Turns Out We Can Completely Power Electric Vehicles With Energy Saved in Our Own Homes


Energy Savings Target Chart

Energy Savings Target Chart

The U.S. is set to construct roughly 60 billion square feet of new buildings by 2030. But when Edward Mazria of Architecture 2030 looked at projections for electricity consumption in those buildings, he found something surprising: energy needs are actually falling. In theory, that means we won’t need to develop new power plants to service those buildings. (Source: Greentech Media, Steven Lacy)

LED Bulbs Can Look and Function Just Like Regular Incandescent

LED Bulbs Can Look and Function Just Like Regular Incandescent

It becomes an even more powerful proposition, and more important to our national security, economy and environment, when we use the power of efficiency to replace oil.

We can drive our cars with the energy we save in our home

In modern homes, there can be well over 100 light bulbs inside and outside. Gone are the days of one light bulb in the middle of the room, or one lamp fixture with one light bulb, or one porch light. Outdoor areas can become lighting masterpieces with dozens of lights in both the front and back yards set on timers illuminating for 2-6 hours per night.

Using a modern home and our lifestyle as an example, I estimate that 1/3 of those 100 light bulbs are on 4 hours a day, 1/3 are on 2 hours a day and 1/3 are seldom or never on. For an average of all the bulbs, two hours per bulb is a fair estimate. Your family or home may vary. That is 200 bulb hours per day. Assuming an average bulb rating of 60 watts, we consume 12 kwh a day, 360 kwh a month, or 4,300 kwh per year in lighting our modern well appointed home.

What happened when we switched those to LED?

The 60 watts that an incandescent bulb used was reduced to 8 watts using the LED bulb. The 200 bulb hours a day for our modern house is now reduced to 1.6 kwh per day, 48 kwh per month, or 585 kwh per year.

Thatโ€™s a savings of 3,715 kwh a year switching from incandescent to LED.

Fit EV Powered by the Sun

Fit EV Powered by the Sun

With an efficient electric car like the Honda Fit EV or the upcoming BMW i3, 4.5 miles travelled per kwh is a good rule of thumb. To dive these cars a typical 12,000 miles a year requires 2,700 kwh a year. So saving 3,715 kwh via the lightbulbs, and then using 2,700 kwh to drive 12,000 miles in one car leaves us with a extra 1,000 kwh to use for our second car.

This simple example is just for lighting our home, A few months ago we replaced our 6 year old 50โ€ plasma TV that warmed the whole living room and used $15 a month of electricity with a 50โ€ LED that uses $15 a year. Computers, appliances, smart thermostats and every electronic gizmo in the home are all getting more efficient each year.

According to the EIA, in 2011 the average home in America used 11,280 kwh per year. (Source: EIA)

Without much effort or cost, it would be very easy for the average home dweller to save the 2,700 kwh a year to power the car in the garage 12,000 miles a year.

We are entering a new energy world where optimized efficient home construction coupled with solar PV generation, will allow for a net zero energy operations cost for both the home and the two cars in the garage, with a capitol cost of construction payoff in less than 5 years. In some parts of the country that’s already a reality.

Tip: Replace the lightbulbs that you use most often first, those that you seldom or never use don’t need to be replaced.

About the author:

Peder Norby is San Diego County Planning Commissioner. He and his wife, Julie, received the 2007 Energy Excellence Award from the California Center for Sustainable Energy for the construction of their net-zero energy home in Carlsbad, Ca. They have driven more than 80,000 miles powered by sunshine in their two plug-in electric vehicles.

Editor’s Note: This article originally appeared on Peder’s blog. You’ll find this article, as well as other resourceful green information there.

Categories: General


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45 Comments on "Turns Out We Can Completely Power Electric Vehicles With Energy Saved in Our Own Homes"

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In the year to early March 2009 we averaged 1006W constant equivalent.
Right now, annualized our usage is under 620W constant equivalent.

Some of that is people not being around as much, but the largest chunk is a bunch of efficiency savings.

