A google search for killing bed bugs with freezing results in suggestions that are all over the map. Even the University sites differ one from the other.
I treated a severely infested suite in the middle of a Winnipeg winter a few years ago and we removed all the baseboards, door frames, etc to allow thorough treatments. The baseboards showed severe staining and the landlord decided to put these items outside for the night to kill the bugs. I suggested that cold was not effective so he placed several hundred bugs that had been caught on a glue board (many were alive and moved when prodded) outside overnight as an experiment. I was very interested in this experiment as a recent study I read suggested all bed bugs died instantly at minus 26c. This was going to be a good test of the study.
The next morning the thermometer on my house showed minus 29c (the calibration is off a bit to the negative so the actual temperature was approximately minus 32c) and the bugs were brought back inside and thawed. When prodded some of the bugs still moved. The study was wrong. The landlord then gave up on the freezing idea and heat sterilized the baseboards along with other furniture.
This experience taught me to be very wary of using cold to kill bed bugs despite the assurances of “studies.” It might be true that extended cold kills all the bugs but we don’t know exactly how cold and how long. The only freezing method I accept is leaving the furniture outside for an entire Winnipeg winter. I did successfully (no bugs) accept a tenant into my apartment block who treated their their belongings (bed and couch had been discarded) in this manner.