HID Team Logo


The objective of this project was to design a metering scheme that would monitor the amount of energy used by the visitors staying at the Samoa hostel. The purpose of this was to show visitors the impact of their choices when they leave a device such as a cell phone charger plugged into an outlet. This is done by placing energy meters within every room of the Samoa hostel. However, most energy meters measure energy usage for a whole household. To meet this observation, we developed a design called the Watt-imus Prime which is able to measure electric flow from multiple circuits and display how much energy is used from one circuit or all of them simultaneously.

Background[edit | edit source]

The Samoa Hostel intends to educate visitors about topics related to ecology and conservation. Part of this is an effort to allow visitors to monitor how much energy they are using, including electricity consumed by appliances that are left plugged into an outlet. Studies have shown that self-monitoring of energy usage cuts consumption by a significant degree. Our solution's purpose is to find a meter to be placed into each of the twenty-four rooms of the Samoa hostel. Most energy monitors on the market only measure the energy usage for an entire building or household. Therefore, we kept a few constraints in mind as we thought of a metering scheme that met the client's wants:

Constraints[edit | edit source]

  • Each room in the Samoa hostel is to have one meter.
  • The location of the meter is at eye-level (around five feet).
  • The meter must have an easy to read LCD screen.
  • The meter is easy for anyone to operate.
  • The meter must be able to measure up to 220V.
  • The meters must not interfere with each other.

Problem Statement[edit | edit source]

The Metering scheme for the Samoa hostel must have an energy meter in every room that is easy to see, operate, and show people the amount of energy used when leaving a device left into an outlet. Yet most meters only measure energy usage for an entire building, or are restricted to outlets. To meet this problem, we developed a list of criteria in descending order of importance:

Criteria[edit | edit source]

  1. Safety The design must meet the National Electric Code.
  2. Education The design must show people the impact of their choices and encourage conservation.
  3. Durability The design must be able to withstand everyday use.
  4. Cost should be less than $250.00.
  5. Aesthetics The design should look professional.
Fig 1: AutoCad Sketch of a room in the Samoa Hostel. Basic setup of a room in the Samoa hostel with an energy meter mounted on the wall. A conversion chart is next to it so people can see where theur energy comes from and the amount of resources used to produce it. Picture courtesy of David Scully.

Final solution: The Watt-imus Prime[edit | edit source]

The metering scheme will use the EM-2500 meter as a means of measuring the Kilowatts of both the circuit for the light and outlet. For our final project, the Watt-imus Prime simulates a wall of one of the rooms in the hostel. According to National Electric Code, the the circuits for the light and outlet must be separate. The EM-2500 uses either a solid core or split core current transformer (CT's) that surround the insulated wire and detects the magnetic field around the wire. The meter comes with two CT's that plug into it on separate channels. The electric flow in each channel can be measured separately or all together as a means to show the total amount of energy being used. For the Samoa hostel, the EM-2500 will be wall-mounted to around 5 feet so visitors will be able to view it easily. It is also able to display the energy in different measurements for the visitors to understand the impact of the leaving the light on or plugged in device.

Video Demonstration of the Watt-imus Prime[edit | edit source]


Costs[edit | edit source]

Fig: 2 Design Hours Input

The following chart shows the amount of time used for the duration of the project. It is split into percentages and also displays the total time taken to complete.

Design cost in hours.
Design cost in hours.

Table 1: Cost List for Model

This is a list of materials we used for the project as well as the amount of money we spent compared retail cost.

Material Quantity Retail Cost Subtotal Our Cost Subtotal
EM-2500 1 $230.00 $230.00 $215.00 $215.00
Plexiglass a lot something something Donated $0.00
Wire Stripper 1 $4.94 $4.94 $4.94 $4.94
Roll of Electrical Tape 1 $0.71 $0.71 $0.71 $0.71
Black Wire 6' $1.02 $1.02 $1.02 $1.02
White Wire 6' $1.02 $1.02 $1.02 $1.02
Ground Wire 2' $0.17 $0.34 $0.34 $0.34
Wire Connectors 6 $0.10 $0.60 $0.60 $0.60
Junction Box 1 $2.24 $2.24 $2.24 $2.24
Outlet Box 1 $7.19 $7.19 $7.19 $7.19
Wall Plate 1 $1.79 $1.79 $1.79 $1.79
Ground Receptacle 2 $0.69 $1.38 $1.38 $1.38
Light Switch 1 $0.79 $0.79 $0.79 $0.79
Light Switch Plate 1 $0.42 $0.42 $0.42 $0.42
Light Bulb Holder 1 $1.79 $1.79 $1.79 $1.79
13 Watt Light Bulb 1 $0.71 $0.71 $0.71 $0.79
Extension Cord 1 $3.00 $3.00 $0.00 $0.00
Total Cost align="right"| 260.00

Testing Results[edit | edit source]

Upon construction of the Wattimus Prime, HID determined that a wooden block needed to be placed behind the receptacle box to provide it stability, and that a board needed to be placed behind the backplate to prevent the model from rocking backwards. The Watt-imus Prime was able to measure real power flow from each circuit separately and simultaneously. It was able to show that a 13 Watt light bulb used that many Watts. When a Macbook was plugged into of the the outlets, the kilowatts were.048 and increased to 0.074. The design was also able to to read the total power flow within the whole model.

Poster Conversions Chart[edit | edit source]

Electrical Usage from Common Appliances Per Day Energy Source in Amount Required Amount Required per Year Amount of CO2 per Year
Portable Space Heater run for six hour (6 hr x 1.5 Kilowatts = 9 Kwh) 9.719 pounds of coal 3549.946 pounds of coal 7383.888 pounds CO2
Home Computer run for twenty hours (20hr x.15 Kilowatts = 3 Kwh) 3.240 pounds of coal 1182.505 pounds of coal 2459.610 pounds of CO2
Dehumidifier run for four hours (4hr x.645 Kilowatts = 2.58 Kwh) 2.682 pounds of coal 978.898 pounds of coal 2036.108 pounds of CO2
Cell phone charger plugged but not in use for twenty-four hours (24hr x 0.084 Kilowatts = 2.016 Kwh) 2.096 pounds of coal 764.906 pounds of coal 1591.005 pounds of CO2
Television on for five hours (5hr x.3 Kilowatts = 1.5 Kwh) 1.559 pounds of coal 569.127 pounds of coal 1183.784 pounds of CO2
Toaster run for half an hour (.5hr x 1.35 Kilowatts = 0.675 Kwh) .702 pounds of coal 256.107 pounds of coal 532.703 pounds of CO2
Hair Dryer run for half an hour (.5hr x 1.2 Kilowatts= 0.6 Kwh) .624 pounds of coal 227.651 pounds of coal 473.514 pounds of CO2

References[edit | edit source]

FA info icon.svg Angle down icon.svg Page data
Authors Alan Ramirez, Rick Wilson
License CC-BY-SA-3.0
Language English (en)
Related 0 subpages, 9 pages link here
Aliases Samoa hostel Wattimus Prime
Impact 448 page views
Created December 1, 2010 by Rick Wilson
Modified July 1, 2024 by Irene Delgado
Cookies help us deliver our services. By using our services, you agree to our use of cookies.