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Therm Billing Frequently Asked Questions

1. Why is Columbia converting from volumetric billing to therm billing?

Columbia Gas of Maryland is improving the way customers are billed. Customers will now be billed for the quantity of energy consumed instead of the volume of natural gas consumed. This change will align the way our customers are billed for natural gas with the value of the product, or energy, and will make our bills consistent with the way natural gas is bought and sold in the wholesale market place.


A good analogy is the purchase of blueberries by the pint. While two different pint containers are the same size (volume), they don’t necessarily contain the same number of blueberries.  Columbia’s new method of billing in therms is like charging a price per blueberry, rather than a price per pint. Instead of charging two customers the same price for pints of blueberries that contain different amounts, customers will now be charged for precisely the number of blueberries that they purchased, as will every other customer.

2. Is this a rate increase?

This is only a change in the units we use to bill, not a rate increase.
It's important to remember that Columbia delivers natural gas without profiting from its sale. Under Maryland law, we pass the cost of the natural gas on to our customers, dollar-for-dollar, without mark-up.

4. What is the difference between a Ccf and a therm?

Ccf: A volumetric measure of natural gas. It represents the amount of gas contained in a space equal to one hundred cubic feet.
Therm: A measurement of energy, or heat, equal to 100,000 BTU (British thermal units). The same volume of gas may contain different amounts of energy.
BTU: The amount of heat it takes to raise the temperature of one pound of water by one degree Fahrenheit.

5. Will I get a new natural gas meter?

No. Meters will continue to measure customer’s natural gas consumption in Ccfs. Columbia will still need to read meters, either manually or through an automated meter reading (AMR) device. The conversion from Ccfs to therms will be reflected on customers' bills, not the meter. Your natural gas meter will continue to measure your usage in Ccfs.

6. Is there a benefit to convert to therms?

Absolutely. Therm billing maintains fair and equitable bills for all customers because bills will be based on the energy consumed. By approving this change, the Maryland Public Service Commission is aligning Columbia’s billing units with other natural gas utilities in Maryland who currently bill in therms.
The Energyguide and Energy Star labels appearing on household gas appliances are also based upon therms, so this change will make it easier for customers to assess the impact their appliances have on their bills.

7. How will you determine the amount of therms used per month?

To convert your usage to therms, we multiply the volume of gas (Ccf) consumed that month by the Btu value of the natural gas. Example: 100 Ccf/month x 1.05 Btu = 105 Therms.
Rates must also be converted to therms. To do that, we divide the rate by the Btu factor. For example, if the Btu conversion factor is 1.05, the conversion would be $1.00 / 1.05 = $0.9524.
After both conversions the resulting bill stays the same. 100 ccf x $1.00 = $100 and after the conversion to therms: 105 therms x $0.9524 = $100.

8. How do I know the BTU value you are assigning me is accurate?

The third-party interstate pipeline companies who supply Columbia determine the BTU value of the natural gas that Columbia purchases using BTU measurement tools such as a chromatograph or calorimeter, just as they have done for decades. The devices are calibrated on a monthly basis to ensure that they are accurately measuring the BTU content of the gas.

9. Is the BTU value constant?

The BTU value used for billing will be updated every month to ensure that bills will be based upon current gas content so customers will pay for the amount of energy consumed that month.

10. Does the BTU value change while being transported to my home? 

The heat content of natural gas does not change while being distributed to your home.

11. Will this conversion affect my bill?

Please keep in mind that there are multiple factors that influence increases or decreases in your bills, such as weather, quarterly gas costs, thermostat settings, insulation measures in your home or business or the condition of appliances and building. It’s also important to keep in mind that the BTU value in your area will be updated every month to ensure that bills will be based upon current gas content so customers will pay for the amount of energy consumed that month.

12. When will therm billing begin?

Effective January 30, 2013.

13. Is Columbia billed in therms for the natural gas it purchases?

When Columbia purchases gas in the wholesale market place, it is measured in decatherms, which is more easily converted to therms than Ccf or Mcf.

14. Will this conversion affect the cost of natural gas?

No. This is only a change in the units we use to bill, not a rate increase.