With the newest technology available, gas furnaces can operate at 98% efficiency. The Coleman Echelon 98% modulating/communicating furnace is the top rated with Energy Star in 2014. Gas packaged units have a 80% efficiency rating with a high efficiency rating. Options for Packaged units vary with 2 stage gas to a Hybrid having heat pump as 1st stage and gas as 2nd. At Capitol City Heating & Air we strive to install the best equipment made in USA.