Power consumption for a domestic house

zagmund · 07-05-2013 12:16pm #1

There was reference in another post to the expected electricity consumption for a house, and this got me thinking. I know there's no such thing as an average house and all households (other than in Stepford) will have different consumption patterns.

I'm starting to track our usage at the moment and have been keeping tabs on the daily usage for different circuits for the last 4 weeks or so. In addition, I kept track in previous years of the overall usage per year.

My current reckoning is that we are on track for about 4,500kWh this year, compared to about 5,000 for previous years. This would be for a family of 4 (2 teenagers), with about 300 clothes washes and 365 dish washes per year accounting for just short of about 1,000kWh. The rest would be kitchen, heating controls & pumps, and then sockets & lights.

So, I'm just wondering do any of you guys out there keep track of your domestic usage? If so, do you want to share here for reference?

z

Dr Silly Bollox MD · 07-05-2013 11:36pm

A lot of people are getting in that prepay I'd imagine theirs a fair amount keeping track now.

Over 3 cent dearer a unit than Airtricitys (this one), don't see the appeal in prepay at all.

A few CFLs, a couple LEDs, turn stuff off at the wall, throw a few quid in a jar, sure isn't it the same thing.

Macha · 08-05-2013 7:21am

Number I always use is an average household consumes 3MWh/year. I think this is an EU average figure.

dardhal · 10-05-2013 4:58pm

zagmund wrote: »

I'm starting to track our usage at the moment and have been keeping tabs on the daily usage for different circuits for the last 4 weeks or so. In addition, I kept track in previous years of the overall usage per year.

My current reckoning is that we are on track for about 4,500kWh this year, compared to about 5,000 for previous years. This would be for a family of 4 (2 teenagers), with about 300 clothes washes and 365 dish washes per year accounting for just short of about 1,000kWh. The rest would be kitchen, heating controls & pumps, and then sockets & lights.

I do (did when still living in my home country). A simple plug-in power meter (two of them in my case) is all what I needed to know what appliances or loads where long term those contributing the most to the electricity bill.

Al things accounted for, electricity consumption for me was under 2100 KWh for the year ending March 2011, including around 500 KWh during the same period for air conditioning (not that these figures are high or low, very difficult to compare a family of four in Ireland to a couple living in a small apartment in central Spain).

But to put things into perspective, base load for the DSL/WiFi device that is powered on 24 hours a day is 14 W, which may seem little, but that's as much as 122 KWh/year. A desktop computer powered on the whole time (typical in the those times people used to download multimedia content via P2P networks) can be 100 W , adding nearly 900 KWh/year.

On top of that, the fridge/freezer can be quite a consumer of electricity. The difference between an efficient and medium sized unit (200 KWh/yr) and a larger, older one (600 KWh) is also very noticeable. Regarding dishwashers and washer machines, it all depends on the program selected, as 90-95% of the electricity consumption will go towards heating water, not pumping water or moving the drum at all. A cold washing cycle could use less than 1 KWh each, but you should add a couple more for a cycle using hot water (60-80ºC), and 4-6 KWh more for the dryer. Same for the dishwasher.

It makes for a good exercise trying different settings while using the power meter to find out the sweet spot, regarding the right balance between power consumption and washing results. In such a busy home you may be saving quite some money.

Lighting is usually not the worst user of energy, unless you have lots of halogen or incandescent bulbs running for many hours. This can be a matter of taste however, as there are people that simply can't stand the color temperature or flood pattern of compact fluorescent, or fluorescent tubes (these being more efficient that compact fluorescent bulbs, cheaper to run in the long term, and leaps and bound better than incandescent or halogen).

Going for LED lighting is a complete waste of time and money but for very few and specific needs. Except you have plenty of money, don't expect any return on investment and you are doing all this for the intellectual experience, and not for saving your hard earned pennies.

zagmund · 11-05-2013 2:46pm

Thanks for the reply, but stuff like this really gets my goat - "Going for LED lighting is a complete waste of time and money but for very few and specific needs. Except you have plenty of money, don't expect any return on investment and you are doing all this for the intellectual experience, and not for saving your hard earned pennies."

