Heating our homes is usually our most expensive home operating expense. It only makes sense to get the most energy efficient heating system possible.
In the past we were far less concerned about energy. Fuel was inexpensive and we treated our energy supplies as if they were endless. Today we are fully aware that energy supplies are not endless or inexpensive. We must find ways to reduce fuel consumption by increasing heating system efficiency.
We can install more efficient boilers and furnaces. We can use energy set back or boiler reset controls. We can use air to air or geothermal heating and cooling systems. We can use radiant floor heating. All of these address the need for energy conservation.
When a furnace or boiler has low efficiently, the heat goes up the chimney instead of into your home. For instance, when the heating system is only 60% efficient, 40% of the heat produced is going up the chimney. This is why modern furnaces are much more complex than their inefficient predecessors. They capture most of the heat from the furnace before exhausting flue gases outside.
More info: Heating and Air Charlotte NC