Which fuel gives you the cheapest heat?
Every fuel is sold in a different unit. This turns each one into the same yardstick, cost per million BTUs of heat that actually reaches your rooms, so you can compare them fairly. Change any price or efficiency; untick fuels you don't care about.
Not sure how much heat you use? The book puts a typical single-family home in a cold climate at 50 to 70 MMBtu over a five-month winter.
Cost per million BTUs of delivered heat, cheapest first
Formula: (price per unit × units per MMBtu) ÷ efficiency. A heat pump's efficiency is its COP (2.5 means 250%).
How much does that space heater really cost?
Find the wattage on the heater's label (most are 1,500 watts on high) and your electric rate on your bill.
Formula: (watts ÷ 1,000) × rate per kWh = cost per hour
What will turning the thermostat down save?
The book's rule of thumb: every 1°F you turn down for an eight-hour stretch saves about 1% of your heating cost.
This is an estimate: real savings depend on your house, your weather and your equipment. Use only the heating part of your bill if you can (the supply charge), not fixed delivery fees.