[docbnj]

BTU is not a metric unit, but a clumsy engineer’s archaicism. Nor is a kilocalorie a true metric unit, but a metric-derived unit which has the additional disadvantage that there is nomenclatural confusing over the term.

The metric unit of energy is the Joule. To use the Joule in commerce would be a problem, because all the mechanisms for dispensing the fuel would have to sense the energy content, which surely is impractical. It is better simply to adjust the price according to the energy content of the fuel, just as we have different prices for Regular and High Test gasoline.

[familyop]

"BTU is not a metric unit, but a clumsy engineer’s archaicism."

It's still the thermal standard in English language metric nations.

"The metric unit of energy is the Joule."

Not for thermal. Like it or not, solar hydronic, drainback heating system installations will increase with or without anti-competition regulations pushed by one-world morons. They can't successfully see and regulate against everything. They can't even get close to doing so without going too far and falling down.

For all others reading this, the BTU is the unit used to measure energy used to heat or cool water (or energy supplied by water heating or cooling) in degrees, Fahrenheit.

Stuff the fuels vended to slaves by anti-American globetrotters. There are all kinds of fuels.

[Cvengr]

Sell the way they sell now. By the Therm.
Since the heat capacity of natural gas varies with the chemical composition, all sellers must comply as in master meter operators.