Here is my 2020 and 2021 usage. 2020 i had gas boiler and got my heat pump in Feb was when my installed didn't go to plan and I was provided heaters which as u can see cost me a fortune. I also just got a phev. So my energy consumption has gone up. But not as much as I though. And it seems to be saving so far even with leaving the pump in 20 during the evening and 21 during the day.  You can see the set up took some time as it was not correctly set up. As indicated by the graph 

@M.isterW  I think in my case I should also consider the different approach we are taking now to heating the house in this discussion, as previously with gas on the timer we heated the house for an hour and half in the morning and four hours evening, but now the heating is on 24/7 and as such the house has never been warmer!

All that and at last count I think our heating and hot water bill is up by 20% or so. 

Luckily our Nest thermostat has been logging our house temperature since 2019, unbeknown to me until last Sunday (!) so I have been able to get 15 minute excel CSV readings for the last two years, and going forward I will be producing graphs showing the difference in home heat month by month. I will post a graph at the end of Nov to show the difference this has made. 

So in essence, I’m unsure if we are comparing apples with oranges when matching gas with electric, unless you heat the house in the same way. With 24/7 heating thermal mass of the house and all the furnishings comes into the equation….. And also what cost is acceptable with all that added comfort?  I am happy to pay more if I get more - I suppose the issue is what do you do if you dont want it, and does the defrost cycle then muck things up as that will use electric whether you like it or not. 

15 Oct to 14 Nov 2020 we used about 160kWh of electricity and 2,116kWh of gas (2,281 total)
15 Oct to 14 Nov 2021 we used 577kWh of electricity and 30kWh of gas (607 total)

So, looking at energy usage it looks like it has has fallen by about 73%, which seems like too much to be true. I’m expecting more like 35-45% when I have a proper data set (I estimate heating & hot water is about 70% of our energy usage, including the EV, and with a COP of 2 and good insulation it should fall by a bit more than half). I’m questioning the data but I can’t figure out whether there’s a problem. I can’t do a broader year on year comparison I’m afraid because we only moved into the house at the end of September 2020 (maybe ask me again this time next year). Our habits aren’t much different, e.g. we already had the EV in 2020. We probably do keep the house a bit colder than before and October was quite warm this year. Also, the house is better insulated now than it was and our old gas boiler was very energy inefficient. So, those things help, but I’m still not expecting 70%+ reduction in usage.

Our bills (gas+elec) are about the same as before, in spite of the price of energy being more expensive, and electricity being a lot more expensive than gas. With a COP of about 2, and electricity is about 5x the price of gas, in my head our heating & hot water bill should be about 2.5x more expensive than it was with gas. In the medium term, I expect our bills will be higher than before, maybe about 1.5x higher.

Whilst the kWh combined may have gone down; with gas circa 4p per kWh and electric now circa 20p per kWh the cost, rather than kWh, has defiantly gone up. 

With this trial we are not allowed / able to make use of Time of Use tariffs or technology. I would LOVE to be able to ‘charge’ ALL the Sunamp batteries using cheap off peak electric. BOVO (Before OVO) on Octopus Go, I would charge the Powerwall, charge the car, heat the hot water, turn on the underfloor in 2 rooms all in the 4 hour off peak period. That would run the house for 80%+ of the day

@briannolan  You need to bear in mind that a modern gas boiler is rated at max 90% efficiency, however due to installation issues and lazy installers I read somewhere that efficiency could be as low as 55%. That obviously impacts on a kWh to kWh comparison but not £ to £. 

I’m interested in the replies to this question as I can’t tell. I was on oil before getting the ASHP which meant spending about £750 to put 1,500 litres in the tank. Never sure how long this lasted. I know my elec bills have roughly doubled. 
 

In November last year we were using about 50kWh of energy per day, split into 40kWh gas  and 10kWh electricity. We only used gas for heating and hot water.

At the moment, with a heat pump we're using about 35kWh of electricity per day. The entire heating and hot water system is using about 25kWh with the heat pump using about 20 of that. It isn't typical for the system to use 5kWh per day but we have an unusual hot water setup that uses an immersion heater a lot more.

I'm not sure comparing one month is particularly useful because energy use is weather dependent. We've only had the heat pump for a month so it will be interesting to see how the numbers compare as we go through winter.

As for cost... we're paying a lot more for our energy but our electricity cost per kWh has gone up 50% since last year, which accounts for a big chunk of the increase.

This is developing into a really interesting discussion and note-swapping on the effect an Air-Source Heat Pump is having on all your energy consumptions!

I’m sure that this information could prove really helpful to those who might be considering making an Air Source Heat Pump upgrade in the near future - With that in mind would anyone who’s posted here already ( @M.isterW , @James_N , @48havelock , @briannolan , @jason.lewis , @hambrook ) object to us moving this thread over to our public Smart Home Area to make it accessible to all?  

I don't mind the thread being moved.

I don’t mind at all

I don’t mind the thread being public. I guess a lot of people will be put off buying a heat pump when they read that their bills are likely to go up. I don’t want to put people off buying a heat pump because they are great (just look at the energy usage and think of the carbon savings!), it’s just that gas is cheaper than it should be, and electricity is more expensive than it should be (there should be a heat pump tariff). Maybe it’s better that people have realistic expectations, I guess.

Completely agree, @briannolan. 

I’ve moved this topic thread into the public ‘Smart Home’ category now. No change other then that, I’m keen to hear from other heat pump members when they come across this topic. 

I know for a fact, @juliamc has some very good looking charts from the data she’s been collecting since her heat pumps were fitted…. which thread did you post those in, Julia? 

