Btu (15.8°C, Canada)
The Btu (15.8°C, Canada) is a variant of the British thermal unit defined as the energy to raise the temperature of one pound of water by one degree Fahrenheit at a starting temperature of 15.8°C. This definition is tailored to Canadian standards reflecting the country's historical reliance on both imperial and metric.
Btu (thermoc.)
The Btu (thermochemical) variant aligns with the thermochemical calorie and is defined as the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere and is equivalent to approximately 1,054.350 Joules.