Mh, I do not see the whole course but... The sustainable real estate is one who can evolve because the best energetic performances of today will be very bad performances tomorrow and the "ideal design" for today will be a very bad one tomorrow. So essentially only small buildings are sustainable because they can be made in an "industrial-like" manner (meaning the same design can fit pretty any needs with just minor changes) and changing them is sufficiently cheap.
Beware that in the past a condo was cheaper than a home per apartment because there was only one roof, a bit less in equipment and so on. BUT that's in the past where there was not much about anti-seismic design, fire safety, HVAC and so on. Today a modern "green" condo cost more in raw materials than equivalent single family homes PLUS the condo can't evolve. A tower? Even FAR worse. Just the mere structure need more steel than homes, just the elevators alone cost more. Similarly modern rails cost MORE than people moving with personal cars. The narrative of course it's the opposite because finance capitalism need big things and profit from rent and services in such setups, but the narrative and the reality are really different.
Today the sustainable real estate economy is those of spread single-family homes mixed with small commercial buildings (sheds, essentially) to reduce significantly the amount of commuting residents needs just to buy some groceries, modern small buildings built locally with mass produced components produced around the territory in most cases in not so big setups simply because there are standards like home appliances sizes or Chinese battery tools connectors (the same battery works essentially any tool from any vendor) or cars (yes, most component of Chinese cars are the same even if cars came from various brands). Essentially today sustainable real estate is a FLOSS/open hardware one spread/personal and built around the world without megafactories for most of the component (we still need some big scale for steel, for some electronics, mining etc, but not much more). This real estate of course is VERY opposed by any means by large actors who know well this model is for individual ownership, SMEs not for them.