The Future Looks Bright for Natural Gas in Earth Advantage Zero Energy Certified Homes

April 9, 2018 | By: Ryan Shanahan

Unlike some net zero home certification systems, natural gas has never been forbidden in Earth Advantage Zero Energy certified homes. In fact, we've certified a few homes that have natural gas cooking ranges, fireplaces, or both. That said, the amount of solar photovoltaic (PV) panels needed to make up for the gas use in a house with gas space heating, gas water heating, or both, has been unrealistically large when measuring energy on a site basis. Therefore, the vast majority of the 50+ homes Earth Advantage has certified since 2011 as Zero Energy or Zero Energy Ready have been all electric, or at least had electric space and water heating systems.

With a simple switch from a site definition of energy use to a source definition of energy use, all of that changes. But, before we get into the juicy details, let's first define the terms. Earth Advantage currently requires Zero Energy certified homes to be EA Platinum certified and to be able to produce at least 90% of the energy consumed on-site from an annual energy basis through on-site renewable power. An EA Zero Energy Ready home has the same certification criteria—except a bid from a solar contractor showing the potential of a future solar PV system on-site stands in the place of an actual installed solar PV array. “On-site" energy use is defined by the energy consumed by the home on an annual basis within the lot lines of that particular home.

Changing the definition of energy use from site to source allows the analysis to move upstream to the power plant and helps us address the associated carbon impact of burning fossil fuels to create energy. The inconvenient truth of electric energy consumption lies in the production of the energy. By coupling the inefficiencies of producing electricity and the line losses associated with transmission to the end user (our homes, businesses, and more) electric energy used on-site has a source energy factor nearly three times that of natural gas piped from the utility to the end user. That means that two-thirds more of the electric energy produced is wasted in the process of getting it to its final destination.
Applying this new source multiplier to site energy use and production changes nothing for the all-electric EA ZE candidate for certification. The real change is that homes that have gas space heating and water heating systems have a real apples-to-apples chance at EA ZE certification for the first time.

Does this change (from a site to source energy use definition) make certification to Earth Advantage's Zero Energy standard easier for gas homes? Definitely not. The 5 cost effective steps of designing and building a Zero Energy home still apply. This change simply levels the playing field for both fuel types to advance our residential construction industry towards a keen focus on smart design and the highest levels of energy efficiency.

For more details on this exciting change including fuel type multipliers, underlying math, and timelines regarding this change look out for my presentation with Gary Heikkinen, PE of NW Natural at the upcoming BuildRight Conference April 25 and 26, 2018, in Portland.