Radiant floor cooling helps keep rooms comfortable on hot days by keeping the floor cool. Radiant cooling generally saves energy compared to air conditioning, as no blowers or fans are used. While radiant cooling is a good idea in theory, when installed in a floor in a humid region, some form of dehumidification is also necessary to prevent condensation on the floor.
How It Works
Radiant floor cooling works much like hydronic radiant floor heating in that water-filled tubing beneath the floor controls the floor's temperature. The tubing is either embedded within a concrete slab floor or is laid into grooved panels installed on top of a concrete slab or a wood subfloor.
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Water that is cooled to anywhere from 55 to 68 degrees Fahrenheit, depending on the cooling system, flows through the tubing to lower the temperature of the floor. The panels help distribute the cool temperature evenly throughout the floor, much like the way a radiator-style heater gets hot and heats the surrounding area.
PEX tubing, a type of high-density polyethylene, is used in place of copper for radiant heating and cooling systems. PEX is more flexible than copper, making it easier to flex into the pre-made grooves in the panels or tiles that house the tubing for a radiant heating or cooling setup.
Long coils of PEX make it easy to span a large area underneath the floor with the same piece of tubing, eliminating the need for some of the connectors that would be required with straight pieces of pipe or tubing, according to PEX supplier SharkBite. PEX is available in different colors like blue and red, making it easy to tell during a repair project whether the tubes carry warm or cool water.
Your chosen flooring material installs atop the cooling system so the tubing is completely concealed. Once up and running, the radiant cooling system does not introduce cold air to the room; it removes heat via the PEX tubing beneath the floor. The water in the tubes absorbs some of the room's heat and then travels through a pump system and a chiller or heat pump that cools the water. The cooled water is pumped back through the PEX, cooling the floor. This type of cooling is quiet because there are no blowers or fans connected to this system within the cooled room.
Dealing With Dew Point
Condensation is one of the greatest potential drawbacks to a radiant cooling system installed in a floor. Since radiant floor cooling systems do not remove moisture from the air, a humid day could result in condensation collecting on the floor. This happens whenever the dew point of the air in the room is lower than the surface temperature of the floor or the panels housing the radiant system.
The dew point is the temperature to which air must be cooled until it can no longer hold water vapor, according to the National Weather Service. Cooling below this point results in condensation similar to the dew found outside on grass on some mornings.
Even opening a door can introduce humidity into a home on a hot, humid day, increasing the potential for condensation on the floor of a home that has radiant floor cooling. To address this, cooling systems often include a dew point sensor that checks for condensation on the water tubing and raises the water temperature as needed to prevent condensation on the floor, according to Arctic Heat Pumps.
Since a radiant floor cooling system does not remove moisture from the room's air like a conventional air conditioner does, a dehumidification system such as a whole-house dehumidifier can be used to keep the home's humidity at a comfortable level. A dehumidifier costs less than an air conditioner of similar size since its only job is to remove moisture, not cool the air. A large dehumidifier — or at least one appropriately sized for the rooms with radiant cooling — offers an alternative to a whole-home dehumidifier.
Not So Common for Homes
While radiant floor cooling uses much of the same technology as radiant floor heating, it's not as common in homes as it is in commercial structures, especially in the United States. It may even be difficult to find residential heating, ventilation and air-conditioning contractors and plumbers willing to install a radiant floor cooling system in a home. For new construction, you may be able to find a contractor to install radiant heating and cooling in the floor at the same time, especially if the installation includes a suitable heat pump.
Radiant cooling panels are also a little more common in walls and ceilings than they are in floors, especially in commercial structures. Since cool air sinks and warm air rises via air convection, a cooling panel on the ceiling helps indirectly cool the air in the room. When used solely on the floor, radiant cooling could make the floor and area near the floor feel cool, while the air closer to the ceiling feels warmer. Ceiling fans or other fans in the room may help the room feel cooler overall as the hotter and cooler air blend together.
Radiant Floor Cooling vs. Air Conditioning
While both radiant floor cooling and air conditioning make a room feel colder, the methods used to do so are entirely different. Radiant cooling occurs when the chilled tubes of water beneath the floor also cool their surrounding panels and therefore the floor itself. Air conditioning is designed to cool air, not surfaces.
Radiant cooling does a better job of keeping an entire room comfortable over time since the cooling system spans the entire floor, while an air conditioner's cool air emits from specific vent locations in the room. On the other hand, an air conditioner does a quicker job of making a hot, humid space feel comfortable, as the humidity and temperature difference is almost immediately noticeable once the air conditioner kicks on.
Radiant cooling requires installation of special materials before the floor is installed, while air conditioning ductwork and vents can be installed during home construction or afterward. Contractors will have to find places between walls and between levels of floors to install ductwork if construction is already complete. For both radiant and forced-air systems, larger cooling units such as the chiller or air conditioner condenser/compressor also require a bit of space either within or outside the house.