I use a conservative 85% efficiency compared to the Leaf’s EPA rating and I’m over at an estimated 30 miles saved _per day_, assuming _driving_every_day_of_the_year_. I actually commute 4 days per week and taking that and holidays/vacations into account I’m over 50 miles per commute saved

Oh and my new bill’s just in today and I dropped 1 to 1.5 kWh/day compared to last September (I’ll check the exact figure this evening). So, my annualized consumption will have dropped yet again.

Yes, we can do it. PEV makes people more aware of electricity use and it’s not surprising to see many owners reporting that with their efficiency improvements, their PEV doesn’t or barely even registers. Plus, with PEV charging being off-peak they’re quite likely to shift to TOU and in sunny places get PV.

It’s just one of many reasons why governments are so keen on PEV.

(Oh on the Leaf, I don’t have one, calculating savings in Leaf miles is just the kind of nerdy thing I like to do.)

First thing to look at is the energy usage curve of the grid. Lowest usage is between 2am and 6am. Highest is 6pm to 9pm. Charging in the earlier morning hours is the first essential thing. If you were to charge at work, then trying to get charged up before noon is best – but also if a workplace could install some solar PV then charging at work is less impactful on the grid. Solar PV at home and charging at night is not a good match (technically). It does help smooth out the electric bill but does not replace the draw of the EV, especially if charging when just returning home from work – as someone with a Tesla may do in order to get a full charge overnight after a long drive. But the main use of energy is actually a lifestyle choice. Two major things to look at. Size of homes (whether a small family in a 3000+ sq ft home) or divorces. Every divorce leads to two homes being maintained for a “family”. The divorce situation extends the number of homes needed across the country leading to higher power usage. Of course, re-marriages and other situations… Read more »

You need to follow with an article as this relates to EVs for this community. Utility companies would like to separate the fight of solar and EVs when really they should be waged as one. No one here connects the dots on this matter any better than you.

Utilities should consider double-incentives for Solar PV installations at workplaces if they also in-tandem install car charging stations. That would be a good one to tie in with Gov. Brown’s recent signing of the unlimited Net Metering solution (or new problem?) in CA where now utilities can allow (hestantly) more than 5% Solar PV in their customer base. I like charging off my own Solar PV at home on weekends if I need a re-charge, but I like using the grid at 2am to 6am better since I know they have excess. I’d rather my PV supply energy to my neighbors mid-day than be sucked up into my Volt. This energy stuff is fun to learn as we go along. But I wish there were more job opportunities in it or in the EV space. I’d love to change careers from my humdrum IT world to something in the EV and PV space. I was warned by a Solar PV installer last year that Solar installs will be shrinking on the east coast in places that will be ending their state-incentives. We also see “companies” like ECOtality failing due to misuse of funds and so on. So, no matter what,… Read more »

In other words… Tesla’s $35K EV promised for 2017 is not what we need. We need a $15K to 20K nice, simple EV for the masses. Maybe the answer really is to do conversion kits and “Jiffy Lube” style of conversion shop that an owner of an old Camry, Civic or VW Golf could roll in, get converted in a weekend and pay $10K for the work. Old cars with a failing engine are prime for conversions but there is no cookie cutter style of doing that which is prevalent.

The $30,000 Tesla may not be the total answer, but another step in the right direction. There are still lots of cars sold in that price range and, as long as tax incentives continue, it would end up costing closer to the $15,000 to $20,000 magic number. I don’t make a lot of money but I can still envision a $30,000 Tesla to be within reach. A quality EV for even less will make it even more possible for me to be able to make my next car an EV.

State incentives are still ramping up, if you look at the renewables space, all those RPS mandates are driven by actual kwh produced. The 5% cap, in CA for instance, was an STC rated limit. MA has >1mm panels to go.

15,000 miles driven per year by me, 1MJ per EV mile = 15GJ per year
833kwh used by my house per month = 36GJ per year

This checks out. If I could decrease my current power bill by 40% I could drive (an EV–gas cars are entirely too inefficient) with the saved power!

