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Comment by Loic | Hacker News Reader

Quick question for the people living in the US (Target customers of the Powerwall). What is your yearly power usage?

On the website[0] they put for sizing 10kWh/day/BR. Which means 14600kWh/year for a 4 bedroom house. Here in Germany, working from home with a 4BR+office house, we are using 2550kWh/year. So, I suppose the Tesla sizing is to support a "peak day" usage, but still, I am surprised by the calculations. This is why this totally informal and unscientific survey :)

[0]: https://www.tesla.com/powerwall

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Interesting to compare different countries.

Helsinki, Finland here. Roughly 2100kWh/year. 2 people, a flat with 2 rooms + kitchen. We have district heating. Several laptops in the house, frequent home cooking, most lights are LED based, no sauna inside the apartment. We don't pay any attention to manually saving electricity, i.e. turning off lights etc. Our electric company provides a comparison report on their web site, according to it we are well below the average for similar household.

'no sauna inside the apartment'

Finnish problems

To give context: there are about 5,5 million Finns, and about 2-3 million saunas in the country.

Finland has 2.1 people per household so ~2.75 million households. Suggesting they are even more popular.

Suggesting there are also soon to be far less than 5.5 million Finns.

That is indeed a problem in Finland! :)

I have a solar installation which makes it slightly harder to work out what I've actually used - I know what I've generated, and what I've paid for, but since the metering isn't net that doesn't quite let me work out actual usage.

I have however got a very nifty graph of my solar generation (3.8kW roof system, 56N Scotland): https://flatline.org.uk/daystats.html

What I think you can see if you poke about the graph is that solar is very variable in practice. There are days in summer when it doesn't break 500W at all, and in winter there's basically nothing for a couple of months.

I'm happy with the installation and its return in feed-in-tariffs, but I wouldn't consider going off-grid unless I had to and had space to put up a wind turbine.

Edit: my heating and cooking energy comes from mains natural gas, as well; currently this is far cheaper than electricity. Might be useful to include that in comparisons.

I don't know if this is available in the UK but in the US we can get devices like the one I got that allows us to monitor our usage and calculate usage vs generation. https://rainforestautomation.com/rfa-z109-eagle/

http://pvoutput.org/list.jsp?userid=41746 This web site collates all the data from your solar system (again, if it supports that like my enphase system) and the power company. $10 per year donation.

https://itunes.apple.com/us/app/pvoutput-pro/id994297624?mt=... And this little app adds a beautiful way to explore the data. $2 to get all the features.

This is all a bit involved to setup but the end product, that iOS app, is just brilliant. It just takes the data from pvoutput and massages it into an addicitive portable display. 1.5 years later and if the monitoring system is down for more than 12 hours my wife yells at me.

I am ignoring the powerwall because we have a sweetheart deal with net energy metering in southern california and the power delivery has been rock solid. So it would just be a minor insurance policy in case of a catastrophic event.

It's no wonder that the EU has half co2 emission per capita than US, given the inefficiencies in US power consumption, cars etc.

https://en.wikipedia.org/wiki/List_of_countries_by_carbon_di...

A lot of it has to do with geography. Europe is quite a bit further north, and doesn't experience some of the heat that the US does.

It always helps me to remember that Rome is further north than New York.

But many parts of Europe need heating instead of AC. I think it has more to do with house sizes. More Europeans live in cities compared to US and thus have on average smaller apartments/houses. Also there might be cultural values in the play, at least central and nordic countries are traditionally quite efficiency oriented.

This left me curious and just checked that in EU, 50% of emissions are due heating and cooling [1] whereas in the US 20% of residential electricity [2] is used for air conditioning. I'd like to have better stats, but assuming numbers are correct this indicates that the difference of CO2 emissions between US and EU per capita are due other reasons than a/c use in US.

[1] http://ec.europa.eu/smart-regulation/roadmaps/docs/2015_ener...

[2] https://www.theguardian.com/environment/2010/oct/08/air-cond...

