how to convert one cubic mter of Natural Gas into 1 Gigajoule?

how to convert one cubic mter of Natural Gas into 1 Gigajoule?

I used a conversion factor of 0.04003726 GJ per cubic meter of natural gas to create the home energy calculator on Green3DHome.org.

There are lots of energy calculators on the Internet that will convert to BTUs, so I used BTUs as the common unit to get this factor.