What used to be a 134 page document has grown to over 2000 pages. There is even a fifth Official Title 24 document for designers (the T24 website didn’t have it ready for release yet).
besides the unwieldy size, there is another major change in the Title 24 code-Starting January 2020 all new residential buildings have to be net zero energy (ZNE for short). What is ZNE? in the most general sense-it means that over the course of a year, the building’s gas and electric bills have to total zero. Note that photovoltaic installations can sometimes produce more than the amount of electricity that the building requires, in which case the utility company buys it back and hence the utility bills have a year to average out.
When one gets picky about what Zero Net Energy means-there are five standards that I know of for ZNE.
The very strictest ZNE standard is a year by year title earned by that year’s energy bills.
The least strict ZNE standard is that on paper-at the time of design-the building has a pretty good chance of being net zero energy.
There is some code training available for the new things added to the T24 code. these are free and are offered by the utility companies.