As more and more jurisdictions and building owners are placing increased emphasis on sustainable and responsible building strategies, design teams are looking beyond traditional HVAC solutions to maximize energy efficiency while maintaining occupant comfort and safety. In-slab radiant heating systems have enjoyed popularity both here in the United States and abroad for years. Now, with the availability of improved control systems and better understanding within the design and construction community, the same concept can be applied to radiant cooling as an energy-efficient and cost-effective solution. This program will cover the radiant cooling heat transfer fundamentals, system performance and capacity, typical construction methods, and control strategies. Attendees will gain an understanding of how in-slab radiant cooling systems can be used as part of an energy-efficient design solution to reduce overall energy consumption.

1. Integrated Radiant Cooling Systems for
Energy Efficiency
Devin Abellon, P.E. – Business Development Manager
Uponor
California Center for Sustainable Energy

2. LEED v3
new construction
LEED Topic Possible
Points
SUSTAINABLE SITES 26
WATER EFFICIENCY 10
ENERGY & ATMOSPHERE 35
MATERIALS AND RESOURCES 14
INDOOR ENVIRONMENTAL QUALITY 15
INNOVATION IN DESIGN 6
REGIONAL PRIORITY 4

3. LEED v3
new construction
LEED Topic Possible
Points
ENERGY & ATMOSPHERE 26
Credit 1: Optimize Energy Performance
Credit 3: Enhanced Commissioning
Credit 4: Enhanced Refrigerant Management
Credit 5: Measurement & Verification
INDOOR ENVIRONMENTAL 6
QUALITY
Credit 1: Outdoor Air Delivery Monitoring
Credit 2: Increased Ventilation
Credit 3: Construction IAQ Plan
Credit 6.2: Controllability of Systems – Thermal Comfort
Credit 7: Thermal Comfort – Design/Verification
INNOVATION IN DESIGN 5
Credit 1: Innovation in Design

4. RADIANT COOLING
High Mass Low Mass
•Thermally Activated Building •Suspended or surface-mount
System (TABS) •Faster response
•Overhead slab or floor slab •Typically less surface area
•Thermal mass •Colder temperatures (e.g.,55F)
•Larger surface area
•Moderate temperatures
(e.g.,65F)

7. 2nd LAW
of thermodynamics
Clausius Statement:
Heat generally cannot flow spontaneously from a material at lower
temperature to a material at higher temperature.

8. HUMAN COMFORT

9. HUMAN COMFORT
ASHRAE Standard 55
Six Factors:
Four Factors:
AIR TEMP
AIR
HUMIDITY
MOVEMENT
CLOTHING METABOLISM
RADIANT
TEMP

10. RADIANT TEMPERATURE
Average Uncontrolled Surface Temperature
Area weighted average of the surface temperatures of all uncontrolled
surface
Mean Radiant Temperature
Average of the AUST and the surface temperature of the controlled surface
Operative Temperature
Average of the Mean Radiant Temperature and the Air Temperature

11. RADIANT TEMPERATURE
Room Temp. = 78.0°F
AUST = 78.0°F
MRT = 72.0°F
Operative Temp. = 75.0°F

12. SOLAR GAIN

13. SOLAR GAIN

14. SOLAR GAIN

15. SOLAR GAIN

16. RADIANT COOLING
System Advantages
• Ability to Deal with High Direct
Solar Gains
• Superior Human Comfort
• Greater Architectural Freedom
• Reduced Drafts and Noise
• Energy Efficiency

17. ENERGY EFFICIENCY
LBNL Findings:
100% peak power
37.5%
Depending on the
Fan and
motor
climate, a radiant cooling
57.7% system in conjunction
18.8% 1.5% - Pumps
7.5%
with a dedicated outside
Load from lights
9.4%
air system (DOAS) could
Chiller
9.3%
Air transport load
1.9% save between 17% - 42%
62.5%
over the baseline VAV
34.4% Other loads 34.4%
system
Conventional Radiant cooling
Source: LBNL HVAC system HVAC system

18. ENERGY EFFICIENCY
Pacific Northwest National Laboratory
A radiant cooling system in conjunction with a
dedicated outside air system (DOAS) could save as
much as 53% over the baseline HVAC system
National Renewable Energy Laboratory /
U.S. Department of Energy
50% Energy Savings over ASHRAE 90.1 can
achieved using a radiant heating and cooling system
American Institute of Architects

