Google's Liquid Cooling

I dream of a future where there's an efficient energy recapture in the house. We waste a lot of heat in the shower, and washing clothes and dishes. We also run the fridge all winter when it's less than 5C outside, and the fridge then produces a lot of heat. And when we're done cooking, the oven is still really hot. Could the home heating system of the future use all this heat (and cold) more efficiently?

I don't see this happening until we have ordinary people living in orbit.

The heat in the oven will slowly leak out into the rest of the house, so the home heating system of the right now already uses that. The fridge example is much more relevant though. If you could get the hot-side radiator part of the fridge thermally-connected with the outside temperature, then it would run much more efficiently. However, you'd lose that heat from the house, so if you're having to heat the house as well it might not be worth it.

The cost of the plumbing would probably exceed the cost of the fridge.

Agreed.

But what if I don't want to heat up the home? Where I currently live I suffer from too good isolation where the kitchen heat builds up too much. I don't need the oven heat and would much rather it be piped out to the water heater.