What's your summer energy use?

[Kelvin]

15.5kWh per day since start of July. We have an EV so it includes charging that. Electric shower and electric cooker. Heating and hot water is from an oil fired boiler. There are only two of us but we’ve had a lot of family and friends  staying through July and August.   
 

I’ve convinced the farmer that owns the house to consider putting in an EV charging point and PV panels (large south facing roof) It also needs to have the insulation upgraded. 
 

 

[SteamyTea]

1 hour ago, rh2205 said:

we use a kettle to boil water for the hob.

So do I, much quicker if you put the right amount of water in.

1 hour ago, rh2205 said:

we have a 5 ring electric ceramic hob because don’t like induction ones

 

1 hour ago, rh2205 said:

To be honest I put this all down to avoiding an induction hob.

How so, an induction hob is more efficient.

 

This years usage

 

Last weeks usage.

 

And the percentage of time that I draw no power at all, I think this is the real secret.

Edited August 22, 2022 by SteamyTea

[rh2205]

I mean an induction hob is not more efficient if I need to buy loads of new pans think of the waste & the extra cost! I just think they are annoying, supported by relatives who quickly got rid of their induction ones once they’d broken (one a chef and was convinced they were slower to cook on than standard ceramic).

[SteamyTea]

29 minutes ago, rh2205 said:

I mean an induction hob is not more efficient if I need to buy loads of new pans think of the waste & the extra cost! I just think they are annoying, supported by relatives who quickly got rid of their induction ones once they’d broken (one a chef and was convinced they were slower to cook on than standard ceramic).

There is so much there to unpack. And it is all wrong.

[MrMagic]

Went induction, will never go back. Didn't need any new pans. Single sheet of glass, piece of cake to keep clean. 'cool' to touch so 'boil overs' don't get burnt on etc etc.

 

To the main topic - Past two months leccy - Total consumption 1072.4kWh @ 6.08p/kWh £65.22 (Battery+PV+EV+House+A/C). Includes all driving, can't even get a single tank of fuel for that anymore (unless it's a moped). (DHW excluded as still on Gas combi)

Edited August 22, 2022 by MrMagic

[Marvin]

36 minutes ago, MrMagic said:

To the main topic - Past two months leccy - Total consumption 1072.4kWh @ 6.08p/kWh £65.22 (Battery+PV+EV+House+A/C). Includes all driving, can't even get a single tank of fuel for that anymore (unless it's a moped). (DHW excluded as still on Gas combi)

PV+EV+House+MVHR+ASHP+hot water:  Last 60 days total power purchase cost:

Mains power used: 318.75kWh @ 24.0762p/kWh  plus VAT £80.58

Standing charge: 60 days @ 22.9524 plus VAT £14.46

(Average 4000miles a year) Additional EV charge purchased away from home 42kWh @ 0.52p/kWh inc VAT £21.84

60 days of PV power (Material supply cost etc divided by 7 years no including my labour) inc VAT@ 1.56 £93.55

 

Total for 60 days: £210.43 or £3.51 a day

 

 

 

[George]

Just had a look.

Summer stats, from late May to today.

Electricity consumption 10.9kWh/day

Of which, 

ASHP consumption 2.6kWh/day 

 

DHW use is pretty high as we have two young children.

 

Solar generation 20.4kWh/day (no idea what the utilisation is -  not very high I suspect) from a 5.5kW install with a 4kW inverter. 

 

No EV, battery or gas. Hopefully getting a battery quote today. 

 

+1 for induction. We were buying all new pots and pans anyway (had been using a motley collection inherited from an old tenanted house. Various states of corrosion and dents.) I did a test with a normal electric kettle vs the induction to boil 1 litre, energy consumption near identical and the induction hob was 20 seconds faster. However, the safety feature of a normal kettle to auto click off means I kept it. 

 

Having lived with electric hob and gas, the induction is superior in every way. The only slight issue is you can't use a wok... but there is a workaround by getting a big flat bottom wok and use a pair of silicone tongs to agitate. It's just as good. 

Edited September 6, 2022 by George

[SteamyTea]

1 hour ago, George said:

Electricity consumption 10.9kWh/day

About 3 times my usage.

Now I know I live alone, but I don't have a third of a fridge, or cooker, or even a third of a water tank.

I also don't have a heat pump.

[George]

1 hour ago, SteamyTea said:

About 3 times my usage.

Now I know I live alone, but I don't have a third of a fridge, or cooker, or even a third of a water tank.

I also don't have a heat pump.

We use less than you per capita then. 

