"All houses" means "housing units," defined as single family houses, townhouses and condos, and individual apartment units.
The following statistics are approximate, as they are from several sources and apply to different years - but here's the big picture:
Based on the average for the last 10 years, about 1,100,000 new housing units are built in the US each year. (Trading Economics)
There are currently about 125,000,000 housing units in the US. (National Multifamily Housing Association, Statista.com)
So, to replace all our current housing units with new, net-zero units, would take about 113.6 years. We don't have that much time before the climate gets unlivable.
Ergo, besides building new housing that generates its own energy, we have to retrofit existing housing to generate all the energy it uses and provide power for plug-in electric cars.
And, we have to start now. Talk about doing this by 2050 indicates living in a dream world.
Man, that's a tall order !
But what's the option ? Give up ?
To convert all our housing and transportation to run on free solar energy will obviously require massive collective investment. That is, a funding program by our federal government.
We can do this.
We managed collectively (through the federal government) to work our way out of the Great Depression, win World War II, and go to the moon and back. We can definitely do this. The technology, the work force, and the money are all here now. And the time is short.
But first, we have to WAKE UP to the urgency of our situation.