I think you're right about house sizes, but there are a lot of the US that needs both summer AC and winter heating - like the midwest, the north east, and probably the west coast east of the mountains (inland Washington, Oregon).

Do people need air-conditioning or is it just a luxury?

I guess now the globe is heating up there is more need for one, but I've always thought of it as borrowing from the future a little, a viscous cycle. More AC, More emissions, needs more AC.

I'm in Indonesia right now and sure the houses are built for the tropics but with locals, AC is rare and people manage to get plenty of good sleep and have loads of energy.

People get used to heat and humidity. If all you know is a more temperate climate or ubiquitous AC then it's hard to image sleeping in tropical heat.

It's rarely productive to talk about "need". Do you really need indoor plumbing? Do you need a private bedroom? A broad variety of foods? After all, plenty of people in the less developed parts (and in the near past in the more developed parts) of the world get by without those just fine.

The history of civilization is largely the history of the taming of nature to better suit the needs (and wants!) of humans.

Insulation is key. From what houses I've seen in the US vs Europe, the former are mostly wood-based (or similar material) and thin-walled, whereas Europe's houses are often stone- or concrete-based, thicker walls and/or (at least for newer/refurbished houses) very good insulation.

Combine that with some (more or less) clever thermal management and you need way less for both cooling and warming the house. There's also multiple government programs/incentives to improve housing energy consumption efficiency.

Electric heating is rarely used; there are many other heat sources available. There are no other energy sources available for cooling (passive cooling design aside), so comparing a heating-dominated climate to a cooling-dominated one will inevitably show more electric consumption in the hot zone. Has nothing to do with efficiency.

It's much, much better to burn fossil fuels for heat than to burn fossil fuels to spin turbines, transmit the electricity long distances, and then run it "back" through heating elements. Stages one and two are pretty lossy.

Particularly when electricity is from coal and natural gas power plants, using it for heating is a staggeringly bad idea.

True, but electric powered heat exchangers can give a 2-8x advantage since it's not generating the heat, just moving it from one place to another.

Just to add more anecdata:

* 150-year-old rowhome in central Pennsylvania, USA.

* 2 adults, 2 small children, dog/cat.

* Window unit air conditioners (2 running most of the time in summer, with a 3rd in the attic office running a lot less since I don't use it much). Hoping to install mini-split system eventually, but it's low priority

* Gas steam heat

* Gas stove/oven

* Gas water heater (I think)

* Electric baseboard heat in 2 rooms

* Electronics: tv/roku, modem/router, 2 laptops. 2 phones charged occasionally

* Lights are almost entirely CFL/LED.

My usage over the past year is just a hair under 14,000 kWh. Around 1500/mo when the A/C or baseboard heaters are on. Lowest months were April/May when both of those were off and I dipped down to 500 kWh.

If my math is right, most of the rest may be due to ceiling fans -- we have 5-6 that are left on pretty much year-round. Assuming they're each 75 watts, that's around 50 kWh/mo per fan. It never occurred to me to wonder how much power they might use.

So, if I leave A/C and baseboard heating off, and only run fans in currently-occupied rooms (bedrooms at night, living/dining/kitchen during the day), my usage would be about 4000 kWh/year.

How do you use so much less? Tiny efficient fridge? That's the only big item left in my house.

I've got an 80-year-old row house in Queens, NY. Family of 4, no pets.

Our electricity usage is well below yours. We don't make a huge effort to conserve, and I don't believe our house is particularly well insulated. We have no special energy tech, unless you count the LED lights. We have a lot of electronic gizmos sipping away at any given time.

Winter: we don't have the baseboard heaters, but I work from home most days and have an infrared heater pointed at my desk for a good 8 hrs or so each day.

Summer: my wife hates A/C when she sleeps, so we only have one air-conditioned room at night (me and 1 kid in the room w/ A/C, wife and other kid in the other). No pets, so we leave the A/C off when we're out, it comes back on (by timer) about an hour before we get home. So big difference in summer.