No idea @Tim_OVO !!!  but here are three more graphs for you 

This is March - Dec 2020 - showing our normal pattern of use before the heat pump, I just accepted the fact that we used loads of gas autumn winter and spring. We had a gas powered warm air heating system, and the hot water was heated just with an immersion. Summer gas use was (unbelievably ) mostly the pilot light on the gas unit, plus the hob. Spikes in the electricity are EV charging.

Then the heat pump was fitted and started working in March 2021. Sorry, graph colours reversed: gas now shown in blue !! The EV data has been removed for this graph.

I look at this with a warm feeling because of all that gas I’m NOT using now. I still have the warm air unit (the pilot light’s off now) and I hope not to use it again. If possible I’d like to repurpose it as a ventilation system one day. Whether the heat pump is enough in the depths of winter is still to be proved of course. It really shows how inefficient the old heating system was. 

Btw: to get the data for these graphs I laboriously copied kWh and price from MyOVO !!

In this graph I’ve shown just the heating costs ie. gas data while the old system was running, then the electricity used for just the space heating function of the heat pump, showing the comparable costs:

The last few days show when I set the ‘Holiday’ mode on the heat pump. Seemed like a good idea as we were on holiday… However, I could see (remotely using the phone app) that the house temperature continued to drop, so I switched it back on after two days. I think it used more electricity warming the house back up than I saved by letting it cool down. Won’t do that again unless it’s summertime !!

Bad electricity day yesterday, with the cold weather. 60kWh, although we did charge the car (it's a phev so takes a max of 7.5kWh).

I don't have daily figures for our gas usage in previous years so I can't see how much gas we used on cold days, which would be a useful comparison.

It isn't so cold today so I'm hoping we're back to a less scary level.

A rough comparison of my energy costs for heating from May to present:

Previous total gas cost for these months in 2020 was around £215 (included a little use on a single burner hob and also the standing charge).

2021 heat pump use since installation in May is £158 for central heating and £32 for hot water (£190 total) including the cold weekend we’ve just had which I think must have added around £20!

This is based on a unit price for gas of 2.77p and day/night electricity of 16.3p/5p. If you run the same calculation with a gas price of 4p and day/night electricity of 24.8p/5p you’d get a cost of £400 for gas v £275 for electricity.

So the numbers are looking ok for me, although without a cheap rate overnight the savings compared to gas would be less.

Do you have any expectations about what the comparison might be over 12 months including the upcoming winter, @nealmurphy ? 

Can I ask how you are finding the i life 2 radiators vs standard radiators in general, @M.isterW ? 

It's difficult to compare radiators as they were fitted at the same time as the heat pump but they work okay. In mild weather the house heats fairly quickly but yesterday when it was very cold it took a long time to go from 18 to 20 in the afternoon/evening. I did see that another person with the same setup had a bad heat day yesterday so I wonder if the systems aren't coping well when it's very cold.

 I do have a few minor annoyances with the rads.

1 - They can't be zoned so we heat the whole house or none of the house. For rads that cost nearly £500 each that's fairly poor.

2 - They thermostats seem to be at the bottom so don't always read the room temperature very well, particularly if you have furniture in front of them.

3 - There are only two sizes. Our smaller rooms have radiators that are too big (not really a problem) and I think our sitting room needs a bigger one. After the trial is over I'm going to ask SGS about fitting a second rad in the sitting room, next to the existing one.

My energy usage with a heat pump not working 100% (maybe that’s helped…)

2020: 3900kwh elec, 13520kwh gas. £1188

2021 estimate: 8500kwh elec. £1106 on previous tariff, so very close to gas equivalent running costs. Unfortunately my company went bust so on new tariff it will actually be closer to £1800. 

OVO - let’s have a heat pump trialists tariff please .

That’s a +1 from me for the heat pump tariff please, or even better lobby the government to drop the 26% renewables electric tax on heat pumps! That would certainly help.

@Jess_OVO @Tim_OVO Seriously though, I am wondering if we can help design a tariff that takes account of the need for a morning warm up time and hot water heat-up, say starting 5am (so as not to wake everyone up too early)  and ending at 7am, maybe 8am (not sure this would be too late to tie with cheap rates). You guys have our data so will know how much energy is needed when to get us up to temperature. 

@Transparent any thoughts?

Thanks that is interesting and what I  wondered having read about the radiators. 

It is almost as though the radiators were designed and built by a completely different company given that there is no integration with the heat pump controller and all the radiators are stand alone.  I can't help thinking that is going to introduce some inefficiencies.

I did quite like the idea of them initially.

Thanks for your time replying to questions. 

The i-life rads are actually labelled Climaveneta which I think is part of the industrial side of Mitsubishi. A friend commented that they're very like the office radiators he used to install. I wonder if they are starting to push them into the domestic market but haven't yet done the work to make them integrate properly with modern domestic heating control systems.

Back to "normal" electricity use yesterday. Still over 30kWh but that seems to be standard in cooler weather. It is a bit frustrating being unable to take advantage of a two rate tariff or a TOU tariff to bring the bills down, particularly as our system, with heat batteries, is perfect for it. But I'm using the trial period to learn how the system performs so when it ends I'll be better informed and able to choose the best tariff.

That is good news. 

Do the Heat Batteries help with the domestic hot water and the central heating in your setup. 

Good to see so much shared learning from all this investment in the trials. I hope we see more in general over the next year. 

The heat batteries allow for some of our energy use to be moved to different times of day but I suspect they have a negative impact on our electricity use because they require hotter water from the heat pump to charge them. Also, one of the hot water batteries is charged with an immersion heater so that's using even more electricity. This wouldn't be a problem if we could charge the batteries overnight on a cheap rate.