What is radiant cooling?
Radiant cooling is an alternative to typical forced air home air conditioning systems. Radiant home air conditioning involves reducing the temperature of floors, ceilings, or walls so they absorb heat from the air, rather than cooling the air itself as with normal A/C systems. By cooling surfaces in the surrounding space, that in turn cools down the people and objects in the room.
Understanding radiant cooling, or radiant heating for that matter, is first about understanding radiant heat transfer because 'cold' doesn't radiate. Only heat radiates. And to split hairs and get super technical for a moment - there is really no such thing as cold; there is just heat, and less heat. Learn more here about heat transfer and thermal comfort in homes.
Warm bodies (mass) radiate heat toward cooler bodies, so in the case of radiant cooled floors, what is actually happening is you and the warm items of your home radiate heat towards colder surfaces. Hot things are 'transmitters' and cold things are 'receivers'. With that disclaimer out of the way I'll keep with the 'radiant cooling' terminology for simplicity.
Radiant cooling refers to a mechanically cooled surface like a floor, wall, or ceiling that lowers indoor temperatures in a home by creating 'heat sinks' that absorb heat from the air and surrounding materials.
Your body, furniture, basically any warmer surface of your home will constantly radiate heat. When nearby surfaces are cooler, heat flows from your body toward them and you feel cooler as a result. This kind of system can be remarkably efficient and pleasant when the conditions are right.
How radiant cooling works
A radiant cooling system relies on pumping cooled water through a network of pipes or panels embedded in your floors, ceilings, or sometimes walls. Cold water circulates through these systems and draws heat out of the room. Because water carries heat far more efficiently than air, radiant systems are quiet, effective, and energy-saving.
This creates a comfortable environment without the drafts, noise, or the dryness that is often associated with forced-air cooling. Because radiant cooling focuses on managing the surface temperatures, it can create a more even and natural indoor climate compared to traditional HVAC systems.
Is radiant cooling in homes comfortable?
A lot of people have experienced radiant heating but not necessarily radiant cooling. I would qualify that by saying - we may not all have experienced mechanically-designed radiant cooling in a home, but those of us in colder climates at least, know the sensation all too well.
In articles about thermal comfort - and specfically choosing the best windows - we discuss the difference in comfort between double pane windows and triple pane windows. The sensation of radiant heating and cooling when you're surrounded by surfaces with vastly differing temperatures is quite noticeable on the body, and arguably 'natural'. On very cold days, your warm body will probably not enjoy the unsolicited radiant cooling from sitting by a double pane window as much as you would a triple pane window.
The first time I stepped into a radiant-cooled home in the middle of a hot summer in New Mexico, I was struck by how comfortable it felt, but absent was any sense of cold air from vents, or any background hum of fans, just a calm, steady coolness that made the space feel like a retreat. That’s the essence of radiant cooling: comfort through subtlety.
Types of radiant cooling systems
Radiant floors:
Tubing is embedded in concrete to cool large surface areas slowly and steadily. Best for new construction.
Radiant ceiling panels:
Lightweight systems ideal for retrofits or spaces where underfloor systems aren’t possible or perhaps just aren’t practical.
Dual-purpose heating and cooling:
One single system of radiant tubing can provide heating in winter and cooling in summer (at least for a single story).
Radiant cooling vs traditional air conditioning
How they differ:
Standard air conditioning systems cool a building by chilling air and blowing it throughout the space. Radiant systems cool by chilling surfaces, which then absorb radiant heat from the room.
Comfort level:
Radiant cooling creates a more natural and even comfort. There's no rush of air or noticeable cycling of equipment. Research shows that home occupants are often comfortable with an air temperature of 75–76°F with radiant systems; compare that to an average setting of 72°F or lower with traditional air conditioning.
Humidity and air quality:
A big difference between these two methods is humidity control. Forced air cooling systems remove humidity as they cool air, but radiant systems do not. So it is essential to have a good dehumidifier or ventilation system if you're in a humid region.
That said, one of the best things about radiant systems is that it helps maintain cleaner indoor air quality in homes. With no ducts or fans stirring things up, there is less dust and fewer allergens being blown around.
Energy efficiency of radiant cooling
Radiant systems have consistently been shown to provide the same comfort while using less energy than traditional forced-air systems, at least in specific climates.
New construction
For new homes being constructed, it’s relatively easy to install radiant tubing in concrete slabs or integrate cooling panels into ceilings.
Renovations and retrofits
Retrofitting radiant cooling into a home during renos depends on the scope of work. Ceiling or wall panels work well and are much less invasive than floor systems, and if you are opening walls and doing wiring anyway, then it may not be much hassle at all.
What kind of climate is best for radiant cooling?
Radiant cooling tends to work best in:
-
Hot, dry climates like Arizona, Utah, and northern Mexico
-
Temperate zones such as Oregon, British Columbia, or the northeastern U.S.
