Off Topic question

Has anyone ever heard of using the radiator system to cool your house in the summer? Any ideas on efficiency and cost?

Cool radiant floors/walls are used in the Southwest part of the states but there wouldn't be enough surface area with rads to make much difference in a house. You can't generate enough Delta T to overcome the comparatively small surface area. Dealing with humidity would also be a problem in your neck of the woods. A cold rad would condense moisture out of the air just like the A coil in a forced air cooling system.