Well I don't know about your colleague, Ric, but my arthritis benefits from the heat - that and not sitting on my backside for too long.
If she wants to come and work in our office, she's welcome. We're in a listed building with a glass-brick roof and high windows. The council say it's too expensive and/or not allowed to either paint over the bricks or install blinds. We can only open two of the windows because we're next to a traffic island and the noise is horrendous. The temperature in the office on Wednesday was 90 degrees, 86 yesterday. So your colleague's welcome to swap.
Tell her to stop moaning and put a b****y cardigan on if she's cold. Why should you all suffer from heat stroke just for her benefit?