When buying insulation for those tired Brooklyn and NY brownstones one of the big considerations is the embodied energy the insulation has.
The May/June issue of Home Energy Magazine has a great article where they discuss the various types of insulation.
In the article they lay out their findings on the embodied energy of the main types of insulations:
Cellulose – 600 Embodied Energy/ft2 at R-20 in BTU
Fiberglass – 4,500
Spray Foam – 14,000
Rigid Board (EPS) – 14,300
Cellulose blows the others out of the water in terms of low embodied energy. Spray foam and foam board are off the charts on the other end. Fiberglass sits in the middle somewhere.
Something to keep in mind when choosing insulation: to not only choose the most healthy but to also choose the one that has least impact on the planet. According to this article cellulose is clearly the winner.