8 needed to make it cost effective. I've also completely ignored the electrical consumption of the boiler - which can be quite significant.

However, cost is not the only factor here. You have the opportunity to remove a significant safety risk from your house as well.

When I do get a HP installed then I don't expect my heating bills to drop massively, though the amount of fuel used will - because even accounting for the <10% losses in electricity transmission I only need a SCOP of ~2.2 to use less gas (assuming *all* of my energy needs come from a gas power station, which won't be the case).
They will probably drop, but that's not the primary reason I'd be making the change.
I had thought that you actually used a heat pump for your heating.
My boiler efficiency is measured at around 90% - I'm certainly not measuring oil flow and energy out because I have a life .
The measurement is based on flue temperature.
I burn around 1000 litres of oil in a year. Last year this cost me £870 which for various reasons was much higher than previously - I anticipate it being less this year. I also have a multifuel stove for very cold weather and I have used £200 of smokeless fuel in that.
I calculate that an air source heat pump will need a SCOP of 400% to be competitive.

You give a figure of 10% for transmission loss but surely the electricity you receive must be generated and you don't give the generation loss figure.

In short there is no real incentive for me to install a CHP even if I got the CHP and the required upgrade free.
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[XAP]Bob
Posts: 19793
Joined: 26 Sep 2008, 4:12pm

Re: UK energy

Post by [XAP]Bob »

The generation efficiency was rounded from the UK CCGT data at 50%:
https://www.statista.com/statistics/548 ... ations-uk/

Flue temperature is not a measure of efficiency, though there will be some correlation.
But even at 100% efficiency (and I think we can all agree that that's not possible) you're not going to be paying more for heat from an appropriate heat pump than you would from heat from burning oil or gas.

1000 litres is about 10MWh of heating fuel per year, so you could reasonably (SCOP 3.5) expect to use less than 3MWh of electricity instead, which at the top end of the profit guarantee would put an upper bound on fuel cost of £990.
That 3MWh of electricity at your house would required about 3.3MWh out of a power station, or 6.7MWh of fuel input - i.e. a third less fuel being burnt for the same heat output in your house.

The installation costs are significant, but actually a boiler is also fairly significant in cost - which is why I (repeatedly) suggest that the time to make the change is when a boiler needs replacing - not just because it's old, but because parts aren't available any more or because it's outright failed.
And to be in a place to do that, you need to look at the installation in advance. Mine will actually be fairly simple, because I've run for a winter at low flow temperatures, so I *know* the rest of the system can cope with that just fine, even on the occasional day when the temp dips to negative 5.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
ANTONISH
Posts: 2958
Joined: 26 Mar 2009, 9:49am

Re: UK energy

Post by ANTONISH »

[XAP]Bob wrote: 12 May 2023, 11:03am The generation efficiency was rounded from the UK CCGT data at 50%:
https://www.statista.com/statistics/548 ... ations-uk/

Flue temperature is not a measure of efficiency, though there will be some correlation.
But even at 100% efficiency (and I think we can all agree that that's not possible) you're not going to be paying more for heat from an appropriate heat pump than you would from heat from burning oil or gas.

1000 litres is about 10MWh of heating fuel per year, so you could reasonably (SCOP 3.5) expect to use less than 3MWh of electricity instead, which at the top end of the profit guarantee would put an upper bound on fuel cost of £990.
That 3MWh of electricity at your house would required about 3.3MWh out of a power station, or 6.7MWh of fuel input - i.e. a third less fuel being burnt for the same heat output in your house.

The installation costs are significant, but actually a boiler is also fairly significant in cost - which is why I (repeatedly) suggest that the time to make the change is when a boiler needs replacing - not just because it's old, but because parts aren't available any more or because it's outright failed.
And to be in a place to do that, you need to look at the installation in advance. Mine will actually be fairly simple, because I've run for a winter at low flow temperatures, so I *know* the rest of the system can cope with that just fine, even on the occasional day when the temp dips to negative 5.
Which all may be true but the cost of a unit of electricity will be much greater than the cost of a unit burning oil.
Your upper bound limit of £990 is higher than my abnormally high figure of £870.
As I've said there is no financial incentive for me to "invest" in an air sourced heat pump.
I expect my fuel cost to be lower this year - even less incentive.
Biospace
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Joined: 24 Jun 2019, 12:23pm

Re: UK energy

Post by Biospace »

If the majority of British homes become heated by HPs, I can see the market for wood stoves increasing as people ensure they'll be warm in the coldest winter weather.
Jon in Sweden
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Joined: 22 May 2022, 12:53pm

Re: UK energy

Post by Jon in Sweden »

Biospace wrote: 13 May 2023, 11:55am If the majority of British homes become heated by HPs, I can see the market for wood stoves increasing as people ensure they'll be warm in the coldest winter weather.
But they may well be outlawed due to particulate pollution. There is also the question of sustainability - the UK forest cover is minimal and a lot of firewood is imported from the Baltic states.