A passivhaus of the same size can use only 20% of the power of my house. So it’s not crazy to think that we could have standards that would get us to 60%. Of course, people get more floorspace when they can, and these are added structures.

Well done Peder! This is an article that needed to be written.

“We are entering a new energy world where optimized efficient home construction coupled with solar PV generation, will allow for a net zero energy operations cost for both the home and the two cars in the garage, with a capitol cost of construction payoff in less than 5 years. In some parts of the country thatโ€™s already a reality.”

You know you have to write the follow up article now.

I am in my 3rd year of net zero energy for my home and at 10% energy usage with my Volt.
In the winter we like it warm and we love a heat source to go to when coming in from outside. A friend in Seattle turned me on to pellet stove inserts to fit into my fireplace six years ago. It is a lot less mess than burning wood and is fully programmable to hold the temperature you desire. It is considered a renewable heat source and the extra electricity sold to the utility offsets the cost of the pellets.

For my EV

And it all starts with the right light bulb………
Again, well done.

Just don’t make me live like a European, ‘k?

Oh wait, I am European, nevermind ๐Ÿ˜‰

Funny vdiv but you make a solid point. People (Americans) don’t like conservation to look and taste like medicine. This is really an important point.

A lot of the sub compact EVs make people think that is what they have to do which is not at all the case. Tesla has showed us otherwise. But of course everybody quickly states “oh yeah but look at the price”. Again if “apples are compared to apples” the luxury Model S kicks butt over its “luxury” competitors.

As for energy conservation, nothing I have done changes my lifestyle. The most important concept is “paying it forward” to reap the earnings. This applies to LED light bulbs, solar PV, solar thermal, energy efficient appliances, and YES EVs!!

So to your point (which was a good one), you don’t have to give up anything, you just have to stop renting your energy…

Speaking of Europeans and their ways, there is a tendency especially among the young people coming out of school to prefer living in the denser urban areas. Often they forgo the car ownership completely and due to poor financials live with roommates. The side effect is of course a much reduced energy use however it is important to recognize that it is not one of the main reasons why they choose the urban lifestyle.

Denser areas allow for a more energy efficient public transportation that includes trains, trams, subways, trolleys, trolley buses, hybrid, and soon all electric buses. I grew up riding on public electric transportation. My Volt allows me escape the madness of the city, but still have a more sustainable and still flexible mode of transportation.

Except that cars are reaching energy parity with public transport (on a per person basis), see:


The emissions are greater with cars, but that is only because public transport is more highly electrified. With EVs, public transport looses its disadvantages. It may even be LESS efficient, since generally folks have to drive to where the trains are and park.

Sorry to add more, but you have to love this quote from the article:

“Transit vehicles also tend to stop and start a lot, which eats a lot of energy, even with regenerative braking. And most transit vehicles are just plain heavy, and not very aerodynamic. Indeed, you’ll see tables in the DoE reports that show that over the past 30 years, private cars have gotten 30% more efficient, while buses have gotten 60% less efficient and trains about 25% worse. The market and government regulations have driven efforts to make cars more efficient, while transit vehicles have actually worsened.”

I think the idea is right, but the numbers are a bit off.. 12 kWh A DAY just for lights? Average home consumes 24 kWh a day, I doubt 50% is lighting.

Globally average annual mileage is approx 15,000 km, not 20,000. And a Nissan Leaf is rated at 120 wh/km.. so to cover 15,000 km would use 1,875 kWh a year..

You can easily generate more than that with a very affordable 1.5 kw PV system which if amortised over it’s 25 year expected life works out at a cost of $0.004 per km.

It might not be an issue much in SD where the author is from, but I installed Nest thermostats in late 2011, and that alone offset half of my Volt energy costs May-September. When you factor in the transition from incandescent to CFL/LED, I’m sure that I’m using less energy now than 5 years ago, despite the fact that I have an plug-in car using about 3000kWh/yr.

