A Guide To Radiant Heating Options

Radiant heating is a way to heat a home where the surfaces and contents are heated instead of heating the air. Compared with forced-air heating systems, this system is typically more efficient, more comfortable, and can improve indoor environmental quality. Once considered an expensive luxury, radiant floor heating systems are now becoming an affordable, efficient, and comfortable way to stay warm throughout winter.

While central furnace heating systems continue to be the most popular option for home heating, more energy-efficient alternatives are becoming available. Heat pumps are a great option, especially for people in areas with mild winters, and you can read about heat pumps in our complete guide.

The image shows how much more effective radiant heating systems are in creating a thermally comfortable space compared to forced air systems. Forced air systems also create thermal asymmetry. Imagine you are facing the exterior wall, and the front of you is warmer than the back of you, as shown in the image with forced air. This is thermal asymmetry, and it creates thermal discomfort. Radiators, when set up in similar locations, can create thermal asymmetry as well. Still, the asymmetry is less, as contents are all warmed throughout the space. When radiant floor systems are installed, thermal discomfort is eliminated.

Distribution of the Radiant Energy

Radiant heat can be distributed throughout the house in several different ways.

Radiator Radiant Heating

Historically in North America, large wall radiators were typically placed under exterior windows. These may have been steam or hot water systems; they may have banged and rattled when they came on, overheated a room, and been a place to dry wet mittens. The banging of old radiators is due to the expansion of hot water from cold and going around 90-degree bends. These radiators still exist and are present in many older homes and multi-units throughout climates where heating is required.

Radiant Wall Heating Systems

Radiant walls, while less common in North America, are much more common in Europe. In North America, radiant wall heating is typically used in indoor spas to create overall warmth in the spaces. The greatest concern is someone hanging a picture on the wall and hammering through a pipe.

Radiant Floor Heating Systems

Radiant floor heating is the most common modern way to heat with radiant energy. This is the most enjoyable and comfortable form of heating because it makes your floors warm. Radiant floor heating might seem like a new concept, but it has been in use for thousands of years. One of the earliest examples of radiant floor heating systems comes from the ancient Romans, who created a network of tunnels underneath large public buildings. The heat from wood-burning fires would then circulate through this system of tunnels that sat below stone floors. Today, radiant heat systems supply heat directly to the floor or panels in the wall or ceiling.

Types of Radiant Floor Heating Systems

In general, there are two types of radiant floor heating systems: electric and water-based systems. Both of these heating systems provide ample heating to a room.

Hydronic Radiant Flooring Systems

With water-based systems, heated water runs through a series of pipes underneath the floorboards. Therefore, a water-based radiant floor heating system requires a connection to a water heater. These are more commonly chosen for new homes, as they are more challenging to install in renovations.

Electric Radiant Flooring Systems

Electric radiant systems heat wire that is also beneath the floor. Electric radiant floor heating setups depend on relatively thin heating cables similar in principle and design to an electric blanket. These electric systems typically operate by a separate 20-amp electrical circuit connected to a wall thermostat. (Smart thermostats can also be used to increase the energy efficiency of these systems.) Generally, these are more easily installed in home remodels.

Often, radiant floor heating systems take advantage of thermal mass in the floor to maximize the amount of heat transferred into a room. By burying either the piping (in the case of a water-based system) or the wiring (in the case of electric systems) between cement boards, ceramic tiles, or even poured adobe floors, the heat is stored in the thermal mass for slow, constant release into the surrounding room environment.

Advantages of Radiant Floor Heating Systems 

Several benefits come with opting for radiant floor heating systems that we will detail below.

1. Increased Energy Efficiency

First, and perhaps most importantly, radiant floor heating systems are generally much more energy-efficient than conventional heating systems. Traditional radiators usually require anywhere between 149 and 167 degrees Fahrenheit to heat a home. On the other hand, floor heating systems only need to run at a temperature of 84 degrees Fahrenheit to warm the room effectively. The lower temperature requirement, especially when combined with thermal mass in the floor, can allow for much lower energy bills. They also eliminate duct losses that are common with HVAC systems.

