The formula to calculate the energy recovery effectiveness (E) is:
\[ E = \left( \frac{ER}{M} \right) \times 100 \]
Where:
Let's say the energy recovered (ER) is 500 units and the maximum possible energy recovery (M) is 1000 units. Using the formula:
\[ E = \left( \frac{500}{1000} \right) \times 100 \]
We get:
\[ E = 50\% \]
So, the energy recovery effectiveness is 50%.