-
Mildly humid areas where added dehumidification can be integrated easily
It can still work in humid places like the Gulf Coast or Central America, but it takes careful design. In those climates, it is even more important to ensure you have:
-
A reliable and properly sized dehumidifier or ERV.
-
Smart sensors to monitor the dew point.
-
Careful control of water temperatures to prevent condensation.
What building types are a good fit for radiant cooling systems?
All homes should be built with energy efficiency in mind, but radiant cooling is especially effective and efficient in buildings that have a tight, well-insulated envelope. Other passive heating and cooling design strategies - like including a healthy amount of thermal mass such as concrete or stone to regulate temperatures and having well-planned shading - are where comfort and efficiency shine with radiant systems. High-performance homes can be cooled to comfort with less energy and less concern of condensation issues.
So radiant cooling is a natural fit for homes built to the high standards of Passive House, LEED, and net-zero energy.
Cost considerations for radiant cooling systems
Radiant cooling systems can be more expensive to install initially than some types of air conditioning systems, but not always. Installing a radiant cooled floor may run between $18 and $35 per square foot installed, whereas a basic central air system might cost between $7,000 and $15,000 total.
But does that AC system provide heating as well? A centralized and ducted heat pump provides efficient heating and cooling, but with a dedicated air conditioning system you still need to factor in the cost of a heating system in most climates.
Any upfront premium there may be for the installation cost of radiant systems starts to look better when you factor in lower energy bills, longer equipment lifespan, and minimal maintenance.
Operation and maintenance of radiant cooling systems
Radiant systems have very few moving parts, so there is not a lot of regular maintenance needed. Most of the maintenance comes down to occasional inspections of pumps and checking water quality. Unlike ducted systems, you won’t be changing filters or dealing with blower motor failures.
PEX tubing used in floors can last 50 years or more - with emphasis on the ‘or more’. Some manufacturers even rate PEX for a hundred years when installed and maintained under ideal conditions. Pex tubes embedded in concrete experiences no friction, have no risk of puncture and experiences no UV exposure.
You need to ensure proper water quality and system pressure, but outside of that there's not much beyond an earthquake that can damage tubes. And if an earthquake is strong enough to wreck tubing in concrete, then you likely have bigger problems to contend with anyway.
What to watch out for when installing a radiant cooling system
Humidity and condensation:
In humid areas, managing indoor moisture is essential. Radiant systems don’t remove humidity, so if the air gets too damp and the surfaces get too cold, you can end up with condensation, the same way a glass of ice water sweats on a hot sunny day.
Installation complexity:
Installing radiant cooling systems will not be a simple DIY plug-and-play endeavor. They require careful design, especially in retrofits or complex builds. You’ll need to think about zones for the system, water flow rates, and how to coordinate with other HVAC components.
Addressing common myths about radiant cooling systems
"Radiant cooling causes condensation everywhere."
Not true – that only happens if a system isn't designed to handle humidity. Properly managed radiant cooling systems, with appropriate dew point monitoring and dehumidification, can operate effectively without condensation issues.
"It doesn't work in humid climates."
It does work in humid climates when it includes proper humidity management and smart controls. When radiant cooling is used in humid climates, careful dew point monitoring is crucial to prevent condensation. If the surface temperature of floors, ceilings, or walls drops below the dew point of the room air, moisture will accumulate, much like condensation on a cold beverage. To avoid this, radiant cooling systems should be paired with smart sensors and well-calibrated dehumidification strategies that keep indoor humidity levels in check.
"You won’t feel cool enough without blowing cold air."
This is also not true. People often feel more comfortable at higher air temperatures because the surfaces around them are cooler. Read more here about the factors that affect thermal comfort in a home.
"It's expensive to maintain."
Not true, maintenance is minimal. There are no filters, no fans, and fewer mechanical parts. the required maintenance involves occasional inspections of pumps and checking water quality but not much beyond that.
"Only luxury homes use radiant cooling."
This used to be true but isn’t anymore. System costs have come down, and the technology is being used in more mainstream projects every year.
Our conclusions on radiant cooling in homes
Radiant cooling, just like radiant heating, isn’t just a technical choice, it’s a lifestyle upgrade. It’s about creating spaces that feel consistently comfortable with very little noise and no blowing air.
Radiant systems are efficient as is, but they also pair well with air-to-water heat pumps to further reduce energy consumption and save you money. This pairing allows for even greater efficiency, making it a highly sustainable choice for modern, energy-conscious homes.
Now that you know more about radiant cooling as an alternative to forced air AC, learn more about sustainable home comfort, energy efficiency and how to reduce the carbon footprint of homes on the following pages and in the Ecohome Green Building Guide.
Find more about green home construction and reap the benefits of a free Ecohome Network Membership here. |
Comments (0)
Sign Up to Comment