The older generation of plasma displays generate significantly more heat than the same size LCD screen. Towards the end Panasonic was able to to reduce the power dissipation so it was close to LCD.

The design of the plasma screen requires more energy. But the trade off is the picture quality is superior to a LCD display.

"But the trade off is the picture quality is superior to a LCD display."

Yep, but unfortunately most people were too stupid to realize it, so plasma has gone the way of the dodo. The better OLEDs are probably as good looking, but here's a huge difference: the phosphors in plasma were inherited from the latter part of the CRT era are are truly known to stay stable for years, even in use. They non-organic, metallic chemicals. OTOH, the first organic dyes used in OLEDs could barely last hundreds of hours! Especially the blue ones. Now, they claim to have improved them, so you don't think you're throwing money away on a $6000 TV, but in my opinion, how can they really test something like that to be sure? It will be interesting if OLEDs can really still look good after 5-8 years of constant use as is the case of plasma. I know someone with a huge plasma that was over $10K in the mid 2000s, but they still use it and it still looks great. It was the last of the Fujitsus.

I have a 42" plasma set, about 15 years old and it puts out a noticeable amount of heat. I also have a 52" LED set, about 7 years old, and it also puts out a noticeable amount of heat. I would replace them both if I were using them 10 hours a day (mine are on about 10 hours a week). Not only are the newer ones more efficient, they have many more features (in my case, neither one is a "smart TV").