A dekatherm (DTH) is a unit of energy used to measure natural gas.

The cost per DTH is determined by:

• Gas costs – the amount Dominion Energy pays for the gas it resells to its customers with no mark-up.
• Non-gas costs – the costs of operating and maintaining the company's distribution system.

These rates are approved by state public service commissions and change periodically through regulatory filings. Learn more about Rates & Tariffs.

Your bill is calculated using an average cost because we apply what is called a Weather Normalization Adjustment (WNA) to the approved cost per DTH.

When WNA is applied to a bill, it more accurately reflects the cost of providing service. You also can be confident you won't pay more than necessary.

Your rates are based on an expectation of “normal” weather, defined as the average daily temperatures over a 20-year period. The WNA works by slightly offsetting the effects of unusually colder- or warmer-than-normal weather by adjusting bills up or down during these conditions.

The adjustment for your bill is based on your weather zone, a climatological area used for gathering normal and actual weather data.

• Basic Service Fee – This fee covers the costs associated with the basic equipment used to deliver natural gas to your home or business (e.g., gas meter and pipe). This rate is approved by state public service commissions.
• State taxes and municipal energy taxes (where applicable).
• Voluntary program fees – If you support programs like GreenTherm or CarbonRight, or third-party programs like HomeServe, these charges will appear as additional line items on your bill.
• Energy Assistance – All customers contribute to local energy assistance programs that help qualified families and invidividuals pay their utility bills. Dominion Energy employees and shareholders also contribute to these programs.

The amount of gas you use in your home is measured by your natural gas meter in cubic feet. A volume multiplier is used to convert this figure to DTHs. This calculation accounts for altitude, gas pressure, and the chemical composition of the gas.

Residential gas meters are read once a month. To determine how much gas your home has used, we calculate the difference between two monthly readings.

Sometimes a meter cannot be read because it is inaccessible or may not be properly transmitting data. In these cases, we estimate the usage based on the time of year and previous usage history. When we receive a meter reading, we adjust the next bill to account for over or underestimations in usage.