Meter Readings Panic and Electricity Costs

[ProDave]

Your "other" sounds about right.  We average about 100kWh per week on non heating / non hot water usage, a figure I just cannot get down (how anyone gets to just 2kW per day non heating usage beats me, they clearly don't watch tv, do any washing dishwashing or tumble drying)

[AliG]

30 minutes ago, canalsiderenovation said:

t's still more than what we are hoping for but let's hope it gets better......

 

This looks to me around what you should be expecting.

 

You are using a bit less electricity than I would guessed at, with a lower thermostat setting probably offsetting the lack of EWI.

 

I know it seems like a lot if you extrapolate the recent number over a year, but you will use no heating at all for 5 months probably and much less in the spring and autumn.

 

My guess is that you are on track to use around 5000kWh for non ASHP and 5000kWh for the ASHP per year (maybe a bit less with your insulation). This is in line with the heat loss report which you were running ahead of before.

 

The PV might offset 2000kWh of this as you likely won't be able to use it all.

 

30 minutes ago, canalsiderenovation said:

We haven't got the house as warm as we would like and have thermostats set at 19-20.

 

Once your EWI is in to be at 21-22C probably won't cost you anything extra and at the moment it might cost you an extra 50p a day or so. No point building yourself a lovely new house then not being comfortable to save a few pounds. 

Edited January 22, 2021 by AliG

[canalsiderenovation]

13 minutes ago, AliG said:

 

This looks to me around what you should be expecting.

 

You are using a bit less electricity than I would guessed at, with a lower thermostat setting probably offsetting the lack of EWI.

 

I know it seems like a lot if you extrapolate the recent number over a year, but you will use no heating at all for 5 months probably and much less in the spring and autumn.

 

My guess is that you are on track to use around 5000kWh for non ASHP and 5000kWh for the ASHP per year (maybe a bit less with your insulation). This is in line with the heat loss report which you were running ahead of before.

 

 

Once your EWI is in to be at 21-22C probably won't cost you anything extra and at the moment it might cost you an extra 50p a day or so. No point building yourself a lovely new house then not being comfortable to save a few pounds. 

 

I'm going to keep monitoring it weekly so I get a really clear picture of usage, especially in the colder months.

 

We have an abundance of wood so are making us of our log burner at the moment in the evenings. Whilst the EWI isn't in I don't want to whack the temperature up, rather walking round wearing something more than a t-shirt is probably a better idea!

 

21 minutes ago, ProDave said:

Your "other" sounds about right.  We average about 100kWh per week on non heating / non hot water usage, a figure I just cannot get down

 

We had builders here for two days using equipment so it's probably more than we would normally use. That said, we could never get to 2 kW a day. But we are both working from home, laptops etc.

 

I've been looking at our solar generation on the inverter today and we have had 2.5kWh for a sunny morning and miserable, rainy afternoon.

Edited January 22, 2021 by canalsiderenovation

[SteamyTea]

1 hour ago, ProDave said:

how anyone gets to just 2kW per day non heating usage beats me, they clearly don't watch tv, do any washing dishwashing or tumble drying

Apart from clothes washing, I don't have the others.  That must be the secret.

And living alone.

Edited January 22, 2021 by SteamyTea

[AliG]

Dishwasher, tumble dryer and washing machine all probably use around 1-1.5kWh per cycle, so if you used each of them once a day as we do that's 4kWh straight away (I have managed to get the dishwasher to every 1.5 days now that I am at home).

 

If anyone is working from home, a laptop probably runs at about 30-40W (the charger will be sized larger so it can run the laptop and charge it at the same time). On the other hand a desktop and monitor could easily run to 150-200W and a big gaming system like my mate has 400W. So don't use your gaming rig for WFH!

 

 

[PeterW]

@canalsiderenovation you’ll be surprised at the phantom loads such as Quooker tap, coffee machine, tv/audio standby etc. They add up really quickly even when nothing is “on”. 

[SteamyTea]

39 minutes ago, PeterW said:

you’ll be surprised at the phantom loads

Why I have done things to reduce them.

