As long as your perennials are still dormant, they should be fine if you move them. The trick, however, will be to dig the plants when the ground is frozen. Construction is not likely to start while the ground is still frozen. Check with your builder about the construction schedule, and plan to stay a step ahead of it with your shovel and flower pots! Because the project probably will take several months to complete, you may need to keep the perennials potted for most of the growing season. Use lightweight potting mix in the containers rather than garden soil. Place the containers in a protected, partially shaded location until you're ready to plant the perennials in their permanent location. Keep them well-watered, and fertilize occasionally through the season. I have successfully moved hundreds of perennials from landscape to landscape following this method.