At 02:24 PM 6/9/2010, Dave Mcneely wrote:
>  It also uses a miniscule amount of fossil fuel compared to that
> used to generate the electricity that drives the air conditioner.

Are you sure of your numbers, Dave?  Modern window A/C units transfer
approximately ten BTU/hr for every watt they consume, and whole-house
units run closer to sixteen.  A nice number but it's apples divided
by oranges;  in consistent units it means that a 5,000 BTU/hr A/C
will consume about 1700 BTU/hr, while a 5,000 BTU/hr vented furnace
will consume about  7,500 BTU/hr at 80% efficiency.  Assuming 30%
power-plant efficiency with no co-generation to help things out, the
A/C will consume about 5700 BTU/hr in fuel, which is ~30% better than
the furnace.

Yours,
David