You could replace "LED" with <any sort of light on the market these days> and someone will come along and tell you it's all a waste of time, effort, money, etc . . . I could possibly have opted for bees wax candles made from my bee colony down the back but someone went and killed all the bees, didn't they? So, I had to pick a light source that is available and LED seemed like a good idea.

When buying lights & light fittings I wasn't looking for a return on investment, I was looking for a light that provided a light quality that I liked, in fittings that I liked & at a relatively low price.

z

zagmund · 11-05-2013 2:52pm

"But to put things into perspective, base load for the DSL/WiFi device that is powered on 24 hours a day is 14 W, which may seem little, but that's as much as 122 KWh/year. A desktop computer powered on the whole time (typical in the those times people used to download multimedia content via P2P networks) can be 100 W , adding nearly 900 KWh/year."

Yeah, I'm working out which of the permanently powered devices are using the most electricity at the moment. It's an ongoing effort. The thing is - I know I'm never going to get to zero usage so there's no question of turning everything off. I'm just working on determining how much each device costs. I've already identified two items which together account for about 8% of my annual usage and which don't need to be plugged in all the time. One of the devices really doesn't need to be plugged in at all.

As you mention, the DSL router is "only" 14W which is "only" 122kWh, but add in a few devices like that (the DVD player that is never used, the VHS player that hasn't seen a tape in years, etc . . .) and you easily start approaching significant double figure percentages of the overall electricity bill. Who wouldn't want to take the opportunity to save 10%+ of their energy bills, given the chance?

z

dardhal · 11-05-2013 7:29pm

zagmund wrote: »

You could replace "LED" with <any sort of light on the market these days> and someone will come along and tell you it's all a waste of time, effort, money, etc . . . I could possibly have opted for bees wax candles made from my bee colony down the back but someone went and killed all the bees, didn't they? So, I had to pick a light source that is available and LED seemed like a good idea.

No, not all light sources have the same price per lumen, and therefore, not all have the same setting up costs and running costs. Going for a direct incandescent/halogen to CFL bulb replacement makes lots of sense (but for those places where lights are subject to frequent ON/OFF cycles). After all, a good CFL costs around 5€ (although you can easily find sale offers at 2-3€/each even for renowned brands). Such a reliable CFL when not power cycles too frequently, will happily last for 5000 hours. It will give you four to five times the lumen per watt compared to incandescent/halogen.

Even if we assume incandescent/halogen cost zero (good assumption considering they are already in service), as long at during the expected lifetime for the replacement lower energy costs offset the initial purchase price, it makes a lot of sense to do the replacement. All, of course, keeping the same amount of light, similar color temperature and as close as it gets to CRI (as there is no technology other than incandescent giving you CRI 100).

So, considering the data above and a KWh price of just 15¢, the CFL (let's do calculations for a 15W) will consume 75 KWh (or 11.25€) during its lifetime, while at the same time the purchase cost (5€) makes for that light source to cost 16.25€.

During the same time period, an incandescent/halogen rated at 60W with no replacement costs (let's assume a normal bulb lasts for 5000 hours, to be on the optimistic side) will have used 300 KWh, or 45€. Even under very pessimistic assumptions (favoring the incandescent vs. the CFL) during its lifetime each CFL will have saved you a whopping 28.75€. Does it make sense to replace the bulbs? If you know what you are doing, absolutely.

