Midwest Eco-Design - Your home for eco-friendly construction, remodeling & housing choices including prefrabricated homes, cabins and other sustainable material choices.

When upgrading or choosing a new heating system, you want a system with a high annual fuel utilization efficiency (AFUE) rating. You can find this information in the product literature. If a salesperson tells you the rating, be sure to verify it by reading the label.

The AFUE is the measure of the amount of heat delivered from your furnace through your house. For example, a furnace with an efficiency rating of 70 percent means that the furnace converts 70 percent of the fuel you supply to heat. What happens to that other 30 percent? It’s lost. The higher the AFUE percentage, the better the efficiency. Good efficiency units today are 85-plus for furnaces and 90-plus for boilers.