Still, that doesn't sem to account for all of the difference. I just checked my con-ed history online. Some typical usage numbers:

  Feb: 310 kWh  
  Apr: 240 kWh
  Jul: 410 kWh
  Sep: 270 kWh

We spend anywhere from $80-$350 a month for electricity. Maybe there's a big difference between an 80-year-old row and a 150-year-old row?

We have

- 3 window A/C units.

- 3 routers, running 24/7

- 2 servers (mostly used as NAS), running 24/7

- FireTV, a few sonos devices, drawing a bit 24/7

- Many lights, mostly LED. We're pretty good about turning them off.

- ~10-15 phones/kindles/laptops/tablets/gizmos constantly being topped off

- Gas for stove, water, and household heating

EDIT: After reading more discussion below, I thought maybe I'd made a mistake, since there is a difference between our usage and most of the other US folks. I double checked, and the numbers are right. Our total usage for the last 12 months is 4340 kWh. We were gone for a few weeks in the summer, else it would have been a bit higher.

The GP had electric baseboard heat. That's a black hole for electricity usage purposes.

That's quite similar to me with a 4BR in Massachusetts.

I'm in the 550-600 kWH range for most of the year. Goes up a little bit in the summer if I'm running my 1-2 window unit ACs on occasion. In the summer, I do run several fans more or less continuously.

I do have an electric oven, dishwasher, washer, dryer, and several refrigerators. I also still have a fair number of halogen or other incandescent lights although I'm slowly swapping in LEDs. On the other hand, it's mostly just me and I do a fair bit of traveling so appliances and lighting probably don't add as much as they could.

I have a little bit of baseboard heat but I rarely use either that or my space heaters. (Forced hot water heat and water heater.)

My electric company says my use is about average in the area for the size of my house (albeit their figure is a few hundred square feet too low).

The reason their calculations are so high is because in the US, typical houses are made as cheaply as possible, pretty much with paper, plastic and vastly insufficient insulation.

That may have changed in the recent years, but holds true for most residential properties built before 1980.

If you think the USA had bad standards, In Thailand it's common (even today!) to build skyscrapers out of cement and single-pane glass.

To bangkok office workers, it's pretty natural to blast the AC all day and have the office still be above 28'C

What a sweeping generalization.

Furthermore, unless you're in an area of the country that requires the use of a lot of AC--or you have electric baseboard heat--insulation doesn't even play that much into electricity usage.

I can see why one would bristle at the term 'cheap', but where energy efficiency is concerned there is a big difference between the EU and US. Energy costs are higher, regulations tend to be stricter, and usage lower in the EU.

On insulation, I'm assuming you mean in areas where AC isn't heavily used insulation doesn't help electricity bills if heat is provided by gas/oil?

>On insulation, I'm assuming you mean in areas where AC isn't heavily used insulation doesn't help electricity bills if heat is provided by gas/oil?

Correct. Heavy use of electric heat is fairly uncommon as it's relatively expensive. (In the Northeast, it would be considered a serious negative if a house had only electric heat.) Of course, insulation helps with overall energy usage if there's either a lot of heating, a lot of cooling, or both--however it's provided. I'm also sure the US tends to have larger houses, more large electric appliances, and other home features that increase electricity use.

I've lived in a lot of cities through the 'rust belt', and I'd estimate that half if not more of pre-1970 houses had no insulation at all.

Seems like Western Europe is getting up to speed with standardized insulation. People are monitoring heat leaks in buildings etc.

Two things: 1) I wonder how much energy could be "saved" with proper insulation. Per Country, per planet. 2) Insulation seems like a human sense, by that I mean, whenever I've lived in an old, stone wall house, I enjoyed the delay in temperature. It's still refreshing when the sun hits hard, and still mildly warm when cold settles.

More efficient lifestyle and better quality of life ? I'd sign.

Partly inspired by this thread, I read a couple of EU reports and realised that 50% of energy consumption in EU goes to heating and cooling. That is huge. Of course it includes industrial heating, but that is 18% in total (~third of 50%).

