Appliances

Add up the number of hours you have decided to turn an appliance off. Then, multiply that by the appliance's energy usage in watts. This will give you the number of watts you are saving. Do this for all the appliances you plan to use less of, or not at all. Now add up the numbers. This will give you the total number of watts you are saving. Divide by 1000 to find out how many kilowatts you are saving. Multiply this by the price of a kilowatt and you will get the costs you are saving. Do it for the month and the year.

Heating

As for heating costs (air-conditioning is reflected in your electricity bill), you already asked your parents how much electricity they use. Now, it's time to calculate how much you can save by not heating your house as much, or by installing insulation. Call your local utility company -- they're listed in the phone book. Ask to speak with their energy conservation department. They can help you calculate how much your family could save by heating the house less or by installing insulation.

Gasoline

Finally, it's time to think about energy conservation on the road. If your family has a car (or cars), you have already learned about how much gasoline your family uses per year. Now find out how many gallons per mile your family vehicle gets. Learn all your family's vehicles' gas mileage; your parents should know these numbers. Now, think about finding a more fuel-efficient vehicle. This can be learned by calling or visiting local car dealerships. You can find out a vehicle's mileage by the sticker printed on the window, or ask a salesperson on the phone. Remember to choose a vehicle that your family can use. If you are a big family, you will probably need a bigger car.

Now divide the gas mileage your family's vehicle gets by how much gas mileage a more efficient model gets. This will give you a fraction. For example, if your family's vehicle gets 20 miles to the gallon and the more efficient vehicle gets 25 miles to the gallon, dividing the two will give you .8. Multiply the cost of your family's gasoline bill (for one vehicle) by .8, and that will give you the gasoline usage for the more efficient vehicle. Subtract that number from your family's current gasoline bill to get the savings, first in gallons and then in costs.

Adding up all of these savings -- appliances, heating, and gasoline -- will show you how much your family can save on energy and energy costs. You can then write it all down in a chart.