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Example Description (Help)

The following gives a description of the sample data that was used to create the help examples. It gives both a high-level description and the details. It assumes you understand the ideas and terminology of units, meters and groups.. For those interested, more details about conversions and units is available.


The units (and conversions) are described graphically in this figure:

Unit and conversion graphic

For now, ignore the arrows that describe the conversions. The different items are labeled as follows:

All units are of type quantity except these:

Why these units exist will be described on other help pages.


The conversions linking the units in the example are shown as arrows in the figure above. The actual value of the conversion is not shown. The different items are labeled as follows:

OED can do what it calls chained conversions. This means that any unit that can be reached via an arrow in the allowed direction can be used for graphing a meter unit. For example, the Recycling meter unit can be graphed in kg because there is a chain of conversions from Recycling to ton, ton to lb and lb to kg. Given this, OED can calculate the overall conversion from Recycling to kg. Note the unidirectional arrows stop undesirable conversions such as converting kg of CO2 to meter units such as Electric_Utility. You cannot use CO2 to create electricity.

The follow table gives the details on each interesting conversion. A conversion is defined by the source, destination, slope and intercept. The row with source of Electric_Utility, destination of US $, slope of 0.115 and intercept of 0 means that each kWh of electricity costs 0.115 U.S. dollars or 11.5 cents. Most conversions have an intercept of 0 but temperature is the exception in this example. The table also indicates if the conversion is bidirectional. The conversion from a meter to its unit of collection (blue, unidirectional arrows) are all slope of 1, intercept of 0 and bidirectional of No so are not listed. The values are meant to be reasonable for each quantity; clearly different locations and times will have different values.

Source Destination Slope Intercept Bidirectional? Note
Electric_Utility US $ 0.115 0 No
Electric_Utility kg of CO₂ 0.709 0 No
Electric_Solar US $ 0.7 0 No
Electric_Solar kg of CO₂ 0 0 No Assumes solar has no incremental CO2
Natural_Gas_BTU US $ 6.75 x 10-6 0 No
Natural_Gas_BTU kg of CO₂ 5.29 x 10-5 0 No
Natural_Gas_M3 US $ 0.25 0 No
Natural_Gas_M3 kg of CO₂ 1.94 0 No
Water_Gallon kg of CO₂ 0.0012 0 No
Water_Gallon US $ 0.011 0 No
Water_Liter kg of CO₂ 0.00031 0 No
Water_Liter US $ 0.00291 0 No
Recycling kg of CO₂ -2890 0 No This is CO2 saved from not going to trash and not the net created.
Recycling US $ 0 0 No Assumes recycling is free.
liter gallon 0.2641729 0 Yes
kg lb 2.2 0 Yes
ton lb 2000 0 Yes
kWh BTU 3412.142 0 Yes
BTU m3 gas 2.73 x 10-5 0 Yes
kg metric ton 0.001 0 Yes
Celsius Fahrenheit 1.8 32 Yes

The value for the example chained conversion above (Recycling to kg) is worked out as follows (all intercepts are 0):

  1. Recycling to ton has a conversion of slope = 1 which indicates that the quantity of recycling is provided in the unit of ton.
  2. ton to lb has a conversion of 2000 so the total conversion is 1 x 2000 = 2000.
  3. lb to kg has a conversion of 1 / 2.2 because the provided conversion is kg to lb so it must be inverted. This gives a final conversion of 2000 / 2.2 = 909.09. Thus, 1 ton of recycling is the same as 909.09 kg of recycling.

Note that units are incompatible if they are not connected by any direct or chained conversion. For example, if you have a meter collecting in Electric_Utility units then it can be graphed in these compatible units: kWh, BTU, m3 gas, kg of CO2, lb of CO2, metric ton of CO2, ton of CO2 and US $. All other units are incompatible so you cannot display that meter in liter, gallon, kW, Fahrenheit, Celsius, kg, lb nor ton.


The meters and groups in the example are showing in the following figure. For now we will ignore the groups.