Clearly, there is lot to win here,with existing insulation techniques. we could do a lot in a short-term with existing technologies, it's mostly policy and financing issue.

It's really going to depend on the location in the US.

When I was living in the southwest, my energy bill per month was ~$500 for a 4 bedroom house. A/C eats a lot of power. After moving to the northwest, my bill is around $80/mo.

To convert that to kWh, assuming a 10-15c/kWh rate, that would equate to 40,000-60,000 kWh per year in the SW and 6,400-9,600 kWh in the NE.

My figure for a 4 bed house in the UK is about 4,800 kWh per year.

I'm unsure about the US but I know that where I live a solid third or so of my power bills are a fixed rate that you pay to access the grid (so pretty much line rental). It doesn't feel to me like that's a particularly unique situation.

So it's worth keeping in mind that the actual power usage figure may be a fair amount lower, and that your SW calcs are a bit of a worst case estimate.

That's not the case on my bill in the Northeast. There's a $4/month customer charge but everything else is kWh based (whether from the supplier or the distributor).

The big difference is because of air conditioning and baseboard heating, two things that are relatively rare in Europe.

> The big difference is because of air conditioning and baseboard heating (...)

Which makes you wonder why there is not as much high-profile attention on A/C (and to a lesser extent electrical heating) as being a problem worthy of rethinking by Silicon Valley (perhaps even ahead of solar, in North America).

There is quite a bit of work being done on solar powered airconditioning. I experimented myself with this about 10 years ago using two back-to-back Stirling engines with the first powered by the sun and the second being run in reverse to cool a working fluid.

It's an interesting field, you'll learn more about Carnot cycles and thermodynamics than you ever wanted to :)

A climatization using DC current from capacitors charged with solar panels might be more interesting in mild hot regions.

If I understood well AC is optimized for carrying current on long distance with minimal loss. But most electric devices use DC. They need an AC to DC convertor with some energy loss.

Solar panels produce DC and is usualy converted to AC with some loss. Then, in most electronic devices, this AC is converted back into DC in the device power transformator.

What waste of energy. Shouldn't we do something about this ?

> What waste of energy. Shouldn't we do something about this ?

Most devices which operate on DC (e.g. computers, TV) have a switching power supply, which is around 90% efficient. So for a computer drawing 100W, only about 10W is lost in the conversion of AC to DC.

Larger appliances such as microwaves, ovens, and air conditioners will use AC directly without conversion to DC (except maybe to power the control electronics).

> But most electric devices use DC.

Yes, but no national grids are DC. There is a lot of interest in using high voltage DC (HVDC) for long distance transmission (and wind farms), since you don't have to expend energy to generate and maintain the sine wave (and your collector field electronics are simpler), but the customer connection is always AC.

With the insane amount of money invested in delivery to homes as 110/220VAC, no one is going to start selling DC devices. Even in regions where this is no electricity and people use off-grid systems, the economies of scale mean that DC appliances such as refrigerators are often 200-400% more expensive than their AC counterparts.

A lot of research has been put into DC distribution, but the main issues are:

- Devices still require a DC/DC converter to step up or down the distribution voltage to their operating voltage. This converter is again not 100% efficient

- High voltage DC is deadly (your muscles will contract instead of releasing, so if you touch a cable you're dead)

- Low voltage DC requires thicker wires, meaning higher cost for distribution

Source: work for a utility company

Another factor is that high voltage DC step-down is significantly harder than AC step-down, especially once you get into the 100's of KV. With AC that's relatively easy, transformers are passive components, very well understood and can be made for extremely large power levels without getting into exotic engineering.

It might be (it is) anecdotal, but as someone from Europe it struck me odd how much Americans love their A/C. Too much, in fact. Almost everywhere I went it was too cold. Somewhat like in SE Asia. That might be the answer to high energy use.

