> CHP is also, IMO, cheating since the retrofits to take advantage of the waste heat aren't simple or non-invasive - i.e. theoretically CHP could power hot wate

> CHP is also, IMO, cheating since the retrofits to take advantage of the waste heat aren't simple or non-invasive - i.e. theoretically CHP could power hot water and air conditioning for me via heat pumps, but in practice doing any of that residentially is prohibitively expensive. CHP is widely used in Scandinavia at least, not to mention almost all new houses here are built with water borne in-floor heating as it is much more efficient (lower circulation temperature due to more surface area for heat dissipation).