What is Net Zero Energy?

As we reach out to more and more people in the Huntsville area and share our goal of reaching 100% Net Zero Energy by 2025, the first question we often hear is: ” What is Net Zero Energy, anyway?”

Net Zero Energy is a concept defined by the use of energy conservation, energy efficiency, and on-site renewable generation to account for 100% of a targeted building’s or community’s energy usage. This concept can also be applied to neighborhoods, states, and the United States as a whole.

Net Zero Energy

[net zeer-oh en-er-jee] | noun
The state that exists when the amount of energy provided by on-site renewable-energy sources is equal or equivalent to the amount of energy used.

It helps to conceptualize net zero energy in the context of a building like your home or office. If your home or office is working at net zero energy, that would mean that it is producing as much or more energy as it is using.

A net zero building means that the total amount of energy used by the building on an annual basis is equal to or less than the amount of renewable energy (energy created by sources that are naturally replenished, such as wind, rain, or solar) created on-site. A net zero building is typically connected to the grid and can sell excess power, as well as buy additional power during times of high energy demand. However, over the course of an entire year, this building will be net zero because it cleanly produces as much energy as it consumes.

If a net zero energy building is one that consumes only as much renewable energy as it produces on-site, a net zero energy community, or state, is one that cleanly produces all the energy it consumes on-site, or locally. 

Once we understand how net zero energy works at the level of a single building, we can expand the concept to our entire community, and to the state of Alabama. Therefore, if a community, or state, is net zero, the community as a whole creates more energy through renewable sources than it uses. If the community creates more energy than it uses, it can sell the excess to nearby communities, which generates income for its own community.

Buildings that produce a surplus of energy over the year may be called “energy-plus buildings,” and buildings that consume slightly more energy than they produce are called “near-zero energy buildings” or “ultra-low energy houses.”

What is equivalence?

Equivalence is an additional concept that must be considered when thinking about net zero energy. Consider a building that’s extremely energy-efficient. Solar panels cover all of its available roof space—and yet it’s still not at net zero. How could it get there?

This is where equivalence comes in. Equivalence is typically obtained through the purchase of Renewable Energy Credits, or RECs. Equivalence allows net zero energy to be applicable to all communities—even those unable to produce all the net energy needed within their geographic boundaries.

There are a limited number of RECs available. However, communities that reach or surpass net zero energy can sell RECs to communities that are unable to do so. This allows communities that can surpass net zero to make a little extra income, while communities that cannot reach net zero through the use of local renewable energies can achieve it by other means.