For Americans, mostly read Texans or maybe Southerners more broadly. A lot of us joke that the hotter the climate in a US state, the colder they tend to crank the AC.

That can't be good for health! SE Asia like to do that too. I joked that tropics there were a sham since I had to wear a jacket all the time because of the polar-like A/C.

I have the same experience in both US (mostly Raleigh, NC) and China; but China has got better over the last twenty years, possibly because air conditioning is no longer an unusual thing in the big cities so it being cold indoors is not such a status symbol, perhaps.

It's worth noting that temperature control is only half the equation. In places like Houston, A/C plays a big part in controlling indoor humidity as well(for both comfort purposes and to prevent mildew from growing all over everything).

There's other (read: more efficient) ways to control humidity than using an A/C. Including making buildings more "airtight" so the dampness doesn't leak into the house (as long as you don't open doors/windows too much, of couse).

Another anecdote: I live in Belize and my girlfriend runs a hostel, and we can always tell which rooms have guests from the southern US because the AC will be set to 18C (~64F). For some reason northerners don't tend to do this, I assume because they don't use AC as often at home. The Texans I know are the worst. They make their apartments so cold I need a blanket if I'm going to stay for a movie, and they sleep under massive down comforters. In the tropics! It's so maddeningly wasteful. I rarely use my AC and sleep under a single top sheet with no discomfort.

I live where it tends to get hot and humid (not tropics humid though), but turn on A/C only if it's really unbearable at night. Even then, at most 5C difference. Usually, single top sheet, as you've said, a cool drink and maybe a fan is enough. I understand that humidity is tough though, but one can get dehumidifying alone from A/C or a standalone dehumidifier.

Baseboard heating, if it's the same thing as radiators, are the norm in central and north Europe IME.

Don't forget gas for heating in Europe. One cubic meter of low caloric gas approximates 10KWh. My household (Netherlands) uses 4k KWh but also 3k m3 north sea gas. So about 34 KWh equivalent total. Suddenly a not so different ballpark. (And I have an eye opening moment. Never knew gas was so full of energy.)

I used a little over 12000k Wh/h over the last 12 months in a 4bed with 2 people in Texas. I also have 2 cats and 2 dogs, so I don't turn the AC down too much during the day.

date-elec-solar

10/15-567-503

11/15-329-312

12/15-290-373

1/16-270-493

2/16-218-535

3/16-269-543

4/16-352-509

5/16-510-383

6/16-994-492

7/16-1292-514

8/16-976-401

9/16-832-???

I changed the password on my router in September and didn't update my solar controller, so I don't have data for my September solar production, but it was probably around 500 (I produced 579 last September!).

I live in California, 4br house with four adults. We use about 200kWh/month in the summer time which is basically just lights, electronics, and fridge (water and stove are gas), and 1000kWh/month peak in the winter time because we heat our rooms with electric space heaters.

We don't own the house so there's not much we can do about it. The windows aren't really insulating at all, and there's one old gas heater that doesn't work, although even when it did it all the heat just went straight up the stairs.

In the summer the upstairs gets extremely hot. But our rent is very cheap compared to other places in the bay area, so we are afraid to bother the landlord about these things. #freemarket

I'd imagine it's based on a home with air conditioning. I'm assuming that being in Northern Europe you don't have AC.

Effectively, we do not have AC and our heating system is not heat pump based but using the local district heating. This means that this power usage is only for: cooking, lights and computer/tv/etc. appliances.

We use heat pumps as well in Northern Europe, but to transfer heat from outside to inside. You can get even five times more heat for the invested electricity compared to direct (resistive) electric heating. The best winter optimized air-to-air pumps work down to -20 °C (-4 °F) with efficiency ratio over 1. For example, I heat my entire house with a single heat pump through the year. Our average electricity bill is ~100 €/month. There are less than ten days in middle of winter when I turn on extra resistive heaters.

Unfortunately, although in Southern Scandinavia we receive about as much sunlight energy than Northern Germany per year, the peak is in summer when the need of energy is lowest and during three winter months almost no usable energy can be harvested from sunlight, meaning that solar-only powered house would need gigantic battery bank (~100 Tesla Powerwalls) to survive over three darkest months.

