Posts Tagged ‘prius’

GreenHomes, home energy…and electric cars

February 23, 2011

Everyone is very excited about the new electric (and kind-of electric) cars coming out – the Nissan Leaf, the GM Volt, the electric Ford Focus, the plug-in Prius, and many more are on the way.

Ford Focus Electric Car 2010What do electric vehicles have to do with homes? Two things right off the bat. First, obviously, if you’ve got an electric vehicle, you’ve got to charge it. The rapid chargers that are used to charge the EV require higher voltage and amperage than your standard breakers and outlets can provide so your home will likely require some electrical upgrades. And second, once you start charging your car, your electricity usage will go up so it will likely result in higher electric bills. There could be an unpleasant surprise in areas with higher electric rates, tiered rates or “time-of-use” metering and rates.

This could get very interesting. The impact on electricity supply will be significant in the future—and every region of the United States in facing electric generation capacity issues within the next 4-5 years, even with all the new power plants on the drawing boards. Here’s a picture a couple of years down the road when thousand of electric vehicles are on the road, many of which will be in states such as California that are struggling to keep up with electricity demand. What will happen when 25,000 electric vehicles are being charged during the middle of the summer in the afternoon during peak load? 50,000? 100,000? Ever heard of brown outs?

It raises some good questions. What will the policy be? All chargers are automatically turned off? How will folks get home if their electric cars don’t have enough battery power left? You get the picture. The emergence of charging stations along with the proliferation of air conditioners (20 years ago no one had an air conditioner within 10 miles of the coast – now they are prevalent), big screen TV’s in homes and businesses, computers in every room or office, etc. is going to continue to put a monster strain on the nation’s electricity grid.

Don’t get me wrong. Electric vehicles are part of the answer, at least in the short term, to wean ourselves off of foreign energy sources. And watching the news over the past several weeks, that certainly seems as prudent as ever. It’s just we’ve got to plan and prepare appropriately. And one of the ways we can handle this is by offsetting the electric load of new electric vehicles with efficiency savings in our country’s building—homes representing half of that energy use.

It’s good energy policy. It’s good national security. It’s good macro economics. And it’s good HOME economics. By increasing the energy efficiency of your home, you can offset the additional electrical load of the EV charging station. You’ll save immediately. And the added benefits are huge, namely increased comfort throughout your home, fixing rooms that are too hot or too cold, reducing home maintenance –all while saving your money.

You can count on a lot more discussion of electric vehicles, home energy use, and the connection between the two, right here, and on the GreenHomes America website.


What’s Greener: A Prius or a Home Energy Retrofit?

August 5, 2010

Thinking about purchasing a Prius to reduce your environmental impact?

You may want to consider all of your choices before stepping into a shiny new hybrid because in many cases, investing in a home energy retrofit may have a bigger impact on your carbon footprint and a faster return on your investment than purchasing a Prius.

number crunching

The Prius vs. A Home Energy Retrofit

So, how does buying a Prius compare with improving your home’s energy efficiency in terms of reducing your carbon footprint and seeing a return on your investment? While these the answers to this question will vary depending on the driver and the driver’s home, our team did some research and found that what might shrink your neighbor’s carbon footprint might not be as cost effective for you.

We’ve crunched a bunch of numbers in hopes of getting people thinking about energy efficiency from a new perspective. The points made here are not meant to convince you that you shouldn’t buy a Prius. We’re using the Prius as a symbol of a more fuel-efficient way to get around; we could have done the same calculations with any fuel-efficient car.

Let’s do a little example to illustrate.

Meet Rebecca — An average driver with a home built in the ’90s. Rebecca drives 12,000 miles per year in a car that gets an average of 23 mpg, and she lives in a house built in 1992.

Buying a Prius:

Rebecca would double her fuel efficiency to 46 mph by purchasing a new Prius. As long as she continues to drive 12,000 miles per year with gas costing $3 a gallon, Rebecca will:

  • Use 267 fewer gallons of gasoline per year
  • Reduce her annual carbon footprint by 1,530 pounds
  • Save $800 in fuel every year
  • See an annual 3.2 percent return on her $25,000 investment

From a carbon footprint perspective, the manufacturing of a new Prius is an energy intensive process – the equivalent of consuming 1000 gallons of gasoline. So, Rebecca will spend the first four years with her new Prius paying off the “carbon debt” associated with making the Prius.

Cost-Benefit of a New Prius for Rebecca: $25,000 invested, 3.2% ROI. Assuming she keeps her car for 7 years, her average annual carbon savings will be 655 lbs per year.

Making Home Energy Upgrade: In a 1990’s era home, comfort and indoor air quality issues are common, and duct sealing is typically the single greatest opportunity for energy savings, followed by air sealing and improvements in the ventilation system. In a house of this era, it is reasonable to expect a savings of 10 – 30 percent in energy efficiency from a $3,000 investment.

Let’s say Rebecca consumes 12,000 kilowatt-hours (average residential consumption) of electricity per year in her home, and purchases her electricity at 10 cents per kWh (the national average). If she improves her home’s efficiency by 20 percent, she will:

  • Save 2,400 kWh of electricity per year
  • Lower her annual utility bills by $240
  • See an 8 percent return on her $3,000 investment
  • Reduce her carbon footprint by 1,360 pounds (with coal as primary fuel source)

Cost-Benefit of an Energy Retrofit for Rebecca: $3,000 invested, 8% ROI, annual carbon savings 1,360 lbs.

P.S. — Rebecca might be able to save a big chunk of the initial investment if she took advantage of all the tax credits and other incentives for retrofitting her home.

Which is the Greener choice?

In this example, an audit and retrofit of her house will provide Rebecca — an average mileage driver in average mileage vehicle living in a newer house — with a greater return on her investment and nearly twice the reduction in her carbon footprint as buying a Prius, for one-eight of the cost.

Of course, we left out a lot of detailed factors on both sides in an attempt to simplify the numbers. But if you think we missed something important, or you’re in Toyota’s marketing department and you want to argue with us, contact us and share your thoughts.

What is the greener choice for you?

Whether you’re better off retrofitting or buying a Prius depends on your unique set of factors: what era house you live in, how much you drive, your current vehicle’s mpg, etc. However, there are tremendous opportunities to reduce your carbon footprint and fuel costs, both at home and on the road. And, while choosing a more fuel efficient vehicle is an obvious step towards reducing your carbon footprint, investing in a more comfortable and energy efficient home can often provide an equal, if not greater, reduction in your carbon emissions — and, in many cases – at a fraction of the cost!

Scott Case is the VP of Product Management for, a company dedicated to making energy efficiency easy and accessible for homeowners throughout the U.S. through tools and resources such as an online energy audit and a directory of energy tax credits and rebates.

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