Radiant flooring has been in use since the days of the Roman Empire when they channeled hot air under the floors of their villas. Basically, radiant systems heat an entire room evenly — not just in localized spots. It is more efficient than baseboard heating and usually more efficient than forced-air heating because no energy is lost through ducts. Radiant systems are also unobtrusive and quiet.But for homeowners who want to save energy, radiant floors are usually not worth the cost of installation. One exception is a hydronic (water) heating system used in conjunction with solar heating — this can be very efficient. More information can be found on the Energy Efficiency and Renewable Energy (EERE) site.