I heard great things about heat pumps efficiency-wise, but that their downside were noise. However, that information is dated because I haven't looked into it in a long time.

Has that improved? I'd expect the market in Scandinavia to be much more developed than in my country.

I would also like to hear about heat pumps. A lot of information is either white papers or scienceless consumer information, with no middle ground.

It's unfair to compare European and American heat pumps. The market is much larger more mature here in Europe and the differences in how you think about heating are large. I've heard that american heat pumps are quite noisy, mainly because you place them away from the living area (there's no reason to lower the noise). In new-built houses here in Europe they are most often placed directly within the living area so the heat pumps must be very quiet.

Disclaimer: I work for one of the heat pump manufacturers in Europe (albeit with connectivity solutions and not actual heat pump technology)

Depends how much you pay. The last time I looked a simple air to air pump the cheapest was 31dB and the most expensive was 21dB. So very quiet indeed.

About one in five houses have heat pumps where I live (about 40km south of Oslo) and I can hear them humming as I walk past but of course they are not the latest models. Still they are orders of magnitude quieter than the units outside the flat I rented in Cary, NC ten years ago.

Air-to-air pumps will probably always make some noise because air has relatively small thermal capacity, requiring relatively big air flow in order to transfer any meaningful amount of energy.

There also exists heat pumps which transfer heat to water-based central heating system (radiators / floor heating), eliminating the noise issue. The heat source can be either outside air or liquid circulating in soil/well (possibly supported by solar). All these combinations are relatively common in Scandinavia, air-to-air pump being most popular because of quick ROI (small initial investment) and easy retro-fitting, althought practically all new houses are built with water-based central heating (the heat source being either of electricity/solar/wood/air pump or any combination).

My 2300 ft^2 (210 m^2) house in NC uses 11000kWh per year. I needed less than half my roof (the southern half) to be covered in solar panels to generate almost all my electricity (I do have gas air and water heating, however).

I'd like to build my next house to PassivHous or similar standards. I think I can get the energy usage to 5000 kWH anually. With the whole roof sloping southward, I think I'd be able to generate more than what I need for the house, even accounting for electric transportation.

Ireland, 4 bed detached, solar water heater which works well for about 4 months of year, oil heating + wood/turf stove for rest of time. No need for air conditioning here but heat recovery thingie is on all time.

5000kWh last year, tho I have computer(s) on 24x7 due to home office, Comes to about 120€/month

Half of all the bills are just standing charges, and renewable subsidies charges and taxes, and taxes on taxes. Hence adding LED lights, low power appliances etc did little to budge the bills

We worked out recently that we spent under £20 pcm on gas and electric over the last year. 2 people, washing machine, fridge, 2 x laptop, LED lights, 1 LED TV, and gas heating. Admittedly we only put on heating in the evening for an hour or so. Southern England (UK). Attribute to it not being cold for the last two winters here. Duvets and hot water bottles are used regularly. Yet to turn on heating this year. Not looking forward to the cold. Water bill however is shocking.

Athens, Greece here. 2BR house with 2 AC units and electrical heating. Around 5.500KWh/year.

That's a very interesting number. Here a comparison, from Germany too: I used to live with 3 flatmates for several years in a 4BR apartment (165m²), our yearly usage averaged 5500-7000 kWh. That included heating water (electric boiler), but no room heating or air conditioning.

I've recently moved out into a 1BR, 63m² apartment, and am targeting 1500-2000kWh - don't have any usage numbers yet since it hasn't been long enough, but those seem realistic to me.

Amsterdam, Netherlands. Around 1200 kWh/year. 1 person, flat with 1 room + kitchen. I am not home that often due to my job/hobbies, but I do have a gaming PC and a laptop. I did buy a power efficient refrigerator and washing machine when I moved in (Not terribly special or something, just bought the ones with a certain label). I also don't have a dryer and I cook using gas.

