The ideal range for germs is between 40 and 120 degrees. Anything warmer or colder than that generally kills germs. But it is best if you do it quickly as a gradual pace will allow these organisms to form cysts which will allow them to survive through extreme temperatures. I would not suggest this for your home environment though as this can lead to other bodily problems, and the germs will return as soon as you change the temperature back to normal.
Instead, what you want to do is make sure your environment is as clean as it can be. This doesn't mean excessively clean as much as an actual "clean room" environment, but a daily cleaning routine should take care of a large share of these germs. Another thing you can look into are Polarized Media Filters. What these do is they go on your furnace and they use your already existing heating system to attract particles from the air to the fibers. This makes for a very efficient air quality system that I have tested and researched.
The best place for price on these are at www.airlifeone.com. And you'll want to look for the Electrobreeze brand to get the best for price.
I hope that this answers your problem. As I said before, I would not suggest altering your environment temperature-wise so drastically just to kill excess germs. There are other more effective ways to have this accomplished that isn't as stressful.
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