We are making plans for our Pretty Good forever home in Northeast Pennsylvania (Zone 6), which will likely have to remain a weekend home in the near term.  I’ve dialed back my initial enthusiasm for passive solar heating, (see “Does Passive-Solar Design Actually Save Energy?” in FHB#262). But, if we’re away from the house, and power and backup systems get knocked out, I  very much like the idea that passive heating alone will be enough to  prevent frozen pipes.  

Has anyone investigated this sort of idea in the past?  Does it result in an overheated home otherwise?  Would it require impractical thermal masses?  I’m assuming a design minimum interior temperature of 40°F will give enough margin against ice formation.  There will be no pipes in the exterior walls (hose bibs will be drained for the winter).

Thanks,
-Matt