The Difference Between Radiant Barrier & Solar Water Heaters

Radiant Heat

• The sun causes houses and other structures, such as sheds, to heat up. With radiant heat, the sun's heat is absorbed by something such as a roof or a solar collector. In the case of your roof, that heat then moves through air to heat up your house, which is not desirable. In the case of solar collectors, used in solar water heaters, the heat is then transferred to the water tank where it heats water -- a desirable result.

Radiant Barrier

• In warm weather, radiant barrier insulation stops heat from getting in, resulting in lower cooling bills. In cold weather, radiant barrier reflects heat back in, resulting in lower heating bills, though the U.S. Department of Energy notes that the primary use is for summer blocking. Typical uses include attaching radiant barrier to a house's rafters, blanketing the floor of an attic or installing the barrier in walls during construction. Radiant barrier is rated on its reflectivity and by its emissivity or emittance, the amount of radiant heat it "leaks." To be true barrier, the material must have a reflectivity of at least 90 percent and emissivity no greater than 0.1 percent.

Solar Water Heaters

• Solar water heaters use radiant heat to warm up water. According to the DOE, two main systems are employed: passive and active. Passive heaters simply use the heat without any controls, while active systems have controls and a circulating pump. A solar collector, which can be a flat absorbent plate, parallel tubes, or tanks, absorbs heat and then transfers it to the tank. In dual-tank systems, sunlight heats up water in an external tank, then transfers it to a regular water heater that can also be heated by other means, such as gas. In single-tank systems, both the backup heater and the solar heater work on one tank.

Considerations

• Radiant barrier comes in sheets and rolls, and is built into roofing materials and chips. It is a very simple product. Solar water heaters are somewhat complex systems with several components, including plumbing, possibly controls, and at least one tank. Unless you are very experienced and know your way around local codes, the DOE recommends having a professional install the solar heater. However, depending on the complexity of the job, you can install radiant barrier yourself.