Question on Wattage / Kwh calculations (or wattage vs consumption)

Louiscar

Hehe Very hard not to when we are predicted to reach over 6k per year cap by April 2023.

MattMattMattUK

Louiscar said:

Hehe Very hard not to when we are predicted to reach over 6k per year cap by April 2023.

Trying to save on devices that are using a few watts is not going to make any substantive difference even at the higher end of the price predictions. Also, ignore the cap, focus on unit rates. As an example when people talk about pensioners having to sit in the dark because they cannot afford to turn on a lightbulb, just the £400 payment (and pensioners get substantially more) is enough to keep an LED bulb on 24 hours a day for more than twenty years in pure energy terms, it is enough to keep the pay the standing charge and keep an LED bulb on 24 hours a day for 30 months.

The things that use large amounts of energy are things that generate heat, space heating, water heating, cooking at high temperatures (ovens, deep fat fryers etc.) and any white goods that heat things up substantially, but even a modern fridge-freezer uses less than a kWh per day, the one that I will have to unfortunately have to buy soon (mine seems to be about to die) only uses around 0.6kWh per day, or 40p per day, meanwhile a ten minute electric shower costs around £1.10 at October prices, so cutting that down to a five minute shower is better, if one is particularly tight on funds then Navy showers would save far more money in one day than turning off lights ever could. 

Spoonie_Turtle

I don't know if this is particularly relevant to your current concern but I've found this calculator to be really useful, especially the ability to change tariff rates and experiment with different lengths of time etc.  https://www.sust-it.net/energy-calculator.php
[I *could* do calculations myself if I really had to, but it all takes extra brainpower that I don't have spare.]

Alnat1

Better to spend your money on thermal underwear than replacing lights 

Petriix

It's an overall picture. If you can shave 10W off your background usage then that's nearly £50 per year at the October price cap. Obviously higher power appliances (and particularly space/water heating) will save you more, but it all adds up. 

[Deleted User]

Petriix said:

It's an overall picture. If you can shave 10W off your background usage then that's nearly £50 per year at the October price cap. Obviously higher power appliances (and particularly space/water heating) will save you more, but it all adds up. 

Or to put it another way, turning off 10W for 8 hours a day (which is a lot of time for kitchen lighting) would save you £15 per year.  Spending £50 on bulbs to achieve this is not economical in the short term, you're better off keeping that £50 to pay the bill and changing behaviour somewhere else.

FreeBear

Louiscar said: Can someone help me understand the relationship between wattage and consumption.

For instance - my desktop computer has a  750w PSU but this does not by any means help me calculate what it costs to run it.

I don't have a smart meter but I do have a monitor and note  the following in relation to my desktop 'puter:

When browsing doing normal tasks this might show as anything between 180 - 250 Kwh. Play a game and that will jump another 150.

So with this in  mind I'm trying to assess where I can make savings but the question is how do I do that when I don't know this relationship.

I can calculate wattage > Kwh easily but I can't actually determine the consumption. Easy when I have a 100w light bulb - that is the wattage but my desktop??

The problem with a computer is that it is not a steady load. As you have noted, the energy consumption varies depending on what you are doing. Sitting idle, it may be using !00W, but play a graphics intensive game with lots of noise, it jumps to 400W. You need to plug it via an energy monitoring plug (e.g. something like the Tapo TP110) and take a reading spread over several hours. Once you have an average energy consumption figure, you can then decide whether to cut back on computer time and/or get something a little less power hungry.

victor2

^^This^^

I've just recently had an energy monitor on my PC for a couple of "typical" days, and it used 0.28kWh per day. The average wattage drawn for different periods of use varied from 2.9W when hibernating to 116W when in use. It hibernates so that scheduled jobs will run overnight. I did switch off the USB power when hibernating, but otherwise it runs with the default BIOS setup.

Louiscar

MattMattMattUK said:

Louiscar said:

Hehe Very hard not to when we are predicted to reach over 6k per year cap by April 2023.

[snip]
The things that use large amounts of energy are things that generate heat, space heating, water heating, cooking at high temperatures (ovens, deep fat fryers etc.) and any white goods that heat things up substantially, but even a modern fridge-freezer uses less than a kWh per day, the one that I will have to unfortunately have to buy soon (mine seems to be about to die) only uses around 0.6kWh per day, or 40p per day, meanwhile a ten minute electric shower costs around £1.10 at October prices, so cutting that down to a five minute shower is better, if one is particularly tight on funds then Navy showers would save far more money in one day than turning off lights ever could. 

Yeah I get that, I have a small freezer and fridge and my monitor always shows between 105 watts to 195 watts when pretty much everything else is off (other things = router, Grandstream Voip adapter, cordless phone chargers). So I have little control over that but these things will use a bit less over winter.

Food cooking comprises of using gas and microwave with convection oven occasionally, Usually Microwave max is 15 mins for baked potato or 5 - 7 mins to heat up a ready meal. Convection (less frequent ) max 18 - 25 mins.

Louiscar

FreeBear said:

Louiscar said: Can someone help me understand the relationship between wattage and consumption.

For instance - my desktop computer has a  750w PSU but this does not by any means help me calculate what it costs to run it.

I don't have a smart meter but I do have a monitor and note  the following in relation to my desktop 'puter:

When browsing doing normal tasks this might show as anything between 180 - 250 Kwh. Play a game and that will jump another 150.

So with this in  mind I'm trying to assess where I can make savings but the question is how do I do that when I don't know this relationship.

I can calculate wattage > Kwh easily but I can't actually determine the consumption. Easy when I have a 100w light bulb - that is the wattage but my desktop??

The problem with a computer is that it is not a steady load. As you have noted, the energy consumption varies depending on what you are doing. Sitting idle, it may be using !00W, but play a graphics intensive game with lots of noise, it jumps to 400W. You need to plug it via an energy monitoring plug (e.g. something like the Tapo TP110) and take a reading spread over several hours. Once you have an average energy consumption figure, you can then decide whether to cut back on computer time and/or get something a little less power hungry.

Sure, I've pretty much got a reasonable sample which correlates to the figures I gave earlier.

I am running and 2009 intel Xeon 5760 and I've kept it running for all this time by little upgrades. The clock does drop when there is little use but now the thing is on it's last legs due to amongst other things Win7.

I have built a Ryzen 5900x system but as I've not had any experience with AMDs since the Athlon days I don't see how to implement the clocking function properly so it doesn't run on full clock.

I've yet to figure out the final OC etc so it's just sat there and now I'm a bit worried about whether to actually use it now.

It may be that the technology these day are better when it comes to power saving ..