## 12.3 Energy Balance

Assuming that an animal’s body temperature is constant (steady state), energy input to the animals must equal energy out. We can write the animal’s energy balance as follows: $$$M + R_+ = R_- + C + H + E \tag{12.1}$$$ where $$M$$ is the metabolic rate, $$R_+$$ is the amount of radiation absorbed by the animal surface, $$R_-$$ is the thermal radiation emitted from the animal surface, $$C$$ is the heat conducted from the animal to any surface it is in contact with, $$H$$ is the heat loss from the animal to the environment via convection, and E is evaporative heat loss.