2. Even Heating

Central furnaces, boilers, and even baseboard heaters often create cold spots in homes. Old insulation or air leaks in the envelope of a home can exacerbate the problem. Because radiant floor heating systems provide warmth from the floor up, the evenly disperse heat throughout the house without any cold spots. 

3. Less Potential Damage to the Building Envelope

Radiant floor heating systems don't require a separate HVAC duct. So, these systems work well with passive homes and other sustainable construction styles that focus on a tight building envelope to maximize energy efficiency and thermal performance. 

4. More Comfort

One of the main perks of opting for a radiant floor heating system is that homeowners will get to enjoy the warmth beneath their feet. The thermal mass that comes with ceramic tile, stone, or concrete will store the heat and be warm to the touch. 

5. Drawbacks

The main drawback of these types of heating systems is the hefty upfront cost. According to one estimate, homeowners can expect to pay between $10 to $12 a square foot for a professionally installed radiant floor heating system in an existing home. While it might cost upwards of $15,000 to install radiant floor heating systems in an entire house, small remodeling projects can be much more cost-effective. For example, remodeling a 50 square foot bathroom that is routinely colder than the rest of the home in the winter might cost as little as $265.

Common Radiant Heating Installation Recommendations

As heat rises, placing radiant heat systems underneath the flooring instead of walls is by far the most common form of radiant heat utilized in residential homes.

• If installing radiant floor heating in a basement, insulation under the slab is recommended. This ensures that the heat is driven up into the living space and not taking the path of least resistance into the ground. Insulating the floor between levels is less important. Still, for efficiency, it is recommended to insulate below every floor as well.
• When installing a wood subfloor, install below the subfloor with reflective, clickable brackets and insulate under the brackets. The pipes can also be installed on top of the subfloor in proprietary channels that look like race car strips, thereby protecting the tubes.
• Optional: about two inches of gypcrete can be poured over the tubes to encapsulate them. This adds thermal mass without the weight of concrete and can dramatically improve the radiant heating system's performance. Why? The gypcrete (or concrete in a slab on grade) will hold the heat longer than lightweight building materials, reducing the need to put the heat on more often. This option is more ideally suited for new construction, as it can be a difficult renovation option.

The Most Energy Efficient Radiant Floor Heating Systems on the Market Today 

Several companies specialize in radiant floor heating systems, both water-based and electric systems. Below, we review three of the top companies on the market today.

STEP Warmfloor®

STEP Warmfloor® offers residential floor heating systems that can be installed under any non-conductive floor covering. The low voltage heating element is only 3/64" of an inch thick and is made from a homogeneous, semi-conductive polymer. This allows the elements to heat with maximum power in cold environments and use less electricity as they warm up. The Step Warmfloor® complies with NAHB standards and can help homeowners earn LEED credits for certification. The company claims that this system can help reduce your heating bill by anywhere between 30 to 60 percent.

Warmly Yours

Warmly Yours offers electric floor heating solutions that are surprisingly affordable, starting at $5 per square foot. They also provide specialized thermostats that operate specifically with the underfloor heating units to maximize energy efficiency. Use their operating cost calculator to get an idea of how much you could potentially save by switching all or a part of your home to radiant floor heating.

Thermosoft

Thermosoft offers a wide range of proprietary radiant floor heating systems. Unlike other competitors, their systems are compatible with various flooring types, including tile & stone, engineered and solid wood, laminate, vinyl, carpet and concrete slabs. Thermosoft offers end-to-end support from consultation to product selection and sizing.

Heat Sheet

Heat Sheet makes hydronic (water) radiant flooring systems with easy-to-install panels that cut down on labor cost and time. The company says the systems can be installed in "half the time" as the tubes are easily walked into place between nodules without the need for ties or clips.

Radiantec

Radiantec is another company specializing in water-based radiant floor heating systems. According to their website, "the best radiant systems will use high quality, high-efficiency water heater instead of a boiler. These systems cost about half as much as one using a typical boiler."

So if you need to replace your flooring, consider installing a heating system underneath. Your warm toes will thank you in the winter!

Article by:

Tobias Roberts

Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.