How difficult could it be to retrofit an 80 year old two-family for state-of-the-art energy efficiency? Really. Stuff a little insulation here, a little caulk there, replace a few light bulbs and yell at the kids to take shorter showers……and you are done.
These are all great ideas, and by all means caulk away, but they won’t get an 80 year old house (or any house already built) ready for 2050 when our carbon budget will be 80% less than it is today. You need to do more, more than can be accomplished with caulk, more than can accomplished by insulating the 3-1/2″ deep cavities of your 80 year old walls, more than can be accomplished by screaming at your kids through the bathroom door. Trust us.