First chart is all my power draws.  41% of the time during 2020, I drew nothing at all.  Then 39% of the time I drew less than or equal to 100W.

Second chart zooms in on the 0 to 100W window.  The main power draw is between 29 and 42W.  Most of that will be the fridge and the PC charging.

 

 

 

[AliG]

Most devices designed in the last 10 years should have standby power usage of less than 1W. I think this was an EU regulation some time ago.

 

I started a thread where I went round and tested devices by plugging them into a Wi-Fi plug and most were negligible. For example an Amazon Exho which is on all the time used only about 2.5W

 

Older devices are another matter. I think our. Nintendo Wii used about 10W so that is now turned off. Things like PS2s and so on may use similar. The devices I have also heard noted as using a lot of standby power are ovens but I couldn’t plug them in separately to check.

 

The constant load that people are unlikely to think about comes from things like Sky Q boxes, Wi-Fi repeaters, UFH pumps, MVHR etc which all can use modest amounts of power all the time. You could easily have 100W+ of constant draw from things like these.

[ProDave]

This non heating power usage.

 

The lowest I have ever seen is 40kWh per week or 5.7kWh per day.

 

That is when we have been away on holiday with everything turned off, not just left on standby.  All that was on, was MVHR, treatment plant pump, Fridge / Freezer and a sky box to record some stuff (and that is on a timer so only powered from 4PM until midnight)

 

And the solar PV will have been generating supplying most if not all the daytime usage (it was summer) so without the PV the background usage would be even higher.

 

How anyone gets to 2kWh in a day living in a house beats me,

 

I suspect (I will measure it one day) a huge amount of that is the FF.

 

I have made some progress in getting our usage down, the total we use now including heating and DHW is about the same as we used to use in the old house where heating and DHW was done with oil.

 

 

 

[SteamyTea]

14 minutes ago, AliG said:

The constant load that people are unlikely to think about comes from things like Sky Q boxes, Wi-Fi repeaters, UFH pumps, MVHR etc which all can use modest amounts of power all the time. You could easily have 100W+ of constant draw from things like these.

You can see that in the charts from @joe90's I put up.  His base load is around 400W.

[SteamyTea]

2 minutes ago, ProDave said:

I suspect (I will measure it one day) a huge amount of that is the FF.

When my old fridge dumped its gas, was running constantly, but still cooling a little, it used about 3 kWh/day.

My new fridge (3 or 4 years old now) is so much better than the old one, which was about 12 years old when it failed (think I go it in 2005).

I logged my fridge separately a while back, when I was away.  If I remember correctly, it drew an average of 5W, Our old mate Ed Davie has a write up about fridges: https://edavies.me.uk/2008/11/house/energy.html

[canalsiderenovation]

I believe Quooker is 3p a day but then we have the cube for filtered water etc which I believe is 3p a day according to the Quooker website. We aren't heavy dishwasher or laundry users. We do make sure TVs are all off overnight but we also have the treatment plant, pump etc but I'm pretty content with our general other usage but will be getting some timers to charge things when we move to Octopus and have a cheaper overnight Tarrif once they confirm if we have a smart meter or not as the wait is significant to get one installed and they put you on a higher tarrif whilst waiting for a smart meter.

[joe90]

1 hour ago, SteamyTea said:

You can see that in the charts from @joe90's I put up.  His base load is around 400W.

Which is......

 

mvhr

hard drive recorder 

router

fridge

freezer

tv (standby)

treatment plant

bathroom radiators

 

all other things are as required (which might contribute to the 400w).

 

[SteamyTea]

1 minute ago, joe90 said:

Which is......

 

mvhr

hard drive recorder 

router

fridge

freezer

tv (standby)

treatment plant

bathroom radiators

 

all other things are as required (which might contribute to the 400w).

 

Yes, it soon adds up.

The only thing on that list I have is a fridge.

[AliG]

Here is the data I found on power consumption of various devices.

 

People expect to use energy for their fridge and freezer, it is the unexpected ones that add up.

 

For example the PoE switch for our WiFi access points uses more than 3x the electricity of the fridge!

