I had an indoor job, but I have always been effected by the heat. Even before I was officially dx with MS, the heat messed with my mind and body in a horrible way.
So even though my job was indoors, if it was hot when I arrived at work, the walk into my job from the parking lot drained me physically and ruined my whole day. Unfortunately, I don't think my job would have bought it (even though I was telling the truth).
For the most part it seems that a majority of jobs really don't care about their workers (especially large corporations like I worked at). They only care if you are there and helping them make money. And if you aren't there to help them making money...well then they figure there is always someone just around the corner to replace you.