However, let's move on to LEDs. Current commercial LED bulbs hardly reach the lm/W efficiency of regular CFL. Let's be optimistic and say the same lumen output can be reached by using a 10W LED light with 10000 hours as expected lifetime and let's forget about CRI. Assuming the LED light is only 15€ (which will be much more to get the equivalent 900 lumens any of the 60W incandescent or 15W CFL will give you), the total cost of that lighting source over its lifetime would be 30€. By using CFL you would have to replace the bulb once, and the total cost over 10000 hours would be 32.50€, on par with the yet to exist cheap, quality and very powerful LED bulb 15€ a piece. Even if the LED is designed and tested to last 50.000 hours, that's the LED emitter only, not the el-cheapo electronics used in the AC-DC converter, and that's of course under lab conditions, such as 25ºC junction temperature for the LED. I would be surprise if any current LED bulb in stores is running the LED below 80ºC after a few minutes.

In summary, do the math, and know what to expect from every light source. If you think the light from a CFL is "poor quality", most LED bulbs would be awful by the same standards. Don't believe too much the life expectancy of no-brand LED bulbs, and of course, don't give any credit to any statement about a 5W LED bulb throwing as much light as a 60W incandescent. Not that there aren't any LEDs capable of doing in excess of 100 lm/W, but those are not (yet) present on the LED bulbs common people have access to at affordable prices (unless you are dare enough to bite the bullet and shell 40€/piece for those with adequate performance).

Sorry if I sounded rude at first.

OssianSmyth · 14-05-2013 9:45am

Domestic electricity consumption in 2011 was 8,283 GWh
That electricity was consumed by 1.65 million households (avg 2.7 people per household)
So that's 5MWh per household per year - I think!
So that means you're doing well, particularly as your household is above average size and you'd expect a lot of usage fro teenagers.

woodi · 18-05-2013 4:33pm

We've recently moved to an off grid system, and wanted to reduce consumption dramatically. As various people have said, lights don't use a vast amount, but we have now moved to 100% LED, which after some experimentation with different sizes and types, works very well. Not just as bright as banging in 60 or 100W incandescents, but certainly bright enough. We've learned which varieties to avoid - some of the surface mount ones get as hot as the sun, so we avoid them now, despite them being very bright, and use older types. Anyhow, they do a good job.
We realised that the small things - wireless router, sleeping laptop etc use a small amount, but cumulatively it makes a huge difference. A++ rated fridge is the only thing that is permanently connected 24/7.
This all works out at about 2Kw/h per day, 3kw/h on a washing machine day, and is as low as we can get and maintain what would be considered a normal life. Annual use certainly well under 1000Kw/H.
Oh and someone mentioned that there wasn't an LED bulb in the stores that ran under 80 degrees after a few minutes? We've got some decent, warm ones that say they are 3W, and I can hold onto quite happily. Certainly they are more reliable than the super bright jobbies, but you need 4 of them in a cluster - I still prefer the light to the equivalent single compact flurorescent.

dardhal · 19-05-2013 2:27pm

woodi wrote: »

Oh and someone mentioned that there wasn't an LED bulb in the stores that ran under 80 degrees after a few minutes? We've got some decent, warm ones that say they are 3W, and I can hold onto quite happily. Certainly they are more reliable than the super bright jobbies, but you need 4 of them in a cluster - I still prefer the light to the equivalent single compact flurorescent.

A 3W LED bulb running at an efficiency of 60 lm/W (which most of those easily available don't even reach) will put out about 180 lm of lighting power, a cluster of four would be equivalent to 720 lm, or much about the light output of a 60 W incandescent or under 15W compact fluorescent.

Even at so dismal efficiencies for the LED bulbs, dissipating 2W is not that much for a regular size bulb socket (E14 or E27), so given enough aluminum mass to the bulb, it should run quite cool.

Of course, replacing a single light source (60W incandescent / 15W CFL) with a cluster or twelve (4 x 3 W LED) may be impractical and can look awful if not designed appropriately, and one off costs will be probably not worth the running cost savings.

One to one bulb replacement with LED bulbs of similar light output and quality is a different ball game, as you will either need a quality 10 W rated LED (which will cost you in excess of 30-40€ each), or a lower quality one (rated 15W or so), in which thermal management will be a huge issue (lower quality usually means lower thermal mass, smaller copper or aluminum mass to dissipate heat, poorer thermal paths from the LEDs to the metallic casing and, as a result, lower light output and reduced bulb lifetime as LED temperature rises to dangerous levels).

