Radiant Cooling

An Innovative Approach to High Efficiency Cooling

How refreshing it is to step inside a comfortably cool space on a sweltering hot day. But this comfortable cool is often elusive, despite the high dollars we spend trying to attain it. Most traditional forced-air cooling systems produce uneven room temperatures. They can also contribute to poor air quality by distributing airborne contaminants, making a space unhealthy and uncomfortable.

Improved Air Quality, No Drafts, No Hot Spots
By circulating cooled water through pipes embedded in your building’s structure, radiant cooling evenly absorbs heat energy from a room, eliminating drafts and hot spots. A radiant cooling system is typically designed in conjunction with radiant heating, and achieves best results when combined with other energy-efficient systems in tight building structures. Radiant cooling may handle the entire cooling load or be used to cover the base loads in traditional cooling applications. Since radiant cooling solutions can improve air quality, they are ideal in buildings such as hospitals and nursing homes where air quality is critical.

Radiant cooling is an innovative approach to comfortable, high-efficiency cooling. The technology is basically the same as radiant heating. RAUTHERM S pipe is installed in floors, walls, or ceilings and circulates chilled water. Radiant cooling is most effective when used in conjunction with other energy-reducing systems.

  • Cooling is more evening distributed; drafts are eliminated
  • Pipes are embedded in floors, walls or ceilings depending upon requirements
  • Requires air movement and dehumidification equipment as part of the system
  • Temperature can be controlled by individual room


Just as ground temperatures keep the walls of your basement slightly cooler and therefore absorb heat from the rooms, a radiant system embedded in your building structure can have a similar effect, providing even, comfortable cooling to your space.

Reduces Life Cycle Costs
Compared to a traditional forced-air system, radiant cooling has a lower operating cost, due to the superior heat transfer properties of water. The installation of a radiant cooling system may also lead to a significant reduction in forced-air system components and ductwork costs.

Improves Energy Efficiency
Compared to traditional systems, radiant cooling operates with moderate water temperatures, allowing you to raise your thermostat a few degrees while still maintaining the same level of cooling. This can lead to a significant reduction of energy consumption and carbon footprint. The efficiency of a radiant cooling system can be even further enhanced with the integration of a water-to-water geothermal heat pump system (see Tab 4 for more information).

Increases Thermal Comfort
The human body feels at its best when it can regulate at least 50 percent of its heat emission via radiation. Radiant cooling optimizes the surface temperature of the occupants’ surroundings, providing a comfortable environment while minimizing drafts and ventilation noise.

How it Works

This diagram of a typical commercial radiant cooling system illustrates two installation configurations: REHAU CCTC (Concrete Core Temperature Control) in the upper floor and a standard in-slab construction with an insulation barrier in the lower floor. Supply lines from the energy source are colored red; return lines are colored blue.
1. RAUTHERM S pipe
2. PRO-BALANCE® manifold
3. Thermostat / humidity sensor
4. System controller
5. Surface sensor
6. Outdoor air sensor
7. Main control
8. Valve
9. Temperature sensor
10. Circulator pump
11. Mixing valve
12. Energy supply (e.g., geothermal heat pump)


In radiant cooling systems, RAUTHERM S pipe is either integrated into a floor structure with insulation to condition the space above or without insulation to condition the space above and below.

Designing and installing a radiant cooling system can be straight forward, especially when integrating with a radiant heating system. A focus on controlling humidity levels and water temperatures is essential to reduce the risk of condensation associated with radiant cooling.

Radiant cooling works best in a tightly sealed building, so you will typically need supplemental ventilation, either to meet the building’s fresh air requirements or to meet peak cooling loads. A controlled ventilation system, such as the REHAU ECOAIR ground-air heat exchanger, is ideally compatible with radiant cooling because it preconditions fresh air with geothermal energy, reducing demand on the cooling system.


The capacity of a radiant cooling system depends on factors such as insulation, pipe spacing, floor construction and floor covering. Under optimal design conditions, capacities of up to 16 Btu/h ft² can be achieved* with more typical capacities in the 8 to 12 Btu/h ft² range.

*Olesen, Bjarne. Radiant Floor Cooling Systems, ASHRAE Journal, September 2008.

Radiant Systems Paired With Geothermal

A natural synergy...
If you’re considering using our RAUGEO ground loop system, you’ll also want to look at radiant heating and cooling, and vice versa. There’s a natural synergy between the two.

Here's why: In order to provide comfortable room temperatures, radiant heating works well with relatively low water temperatures and radiant cooling works with moderate water temperatures. It’s precisely in these temperature ranges that your water-to-water geothermal heat pump operates most efficiently.

So, by combining RAUGEO with REHAU radiant heating and cooling, you’ll enjoy the greatest comfort at the lowest operating cost. You’ll also appreciate the reliability of REHAU quality components from the geothermal probe to your thermostat, including durable PEXa pipes, secure EVERLOC® joints and manifolds with individually controlled circuits.

It could be all you need for total comfort.
In many cases, a properly designed geothermal-radiant system can provide enough energy to heat and cool your entire space even in extreme temperatures.


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