The main advantage of AAC /ALC panel when it was first developed in Sweden in the early 20th century was simple: it wasn't wood. It's still not wood, but in North America (unlike in Sweden at the time and in most of Europe now), wood is still plentiful and cheap.
Compared with conventional concrete, Eastland AAC/ALC panel still has advantages, though:
It uses less material--important for concrete, since portland cement is one of the most energy- and carbon-intensive building materials.
Despite the energy-intensive autoclaving process, manufacturers say it takes about 50% less energy to make, because of the lower portland cement content by volume (we're haven't found anyone to challenge those claims, but are still looking for data).
It's lighter, which cuts down on transportation costs and fuel use.
It's a better insulator, with a steady-state R-value just a hair above R-1 as opposed to something more like R-0.2 (neither of these factors in thermal mass, which we'll get to later).
Air leakage is minimal.
Eastland panel also has excellent soundproofing properties.
Eastland AAC/ALC panel can also be used as a firebreak.