Measurement Definitions

Cubic Foot (cf)

A measurement of gas volume. One cubic foot is equal to the amount of gas required to fill one cubic foot under standard temperature and pressure (60 degrees Fahrenheit and 14.7 pounds per square inch pressure)

CCF

100 Cubic Feet

MCF

1,000 Cubic Feet

British Thermal Unit (BTU)

A measurement of heat. One BTU is equal to the amount of heat required to raise on pound of water one degree Fahrenheit.

Therm (th)

A unit of heat equivalent to 100,000 BTUs

Dekatherm (Dth)

Equal to 10 therms, 1,000,000 BTUs, or 1 MMBTU

The heating value of gas (or its calorific value) is an important factor in its purchase and sale. This "heat content" of the fuel is the principle measure of its ability to perform a heating service.

Gas is usually sold on a "therm" basis, which necessitates an accurate handling of its calorific value. So basically, a therm is a quantity of gas with the heating value factored in. The Interstate Pipelines from which Middle Tennessee Natural Gas receives its gas determines this calorific value, or BTU factor, with the use of a water flow calorimeter, and passes the value on to us. This value is then used in buying and selling natural gas.

MTNG’s BTU factor ranges from 1.020 to 1.050. Its average value is 1.032. A higher BTU factor results in fewer cubic feet of natural gas required to produce a given amount of heat; a lower BTU factor results in more cubic feet of natural gas required to produce the same amount of heat.

We bill as follows:

• A MTNG meter reader reads each customer's meter monthly and records the reading in hundred cubic feet (ccf).
• We multiply the reading in hundred cubic feet by the monthly BTU factor given to us by the Pipeline to determine the amount of therms used.
• We then bill using the cost as given in the appropriate rate sheet.

Fuel Cost Comparison

The Fuel Cost Comparison can be viewed using Adobe(R) Acrobat(R) Reader. This software can be freely downloaded by clicking on the following icon: