A small town with 100 homes will burn 10,000,000,000 BTU’s during a cold winter. All of this heat returns to the atmosphere. The colder the air, the more rapid the heat loss and more effect on the temperature.
Crossing the boundary from open space into a neighborhood on my bicycle, I typically see five degrees difference in temperature on a still night, due mainly to asphalt and heat escaping from houses.
Berkeley Earth makes no correction for this huge problem.