From an article in Solar Today by Bob Ramlow, Amherst, a solar consultant for Focus on Energy:

For its comfort and economy, radiant heating is growing in popularity. Pairing a radiant heat-delivery system with solar energy as the heat source is an excellent choice for several reasons. Above all, these systems and operate efficiency and effectively at the relatively low temperatures common with solar energy systems. They‘re relatively easy to retrofit into an existing building and can be easily incorporated into new construction.