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.
- 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.
- 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).
- 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.
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.