By the way, congrats for living off the grid. That's something I would definitely want to do some day, but still at the "saving money" phase :-)

private · 06-08-2013 4:49pm

Have been suspicious of my old upright freezer as it is more than 10 years old ( maybe 15) and anything but frost free but working perfectly. We keep it full but in a rather hot place near the gas tumble dryer ( does this matter?). Just plugged it into a power measuring device and will post the kwh per hour tomorrow. It is opened maybe twice a day as it is away from the kitchen.

Pretty sure I will have to buy a new one when I see the results but I hate getting rid of things that are still working.

Next thing to test will be the router I guess but it has to run 24/7 as it does the phone line too. Will be interesting to see waht the results are.

heres what I'm using
http://www.amazon.co.uk/gp/product/B003ELLGDC/ref=oh_details_o03_s00_i00?ie=UTF8&psc=1

zagmund · 06-08-2013 9:14pm

Your router doesn't have to operate 24 hours a day. Depending on your household you could probably power it off from 00:00 to 8:00 and save 33% of the daily consumption. Or, if you are in the office all day you could probably turn it off from 00:00 to 16:00 and save 66% of daily consumption. I could have said until 17:00 but that would have made the maths harder.

z

Heroditas · 06-08-2013 9:21pm

OssianSmyth wrote: »

Domestic electricity consumption in 2011 was 8,283 GWh
That electricity was consumed by 1.65 million households (avg 2.7 people per household)
So that's 5MWh per household per year - I think!
So that means you're doing well, particularly as your household is above average size and you'd expect a lot of usage fro teenagers.

Correct, the figure used by electricity suppliers is 5300kWh per annum.
I'm impressed that a family with two teenagers is using less than the average! Depends on whether they're boys or girls though!

private · 06-08-2013 10:11pm

zagmund wrote: »

Your router doesn't have to operate 24 hours a day. Depending on your household you could probably power it off from 00:00 to 8:00 and save 33% of the daily consumption. Or, if you are in the office all day you could probably turn it off from 00:00 to 16:00 and save 66% of daily consumption. I could have said until 17:00 but that would have made the maths harder.

z

Not possible as I run a b&b. Hence the obsession with kwh.

zagmund · 06-08-2013 11:20pm

"Depending on your household"

My psychic antennae are a bit out of focus tonight, so I didn't realise you ran a B&B. That is going to greatly limit your options for energy saving.

z

private · 07-08-2013 10:24am

zagmund wrote: »

"Depending on your household"

My psychic antennae are a bit out of focus tonight, so I didn't realise you ran a B&B. That is going to greatly limit your options for energy saving.

z

The guests use very little electricity, it's the rest of us. I go around turning off lights like a mad woman. Have gotten rid of my halogen uplighters and learned to live with florescent lighting and lcd. Am now tracking down big energy culprits. The freezer is on target to use 3 kwh in 24 hours. That's over 1000kwh a year.:eek:

Am hoping to cut my electricity bills by 20% this year. That's going to save me a grand.

OssianSmyth · 08-08-2013 1:21am

A modern freezer uses less than 1kwh/day. In the shop there is a handy energy label showing the number of kwh used by the appliance per year.

In a very hot room, the condenser on the freezer will struggle to dissipate the heat removed from the freezer interior to the air in the room. So the appliance will work inefficiently or stop altogether. The operating range is specified for each appliance but I wouldn't expect it to work well over 25/30c

Ice in the freezer reduces efficiency according to SEAI but I don't know why. Anyone?

Heroditas · 09-08-2013 8:18pm

OssianSmyth wrote: »

Ice in the freezer reduces efficiency according to SEAI but I don't know why. Anyone?

