Zero energy ready homes are coming

To be fair - technology is lacking for people living in the city to be able to go off grid in a meaningful way.

Disconnecting from the grid - that sounds like there's some kind of clause in the area that you live that essentially ties you to the utility. You must live in on the pacific coast or SW.

EDIT: To all the responses - I'm talking off grid as in all functionality. Sure you can add solar / solar thermal etc though in many places it isn't cost effective and doesn't make a lot of sense in a city where the alternative is that those costs are defrayed across a large base that provides reliability and service. I don't have much love for utilities but they do provide a valuable service.

To get really high R value on insulation, often that means a 2x6 or 2x8 framed outer wall to allow for the additional thickness needed by the insulation. Double pane windows are well-surpassed by those with many panes and carefully designed frames with low thermal bridging. Aside from more insulation you need great air sealing, across every joint and in every window and door frame. Older construction had no explicit ventilation, just a lot of leaking such that the house "breathed". On modern, efficient homes, the air seal is very tight for efficiency reasons, so you need an ERV/HRV system to exhange air for you to keep the air healthy, while minimizing energy loss for that airflow. Insulating materials used inside the roof and sheathing are typically closed cell foam or rockwool, or in Europe they sometimes use a wood fiber based insulation. There are lots of caulks and adhesive tapes for getting a good air seal, and there's also a technique where one pumps the house frame full of a vapor that reacts across pressure drops and plugs any holes it flows through.

Last, well insulated homes can get cheap heating and cooling from modestly sized heat pumps which are very efficient. One zero energy home I saw has heat exchangers on the roof to capture energy from the sun for warm water as well, supplemented by heat pumps powered by photovoltaics.

When you've confused "per kWh cost" with "energy to the house delivery costs," this sort of stuff sounds good on paper, but it doesn't fundamentally solve the problem that in the winter, homes use a lot more energy than they can generate, and in the spring/fall, they will generate a lot more energy than they need.

I've got a large ground mount solar install I put in a few years ago (15.9kW nameplate, though mostly east-west facing panels so a bit less annual production than you'd expect, just more "sunup to sundown" production), and it's been a chilly winter, so with an air source heat pump and keeping the house fairly cool, I'm still net +4MWh from the grid in the last 4 months.

Meanwhile, when it warms up a bit more, I'm generating 10x what the house uses during spring/fall mornings (10+ kW production on a sub-1kW house draw for long periods of the day). It's not a big deal with only a few people on the grid, but if every house were doing this, it would be a very big problem for grid stability.

I've also got experience with the off-grid lifestyle, as my office is 100% off-grid/standalone, and I don't pretend that system is cheap. Just neat. And even with 5kW of solar hung for a ~100 sq ft shed, I still need propane or a generator in the winter every now and then to keep things sane in here.

Competing element though is they probably have more land to put solar on, so if they don't find it to be aesthetically incompatible, they could probably push through those energy losses.