We use our stove here in Sweden when the electricity price is high (we're on an hourly price) and we reduce the heat pump temperature. It's really not needed to provide supplementary heat. It's only used to save money on occasion.
Biospace
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Re: UK energy

Post by Biospace »

Jon in Sweden wrote: 13 May 2023, 12:52pm
Biospace wrote: 13 May 2023, 11:55am If the majority of British homes become heated by HPs, I can see the market for wood stoves increasing as people ensure they'll be warm in the coldest winter weather.
But they may well be outlawed due to particulate pollution. There is also the question of sustainability - the UK forest cover is minimal and a lot of firewood is imported from the Baltic states.

We use our stove here in Sweden when the electricity price is high (we're on an hourly price) and we reduce the heat pump temperature. It's really not needed to provide supplementary heat. It's only used to save money on occasion.
It is absolutely about particulate pollution - one of the larger short-term drivers of climate change. Despite the UK's widescale use of gas and electricity for heating, wood burning accounts for more than all the particulate pollution from traffic.

I'm interested in how, if you're not struggling to make ends meet and fully believe in the climate change narrative, you justify the use of burning wood when the price of your electricity rises? This isn't a criticism, just that I've been in a similar place in recent years and it made me question all sorts of things.
Jon in Sweden
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Joined: 22 May 2022, 12:53pm

Re: UK energy

Post by Jon in Sweden »

Biospace wrote: 13 May 2023, 1:16pm
It is absolutely about particulate pollution - one of the larger short-term drivers of climate change. Despite the UK's widescale use of gas and electricity for heating, wood burning accounts for more than all the particulate pollution from traffic.

I'm interested in how, if you're not struggling to make ends meet and fully believe in the climate change narrative, you justify the use of burning wood when the price of your electricity rises? This isn't a criticism, just that I've been in a similar place in recent years and it made me question all sorts of things.
It's a question of cost and habit. I think that using the fire has saved us about £700 -800 over winter, and working in forestry and sawmilling means I pay very little for timber.

Also, our area is 70% forest and extremely sparsely populated. Us and the neighbouring 6 municipalities only have 117k people living in nearly 9200 square kilometres. That's 12.77 people/km2, compared to England at 434/km2. Particulates aren't going to be an issue with so few people.

I feel that given the volume of forest, that heating with wood is quite sustainable too. It's locally produced.
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[XAP]Bob
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Re: UK energy

Post by [XAP]Bob »

Biospace wrote: 13 May 2023, 11:55am If the majority of British homes become heated by HPs, I can see the market for wood stoves increasing as people ensure they'll be warm in the coldest winter weather.
No - I would expect that they would be nice and warm with the heat pumps... that's what they're designed to do.

What complete and utter twaddle gets typed at times :roll:


Which all may be true but the cost of a unit of electricity will be much greater than the cost of a unit burning oil.
Yes, but the efficiency is also much higher - that's the whole point.
The cost per kWh of *heat* isn't substantially different between gas/oil and electricity, though it's likely slightly in favour of the electricity. The 990 assumed the low end of my range, and the very highest price for electricity - the 870 was your actual price for the year...
The expectation is that the oil price will drop - and that gas, and with it electricity, prices will also fall. I deliberately took a price which is higher than the average over the last twelve months, and a not very good scop, to bias *against* the heat pump as much as I could - and still came in at the same ballpark price.

If I was to take a more reasonable "usual" cost of electricity at 15*p/kWh, and a SCOP of 3.5, or even 4, then the cost would be £430 or £375.
Oil has a long term average of about 5p/kWh (£500)

Now you might predict wildly different prices... but as long as the price for electrons is about 4x the price for a fossil fuel then the heat pump running cost will be about the same as a boiler.

There isn't a huge financial incentive to switch a well serviced, and serviceable, boiler - but there are other reasons you may consider switching - the 30% less fuel being burnt is good for all sorts of reasons, and it being burnt somewhere that isn't in your house/garden is also a benefit.
When you do come to change the heat source in your property then *that* is the time at which the change can be made - and if it's been prepared for then it shouldn't be a huge deal.

My prediction, looking at our usage over the winter, is that it would be about the same, or slightly cheaper for us over the course of a year, and it would be *much* cheaper if we got a V2H capable car/charger (i.e. a 2nd hand leaf) - again, more capital expenditure, but we've been a one car household for 15 years, and it's not that long until miniBob will be looking to learn to drive (which won't be possible on my motability lease).
There are a myriad of decisions which need to happen before that's an issue though - and I might decide to add a second battery to the home setup...
First things first though - get a decent portable induction hob (with physical controls) for use this summer (since I hope we'll have plenty of sunshine to use).


* The ONS data references 2015 as a baseline of 100, I can't see a raw data series.
However I did find a report which has a pair of tables (1&2) which suggest a price of 15.4p for 2015 - pretty close to my estimate, particularly since that value includes the standing charge, I don't have a 2015 bill handy, but guessing at 25p/day that would drop the price to 13p (or £370-£325 in the above calculations)
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
Biospace
Posts: 1990
Joined: 24 Jun 2019, 12:23pm

Re: UK energy

Post by Biospace »

[XAP]Bob wrote: 14 May 2023, 12:01am
Biospace wrote: 13 May 2023, 11:55am If the majority of British homes become heated by HPs, I can see the market for wood stoves increasing as people ensure they'll be warm in the coldest winter weather.
No - I would expect that they would be nice and warm with the heat pumps... that's what they're designed to do.

