Plain-language answers to the home-energy questions people actually search. Each guide links to a calculator that shows its work.
A ceiling fan costs about 1 to 3 dollars a month to run, drawing 10 to 75 watts depending on blade span and speed, at the U.S. average electricity rate.
A typical 50-pint dehumidifier costs about 8 to 14 cents per hour to run at the U.S. average electricity rate, which adds up to roughly $25 to $45 per month for standard summer use.
A window AC uses about 450 to 1,500 watts depending on BTU size, which works out to roughly 8 to 26 cents per hour. Here is the wattage by common unit size, the formula, and what it costs to run.
A 12,000 BTU mini split draws about 1,000 to 1,200 watts and costs roughly 17 to 20 cents per hour at the U.S. average electricity rate, around 40 to 50 dollars a month in steady summer use.
In almost every house the attic comes first. It is the cheapest, most accessible place to add R-value. Here is why, and when walls matter.
Adding attic insulation is usually worth it if your attic is under about R-30, with payback in a few years. Here is how R-value and payback actually work.
A fridge, a gas furnace blower, and some lights usually run on a 3,500 to 5,000 watt generator once you account for startup surge. Here is the math.
Most homes need a 5,000 to 7,500 watt generator for essentials, or 10,000 watts and up to run nearly everything. Here is how to land on your number.
A typical 3 ton central AC pulls about 3,000 to 3,500 watts and costs roughly 50 to 60 cents per hour, around 90 to 180 dollars a month in peak summer.
A 1,500 watt space heater costs about 25 cents per hour at the U.S. average electricity rate, roughly 2 dollars a day and 60 dollars a month for typical use.
Yes, you can tell if your furnace is oversized. Watch for short run cycles, frequent on and off, hot and cold swings, uneven rooms, and higher bills.
A typical home refrigerator draws about 100 to 250 running watts and 700 to 1,200 watts at startup. Here is what that costs to run and how to find your own number.
For one room, figure about 20 BTU per square foot of cooling, so a 400 sq ft room lands near a 9,000 BTU head. Here is the table and the adjustments.
A quick rule of thumb is about 20 BTU per square foot, so a 1,500 sq ft home needs roughly 2.5 tons. Here is how to size it right and avoid going too big.
A 1,500 sq ft home usually needs a furnace in the 45,000 to 90,000 BTU range, depending on climate and insulation. Here is how to land on your number.
A typical 2-car garage of about 400 to 600 sq ft usually needs 30,000 to 60,000 BTU, depending on climate and insulation. Here is how to land on your number.
A 2,000 sq ft home usually needs a furnace in the 60,000 to 120,000 BTU range, set mostly by climate and insulation. Here is how to find your number.