Freezer has to work harder to keep the ice frozen than it does to maintain the temperature if that space is just air.

hfallada · 12-08-2013 6:20pm

Remember how expensive CFLs were went they were released at first? But now you can get a Phillips one for about €3/4. I have one on my landing which is on about 8 hours at night so people can see there way to the toilet and is still going strong 6 years old.

LEDs are the new CFLs, in the sense they are extremely expensive now but will be cheap in a few years. The R&D on them must be huge and the manufactures( mainly Phillips) are trying to recoup costs. They make financial sense with downlighters that are about €1,80 for a 35 watt bulb but only last 2 years but a €10 LED bulb will probably last about 15-20( apparently LEDs never burn out but lose their brightness over time). But that €10 LED bulb in 5 years will probably be about €5

Macha · 16-08-2013 3:18pm

Heroditas wrote: »

Freezer has to work harder to keep the ice frozen than it does to maintain the temperature if that space is just air.

Funny, I heard a full freezer is more efficient that an empty one but I'm not sure how that could work - thermal mass? The proper circulation of air and making sure the seal isn't blocked also play a role I imagine.

zagmund · 12-10-2013 10:18am

Attention fact fans. I realised the other day that it's just over 6 months since I started recording the power usage around the house so I thought I would do some quick figures based on the half year.

*IF* everything were to continue at it did for the last 6 months, the house would be on target for consumption of just under 4,000kWh of electricity for the year and almost no gas. Of course, things won't continue the same as we are heading into winter.

The electricity shouldn't vary too much - the only extra usage we will have will be more lights (which still won't account for much) and the pump for the heating (which could account for a reasonable bit). I'm predicting around 4,500kWh

The gas is going to shoot up, of course. My conversion figure may be a bit out, but I reckon we used ~650kWh since March. I expect we will use in the region of 7,000 more over winter.

Stay tuned.

z

ted1 · 27-10-2013 9:59am

dardhal wrote: »

I

Going for LED lighting is a complete waste of time and money but for very few and specific needs. Except you have plenty of money, don't expect any return on investment and you are doing all this for the intellectual experience, and not for saving your hard earned pennies.

Rubbish, I replaced 8 50w Gu10s with 8 4w LEDs. So iI removed 468W forr 85 euro,
That's a saving of roughly 9 cents an hours. Which equates to 944 hours which gives a payback off roughly 9 months. You also save as they lady longer, and hence you don't need to be replacements, after the payback period there's virtual no running costs so your saving 9c an hour +the replacment costs

ted1 · 31-10-2013 7:20pm

Just got a 12 month statement. 3 bed semi d, used 3560kwh between 2 adults and 2 kids under 4,
We have has heating, well below the average.

Guess my LEDs paid off. Remember lighting is about 40% of all energy usage.

Sure kettles and all heating elements have a higher load but it's only really for a few minutes.

fclauson · 12-12-2013 11:39pm

If you wish to know the "standard" amount of energy used then you could use the BER software DEAP - see http://www.seai.ie/Your_Building/EPBD/DEAP/

its all well and good saying that I used xxx Kwh of electrify when you then use yy L of oil or zz CuF of Gas

Energy sustainability is about whole energy usage (and embedded energy as well if you wish to go that far)

zagmund · 18-01-2015 10:55pm

Here's my figures for 2014.

Total electricity kWh - 4008. My estimate earlier in the thread for 2013 was for just under 4000, so I think that's pretty good. We used more gas this year than planned - about 9000 kWh. Given that the "average" according to bonkers.ie is 5,300 for electricity & 13,800 for gas I think we're going quite well.

The breakdown between lights, sockets & cooker is below -
Lights 22.13%
Sockets 63.96%
Cooker 13.91%

The biggest usage by far was the kitchen sockets (which is primarily the dishwasher & washing machine) which accounted for over 40% of the total electricity consumption for the entire house.

Interestingly, even though we have LEDs all over the place lights managed to account for over 20% of the electricity total. This circuit also includes things like smoke alarms & probably the two bathroom extractor fans so it's not pure lights.

Anyone else got figures for the year?

z

Power consumption for a domestic house

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