Finding out the efficiency of your furnace or air conditioner
The simplest way to find out the efficiency of your heating and cooling equipment is to go to the equipment itself and see if it is listed there.  If not, then look for a model or serial number on the furnace and/or one on your compressor outside.  Go to the manufacturer’s website for your particular piece of equipment and search that model or serial number.  If nothing comes up, contact the manufacturer with this data and ask for the efficiency ratings.
In terms of determining if you have a high-efficiency furnace, a quick visual indication of this will be plastic venting pipes that extend from your furnace to the side of your house and outside versus going up through a chimney that exits at your roof.