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Sep. 08, 2018
Blog Post
by FreeVolt

Is your home efficient?

In just a couple of years, if you live in California and you purchase a home that has been newly constructed, then you will know that your home is efficient. So efficient, in fact, that it will produce as much power as it uses over the course of a year. This is referred to as a “Zero Net Energy” home.

Starting January 1, 2020, all new single-family residential homes constructed in California are mandated to be Zero Net Energy or ZNE homes. This is the next progression of Title 24 of the California Code of Regulations, which was originally established in 1978 as a response to a legislative mandate to make California more energy efficient. These are essentially building standards for all residential and nonresidential construction in California. The standards have been updated several times since their inception, but the 2019 residential standards, which go into effect on January 1, 2020, are the most ambitious yet.

So how do you create a ZNE home? Since the goal is to produce as much energy as you use, then the first thing you need is a way to generate power. The most logical way to do that is to have a rooftop solar system, although it is theoretically possible to use a wind turbine or other renewable energy generation system. Most homes built in California after January 1, 2020, will either have an appropriately sized solar system already installed, or they will be designed so that the homeowner can install the solar of their choice. Producing energy is only part of it. Many, if not most ZNE homes will also have energy storage capabilities in the form of home batteries. Home batteries have come a long way in recent years, with the ability to handle more amperage and circuits than previous models, and there’s no reason to believe that they won’t improve even more in the near future. While ZNE homes will still technically be connected to the grid, they will produce and store most of the energy that they need.

For ZNE homes, it’s not just about power, it’s about efficiency. ZNE homes will have dual-paned, vinyl-framed windows – often filled with argon gas. These windows provide better insulation for the home and argon gas helps reduce the transfer of heat from outside the home on hot summer days. Regulations also call for water heaters that are tankless and heat on demand, or something of equivalent efficiency. The walls and attic will be more insulative, with blown cellulose insulation instead of the old-fashioned fiberglass kind. HVAC systems will be more efficient, and in ideal situations, they will be ductless. ZNE homes will use CFL or LED lighting instead of traditional incandescent lighting. These bulbs use 5 to 10 times less power and last up to 25 times longer. Other optional items that will improve efficiency may include radiant barrier and/or whole house fans in the attic, and energy management systems to help regulate and control thermostats and loads or to even shut them off when not in use.

California is already an expensive state to have to buy a home in, and some analysts fear that adding some or all of these features will increase the cost of homes to a point that will price many buyers out of homeownership. However, proponents argue that the utility savings will offset any increase in mortgage payment. Also, there may be incentives available to builders, as well as the federal tax credit that they will be able to take advantage of, which can bring the costs down. Many cities are starting incentive programs early so that builders and developers can get a head-start on the new regulations. Plus, the 30% federal tax credit for solar and batteries is going down in 2020, so builders and developers have an extra incentive to get started on their ZNE projects early.


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