Zero Net Energy Homes – Part 1

Beautiful sunset (CC 2.0 license)
Beautiful sunset (photo by Santa Rosa OLD SKOOL, CC 2.0 license)

This is the first post in a series on zero-net energy homes. Over the course of the series I will be covering all aspects of this topic, from the technology and knowledge available today, to the changes needed in technology, building codes, trade skills, design approaches, and will to achieve the goal of all new homes eventually being zero net energy.

Definitions and feasibility

What is a “zero-net energy home?” Zero net energy homes generate as much energy as they use. Energy used = Energy Generated. The experience of thousands of “off the grid” home owners and those bleeding edge homeowners with big solar panel installations on their roofs show that zero-net energy homes are technically feasible today. For example, see this article on Amory Lovins’ home and office in Snowmass, CO.

We know how to build them. Unfortunately, for most homeowners, they are too expensive, because the energy generation side of the equation is too costly. There are three ways to address this problem.

  1. Reduce the cost of home-based energy generation, typically either solar or wind. That depends on technological improvements and manufacturing efficiencies by the solar panel companies, and they are busily doing their best to address this situation.
  2. Change the cost basis for comparison – energy generation is expensive compared to the cost of electricity from coal-fired plants, but a carbon tax on those plants would automatically make solar more competitive (and raise the cost of energy for all of us).
  3. Make the demand side of the equation – energy used – smaller. Reducing the energy used by half cuts the energy required by half, which cuts the cost by half. And typically reducing energy use has numerous other cost benefits, and often performance benefits as well.

Over the course of this series of articles, I’ll be looking at how both sides of the equation can be reduced, but the particular focus will be on getting the demand side down.

Privation is not the solution

One way to reduce the energy use of the home is simply to do less – for example, you can save a lot of hot water if you simply stop showering every other day. Other techniques are leave the heater off when it’s cold, or the AC off when it’s hot. There’s also sitting in the dark – lighting accounts for about 15% of home energy use. Strangely, most homeowners in the U.S. are unwilling to reduce their energy demand by cutting “services” in this way.

Therefore, we have to find ways to reduce energy usage while not cutting the “services” the home provides. We all need our showers, our lights, and our comfortable temperatures. The good news is that by making small changes in how homes are designed and built, typically at a very small increment to the cost of the home overall, we can build houses that use one half the energy or less, and often at a higher level of comfort and “service” than standard-built homes.

As we will see over the next few articles, we already have all the technology, and some people have the experience, to build “zero-net energy ready” houses cost effectively.

On the energy generation side, although there’s currently a premium to get to zero-net energy, over the next ten years this premium will go to zero. In fact, looking farther ahead, it may become cost-effective to get to positive-net energy – where the house is generating more energy than it needs! Such a change has world-changing implications – but we’ll cover that later in the series.

Coming up

Zero-net energy homes is a huge topic, and some of the areas we’ll be covering in future posts are:

  • Integrative design
  • Passive heating
  • Home energy storage
  • Zero-net energy for existing homes
  • Zero-net energy and LEED
  • Practical steps for finding a zero-net energy home builder
  • Examples of zero-net energy homes
  • Achieving a zero-net energy home cost-effectively
  • How the cost-benefit equation on zero-net energy homes is likely to change over the next five and ten years

As I get started on this series, I’d love to hear your comments and thoughts on what I’ve presented here, as well as other topics I should cover in future posts.

Green Building, Carbon Footprint, and Santa Explained

Santa and His Sleigh, Compressing Space and Time
Santa and His Sleigh, Compressing Space and Time

In the last week or two I came across a number of interesting energy-related resources, blogs, websites, and talks that I wanted to share.

  • I was happy to run across Barry Katz’s new blog, The Future Is Green, because Barry, a home builder, is where all home builders need to get in the next 5-10 years. He’s committed to building zero-net energy homes and remodels. His web site has examples of the some of the work he’s done so far.

