thermodynamics - Connection between entropy and energy

An isolated system $A$ has entropy $S_a>0$.

Next, the isolation of $A$ is temporarily violated, and it has entropy reduced

$$S_b ~=~ S_a - S,\space\space\space S\leq S_a.$$

Is it true to say: the process of lowering entropy of a system requires work and energy?

I am not sure if energy of the system must be changed when entropy is reduced. However, energy certainly is required – changing entropy is work and uses energy?