 

Aside from the ASHP, much of the usage is a large fridge, a separate chest freezer, daily dishwasher (0.74kWh per eco cycle) and very frequent washing machine cycles.

 

I also wfh so computer, screen and modem is on almost always 

Edited September 6, 2022 by George

[SteamyTea]

14 minutes ago, George said:

We use less than you per capita then. 

Depends how you class 

 

2 hours ago, George said:

two young children

 

Maybe we should class people by mass.  Not sure the mass should be inverted or not.  One very fat person could be the same as 3 normal people.

[George]

1 minute ago, SteamyTea said:

Depends how you class 

 

 

Maybe we should class people by mass.  Not sure the mass should be inverted or not.  One very fat person could be the same as 3 normal people.

I would definitely drag the average up.

[Adsibob]

5 hours ago, SteamyTea said:

About 3 times my usage.

Now I know I live alone, but I don't have a third of a fridge, or cooker, or even a third of a water tank.

I also don't have a heat pump.

Sure, but you open your fridge a third as much as most households, I suspect. it is when You open a fridge that it loses its coolth and the electrics have to fire to cool it. That’s why I’ma power cut, as long as you don’t open your fridge and freezer, your food should remain safe for many hours.

[AliG]

Missed this thread.

 

We use massive amounts compared to you guys. My base usage of electricity is around 800W.

 

For hot water, you cannot get past the physics. It requires 5.24kWh of energy to heat 100l of water by 50C.

 

So if you use 300l of hot water a day, that is 16kWh, plus efficiency and heat losses, would be probably 20kWh plus of gas. I would assume around 100l/person/day. A lot depends on whether anyones likes to take baths vs showers.

 

I have been running an experiment for around two weeks now to compare how much energy we use by heating the hot water tank with the immersion versus the boiler. It is not easy as i cannot switch everything else off.

 

Basically what I found is that we had hot water on from 5am to 9pm. The boiler came on as and when needed. Doing this we were using around 40kWh of gas a day for hot water. My guess is that we use around 400l a day, which should use closer to 25kWh including the losses in the tank, so efficiency was running at 60-65%.

 

I have tried a couple of things -

 

1. Just turning on the hot water twice a day. This seems to save around 5-10kWh, efficiency improves to around 80%. My guess is that there are enormous losses over and above the efficiency of the boiler in heating up pipework and letting it cool down multiple times a day. Our hot water has always just been on all day. At 2-3p a kWh, this may well have been wasting 5kWh a day for some time, but as this cost 10p, no one cared. When it costs closer to a pound you start to notice.

 

2. Running the immersion on Octopus at 7.5p during the night and then running the boiler once during the day for a top up. Doing this seems to use a similar amount of energy to running the boiler twice a day. Sadly it is almost impossible to measure exactly how much energy the immersion uses. Assuming the immersion is 95% efficient it is better to use it than the boiler.

 

Anecdotally, the plant room feels a lot cooler than before. I think the temperature hs dropped by about 2C.

 

I have also turned off our hot water circulation system which maybe used 80l of hot water a day. Heating the tank with the immersion for some reason, hot water comes through much faster than using the boiler. It might be due to where the immersion is or the tank getting hotter as the immersion will keep running until 70C, whereas the boiler themrostat for the boiler is set at 55C.

 

Anyway I am hoping that this is going to save me around 3-4000kWh of gas a year, 20-25% of our use for DHW. As houses have got better insulated DHW has become a larger part of energy use and I suspect this has not been focused on much. I am guessing for many on Buildhub it is actually a larger use of energy than heating.

[SteamyTea]

3 hours ago, Adsibob said:

Sure, but you open your fridge a third as much as most households, I suspect. it is when You open a fridge that it loses its coolth and the electrics have to fire to cool it.

Most of the energy is used keeping goods cool, not the air.

The air in a fridge is a few tens of grams, with a SHC of 1.

Just a litre of water, mass 1kg and a SHC of 4.2 will swamp the 'noise' of door opening.

Edited September 6, 2022 by SteamyTea

[Adsibob]

3 hours ago, AliG said:

Assuming the immersion is 95% efficient it is better to use it than the boiler.

Do you have a gas boiler? If so, I find this Really surprising. I always thought electricity was more expensive for heating water than gas. But I guess times have changed.

[AliG]

We have Intelligent Octopus which gives us electricity for 7.5p/kWh during the night. At least 1130-530am and sometimes much longer. I have shifted way over half of our electricity use to this period.

 

Gas is 7.33p/kWh, so if it is running at around 80% efficient to heat hot water, the immersion is cheaper during the night.