 

One thing not in this table that I looked into is using the short programmes on the dishwasher and washing machine. It feels like they would reduce energy consumption because they are on less, they actually dramatically increase it.

 

Device Consumption.xlsx

Edited January 23, 2021 by AliG

[canalsiderenovation]

Another interesting week, we have used 304 units on our heat pump this week which is up on last week but we had some colder temperatures over the weekend and earlier in the week and I raised the thermostats a little. @Ultima357 has given me some great information having the same ASHP as me and things are looking a bit better albeit we have had warmer temperatures the past couple of days.

 

Some things that have helped and made me notice a real difference. For the past couple of days I've programmed a schedule for the hot water and it now comes on for a couple of hours just after tea rather than it having no schedule and being just set to a permanent temperature. We have found that just this couple of hours is enough to satisfy my hot baths and showers in the evening and remains warm and is completely sufficient through the next day even without the solar PV immersion (which isn't having any impact at the moment as we are only getting around 2.8kWh at the highest day this week due to some pretty crap weather so there isn't any excess to divert to the immersion).

 

The past couple of days we have had the DHW schedule our HP meter is showing between 22-27 units in a 24 hour period which seems fantastic to me given we raised our thermostat temperatures too so I do believe a significant proportion of our electricity use was the DHW rather than the heating though I'm going to monitor it over the next week to give us a clearer picture.

 

Our 'other' use has gone up significantly this week to almost 180 units due to builders being on site for a few days and we can pinpoint why this has increased a lot so this should be an exception.

 

And the immersion reading hasn't changed since I have deactivated the 'disenfectent' aka legionella cycle for the time being.

Edited January 29, 2021 by canalsiderenovation

[AliG]

4 minutes ago, canalsiderenovation said:

so I do believe a significant proportion of our electricity use was the DHW

Due to the higher temperature hurting the COP, ASHP's are less efficient for DHW than they are for heating. This is then exacerbated in cold weather when the COP falls further.

 

In a well insulated house, DHW becomes a higher proportion of energy use which reduces the effective efficiency of an ASHP.

 

If you look at the chart I put up earlier-

 

 

You can see at 50C and 2C outside the COP isn't much above 2, whereas in the 35-40C range where you might run UFH it is around 3.

 

From these figures an ASHP would cost around 3x as much to heat water as a gas boiler in the coldest days of winter. In summer when the temperature is in the 15-20 range the COP rises to between 4 and 5 and the penalty is much less.

 

I am not sure that this quirk is well understood or advertised. ASHP works far better with low UFH flow temp and if you don't want your hot water to be too hot, 48C seems to be the recommended hot water temperature.

[canalsiderenovation]

2 minutes ago, AliG said:

I am not sure that this quirk is well understood or advertised. ASHP works far better with low UFH flow temp and if you don't want your hot water to be too hot, 48C seems to be the recommended hot water temperature.

 

We have our temperature set to 48 degrees now too. I'm also in the process of changing to Octopus and will be taking their Go tarrif, one of which gives us cheaper electricity from 8:30pm so I plan to heat water for a few hours during this period too. 

[Spoogster]

15 minutes ago, canalsiderenovation said:

Another interesting week, we have used 304 units on our heat pump this week which is up on last week but we had some colder temperatures over the weekend and earlier in the week and I raised the thermostats a little. @Ultima357 has given me some great information having the same ASHP as me and things are looking a bit better albeit we have had warmer temperatures the past couple of days.

 

Some things that have helped and made me notice a real difference. For the past couple of days I've programmed a schedule for the hot water and it now comes on for a couple of hours just after tea rather than it having no schedule and being just set to a permanent temperature. We have found that just this couple of hours is enough to satisfy my hot baths and showers in the evening and remains warm and is completely sufficient through the next day even without the solar PV immersion (which isn't having any impact at the moment as we are only getting around 2.8kWh at the highest day this week due to some pretty crap weather so there isn't any excess to divert to the immersion).

