Estimate Your Cost Savings from Solar Cooking

The Solar Cooking Archive

Estimate Your Cost Savings from Solar Cooking The following survey (formula) was devised as a means of estimating energy dollar savings during the summer months from using a solar cooker. To complete this survey we need to make some basic assumptions with regards to cooking times (all times are based on averages as observed in Arizona). For the purpose of this survey a full meal is a main course (meat, fish, or poultry) plus rice, steamed vegetable or other side dish. We will assume that an average cooking time of two hours for the oven and one hour for the range is necessary to cook a full meal. A main dish (meat, fish, or poultry) would thus be a partial meal and require only two hours cooking time for the oven. A side dish (something cooked on the range) would equal one hour cooking time. Cookies or a snack would require half-an-hour of oven time. With these definitions, fill out the section below based on your experience with your cooker during the months of June, July and August. (Or, if you don't have a solar cooker, fill out the section below based to see how much money you could save by solar cooking in the summer time.) How many full meals did you cook? ________ How many partial meals did you cook? ________ How many side dishes did you cook? ______ How many snacks did you cook? ______ The formula we will use for determining your energy savings is based on how much energy you saved by not using your kitchen oven/range (cooking hours avoided). The amount of time you spent solar cooking does not figure into this equation. Using the numbers previously assigned for cooking times for the four various types of meals, multiply the number of meals by the hours of oven or range time assigned that category. Make sure to keep the oven times separate from the range hours. __ (number of full meals cooked) x 2 oven hours = ___ hours oven not used __ (number of full meals cooked) x 1 range hour = ___ hours range not used __ (number of partial meals . . . ) x 2 oven hours = ___ hours oven not used __ (number of side dishes . . . . ) x 1 range hour = ___ hours range not used __ (number of snacks . . . . . . . ) x .5 oven hour = ___ hours oven not used Because the elements in an electric oven/range heat up and then go on and off as electricity is needed to maintain certain temperatures, energy is not being consumed during the entire cooking time. Here again we have to make another assumption, and figure that the element is drawing electricity only half the time (other formulas that have been published do not include this step, and therefore the results are twice as high). Add all the hours the oven was not used together and divide this number in half. Do the same calculation for the range. ___ total # hours oven not used (full, partial and snacks) divided by 2 = _____ ___ total # hours range not used (full, side dishes) divided by 2 = _____ Take the number of hours the heating element for oven and range were not used and plug them into the following equation: {# of oven cooking hours avoided x 3.2 kW + # of range cooking hours avoided x 1.2 kW} = _____kWh This equation has allowed you to determine the number of kilowatt hours you have saved. To calculate how much money this is equal to you must now take this number and multiply it by the amount the utility company charges its customers per kilowatt hour. In Arizona the average rate is .10/kWh. Thus, the next step would be to take the number of kilowatt hours saved multiplied by the cost. _____kWh x $0.10/kWh = $ _____ If you have air conditioning, you've earned an additional savings. It is estimated that for every dollar you spending on cooking (oven/range), an additional $.50 is required to cool and dehumidify an air conditioned home. Solar cookers not only use no electricity or natural gas, but they don't heat-up the house. The following formula will determine the total dollars saved (cooking and cooling). Enter the amount you saved by solar cooking in the first blank and multiply by 1.5. The number 1.5 represents $.50 in cooling cost for every dollar spent on cooking. The answer is the mount of money you saved this summer by solar cooking. $ _____ x 1.5 = $ ______ This is the amount you saved by solar cooking this past summer. However, this formula does not apply to solar cooking in the winter time, because the heat from the oven and range could actually lower your heating bill. E-mail us your estimated savings figure at jima@ep.state.az.us .