Since you don't seem to be getting a single clear answer to your question, Phil, I have a modest proposal ...
I am sure as an old time Viking fan, especially one from Idaho, you feel your team sold out to a certain degree (pun intended) when they moved their games indoors. Part of the Viking lore was having those warm weather sissy teams come up from Los Angeles, Dallas, or Miami and having them play in below zero weather. (I never did understand why it was unfair for those teams to have to play in below zero weather while it was perfectly fair for the Vikings or the Packers to have to go down to Tampa and play in 90 degree weather with 90 percent humidity in December.)
Well tomorrow your Vikings have a big game coming up with a spot in the playoffs at stake. Why not relive the past a bit while conducting an experiment?
You can turn your thermostat down to fifty degrees and then sit and watch the game on TV while sitting in your underwear. This would be a win-win situation. You could pretend that you are watching the game in the old Metropolitan stadium while you find out the answer to your question. (Is the house safe at that temperature.) In fact, if the Vikings do win (and I'll be rooting for them too), you would then have a win-win-win situation - memories of the good ol' days, an answer to your question, and a Viking place in the playoffs. It might even be so much fun, you could try setting the thermostat at 45 for the first playoff game.