On Fri, 03 Dec 2010 08:02:49 +0100, Sjouke Burry
wrote:
If you heat with electrcity, then yes, there is no net loss.

This and several other replies assume that "heat with electricity"
means electric resistance heating.

A heat pump (which is also electric) is more than 100% efficient, in
the sense that the thermal energy delivered to the interior is greater
than the electrical energy used to pump the heat. This applies to an
interior temperature of about 70F and exterior temperature down to
about 15F. With a greater temperature difference (exterior below 15F)
the heat pump efficiency drops below 100% and you are better off
switching to resistance -- as some heat pumps do automatically.

Edward