Interesting statement.
You could go back to the Kelvin Scale. That way 0K is really a zero temperature.
As zero celcius is 273.15K, and it follows the same increments as celcius, so therefore 20 celcius is 293.15K.
Double that is 586.3K, which is equivalent to 313.15 Celcius.
I think the question is very ambiguous at best.
Do not think temperature is linear to the amount of energy stored. So it may be something wired like 25 Celcius... I'll have to dig out university notes on thermodynamics!
L8rs
J