What is a net zero energy home?

By: Matt Grocoff , Contributing Writer
In: Green Renovations

Matt Grocoff's net zero energy home

Net Zero Energy (NZE) homes are popping up across the country in every climate zone. With the cost of solar panels continuing to drop in price, net zero energy homes will soon be a common construction standard.

But what is an NZE home and why is it so important? The simplest definition is a home that receives all of its energy from on-site renewables. This means that the home has no electricity bill . . . ever. Here's what else you should know.

Watch out for NZE fakers

When things gain in popularity, everyone with a similar product to market rushes to grab onto the language of the popular product or idea. Think about "natural" or "farm fresh" eggs. Consumers started to demand eggs that come from chickens that were treated humanely and without harm to people or the environment. Soon, egg sellers were adopting the language that created images of healthy chickens on a farm with a red barn, even when the reality of the industrial farming conditions was far more grim.

With NZE, builders are beginning to engage with what might be called "Zero Washing." The industry uses it as a marketing tool without backing up the claims with actual performance.

The highest standard for calling a building Net Zero Energy comes from the Living Building Challenge. The Net Zero Energy Building Certification is the world's only program that verifies actual building performance. It's one thing to call a building Net Zero. It's another thing to prove it.

How a building or home is deemed NZE

While there is some debate about how to define NZE, the Living Building Challenge has the simplest and most sensible definition: "One hundred percent of the project's energy needs must be supplied by on-site renewable energy on a net annual basis, without the use of on-site combustion."

Achieving this goal is easy to understand. After one year of occupation in the building, you show that more energy was produced on the site than was used on the site.

The Department of Energy has a term called Zero Energy Ready (ZER). They define ZER as a building that can supply 90% or more of the annual energy demand (or could, if/when renewable energy is added or system capacity is increased); AND/OR energy use data are not available. I'm not a fan of this standard. It is at best an educated guess about how the home will perform. It is not a performance standard, it is too complicated, and it doesn't define the ideal about where we need to go.

We know NZE works in all climates. We know that it is a wise investment that costs less over the life of the mortgage than conventional homes. We know that it can be measured. We know that the cost of energy efficiency and renewable energy are cheaper than ever before and getting cheaper every day.

Net Zero Energy is no longer a challenge. It's a choice.

Learn about my family's Victorian-era Net Zero Energy Building Certified home.


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