I've looked at this thread with some interest.
Yogandy, you stand strongly accusing the "Hot Yoga" community of environmental wickedness. Even so far as to imply that they are 'earth-killers', 'flagrant energy wasters' and guilty of 'outrageously selfish conduct'. I remain open to a verdict in your favor, but I would like to see more information to support your case. More science, really.
So far, I suspect that you have accused them TOTALLY in the wrong.
There is no doubt that hot yoga means MORE heat, more energy consumption. But what are the proportions involved? Obviously the proportions are important. In fact, the proportions are everything.
How much energy per person per session (what is the session, usually one hour or one and a half hours?) is going on the 'hot yoga' part of the heating in a representative session, or indeed, even in the ones you complain about? That is, the part of the heating that goes beyond what it takes to heat it for regular (non-hot) Yoga.
It should not be hard at all to estimate this very well from people in the Hot Yoga business: basically from hot yoga studio heating bills, as they vary throughout the year; and subtract as a baseline how much it would have cost without the hot Yoga. Divide that by the number of hot-yoga-person-sessions; this is the cost of hot yoga heating for one person for one session. I don't have any such information myself.
Do you have any such information? Does anyone here? Dave007? I'd be interested in seeing your case proven, Yogandy. Until I see some good data, I see your prosecution, while vehement, as unproven; and I remain strongly inclined to suspect that you have accused the Hot Yoga community in the wrong.