[Porsche-O-Phile]

Typically R60 or greater roof/rafters and R40 or greater walls, thermal imaging to attack infiltration points/cracks, deliberate elimination of thermal bridging in door and window frames, where possible in exterior wall assemblies, etc. The idea is to make the building so "tight" that supplemental heating is all but unnecessary and most heating can be provided via things like lights, computers, appliances, people, etc.

One potential downside is there has to be attention paid to ways of evacuating moisture to prevent mold and other humidity-related issues since these buildings are not able to "breathe" or exchange air as well with the outside. I've also heard some concerns about air quality but haven't seen anything conclusive one way or the other.

This is something I'm considering too but it all depends on my long-term plans to stay here - it would take between 7-10 years to pay back the cost of all the upgrades to bring my house up to this level (1940s era construction with relatively poor insulation as is now). Energy savings as I've projected would be considerable, but so would the cost of insulating...