By Ari Vanrenen
California has set ambitious energy goals for all new homes to be built to a zero net energy (ZNE) standard by 2020. These homes are designed from the start to be super energy efficient and offset the energy they do consume through onsite renewable energy generation such as rooftop solar.
Not only do ZNE homes support California’s goals for combating climate change, they help families save money every month on their energy bill — adding up to long-term savings that can make a big difference in homeowners’ lives.
And now, we know that ZNE homes can also be more affordable to build than traditional homes.
Habitat for Humanity of San Joaquin County and PG&E worked together to build a ZNE single-family home in a Stockton neighborhood. All in all, the ZNE design and construction practices used actually reduced the cost of building the home by nearly $3,000 — factoring in both materials and labor.
“This project shows that ZNE is highly affordable,” said Peter Turnbull, ZNE Program Manager at PG&E. “In fact, this modestly-sized home was built at slightly lower cost than similar new homes nearby, contrary to the mainstream belief that ZNE costs more. We’ve worked with larger homes with more generous budgets that have likewise achieved ZNE at little or no extra cost: it’s all about design innovation and attention to detail as shown here by Habitat for Humanity of San Joaquin County.”
Beginning in 2015, Habitat for Humanity of San Joaquin County partnered with PG&E to participate in the company’s ZNE Production Builder Demonstration program. Through the program, PG&E provides design consultation before, during and after the construction of the home.
Once homeowners move in, PG&E monitors the house for 12 months to evaluate the home’s energy performance as well as identify opportunities for future enhancements to design, construction or occupant considerations for ZNE homes.
While the project involved investment in new or different aspects of labor, materials and equipment, these changes were more than offset by cost savings over tradition design and building practices. For example, building this ZNE home required more time and attention spent on air sealing and insulating the building shell compared to traditional building practices.
However, this was offset by savings achieved by reducing the amount of lumber, ductwork, and other materials as well as the size of the heating, venting and air conditioning system for the home.
The real key to the success of this project was establishing the goal of building to the ZNE standard during the initial process of designing the house. Additional lessons learned during this project include:
- Attention to detail in design, construction and commissioning is instrumental to achieving ZNE goals in a new home.
- Training in energy-efficient design and construction is imperative to meeting goals, as well.
- Targeted education for building professionals helps them achieve ZNE on their own without relying on unfamiliar technologies or consulting support.
Moving forward, Habitat for Humanity of San Joaquin County will build all future homes in their service area using all of the energy practices and goals implemented at this home in Stockton — a win for California’s goals and the families that benefit from living in ZNE homes.
Email Currents at Curents@pge.com.