To answer the OP, one of the main goals for my system was to reduce the heat in my room. I live in SoCal where temps average 85-95 degrees in the summertime, sometimes more, and electricity rates are high. I like to avoid using the air conditioner if I can.
In 2015, I had an 80 watt OTL amplifier, Class A. It was the proverbial space heater. I had a listening outfit - tank top and shorts, no socks. Not really a good look for an aging, balding audiophile. But the sound was marvelous and worth it.
The amps that replaced it are 8 watt SET mono blocks, also Class A. They barely raise the temperature in my room. It is only 70 degrees today, which is also the temperature in my listening room. I am wearing a sweater, long pants, and socks. I feel dignified. I have had my SET mono blocks for 7 years now.
When I got my SET's, I noticed that my electricity bill went down by about $75 a month. 7 years at $75 a month is $6300. My SET amps cost less than that, so I like to think that the energy savings ended up paying for them. In addition, the sound is better than ever before. Hallelujah!