[Discussion] Is underclocking to reduce heat output a thing?

I read a lot of discussions here about overclocking GPUs/CPUs to increase performance in games, but never the opposite.

I live in a house with no air conditioning and my computer is in a small bedroom on the second floor. During the summer, it gets hot. Nevermind booting up my computer and playing games on it, some days it's so hot I stay off the second floor entirely. Ambient room temp ranges from the high 20s to low 30s (celsius), and it feels much hotter when I'm sitting next to my computer.

What I'm wondering is, is it viable to underclock my CPU and or GPU to lower my computer's overall heat output without affecting my ability to use my computer for everyday tasks or low intensity games? (mostly Hearthstone).

As it stands now, my CPU idles at 30 and my GPU at 40. When I watch youtube or twitch my GPU goes to around 50 degrees, when I play Hearthstone my GPU goes over 60 degrees and I can really feel the hot air blowing out of my computer. CS:GO and other intensive games, my GPU goes over 70 degrees and at that point I can't even.

Again, my only concern is the actual total heat being created by my components. I know 70 degrees at load for a GPU is totally fine in terms of performance/safety, but I'm just talking about the amount/temperature of hot air that is being blown out of my case and into my room.