I’m a European too – and funnily enough in the lighting sector. About six months ago, we started really pushing the LED bulbs, having the confidence to do so, since the technology has come on a lot and is ready for the mass market. The light colour is now much warmer and the lumen per watt figure are improving all the time. Add to the you won’t have to change the bulb for around 35000 hours and the savings start to add up. I did two things last year to save energy. I changed all my bulbs out for LED and replaced my shower head with a lower flow one going from 15 ltrs / min to 9 ltrs / min. My lighting (for my small European flat went from around 600Wp to 150Wp. I also obviously saved a load of electricity by not heating as much water. End result: I cut around 30% off my electricity bill for the last year (the bill just came through in October). Bearing in mind I only made the changes half way through the year, I should drop another 20% this year. So I’m in the black with the power company, they in… Read more »
Speaking of LED light bulbs I am really happy with the CREE ones available at Home Depot: http://www.cree.com/lighting/landing-page/cree-bulb Ok, it’s a shameless plug, but I do like the shape, the unobtrusive heat sink, the even light diffusion, the PFC that allows dimming and keeps the light output constant with varying supply voltage. And when I say varying consider that a buddy of mine connected a CREE LED bulb to his Prius 220V DC battery and it worked just fine. When replacing bulbs at home do not forget the kitchen and appliances. I put a CREE daylight LED bulb in the freezer and a warm white one in the refrigerator (800 lumens each). I have also replaced the 35W GU-10 reflector halogen bulbs found under the vent hood with 3W LEDs. Under the counters I’ve gone with GE’s super-slim linkable fluorescent tubes as they disperse the light more evenly. I have yet to replace the track lights’ halogen bulbs as I need to also replace the dimmers with ones made to control LEDs. Also consider your other appliances. My 25-year old air-handler and 12-year old 10 SEER ridiculously loud heat pump were not cutting it so I went with a new… Read more »

That reminds me. A few small things:
Tea kettle on stove => Small eletric kettle
Standing fan for help sleep => Sound machine (2-3W)
(Could go fan + radio-alarm clock => combined sound-machine-radio-alarm clock and knock off a couple more Watts. We tried Homedics but the backlight couldn’t be turned off making our blacked-out bedroom too bright. There’s a Conair that may have the same light problem.)
(The Sound machine goes with us on vacation: just have to keep it in its box. Despite having to replace one damaged in travel it will now have paid for itself).

Use of microwave night-light => CFL/LED night light.
– Over-the-stove microwave uses small intermediate-base high-intensity (40W) bulbs which is horribly inefficient. I don’t know how much power the night-light setting uses but I bet it’s still pretty bad.
– I’d been using a 2-3W CFL night light but that’s blown so I’m looking for a “bright” LED night-light to replace it. Unfortunately a lot of the small night-lights are too dim. It would also be at counter height and night-lights are typically designed to throw light up instead of across.

This is a joke considering a electric car is after all a car and that cars are big and bulky and need a lot of power to move two tons of metal. I really think they should be based off of giant space heats such as we had this six kilowatt space heater at home that has 220 volt wiring and when we turn it on it can really drink down the power juice. Now think of what would happen if there where tens of millions of these things drinking down juice. I’m not saying it’s going to crash the grid but I do expect we are going to have add extra transmission lines and rows of cross arms on some of the local power poles to take this need for power into account.

Well, generation and distribution is built for _peak_ demand.
PEVs’ natural charging time is during periods of otherwise low demand, so the effect should be felt more locally and if PEV charging were managed to smooth out demand I suspect the changes would not be significant.

“…we had this six kilowatt space heater at home that has 220 volt wiring”

Funny, that’s precisely the number I often see in the 2013 (and later) Volt’s energy display when I turn the resistence heater on. It’s a big delta.

Yeah, huge difference between studying incremental PEV kwh demand, and the capacity needed. Battery storage, in general, is all about equalizing the off-peak, and peak, load through what in most cases will remain free-market mechanisms. This is one place where early adopters get a bigger dividend from “paying it forward”.

