Estimate Computing Energy with a Stated Model
Multiply watts by hours and divide by 1000 to express modeled energy in kilowatt-hours.
About 22 minutes, plus any extended practice
Supplied materials
- Paper and pencil; answers may also be spoken or typed.
- All cases, labels, numbers and rules are supplied on this page. No real account, private information or purchase is needed.
Learn the idea
Energy use can be modeled as power multiplied by time. Watts times hours gives watt-hours; dividing by 1000 gives kilowatt-hours. The supplied power is constant and measured in watts. This model does not include cooling,network equipment or an entire lifecycle, so its boundary must be stated.
Multiply watts by hours and divide by 1000 to express modeled energy in kilowatt-hours. Do not call a device-only estimate the whole service’s lifecycle footprint.
Use this supplied case: Constant device power 50 W for 4 hours. Modeled device-only energy in kWh? The task is to connect the given information to the computing idea. Write a short evidence trail so another learner can reproduce your choice. The simplified case describes the stated model, not every real system.
- Represent the supplied worked case with a labeled drawing, table or short trace.
- Multiply watts by hours and divide by 1000 to express modeled energy in kilowatt-hours.
- Explain why the worked answer fits and why one alternative does not.
- Try the new check and practice cases; revisit the stated rule if your evidence does not match.
See the method in action
Constant device power 50 W for 4 hours. Modeled device-only energy in kWh? The supported answer is 0.2 kWh. Applying the stated rule gives 0.2 kWh. Multiply watts by hours and divide by 1000 to express modeled energy in kilowatt-hours. Do not call a device-only estimate the whole service’s lifecycle footprint. Energy use can be modeled as power multiplied by time. Calculation: ((50*4)/1000) = 0.2.
Check your reasoning
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Helpful tips
- Multiply watts by hours and divide by 1000 to express modeled energy in kilowatt-hours.
- Do not call a device-only estimate the whole service’s lifecycle footprint.
See the answer and explanation
0.3 kWh
Using the supplied inputs: ((60*5)/1000) = 0.3. Multiply watts by hours and divide by 1000 to express modeled energy in kilowatt-hours. Do not call a device-only estimate the whole service’s lifecycle footprint.
Take it further
New device 80 W for 5 hours gives 400 Wh=0.4 kWh. A wider service estimate would need additional included components and measurements.
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More practice: try new cases
Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.
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Check the subject sources
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