On Fri, 6 Nov 2009 04:11:44 -0800 (PST), ransley
wrote:

The same reason new refrigerators can be 75% more efficent than units
30 yrs old, they were designed with efficency, not profit, as a goal.

I think the new ones are profitable for the manufacturers, too.

I assume more expensive too - with energy prices up, the math just
says it's worth spending a few more bucks up front to save energy for
X years. Times change, optimal design decisions change.

And there is simply better tech, better insulating materials, better
thermostats, better electronic motor controls, more precise machining
of compressor parts, better engineering of airflow within, etc. Just
making some of the heat exchanger elements 5% larger can increase
efficiency, it doesn't have to be rocket science.

J.