I think there’s a lot of opportunity for reducing wasted energy in many buildings. Even the term “waste heat” is indicative that energy is typically exhausted when it could be used for space or water heating. Obviously mechanical modifications would be needed, sometimes extensive, but it’s a good option for reducing energy use.
One huge use I can see, but isn’t being used as far as I’m aware, is data centers. They use a ton of energy, but when it turns to heat it’s only seen as a negative to expel. Why not capture it and use it to heat houses/water or something? It turns the massive energy use into effectively near zero, since heating is needed anyway in a lot of places.
Waste heat reclamation for water heating purposes seems like a no brainer. For small buildings as well as large ones, but no one talks about it.