What complete and utter twaddle gets typed at times :roll:

If British Gas is the installer then chances are they'll be warmer than some as they've recently said they'd guarantee someone with a HP fitted by them will remain warm (for 12 months) and said "heat pumps can leave your house colder than [with] a gas boiler".

Our friend Jon in Sweden could likely explain why a wood stove works well in conjunction with a heat pump, but I would imagine that the instant heat (and hot water) would be very useful at times, either as a back up in very cold weather or when (as in Jon's case) electricity prices are high and (something I would value) if powered by PV panel, on days with very little solar radiation.
Last edited by Biospace on 14 May 2023, 2:12pm, edited 1 time in total.
Biospace
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Re: UK energy

Post by Biospace »

Jon in Sweden wrote: 13 May 2023, 9:33pm It's a question of cost and habit. I think that using the fire has saved us about £700 -800 over winter, and working in forestry and sawmilling means I pay very little for timber.

Also, our area is 70% forest and extremely sparsely populated. Us and the neighbouring 6 municipalities only have 117k people living in nearly 9200 square kilometres. That's 12.77 people/km2, compared to England at 434/km2. Particulates aren't going to be an issue with so few people.

I feel that given the volume of forest, that heating with wood is quite sustainable too. It's locally produced.

Yes, local pollution is a problem where population density is high, but the climate scientists are most concerned that the carbon black particles from the Northern hemisphere are greying the Arctic ice and so having a very rapid and heightened effect on climate change as more solar radiation is absorbed.

I'm not one of the fundamentalists with respect to the planet's climatic reaction to Man's behaviour and see that it's regular air travel and high levels of consumption of cheap products (especially industrially produced meat) which likely create most overall harm. And that the further we remove ourselves from Nature, the less aware we are of our intimate relationship with it.
Jon in Sweden
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Re: UK energy

Post by Jon in Sweden »

Biospace wrote: 14 May 2023, 2:06pm
Yes, local pollution is a problem where population density is high, but the climate scientists are most concerned that the carbon black particles from the Northern hemisphere are greying the Arctic ice and so having a very rapid and heightened effect on climate change as more solar radiation is absorbed.

I'm not one of the fundamentalists with respect to the planet's climatic reaction to Man's behaviour and see that it's regular air travel and high levels of consumption of cheap products (especially industrially produced meat) which likely create most overall harm. And that the further we remove ourselves from Nature, the less aware we are of our intimate relationship with it.
I certainly appreciate what you're saying. We really don't use much now. We did in the UK though, as I had larger supplies of firewood available to me and a less high tech central heating system. And crappier houses.

Timber is the main farmed product here. Very little of it is actually burned though. Almost all of it goes for other purposes, such as wood pulp, paper, sawmill products. It's quite diverse.
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[XAP]Bob
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Re: UK energy

Post by [XAP]Bob »

Biospace wrote: 14 May 2023, 1:48pm
[XAP]Bob wrote: 14 May 2023, 12:01am
Biospace wrote: 13 May 2023, 11:55am If the majority of British homes become heated by HPs, I can see the market for wood stoves increasing as people ensure they'll be warm in the coldest winter weather.
No - I would expect that they would be nice and warm with the heat pumps... that's what they're designed to do.

What complete and utter twaddle gets typed at times :roll:

Please note the way you've quoted further down your last post, it appears a quote is attributable to me when it is not. And as a gentle reminder, you still haven't substantiated your (fairly wild) claims on a different thread, although politely requested.


If British Gas is the installer then chances are they'll be warmer than some as they've recently said they'd guarantee someone with a HP fitted by them will remain warm (for 12 months) and said "heat pumps can leave your house colder than [with] a gas boiler".

Our friend Jon in Sweden could likely explain why a wood stove works well in conjunction with a heat pump, but I would imagine that the instant heat (and hot water) would be very useful at times, either as a back up in very cold weather or when (as in Jon's case) electricity prices are high and (something I would value) if powered by PV panel, on days with very little solar radiation.
Quote system is a pain at times.

There are a few threads which I simply don't read - maybe you've asked on one of those, or maybe I missed it.
I struggle to think of any claims I have made which could be called "wild" - any suggestion that "a heat pump will leave your house cold" is provably utter tosh.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
Biospace
Posts: 1990
Joined: 24 Jun 2019, 12:23pm

Re: UK energy

Post by Biospace »

[XAP]Bob wrote: 14 May 2023, 2:15pm Quote system is a pain at times.
Yes, you'll see I deleted some of the text when I saw you have replied, covering your wild claims (that BEV tyres are being found to last over 2.5 times longer than on diesel vehicles in a fleet) by saying there were "confounding factors". :wink:
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