    In fact, the homebuilding industry can do something that not even hybrid cars can do. It is entirely possible, using currently available technology and materials, to build homes that consume zero-net energy. And not only zero net energy, but energy positive enough to recharge our plug-in hybrids. Such houses exist already. If we can build one, we can build many. (From Barry’s post, What We Need Now.)

    Barry’s also writing a book on green remodels, which should be useful for people like me who live in a house that’s already been built.

  • Saul Griffith, of Makani Power, calculated his current carbon footprint, and then his “allocated” carbon footprint as a global citizen. In this talk at the O’Reilly Emerging Technology Conference earlier this year, he walks through those numbers – which are both scary and heartening. His calculations suggest that we need to throttle our energy usage at about 15 terawatts (TW) for the entire earth. As he puts it:
  • My life today is 18 horsepower, my new life should be three horsepower

    I found the section on the energy available for us to use – the total solar flux, the tidal power of gravity, nuclear, and geothermal – extremely interesting (about 30:30 into the recording).

    There are only four sources of energy – sun (85,000 TW), gravity (tidal – 3.7 TW), geothermal (constant flux of 32 TW), nuclear. All photosynthesis is 90 TW, which is the major argument against biofuels.

  • Science Daily reports on some research by Larry Silverberg, a professor of mechanical and aerospace engineering at North Carolina State University, regarding Santa Claus’s ability to “travel around the world in just one night on his reindeer-pulled sleigh and deliver toys to all the children.”
  • “He understands that space stretches, he understands that you can stretch time, compress space and therefore he can, in a sense, actually have six Santa months to deliver the presents,” Silverberg told Reuters.

I hope you enjoy these links – let me know your thoughts, especially about the Griffiths talk if you have a chance to listen to it on your iPod – or on your computer at work.

Why I Am Optimistic

GDP per capita vs. 'Economic Energy Efficiency...Image via Wikipedia

The signs are pointing to a critical convergence that, to be honest, is coming just in time. The world’s will is aligning. Climate change, oil prices, pollution, growth, commuting – these and other factors are forming a message in society’s mind that says “things are not good and they must be fixed.” Businesses and governments, at the same time, are realizing that the changes needed to achieve sustainability are not going to be a drag on the economy but can actually be profitable while being good for society as a whole. Of course, the high and rising price of oil has something to do with this as well.

And technology is improving – finally – to the point that our remaining energy needs, after the 50% reduction in energy intensity possible via efficiency, can be cost-effectively replaced by renewables. Scientific and technical announcements just in the last two weeks – factor of 10 reductions in fuel cell and hydrogen splitting catalyst costs; new materials lighter, stronger, and cheaper than carbon fiber; and new ways to collect sunlight and convert it to electrical, thermal, and chemical energy – will, when available commercially, combine with all the other technologies that continue to stream out of labs and corporations, to drive the prices of sustainable energy down, down, and farther down.

So what we’re seeing at this moment in history is a powerful combination – the will to change with the technical ability to make the change, and the understanding that the change is cost-effective and in many cases profitable.

And that’s why I’m optimistic.

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Leading VC talks about investing in energy efficiency

Public Domain. Credit information: Hinode JAXA/NASA
Public Domain. Credit information: Hinode JAXA/NASA

Every day I get emails about “clean tech financing this” and “clean tech financing that” – last year there was over $7 billion in investments in clean technologies in the U.S. In this interview in the San Jose Merc, Paul Holland of Foundation Capital describes some of his philosophy on clean tech investment, including a strong focus on technologies that will reduce energy demand:

“The first lesson is there’s nothing wrong with a capital-efficient investment, even in clean tech. The second lesson is, look what happens when you don’t pay attention to the first lesson.”

Foundation has just closed a new $750 million fund, $250 million of which will be focused on clean tech, primarily on the demand side, although they are making some investments in supply as well – solar and biofuels.

Holland is also building a new, extremely energy efficient home in Portola Valley, CA. One of his goals for the building is to make much of the design reusable for other new homes.

“Once you get over the custom elements, it can be reproduced if you want to go down that road.”

You can hear more about Holland’s green energy investing in this Weather Channel interview on Forecast Earth: “Green Venture Capital In Depth”.