 

The past couple of days we have had the DHW schedule our HP meter is showing between 22-27 units in a 24 hour period which seems fantastic to me given we raised our thermostat temperatures too so I do believe a significant proportion of our electricity use was the DHW rather than the heating though I'm going to monitor it over the next week to give us a clearer picture.

 

Our 'other' use has gone up significantly this week to almost 180 units due to builders being on site for a few days and we can pinpoint why this has increased a lot so this should be an exception.

 

And the immersion reading hasn't changed since I have deactivated the 'disenfectent' aka legionella cycle for the time being.

 

Interesting info @canalsiderenovation. I am trying to look at DHW costs for an install that is yet to be planned, and am assuming I can heat the water tank to 48 degrees C with the ASHP and if I need to get up to 60+ degrees would use the immersion for the top up.

 

On the basis of your latest figures are you able to estimate what your latest two-hour afternoon top up strategy is costing you per day? In kWh and £?

 

Much appreciated. 

[ProDave]

5 minutes ago, canalsiderenovation said:

 

We have our temperature set to 48 degrees now too. I'm also in the process of changing to Octopus and will be taking their Go tarrif, one of which gives us cheaper electricity from 8:30pm so I plan to heat water for a few hours during this period too. 

Have you started the transfer?  If not I can give you a referal code that will give you £50 credit.

[AliG]

9 minutes ago, canalsiderenovation said:

I'm also in the process of changing to Octopus and will be taking their Go tarrif, one of which gives us cheaper electricity from 8:30pm so I plan to heat water for a few hours during this period too. 

This is the correct strategy. If you can only heat water during the low price period then this eliminates a lot of the cost premium. On Octopus Go the off peak price is around 1/3 of the peak price.

 

For this reason it might be better to have a larger tank than you otherwise would have with an ASHP.

 

5 minutes ago, Spoogster said:

if I need to get up to 60+ degrees would use the immersion for the top up.

 

An immersion has a COP of 1, so it would still be better to heat the water up to say 55 with the ASHP if you want it that hot. Better would be to find a way to have your water less hot. Do any ASHPs heat the water first to 55C for the legionella cycle before the immersion kicks in? I don't think the generally can get above 55C. Maybe it is considered less hassle to have one water temp for normal times and just use the immersion for legionella. Using the ASHP would seem to be cheaper, especially in summer if you want to have a legionella cycle.

Edited January 29, 2021 by AliG

[canalsiderenovation]

8 minutes ago, Spoogster said:

On the basis of your latest figures are you able to estimate what your latest two-hour afternoon top up strategy is costing you per day? In kWh and £?

 

 

I have no idea but our temp is set to 48 degrees. The hot water is scheduled to come on for two hours, the rest of the time it is off and remains hot from what has been previously.

[canalsiderenovation]

8 minutes ago, AliG said:

For this reason it might be better to have a larger tank than you otherwise would have with an ASHP.

 

Yep thanks to advice on here we went for the 400 litre Gledhill.

 

We are not using the legionella cycle at the moment. Having read a few posts on here it doesn't seem many people do and just tend to run at 48 degrees.

 

11 minutes ago, ProDave said:

Have you started the transfer?  If not I can give you a referal code that will give you £50 credit.

 

Not yet as I'm tied in to a contract til end of Feb so in a week I am, I've confirmed with Octopus I already have a smart meter so I'm ready to go but @joe90 sent me his referral a while ago and beat you to it! Perhaps he will split it with you....

[AliG]

The heat loss should be the same other than slightly lower standing losses due to a lower average tank temperature.

 

It may be that heating the water in the afternoon you are doing it at the warmest point in the day which would slightly improve the COP, but I wouldn't have thought the difference would be enormous.

[Spoogster]

Doing some man math here.

Assuming the ASHP runs at a different COP over the year between 2.5 and 4, Octopus Agile is slightly more expensive over night in winter (which it is for Jan so far) and 4kWh per day needed to heat to 48c for ASHP and top up immersion at 4kWh (to whatever temp that top up gets me), I get to about £112 per annum cost for DHW (excl. standing charge):

 

Barking up the right tree?