Workers install solar panels on the roofs of homes under construction south of Corona, California. The California Energy Commission in May 2018 adopted new energy building standards requiring solar panels for virtually all new homes built in the state starting in 2020. MediaNews Group/Inland Valley Daily Bulletin via Getty Images | Digital First Media | Getty Images

In 2013 De Young Properties built a single-family house in central California that defied nearly three generations worth of homes the family business had constructed. It was a net-zero energy building — it had the potential to produce as much energy as it would consume in a year. De Young didn't build another one for four years, but within that period the company refined its designs to be more energy-efficient and technology-focused and drove down costs. "Energy bills tend to be pretty high and onerous, and you usually have to sacrifice comfort for your energy bill or your energy bill for comfort, and we saw an opportunity to advance in this realm and become a leader," said Brandon De Young, executive vice president. In 2017 De Young Properties started the process of constructing three communities near Fresno, California, with more than 140 single-family homes in three different communities that will have the same level of energy efficiency. So far the homebuilder has constructed half of the first community, Envision at Loma Vista, and is in the process of beginning the other two. The cost of each home is typically between $350,000 and $450,000 — and carries an additional $10,000 over the cost of De Young's comparable non-zero energy properties. The homebuilder's early investment in zero-energy construction was prescient. If you buy a new house in California within the next few years, there's a good chance it will be built along similar lines. In December, California instituted a new requirement that calls for most new homes and multi-family residential buildings up to three stories high to include solar rooftop panels beginning in 2020. Depending on the specifics of the design and the residence's energy consumption pattern, solar panels could produce all the electricity needed for the home. The state's ultimate goal is to produce net-zero energy homes that reduce the state's carbon footprint and make buildings energy self-sufficient.

California is one of the world's largest economies

This is the first time a state has built this requirement into its code, but similar regulations exist in cities like Tucson, Arizona, as well as the City of South Miami, the first introduced in Florida. Renewable energy mandates like residential rooftop solar come at a time when California has faced an unprecedented series of wildfires, with at least some of the natural disasters linked to more extreme weather patterns in an era of climate change. The Net-Zero Energy Coalition estimates the U.S. has only 5,000 net-zero energy single-family homes and over 7,000 net-zero multi-family homes. That number could expand in 2020 to over 100,000 net-zero energy homes, based on the average annual new home constructions in California. "California by itself is one of the largest economies in the world," said Jacob Corvidae, a principal at the Rocky Mountain Institute. "What happens there has some impact, and it's going to be an impact that has an effect on the rest of the country because they're going to be figuring out ways to make solar cheaper and that scale will help bring down the cost."

A home within De Young Properties' Envision at Loma Vista community outside Fresno, California. De Young Properties

In 2017, the U.S. Department of Energy estimated about 39 percent of the total energy consumed in the country was in the residential and commercial sectors. A majority of the energy was produced by fossil fuels like coal, petroleum and natural gas. Net-zero energy and zero energy-ready homes — which can be zero energy if solar panels are installed or their capacities are increased — are built to be more energy efficient than a typical building. This includes adding extra insulation, high-quality windows, LED lighting, low-flow water fixtures, heat-reflecting roof tiles and energy-efficient appliances that, when combined, reduce the amount of energy the house consumes. On the outside, the houses are built to optimize energy efficiency with significant airtight construction and economical roofs, walls, windows and foundations, said Sam Rashkin, Chief Architect of the Building Technologies Office in the Department of Energy's Office of Energy Efficiency and Renewable Energy. These technologies also allow for better temperature regulation, low-humidity, less noise and minimize exposure to dangerous pollutants.

Cities with the most zero-energy buildings City Number of Units Sacramento, CA 853 Vancouver, BC 723 Davis, CA 664 Portland, OR 365 New York, NY 361 Austin, TX 346 Honolulu, HI 338 Clarkdale, AZ 323 Washington DC 317 National City, CA 268

There is no one-size-fits-all design for zero-energy homes. In De Young's housing market, the modern style — homes you might find on a Google search with flat walls and a box-like look — are not as prevalent, so the company configured the homes to come in an array of styles, such as cottage, modern-farmhouse, and Italian-inspired variations. "You don't have to do it that [modern] way. We found out that you can build a zero-energy home that looks just as beautiful as any other home," De Young said.

Costs of going zero energy

California commissioners anticipate the new mandate will add $40 more to a monthly mortgage payment, but with an $80 return on heating, cooling and lighting over a 30-year term. The upfront cost to a single-family house will be approximately $9,500 with savings of $19,000 over 30 years. Ann Edminster, a board member of the Net-Zero Energy Coalition and a green building consultant, argues that people shouldn't be thinking of the upfront costs in isolation. Home buyers can make decisions in a house's design that offset the additional costs for net zero-energy upgrades, such as sacrificing decorative housing elements. "It's the same thing as asking for a roof rack on your car. You're going to pay extra," Edminster said, referring to design choices homeowners already make which result in higher costs, and in some cases, less energy efficiency.

A net zero energy home under construction by De Young Properties. Adding solar panels to a roof will not alone get a house to net zero energy. Choices in the framing and window design are part of required energy-efficiency upgrades. De Young Properties

In De Young's case, making a home energy efficient usually costs an additional $10,000 before adding solar panels, which makes the home zero energy. Purchasing a solar system outright could add between six to 12 percent to the price, De Young said. The company has a partnership with Tesla which offers zero-down leases on its solar panels, among other financing options. In 2017, 41 percent of residential solar was owned by a third-party, which includes monthly leases and power purchase agreements, or PPAs, that allow customers to pay per kilowatt-hour of generation. Charles Kibert, a professor at the University of Florida's College of Design, Construction and Planning, said there are some drawbacks to relying on solar. The panels require ample roof space, a certain orientation that allows for optimum energy production and consistent weather conditions. "All those factors put together and my experience is that you have to try really hard to have a net zero home," Kibert said, adding that how people manage their home is a big factor. "Living behavior every day drives energy consumption pretty reliably."

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