I'm guessing that would be below peak day usage for me--i.e. two window AC units running (which isn't common)--but 14600kWh/year seems pretty close as an average based on my $100 or so monthly electrical bill. That's for a 4BR house, albeit a smallish one, that uses oil heat almost exclusively in the winter and runs fans, and only sometimes AC, in the summer.

My electric company sends out a comparison statement periodically and says I'm about average for similar-sized neighbors. (Albeit, it thinks my house is a bit smaller than it is.) So I'd say Tesla's calculator is about right for the US although it's going to vary a lot based on AC and electric heat.

1BR+office (home office with 2 always on computers), air circulation with filtering, around 80 square meters, 2 people, also Germany, 3600kWh/Year (~90€/month)

That could probably triple if we had AC. Far worse if we had electrical heating.

I'm in the US (suburbs near NYC) and over the past 12 months we've used 15714 kWh. 5 bedroom house built in the 1950s. With all my electronic toys, our love of air conditioning in the unbearable NY summers, and the tendency for nobody to pay any attention to turning things off, I'm almost surprised it's not higher. Also, we have a Nissan Leaf (electric car) which is responsible for 2500-3000 of that usage. Total electric bills for the past year comes to $2885. I don't think we get enough light here for solar to be worth it, but occasionally I think about it.

It probably depends on number of electric appliances.

If you live where you have electric heating/cooling, electric water boiler, electric stove/oven, you'll burn a lot of electricity. I burn 2500-3000kW/year in 1B apartment, but except heating/cooling - everything is electricity. If I had a gas stove and hot water I'd probably use less than 1/3 of that.

Also I'd guess that in US people do not built as well insulated buildings as in Europe, thus more power for heating/cooling

Our family of 4 in a 4BR house lives in the humid SE USA. We use about 5000 kWh/year. Our efficiency report says we use roughly half as much as comparable households.

> What is your yearly power usage?

Shouldn't that be 'What is your yearly _energy_ usage?' ? Or alternatively: 'What is you average power comsumption?'

2500 kWh/year = 6.85 kWh/day = 285 W, which sounds pretty reasonable

For comparison, an average male requires 8700 kJ/day = 100 W

40 kWh/day for a four bedroom house = 1.67 kW, which is huge. Maybe it includes charging a couple of Tesla cars as well.

Another data point. Past 12 months we're at 22,000 kwh. Average of 60kwh a day. Older 4 br house with people almost always in it. USA, TN.

I think the main difference for us is that my wife and some of the kids are at home almost all the time and we kept the house warmer for the baby this winter.

Me in my 2BR apartment: 550 kWh / year. My startup office (3 developers and a lot of computers): 600 kWh / year.

Not including heating. Location: Wiesbaden, Germany.

I have a car but hardly use it. I go to work by bike every day. Guess I'm not quite the target audience for this powerwall thingy :-)

Over the past 12 months, 12000 kWh, in the Pacific Northwest [1]. I expect that to be lower this year, because I just had my house insulation improved. My house was originally a two bedroom house of approximately 1000 sq ft (92 m^2) built in 1964, and an additional bedroom was added in 1984, bringing it up to approximately 1400 sq ft (130 m^2). There was no insulation under the floor in the original house, and just a small layer of some kind of shredded paper-like material in the attic. The added room had decent insulation under the floor, and some real insulation in the attic, although not up to current recommendations for attics in this area. I now have a properly insulated floor, and the whole attic has been brought up to R49.

Here's a month-by-month breakdown, giving kWh for the month and average temperature.

