Temperature is a critical experimental variable and it is super easy to record. There are lots of temperature data loggers online. Or check out Pallidus.io for more complete solutions for monitoring in-cage environment and behavior!
In the study by Unger et al they noted that a ~5°C difference in housing temp can account for large (~30%) changes in metabolic rate and food intake. I agree with their first recommendation: "Monitor, record, and publish the housing temperatures exhibited throughout your experimental protocol."
We were inspired by a recent paper (www.sciencedirect.com/science/arti...) to perform a crowd sourced analysis of rodent in-cage housing temperature across 12 different colonies. We analyzed 220,000 temperature measurements and found a ~4°C range among the different colonies.
I'm aware of this one: pubmed.ncbi.nlm.nih.gov/31390574/