When you look at the dial on your gas meter or the meter reading on your gas bill, you are looking at the total volume of gas your household has used in cubic metres.  

Each movement on the meter dial represents one cubic metre of gas used. 

Gas composition and pressure vary depending on your location in the gas network. These differences mean households may use different volumes of gas to receive the same amount of energy. 

ATCO, the WA gas network distributor, converts the volume of gas used to the amount of energy consumed, using a heating value and pressure correction factor. This provides gas retailers, including Kleenheat, with the total number of energy units consumed by a household.  

Calculating your natural gas usage – step by step: 

1. ATCO reads your gas meter every three months.
2. ATCO calculates the volume of gas used by subtracting your previous meter reading from your current meter reading. 
3. The meter reading is converted from cubic metres to megajoules by applying a heating value and pressure factor. The latter is based on the average temperature, pressure, and elevation of the gas meter at your address. 
4. The megajoules are converted into energy units by dividing the megajoules by 3.6.  
5. Your meter reading and total energy units are shown on your gas bill.

The calculation: 

(Current Reading – Last Reading) x Heating Value x Pressure Correction Factor ÷ 3.6 = Total Energy Units 

Example calculation: 

Current Meter Reading	Previous Meter Reading	Volume of gas used (cubic metres)	Heating Value*	Pressure Correction Factor*	Gas Usage in Megajoules (rounded)	Unit conversion ÷	Energy Units^
4121	4093	28	37.91	1.0291	1092	3.6	303

*The pressure correction factor and heating value are unique to your property. In this example, the heating value is 37.91 and the pressure correction factor is 1.0291.

^referred to as ‘units’ on your Kleenheat bill. 

Please call our Customer Service Team on 13 21 80 for information about the pressure correction factor and heating value at your property.