red radiant floor cooling tubes with a graphic of a hand holding a temperature gauge and a thermometer on the right

Radiant floor cooling is an energy-efficient way to cool your house in summer. However, frigid temperatures can make your floors uncomfortable. 

This article will discuss the factors that affect how cold radiant floor cooling gets. We’ll also share tips on choosing an excellent radiant floor cooling system. So keep reading to learn everything you’ve ever wanted to know about this home cooling technology.

How Cold Can Radiant Floor Cooling Get?

Radiant floor cooling can get as cold as 68-76°F (20-24.44°C) in an average building. However, the structure must use a 66-68°F (18.89 to 20°C) chiller like water. Such temperatures ensure a conducive indoor environment in summer or hot conditions.

Here’s what you need to know about radiant floor cooling and how cold it can get.

Factors That Affect Radiant Floor Cooling Efficacy

Radiant floor cooling circulates a mixture of water and glycol through PEX tubing or other types of piping embedded in the floor. 

Closeup on some radiant floor cooling lines installed in a floor of a home

The glycol-water combination picks up heat radiated from the floor and transfers it to a chiller. The chiller then cools the mixture and returns it to the floor, creating a cooling effect.

Factors affecting how cold radiant floor cooling gets include:

Solar Radiation Intensity

According to Energy Saver, radiant floor cooling works by absorbing heat radiated from the floor. The amount of heat emitted depends on the intensity of solar radiation.

For example, if you live in an area with high solar radiation, your floors will radiate more heat than in a location with low solar radiation. According to Science Direct, radiant floor cooling is effective in areas with high solar radiation intensity. 

A high solar radiation intensity increases the cooling capacity of radiant flooring systems by making the chiller extremely cold. Consequently, the liquid gets colder, translating into a cold room.

Tubing Size

The cooling tube’s diameter affects how cold radiant floor cooling gets by altering the flow rate. Therefore, you need a high flow rate for colder radiant floor cooling.

A high flow rate delivers a high coolant volume within a given time. The increased coolant volume in the tubes absorbs more radiated heat from the floor, transferring it to the chiller. The more heat absorbed, the cooler the floor gets.

The tubing size is also essential because it determines how much heat the system can transfer within a given time. A larger tubing can carry more heat away from the floor than a smaller tubing.

Closeup on an exposed hydronic radiant floor and the homeowner's feet who is installing it.

As a result, the larger the tubing, the colder your radiant floor will be.

Chiller Capacity

The chiller capacity is another factor that affects the efficacy of radiant floor cooling. A higher chiller capacity means it can transfer more heat from the glycol-water mixture to the chiller.

The chiller then cools the mixture, and the cooled mixture returns to the floor, creating a cooling effect. The more heat can be transferred from the glycol water, the colder your radiant floor cooling gets.

Coolant Temperature

The temperature of the mixture determines how much heat is absorbed from the floor based on the second law of thermodynamics. According to this law, heat flows from a hot body to a cold body.

Therefore, the colder the glycol-water mixture, the more heat it will absorb from the floor. The more heat the coolant absorbs, the colder your radiant floor cooling becomes.

Amount of Glycol in the Mixture

Glycol is a high-viscosity fluid with low heat transfer and expansion coefficients. It is added to the water to prevent freezing and improve heat transfer.

The amount of glycol in the mixture affects how cold radiant floor cooling gets by altering the coolant’s properties. For example, a higher glycol concentration decreases the coolant’s thermal conductivity, while a lower glycol concentration increases it.

A lower glycol concentration results in colder radiant flooring because the coolant’s thermal conductivity increases. The increased thermal conductivity means more heat is transferred from the floor to the coolant.

Selecting a Radiant Floor Cooling System

It’s essential to consider the following factors when choosing a radiant floor system:


Radiant floor cooling works best in dry climates with less humidity. An arid climate entails more radiation for the efficient functioning of radiant floor cooling. Dry air facilitates radiation by reducing the amount of moisture in the air.

On the other hand, excessive air moisture inhibits radiation by absorbing heat, making it difficult for radiant floor cooling to work effectively. If you live in a dry climate, your floors will radiate more heat, and your radiant floor will be more effective.

Building Materials

The material used to build your house will affect how cold radiant flooring gets. If your home is made of good conductors of heat, your floors will radiate more, and your radiant cooling will be more effective. Some good heat conductors include concrete, tile, and stone. 

A beige tiled floor with a cutaway chowing the grout and an underfloor radiant heating system beneath.

However, if your house is made of poor conductors of heat, the floors will radiate less heat, and the radiant floor cooling will be less effective. Some poor heat conductors include wood and carpet.

Your Budget

Radiant floor cooling systems come in two main types:

  • Chilled slabs (thermally activated building systems (TABS) – these are the most common types of radiant floor cooling systems. They use a concrete slab or metal plate to transfer heat from the floor to a refrigerant-filled tubing system and are the cheapest option on the market.
  • Radiant panels – this option circulates chilled water through unique panels. Radiant panels are more expensive than chilled slabs, but they offer a more even cooling distribution throughout the house. They also facilitate localized cooling.

It would be best to choose between the two depending on your budget. However, it’s worth noting that compromising quality over price can be costly in the long run.

Best Practices for Radiant Floor Cooling

Using radiant floor cooling efficiently requires following some best practices, which include:

Use a Programmable Thermostat

You can use a programmable thermostat to automatically adjust the temperature of your radiant floor cooling system. This apparatus will help you save energy costs while maintaining a comfortable indoor temperature.

A smart thermostat on the wall in our second net-zero home
A smart thermostat on the wall in our second net-zero home.

A programmable thermostat will also help you regulate the temperature of your radiant floor cooling system more effectively. For example, you can set it to a lower temperature when you’re not home and raise it when you need extra warmth.

Keep the Temperature at a Comfortable Level

The ideal indoor temperature for radiant floor cooling ranges from 66-84°F (19-29°C). Keeping the temperature at this level will help you save money on energy costs while still maintaining a comfortable indoor temperature.

If the temperature is too low, you may feel cold and uncomfortable. But, conversely, when it’s too high, you waste energy and money.

Use a Dehumidifier

Using radiant floor cooling in humid areas exposes your house to water damage and mold due to condensation. Condensation happens when the air dew point in the room is lower than the floor’s surface temperature.

The living room of a Florida home with a dehumidification system on the floor and homeowner sleeping on the couch

You can use a dehumidifier to remove the excess moisture in the air and prevent condensation. A dehumidifier will also help you regulate the humidity in your house more effectively.

Avoid Heavy Carpets

Heavy carpeting insulates the floor and prevents heat from being transferred from the room. Unfortunately, this makes your radiant floor cooling less effective.

It’s best to use light-colored, lightweight carpets or rugs that allow heat radiation from the room to the floor. These carpets ensure your radiant floor cooling system absorbs more radiated heat, cooling the house to your desired temperature.

Final Thoughts

Radiant floor cooling is a practical approach to keeping your house cool as it maintains uniformity. 

The embedded tubing around the floor absorbs heat uniformly, ensuring an equal cooling distribution throughout the house. However, you must set the correct temperature and avoid heavy carpets for efficient results.


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