It is true that one air exchange of the basement air per hour would cost about $5 per month for gas and about $12 per month in electric to heat the air; but the issue is: Where would the air come from to exchange? A central exhaust would assume an uncontrolled intake of zero (or below air in some months) from any crackeage in the walls or around doors and windows. The air movement would be percieved as a chilling draft. Fresh air intake into the return blower plenum of a furnace would control the air better; but not necessarily exchange basement air. If the unit is a hot water system, the air exchanger would be a better choice, because the air could be introduced and exhausted from the basement alone. You would not want moist basement air to travel upstairs to a central exhaust.