Install a heat recovery ventilator to reduce the amount of work your furnace has to do. If your house is already well-insulated, consider replacing the furnace with a heat pump. A heat pump typically uses 3-4 times less energy than it produces and the system can be reversed so it functions as an air conditioner in the summer. If you plan to replace an appliance soon, consider getting an Energy Star-certified product. Energy Star appliances such as refrigerators, televisions, stoves, dishwashers, washer & dryers, air conditioners, and hot water heaters use 10-50% less energy than standard appliances.