One BTU is the amount of heat energy required to raise one pound of water by 1ºF . Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF.
https://plumbingperspective.com/key-water-heating-charts
Where C p is the heat capacity of water (1 BTU/lb/F) and m is the mass of the water (Assume 1 gal has 8.3 lb of water and the 3,412 BTU = 1 kWh) In a 10 year period, the energy required is 166,622,500 BTU which is equal to 48,834 kWh . In a 10 year period, the energy required is 136,327,500 BTU which is equal to 39,995 kWh .
https://www.e-education.psu.edu/egee102/node/2003
Calculate the area in square feet of the space to be cooled, and multiply by 31.25. Calculate the heat gain through the windows. Calculate the heat generated by occupants, allow 600 BTU per person.
https://www.wikihow.com/Calculate-BTU-Per-Square-Foot
You have all heard of the BTU of heat energy (British Thermal Unit), it takes one BTU to raise one pound of water one degree Fahrenheit. So if the water in the pan on the stove is put in at 32°F, it will then require 180 BTU’s to bring the water to boiling temperature, or 212°F.
https://solefoodkitchen.com/boiling/how-much-water-do-i-need-to-boil-5-gallons-of-beer.html
pdf for "btu required to heat water".(Page 1 of about 18 results)