 

At the normal price of electricity then the boiler would be considerably cheaper. My daytime rate is 30.83p/kWh

 

This is fixed until February so if there is a further gas price increase in October (not sure what is happening to the cap as of today) then it will be even cheaper to use the immersion.

 

[Adsibob]

11 minutes ago, AliG said:

We have Intelligent Octopus which gives us electricity for 7.5p/kWh during the night. At least 1130-530am and sometimes much longer. I have shifted way over half of our electricity use to this period.

 

Gas is 7.33p/kWh, so if it is running at around 80% efficient to heat hot water, the immersion is cheaper during the night.

 

At the normal price of electricity then the boiler would be considerably cheaper. My daytime rate is 30.83p/kWh

 

This is fixed until February so if there is a further gas price increase in October (not sure what is happening to the cap as of today) then it will be even cheaper to use the immersion.

 

Ok, that makes sense. Except for one point: why is your boiler only 80% efficient? 

[SteamyTea]

2 minutes ago, Adsibob said:

Except for one point: why is your boiler only 80% efficient? 

No one, apart from the manufactures, actually test the efficiency of their boilers once installed.

I would think that overall, 80% is towards the upper limit.

[Adsibob]

1 hour ago, SteamyTea said:

No one, apart from the manufactures, actually test the efficiency of their boilers once installed.

I would think that overall, 80% is towards the upper limit.

If that is true, there would be a massive mis-selling claim against the manufacturers. Viessmann advertise their boilers as having 95% plus efficiency. But maybe this doesn’t account for external pipe work, long runs to the Hot water tank etc.

[SteamyTea]

1 minute ago, Adsibob said:

If that is true, there would be a massive mis-selling claim against the manufacturers. Viessmann advertise their boilers as having 95% plus efficiency. But maybe this doesn’t account for external pipe work, long runs to the Hot water tank etc.

It is the old 'Up to'.

My car can do 73 MPG, I have a picture of the dash that shows it when I got to Exeter, so that was after 200 miles.

But usually it does mid 50s.  And running around small towns, mid 40s.

Which is right?

(interestingly my mileage and the official mileage match quite well)

[Adsibob]

2 hours ago, SteamyTea said:

Most of the energy is used keeping goods cool, not the air.

The air in a fridge is a few tens of grams, with a SHC of 1.

Just a litre of water, mass 1kg and a SHC of 4.2 will swamp the 'noise' of door opening.

Sure, but get two very well insulated cool boxes. Fill both with equal amounts of ice. Leave one closed for 8 hrs. Open the other one for 1 minute every hour. I bet the amount of thawing vs ice will be quite different across the two boxes. A pocket of cool air is a good insulator. Displace that with warmer air every time you open a fridge/freezer, and you will quickly see heat  gains.

[Marvin]

7 minutes ago, Adsibob said:

If that is true, there would be a massive mis-selling claim against the manufacturers. Viessmann advertise their boilers as having 95% plus efficiency. But maybe this doesn’t account for external pipe work, long runs to the Hot water tank etc.

How could you guarantee the efficency of the boiler if it included the losses from all sorts of  on site pipework variations?

 

I think you answered you own thought. The same is true with ASHPs which seem to be more affected by the location of tanks and pipework.

[Adsibob]

22 minutes ago, Marvin said:

How could you guarantee the efficency of the boiler if it included the losses from all sorts of  on site pipework variations?

Because a lot of kit has recommended installation requirements. Eg my hot water cylinder had a note in the manual that says it will only meet the advertised performance if all external pipe work is insulated, if the room it is installed in its within the thermal envelope and if the cylinder itself is insulated with a jacket. I thought this last point really took the piss, given I’ve not been able to find a jacket big enough to insulate a 300L cylinder and even if I did, I don’ti have space to fit it, as the cylinder is installed right up close to an internal stud wall.

Edited September 6, 2022 by Adsibob

[Marvin]

6 minutes ago, Adsibob said:

Because a lot of kit has recommended installation requirements. Eg my hot water cylinder had a note in the manual that says it will only meet the advertised performance if all external pipe work is insulated, if the room it is installed in its within the thermal envelope and if the cylinder itself is insulated with a jacket. I thought this last point really took the piss, given I’ve not been able to find a jacket big enough to insulate a 300L cylinder and even if I did, I don’ti have space to fit it, as the cylinder is installed right up close to an internal stud wall.

Well they obviously don't want to be sued!!!

[Marvin]

9 minutes ago, Adsibob said:

I don’ti have space to fit it, as the cylinder is installed right up close to an internal stud wall.

I assume you don't have a bare copper or stainless steel 309ltr tank? That would be criminal.