Nice Article Peder … you’ve taken a page out of Amory Lovins’ book, the term he uses for this kind of energy “production” is a Negawatt, see: http://en.wikipedia.org/wiki/Negawatt_power. An EV is a perfect example of how we can use Negawatts productively.

Incidentally, I agree with the point about encouraging solar and EVs together. It makes a lot of sense to offset an additional load with a renewable supply, and if the load is off-peak and the supply, generally, peak, the actual electric power generating capacity at the source is dramatically reduced AND leveled out.

Peder- you note “4.5 miles travelled per kwh is a good rule of thumb.” That seems pretty high to me; is anyone actually getting that kind of mileage from the grid? I’m not talking what the car takes to drive, be also that charging the car is far from 100% efficient; the Volt is rated at around 90% efficiency, and also there is considerable parasitic loss just leaving a charged vehicle (especially a Tesla) plugged in when it’s not charging. Not trying to rain on the parade here, but I think your 4.5m/kWh is way too optimistic. I usually use a more conservative 3-3.5 m/kWh when making my calculations.

I agree with you. You have to have a REALLY efficient EV or drive your EV like a grandmother to get miles/KWH like that.

Enjoyed the post. I received my sons 56 inch (used do not know how old) Plasma from our son when he upgraded to LED. When checking usage with my watt meter,I was suprised to see that it pulled 75 watts.MY my 40 inch LCD TV (6years old) pulls 100 watts at low screen brightness setting. We also have a 12 year old 32 inch tube Sony that pulls 250 watts
Time to dump that!!
Phx Jim

It is a cool aspect about EVs that you can reduce your fuel costs by doing things like changing your light bulbs, get a more efficient refrigerator, and using a power-strip to turn off your entire home entertainment center with a single switch. I know, those don’t directly improve the efficiency of your EV but they do reduce the single electricity bill you pay for both.

This is 2013. Who still has a home full of incandescents at this point except for some Michelle Bachmann worshipping Tea Partiers?

Equating conservatives as being against energy efficiency.

Biased and completely untrue.

Educate yourself. The Tea Partiers made jihad against the new light bulb standards that require more efficiency. Tea Partiers have been hoarding old incandescents. Read for yourself:

Reality has a well known liberal bias.

Couple of points: First, that “compare to incandescent” trick is getting tired. At $1.80 for a 75 watt incandescent vs. $2.80 for a CFL bulb (Home Depot pricing), nobody in their right mind has incandescent lighting anymore, since the power savings overwhelms any cost of the bulb, or even the labor to pay someone to change the bulb. What you have left now are folks who believe that: 1. CFLs don’t look “natural”. 2. Florescent is hard on the eyes due to flicker rate. Both myths (you can get CFLs in matching color temperature, and virtually all florescents now have a discharge rate far higher in frequency than 60 cycles). Second, LED lighting as used for household lighting replacement is not more power efficient. It is true that the light itself is more efficient, but the difference in power is lost in the electronics used to convert from 60VAC power to the lower powers used to run the LEDs. Look on the LED vs. CFL packaging, they are about equivalent in power, matching lumen for lumen (again home depot, typical 69 lumens per watt CFL vs. 62 lumens per watt LED). You can prove this to yourself by feeling a… Read more »

LED still has key performance benefits for instant brightness, and performance in cold. They also scale down nicely for nightlights.

And of course lumens per Watt is still improving.

I’d like to say the reason my overall electricity costs went down when I switched to an EV was because I also went to LED’s, but most of the cost reduction was actually in adopting a Time of Use (peak/off-peak) pricing plan. If I get my act together, I’m going to submit a piece showing empirics for the off-peak, to base rate, spread. I don’t think I’ve ever seen anyone do such a study. Peder?

I did the same as pjwood when I got the Volt. Switch to TOU, wifi thermometer running A/C at low cost times, and charging the car in the middle of the night. My electric bill is less now than before I owned the Volt.