  2015-11:  730 kWh, 54 F (12 C)
  2015-12: 1780 kWh, 42 F ( 6 C)
  2016-01: 2100 kWh, 40 F ( 4 C)
  2016-02: 1600 kWh, 43 F ( 6 C)
  2016-03: 1420 kWh, 46 F ( 8 C)
  2016-04: 1130 kWh, 48 F ( 9 C)
  2016-05:  580 kWh, 57 F (14 C)
  2016-06:  460 kWh, 59 F (15 C)
  2016-07:  490 kWh, 62 F (17 C)
  2016-08:  460 kWh, 66 F (19 C)
  2016-09:  530 kWh, 67 F (19 C)
  2016-10:  560 kWh, 59 F (15 C)

(Note: dates are the dates on the bills, which come about a week into the month, so the actual period covered is mostly in the prior month)

Rates here are $0.09/kWh for the first 600 kWh per month, and $0.11/kWh for whatever is over 600 kWh.

I don't see how you can use so little power. 2550 kWh/year is under 7 kWh/day.

During the summer months I turn my heat pump off, doing climate control by opening windows and using a couple of box fans to ensure air flow through the house. I typically have two fans running at opposite sides of the house. Figure 50 watts each, running whenever I'm home (weekends, plus one day a week working at home, plus 2/3 of the day on days I work at the office), and that comes to about 2 kWh/day average.

I usually have my entertainment system on when I'm home. If I'm using the TV, it's a total of about 100 watts. If the TV is off because I'm just listening to the streaming radio services my cable provider provides, it's about 60 watts. Call it 75 watts on average, and rounding to the nearest kWh, that's another 2 kWh/day.

My desktop computer uses 150 watts when used casually, such as reading and posting on HN, or browsing the web. Figure 4 hours a day on the computer on work days, and double that on my work at home day and weekends), and that's another kWh.

I'm up to 5 kWh/day now, just for fans, TV/stereo, and one desktop. Then there is my refrigerator, the pump for my well, my water heater, a washer and dryer, cooking appliances (stove, oven, microwave, electric griddle), and lights. Some of those use quite a bit of power. For instance, cooking baked french fries in the over (preheat to 450 F (230 C), then bake for 35 minutes) uses 3 to 4 kWh. I only do that maybe once a week, though, so it maybe contributes 0.5 kWh/day. Lights (all LED) are probably about 0.25 kWh/day (mainly two 14 watt (100 watt equivalent) Cree bulbs running 8 hours a day). All in all, these other things are going to probably average 2 to 3 kWh/day combined...and that puts me at or above your usage.

So, best case I should be able to maybe get down to your usage, during times of year when I can turn off the HVAC system and rely entirely on a couple of fans for climate control. And the best I've actually achieved is twice that...which means I've got something drawing more power than I accounted for above. My first guess is the refrigerator, as it is quite old. Time to stick the Kill A Watt meter on it and see what it is going on. The only other things I can think of that I left off are battery chargers for phone, tablet, handheld ham radio, and rechargeable batteries.

During months when I have to use the heat pump, I don't see any way I could get down to anywhere near your usage. How do you keep your house warm in winter?

I have noticed that if it is sunny out, then if I open blinds and drapes to let the sunlight in, I can reasonably heat the house that way even if the outside air temperature is low. I did that today, and got the house up to 68 F (20 C), and the insulation was good enough to keep it warm enough to keep the heat pump off for most of the night. It's now 4 AM and 43 F (6 C) outside, but the heat pump has not come on yet. Unfortunately, it is usually overcast during most of the winter around here so most days that won't work.

[1] West across Puget Sound from Seattle. Here's monthly temperature data for this general area: http://www.usclimatedata.com/climate/bremerton/washington/un...

14,130 kWh for a 4000 sq ft 4 bed in Boston over the last 12 months for a 150 year old house. It looks like AC is a large portion of that. Thankfully, we use gas for heat and cooking.

I used 2400kWh in Canada last month! What are the temperature swings like where you live? We can go from -40F to +100F throughout a year.

Could it be because of the warranty? For example, those batteries in 2 years won't be able to keep half the original charge.

Spain, 4BR/200m2 house, roughly 5.500KWh/year. No A/C, heating used pretty much only in winter.

They're probably factoring in a charging Tesla in the garage.

Throw in charging a Tesla in your figure..

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