Radiant cooling does not affect the air quality within the home at all, while a forced-air system blows air through each vent, potentially introducing or recirculating allergens such as pet dander or kicking up allergens already present. Air filters are a must for forced-air systems to help keep indoor air as clean and healthy as possible.
Radiant Cooling Benefits
Radiant floor cooling is an excellent choice for those with asthma or allergies, as this type of cooling doesn't have vents, fans or blowers that may recirculate allergens around the house. Radiant cooling is also incredibly quiet; there's no noise from whole-home or window-unit air conditioners turning on or off, making it a good choice for light sleepers easily startled by sounds. It could also be a good choice for pets that prefer cool temperatures, as sleeping on the floor will provide plenty of cooling comfort for the dog or cat that's easily overheated during the summer.
A home with radiant cooling could save significantly on energy costs compared to one with air conditioning, although the savings will vary based on the temperature and humidity level during the hot season. In dry climates such as the southwestern United States, the savings will be greater than Florida, for instance, where summer humidity would require the addition of a dehumidifier or air conditioner.
Radiant Floor Cooling Drawbacks
Although radiant flooring uses less energy than an air conditioner, it could cost more for the initial installation depending on the installation method and type of flooring as well as the cost of the chiller or heat pump.
Radiant floor cooling may not be effective through thick carpeting, as the carpet acts as a layer of insulation. A hard floor such as tile, wood or laminate is a better option. As far as effectiveness is concerned, radiant cooling installed in a ceiling is a better choice than in a floor when it comes to making the air temperature feel cooler, as the hottest air, which rests near the ceiling, will be cooled by the ceiling panels. That cooled air will drop down toward the floor.
Although an unlikely situation, if any part of the radiant tubing system fails, replacing it could be a major undertaking, as the floor must be ripped up to access it in the typical installation. If the tubing is embedded in concrete, the project could become even more invasive and expensive.
Radiant Floor Cooling Installation Basics
Pre-made panels or tiles designed for radiant floor heating and cooling make the installation process a lot easier, but they're not the only method. In some cases, especially with new construction, the contractor may install the radiant cooling lines before pouring concrete over them to create a slab.
In other cases, the lines may be installed atop an existing slab, with additional concrete poured over the tubing. In still other instances, the tubing might be stapled to the bottom of a wood subfloor. The method the contractor chooses depends on an assessment of the project area. Whichever method is most efficient and effective given the space is the method the company will most likely choose.
With pre-made panels, everything snaps together in a layout designed by a contractor experienced with radiant floor systems. The tubes connect to the chosen cooling system, such as a geothermal heat pump as well as a thermostat and dew-point sensors as applicable. In most cases, design and installation of a radiant cooling system for a room or an entire home is best left to a professional. Even on the professional level, contractors experienced with residential radiant cooling systems may be hard to find.
If you already have radiant floor heating in the home, adding the cooling option may still involve a bit of work, as it will most likely require separate cooling tubes and potentially an entire new chiller or cooling system. In some cases, however, your existing heat pump that heats the floors can be set to cool them during warm weather. Talk to the original installer to determine whether this is possible and whether new tubing is necessary for the cooling setup. It really depends on the type of radiant heat and heat pump already in place.
Initial Installation Costs
Installing a radiant cooling system in a floor can be quite expensive, with the potential expense varying widely depending on the installation method and how much work must be done to prepare the slab or subfloor for installation. Expect to spend at least $10 to $20 per square foot including labor to install a radiant heating or cooling system in the floor plus around $5,000 for a chiller or heat pump with cooling capabilities.
A geothermal heat pump, which uses less energy than some other similar systems, costs $3,000 to $8,000 on average. Although pricey up front, a geothermal heat pump saves money over time with lower utility bills, especially if you are using the system for both heating and cooling.
If you are using radiant cooling in a humid climate, the rooms also require some form of dehumidification. A whole-home dehumidifier could cost as little as $1,000, while individual units designed for smaller areas cost less.
- United States Department of Energy: Radiant Cooling
- Arctic Heat Pumps: Radiant Floor Cooling
- Heating Plumbing Air Conditioning Magazine: Radiant Cooling: Emerging Technology Shows Promise
- Green Building Advisor: Does Radiant Floor Cooling Make Sense?
- SharkBite: PEX FAQs
- National Weather Service: Dew Point vs Humidity
- Uponor: Radiant Cooling Vs. Forced Air Systems
- Messana: Is Radiant Cooling Expensive? How Much Would it Cost for My House?
- HomeAdvisor: How Much Does Radiant Floor Heating Cost?
- HomeAdvisor: How Much Does it Cost to Install a Geothermal Heating or Cooling System?
- Green Building Advisor: Adding Air Conditioning to Radiant-Floor Heat