He's implying that if the energy efficiency is a primary cost driver -- e.g. worth even discussing in the context of affordable housing -- then it would take a long time to break even fiscally. Assuming it's 50% is just a little bit of hyperbole.

This is a straw man to begin with because the building codes are not the issue… the permitting apparatus is.

However, your analysis is simplistic and assumes:

1. The house uses no natural gas (most do)

2. The cost of electricity never goes up (it will in the short term at least)

3. CO2 emissions from wasted energy have no cost (they do)

4. Building energy efficient buildings is way more expensive than the alternatives for new construction (it isn’t)

Just ordered new replacement windows from my house. Granted we picked out the most expensive line of windows for aesthetic reasons but the marginal increase for the CA mandated coating was ~5% of the overall cost of the windows. Do I expect to save the entire $22k cost of the windows on my energy bills any time soon? No I do not. Do I expect to save the ~$1500 that I spent on the coating? Sure I'll probably get ROI in 5-10 years with energy bills averaging ~$300/mo (no solar and it's 100 degrees outside today).

Weird to look up one number, then fabricate $100k out of nowhere to compare it too. Plus, you are looking only at the energy bill, not the cost of energy saved...

The top comment in this thread states that 1.7% of the upfront cost of the apartment, $17,000, is for energy efficiency improvements.

In fact, the codes that mandate energy efficiency improvements take a detailed cost analysis into account, and only mandate cost-saving energy efficiency improvements.