Radiant Heating

Radiant heating warms a space by directly warming surfaces instead of the air. It usually employs water heated to near-boiling temperatures or electric elements installed beneath floors, in walls, or ceiling panels. Heat radiates from these surfaces and warms objects and people in the room. You experience it as if the sun were shining down on you, and it couldn't be more different from the way a forced-air system warms a room.

Radiant heating works by sending heat through infrared radiation from warm surfaces to cool surfaces. In hydronic systems, warm water travels through pipes in the floors or walls. As the water temperatures drop from their initial heat, the heat moves to the space around it. Electric radiant systems use heating cables or mats that generate heat when electricity passes through them. The heat moves directly from the warm surface to people and objects, similar to how sunlight warms you on a cool day.

More even and more efficient, radiant heating is several steps ahead of forced air, the most common alternative. “With forced air, the system has to work longer and harder to do its job,” says Barrett Kauffman, a mechanical engineer with Texas A&M University who has studied radiant heating. “You get a lot of temperature variability with forced-air systems—you not only have the problem of warm spots and cold spots, but you also have the kind of draftiness that you get with an open window on a cold day.”

There are two main types of radiant heating systems: hydronic and electric. Hydronic systems use water. They pump heated water through pipes that are installed beneath the floors or within the walls. These systems are often more cost-effective for large spaces. Electric systems, on the other hand, use wires and are more suitable for smaller spaces. You can also consider cost-effectiveness in terms of installation as well as use. Electric radiant heating systems are easier to install in your space, be it a small room or an addition to your home. That said, if you’re considering a larger room or space, a hydronic system may be more economical over time.

Radiant heating works effectively in many different climates, but its efficiency can vary with specific environmental conditions. In cold areas, consistent and comfortable warmth marks the peaceful indoor life that radiant heating can create. This makes it an excellent choice for the sorts of places (and people) that need maintaining indoor warmth. But even in warmer places, or milder parts of the same place, you can achieve energy-efficient and direct warmth. Even here, though, California, say, or southeastern Michigan, you need to consider the costs before going ahead with any installation. In-radiant warmth is a flexible heating solution, but the variables around its effective use make it a somewhat unnervingly stable or predictable choice. So, what are the characteristics of the places in which it works best?

Radiant heating can have a wide range of installation costs. They depend chiefly on the system type (there are a few), the size of the home, and what sort of infrastructure the home has to support different kinds of systems. A water-based system, called hydronic, is the way to go if you want to be as fancy as possible. And even though they might be working the hardest, they're the least likely to break down and the most energy-efficient. Nonetheless, you could expect to pay between $6 and $20 per square foot; that makes the total for a standard 2,000-square-foot home anywhere from $12,000 on the low end to $40,000 on the high end.

Many flooring materials can be used with radiant heating, making it suitable for a variety of home designs. The best flooring types are ceramic and porcelain tiles, as they conduct heat extremely well. Conductive Good and Conductive Better flooring types are good for radiant heating installations. These flooring types have the best compatibility with radiant heating. Conductive Better flooring types will have some compatibility, but not as much as the previous two groups. Conductive Good and Conductive Better flooring types will very likely not warp, bend, or otherwise distort to a noticeable or problematic degree.

When we talk about energy efficiency, we typically mean the ways in which we can conserve energy—like not leaving the lights on when we're not in a room, for example. But radiant heating is energy-efficient not just because it conserves energy, but also because it uses energy in a way that's effective and sensible. It's effective on a fundamental level because it uses the heat directly in the places where we most need to feel warm. So why is using radiant heat as a way to keep our indoor space warm an effective way to use energy? Well, there are several reasons.

Compared with old-fashioned heating systems, modern radiant heating systems require very little maintenance. Those who have a hydronic system in their home might take a few moments every month to check the system's water pressure, pipe connections, and the boiler to make sure everything is functioning properly. The rare electric version of a radiant heating system in the home may require even less time because it involves no water, and its periodic inspections might instead focus on the many electrical connections and the heating elements themselves.

Some high-level radiant heating systems can be made to provide both heat and coolness. These setups use basically the same piping as the heating systems, but the setup is capable of reversing the flow and sending in cooler water during the warmer months. Not all radiants are reversible, so engineering must consider these options when designing the system.