The apparent brightness of a star is how much energy is coming from the star per square meter per second, as measured on Earth.
It’s burning wood ,heating water,Roasting food
That would be the R-value
Liquid water, which is necessary for life as we know it, continues to exist on the surface of Earth because the planet is at a distance, known as the habitable zone, far enough from the Sun that it does not lose its water to the runaway greenhouse effect.
For example bees they use wax to build shelter
