Directions and Analysis

Task 1: Home Energy Use

In this activity, you are going to perform an experiment to track the amount of power you and your family use, then look at some basic patterns in that usage. (NOTE: If you live in an apartment or home in which you do not have access to the electrical meter, consult with your instructor about alternative arrangements, like teaming with a classmate to gather this data.)

This experiment is going to span the course of a full week and require 12 meter readings. It really involves two separate experiments:

tracking daily energy use for a week to compare any usage variations from day to day

comparing a single high-usage time period of a few hours with a single low-usage time period of a few hours to help you identify the extremes in your household electrical use

You can easily do both experiments during the same time period. This approach would be the easiest and fastest way to proceed. Read the instructions for both part 1 and part 2 if you wish to do both experiments at the same time.

To begin, youll need to find your electric meter, which could be inside or outside of your home. Many electric meters these days are digital and pretty easy to read, but if you have an older dial-type meter, go to this electric meter reading guide to learn about how to read and understand it.

For each of the two experiments below, you will first record three simple pieces of data in a table: 1) day and date, 2) time, and 3) the kWh reading from the meter.

Then record the results of three simple calculations:

kWh used: Calculate kWh used since the last reading (subtraction).

Hours elapsed: Calculate the number of hours since the last reading (subtraction rounded to a whole number).

Average kW used: (kWh used)/(hours elapsed). If this number turns out to be 0.36, for example, it means that your average household power usage for the time period was about 360 watts, the equivalent of running six 60-watt bulbs for that whole time period.

Daily Electrical Usage: Data Collection

Pick a convenient time of day to take readings from your electric meter. Youll need readings roughly a day apart, but if they differ by only an hour or two, that should be fine. Pick a consistent time youll remember, though, such as after getting home for the day. You need to start by doing an initial meter reading, then follow up with a reading every day for the next 7 days. Youll do 8 readings in all.

Record your readings in the tables below. In addition to the data fields described above, there is a lot of room for usage notes. Record anything that might have substantially affected the electrical usage since your previous reading. This might include the amount of time people were around and awake at home, use of specific devices such as an air conditioner, clothes dryer, TV, or lighting.

Type your response here:

Initial Reading
day & date
time
kWh reading

Day 1 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Day 2 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Day 3 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Day 4 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Day 5 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Day 6 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Day 7 Data	Usage notes (since last reading)
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Usage Extremes: Data Collection

For this experiment, youll measure electrical usage during a time period when you expect to have very light electrical usage (for instance, while youre asleep at night or during the day when no one is at home). Likewise youll measure electrical usage during a time period when you expect to have heavier than average electrical usage. This time period might be in the evening, when lights and other appliances are on. Both of these time periods should be at least 4 hours long, to increase the accuracy of your results.

Record your results in the tables below for each situation. For each time period, youll need to take an initial and a final reading.

Type your response here:

Low Usage - Initial Reading
day & date
time
kWh reading

Low Usage - Final Reading	Energy Usage Notes
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

High Usage - Initial Reading
day & date
time
kWh reading

High Usage - Final Reading	Energy Usage Notes
day & date
time
kWh reading
kWh used
hours elapsed
avg. kW used

Lets start the analysis by looking at your extreme usage cases. Compare the two cases in detaillow usage period versus high usage period. Discuss differences between the two as well as any surprises. Things you should cover in your discussion: How much difference was there in average power usage (avg. kW) between the low-usage and high-usage time periods? What might have been running during the low-usage period that used energy? Identify likely stealth energy users that you could not turn off during the low-usage period. What do you suppose contributed most to the usage during the high-usage period?

Type your response here:

Having looked at your extreme usage cases, analyze your day-to-day usage. Discuss in detail. Specifically, compare higher usage days to lower usage days. Were there significant variations? Do your conclusions regarding the extreme cases help to explain any daily variations? What were the surprises or new insights you had in reviewing this day-to-day usage record?

Type your response here:

It is possible to save a great deal of electrical energy (and money and natural resources) with some simple changes. Youre probably familiar with what some of those changes are and are now more attuned to your own electrical usage. The trouble is, most of these changes either mean changing behavior or spending money. Search the Web for a few ways to save electrical energy. Record them below and categorize them, if possible, as change behavior or spend money. You might want to consider adding a neither category. There are a few things that dont really require much change or money at all. (Be sure to record your Web sources in the Resources section near the end of this document.)

Type your response here:

Based on what youve learned from your household energy investigation, which of these methods seems reasonable to do in your own home this year? (Do you plan to do it?) Provide your rationale.

Type your response here:

Task 2: What Is Wasted Electrical Energy?

Discuss the production, transmission, and usage of electricity in the context of conservation of energy. When electricity is used or we say that energy is wasted, what is actually happening?

Type your response here:

Task 3: Electrical Safety Devices

Perform an Internet search to learn about grounding wires, fuses, and circuit breakers. Specifically,

describe how each device works; and

relate its function to what youve learned in this unit about electric current, voltage and resistance.

Type your response here:

__________________________________________________________________________

Evaluation

This project will be evaluated on a rubric that is based on the completeness, clarity, and thinking you exhibit in the Directions and Analysis section above. Points possible: 10

Task 1: Home Energy Use: 8 points maximum

Task 2: What Is Wasted Electrical Energy?: 1 point maximum

Task 3: Electrical Safety Devices: 1 point maximum

Home Energy Use 8 points	What Is Wasted Electrical Energy? 1 point
daily data of meter readings and observations (2 points)	explanation from a physics perspective of where wasted electrical energy goes
data of high- and low-usage periods (2 points)
extreme usage analysis (part c, 1 point)
daily usage analysis (part d, 1 point)
behavior vs. money (part e, 1 point)	Electrical Safety Devices 1 point
action plan (part f, 1 point)	definition of each device and description of how its related to current, voltage, or resistance