Meter and group graphic

The meters are on the left-hand side of the image in the blue rectangles. The beginning of the meter name is the building it is associated with: Library, Dining Hall, Theater or Great Dorm. The exception is "Campus Recycling" which is a campus-wide meter and not associated with a building. It is also unique because this type of data would normally be manually entered into OED and not received from a automated meter. All meters collect for its entire building except the electric meters for "Great Dorm" which has separate meters for the first and second floor of the building.

The following table gives information about the meters. The headers for the columns indicate it contains this information:

Name Unit Default graphic unit Area Reading frequency Note
Dining Hall Electric Electric_Utility / kWh kWh 1,000 15 minutes
Dining Hall Gas Natural_Gas_BTU / BTU BTU 1,000 15 minutes
Dining Hall Water Water_Gallon / gallon gallon 1,000 1 hour
Dining Hall Electric Power Electric_kW / kW kW 1,000 5 minutes Note that all Power meters are kW (not kWh). The meter reads at a highest frequency.
Theater Electric Electric_Utility / kWh kWh 10,000 20 minutes
Theater Gas Natural_Gas_M3 / m3 gas BTU 10,000 20 minutes Note that the default graphic unit differs from the meter unit.
Theater Electric Power Electric_kW / kW kW 10,000 20 minutes
Theater Temperature Temperature_Celsius / kWh Fahrenheit 20 minutes Note that the default graphic unit differs from the meter unit.
Library Electric Electric_Utility / kWh kWh 100,000 23 minutes This is an unusual reading frequency but shows OED can handle it.
Library Temperature Temperature_Fahrenheit / Fahrenheit Fahrenheit 20 minutes
Great Dorm 1st Floor Electric Electric_Solar / kWh kWh 5,000 20 minutes Only the first floor of a two story building and half the area. Note it gets electricity from solar.
Great Dorm 2nd Floor Electric Electric_Solar / kWh kWh 5,000 20 minutes Only the second floor of a two story building and half the area. Note it gets electricity from solar.
Great Dorm Gas Natural_Gas_BTU / BTU BTU 10,000 20 minutes
Great Dorm Water Water_Liter / liter gallon 10,000 15 minutes Note that the default graphic unit differs from the meter unit. Also, water is read at a different frequency than other meters in this building.
Campus Recycling Recycling / ton lb 7 days Note that the default graphic unit differs from the meter unit. Also, the reading frequency is very low because it is entered manually but OED can deal with that.


The figure above has the groups shown in the yellow rectangles. A line from a meter to a group indicates that the meter is a member of the group. A line from a group to a group indicates the group on the left is a member of the group on the right. Each group shows all of its members with the same color line. For example, "Dinning Hall All" contains the meter "Dining Hall Water" and the group "Dining Hall Energy" where they are connected by a pink line.

As an example shown another way, the "Campus Gas" group can be visualized similarly to the map shown in OED as in the following figure that shows it includes "Dining Hall Gas", "Theater Gas" and "Great Dorm Gas" meters.

Campus Gas group graphic

As another example, the "Campus Electric" group can be visualized as in the following figure that shows it includes "Library Electric", "Dining Hall Electric" and "Theater Electric" meters along with the "Great Dorm Electric" group.

Campus Electric group graphic

The following table gives information about the groups where the headers indicate similar information as the meter equivalent.

Name Default graphic unit Area Note
Dining Hall Energy kWh 1,000
Dining Hall All ton of CO₂ 1,000
Theater Energy kWh 10,000
Theater All ton of CO₂ 10,000
Dining & Theater Electric Power kW
Library Energy kWh 10,0000
Great Dorm Electric kWh 10,000
Great Dorm Energy kWh 10,000
Great Dorm All ton of CO₂ 10,000
Campus Electric kWh 121,000
Campus Gas BTU 121,000
Campus Energy kWh 121,000
Campus All ton of CO₂ 121,000
Campus All - Another ton of CO₂ 121,000