Roger Pielke Jr. offers a nice example of the Jevons Paradox, and what it means for energy policy in the closing paragraph:
(…) Jevons Paradox is very real. It tells us that increasing efficiency is necessary if we are to met energy needs, because those energy needs will continue to grow even in the face of rapid growth in efficiency. Thus, the practical consequences of the paradox are that we need to become more efficient and we need more energy, all at once. How efficient we can become will of course influence the amount of energy that we need, so improving efficiency is a worthy goal. But no one should imagine that efficiency gains alone can eliminate the need for more energy — they can’t and they won’t. Policy needs to be able to focus on advancing efficiencies and creating ever greater sources of energy.