[swimorsinka]

Looks like you’re right. This https://insideenergy.org/2015/11/06/lost-in-transmission-how... claims it’s only 7%. I’ve updated the original comment. You still have the problem of non green generation sources, and you could still do better with a high efficiency gas furnace on-site, although I think most people go with low efficiency (~80 or 85%) units.

[Thorrez]

Even if electricity is generated with gas, and with the energy lost in the generation and transmission, with a really good heat pump and optimal conditions, it could outperform a gas furnace, because a heat pump can be more than 100% efficient.

https://en.wikipedia.org/wiki/Coefficient_of_performance

>The efficiency of air source heat pumps is measured by the coefficient of performance (COP). A COP of 4 means the heat pump produces 4 units of heat energy for every 1 unit of electricity it consumes. Within temperature ranges of −3 °C (27 °F) to 10 °C (50 °F), the COP for many machines is fairly stable.

>In mild weather with an outside temperature of 10 °C (50 °F), the COP of efficient air source heat pumps ranges from 4 to 6.

https://en.wikipedia.org/wiki/Air_source_heat_pump