19. ENERGY EFFICIENCY
Case Studies
Suvarnabhumi Bangkok Airport California Academy of Sciences Western Science Center Cooper Union
Bangkok, Thailand San Francisco, California Hemet, California New York, New York
30.5% Energy Savings LEED Platinum LEED Platinum LEED Platinum
NREL Research Support Facility David Brower Center The Chartwell School Portola Valley Town Center
Golden, Colorado Berkeley, California Seaside, California Portola, California
LEED Platinum LEED Platinum LEED Platinum LEED Platinum

20. RADIANT COOLING
Performance
Sensible Cooling
A radiant cooling system can effectively manage a
portion of building’s sensible load
12 – 14 BTUH/SF
Direct Solar Loads
In areas with high direct solar loads, the systems
capacity can significantly increase to
25 – 32 BTUH/SF

21. RADIANT COOLING
Typical Parameters
Tubing
Cross-linked polyethylene (PEX) barrier tubing
5/8” diameter
6” to 9” on center spacing
Maximum tubing length per loop – 350’
Operating Water Temperatures
55°F to 58°F
5°F to 8°F temperature differential
Surface Temperature
Minimum 66°F

22. RADIANT COOLING
Typical Construction
Slab on Grade
Flooring
Structural Slab
PEX Tubing
Wire Mesh / Rebar
Insulation
Compacted Grade

23. RADIANT COOLING
Typical Construction
Suspended Slab
Structural Slab
PEX Tubing
Wire Mesh / Rebar
Metal Deck
Insulation

24. RADIANT COOLING
Typical Construction
Topping Slab
Topping Slab
PEX Tubing
Wire Mesh
Insulation
Structural Slab

25. RADIANT COOLING
Typical Construction
Wood Deck
Flooring
Topping Slab
PEX Tubing
Wood Deck
Insulation

26. RADIANT COOLING
Manifolds

27. RADIANT COOLING
Manifold Locations

28. RADIANT COOLING
Piping Diagrams
Mixing with Heating/Cooling Switchover

29. RADIANT COOLING
Piping Diagrams
Primary/Secondary Piping

30. RADIANT COOLING
Piping Diagrams
Local Secondary Injection

31. CONTROLS
Control Points
24vac
ON
CAT5
TX TX Port
RUN RX RX 1
10 Thermostats per controller
Digital Zone Control Modules
FILED MODULES Port
Link
Ethernet
DZCM 2
Port
OAS
• Space Temperature
Active uponor 3
To Building
Service
Network Port
4
• Indoor Relative Humidity
uponor uponor
Port 5
Modem
Port 1
• Operative Temperature Port
2
24vac
uponor DZCM
Field Modules
• Operating Water
Port 3
Port 4
24vac uponor ZVDC
Temperatures TX TX
Router Port 5
• Slab Temperature
ON
RUN RX
Secondary1 Mix1 HOT WATER RETURN
uponor
• Control Valves
HOT WATER SUPPLY
Secondary2 Mix2 COLD WATER RETURN
COLD WATER SUPPLY
Mix3
• Circulating Pumps
Secondary3
DIVERTING
GLOBE VALVE GLOBE
VALVE / VALVE /
Secondary4 Mix4
CIRCUIT DIVERTING VALVE CIRCUIT
SETTER SETTER
Outdoor Temperature Secondary5
Snowmelt 1 Snowmelt 2
Mix5
• Outdoor Relative Humidity
Supply Temp
LOW LOSS
Snowmelt 4 HEADER / 3WAY MODULATING
Snowmelt 3
DECOUPLER VALVE
Uponor
Return Temp
Supply Water Controller

32. CONTROLS
Control Strategies
• Base load with radiant cooling system and
operate as a differential to air setpoint
• Utilize indoor adaptive rest strategy to optimize
target water temperature for maximum
effectiveness
• Continuously monitor indoor relative humidity for
condensation control

33. RADIANT COOLING
Condensation Concerns
Condensation
Surface condensation will occur
if the surface temperature drops
below the dew point
Solution
Continuously monitor indoor relative humidity and
maintain supply water temperature 2 degrees above
dew point at all times

34. CONTROLS
Control Strategies
Responsiveness
• High thermal mass provides “inertia” against
temperature fluctuations
• Heat transfer from the thermal mass to the
space is instantaneous whenever there is a
temperature difference
• Thermal mass evens out fluctuations in internal
temperature
• Secondary system used to handle high load
densities

35. COST
Typical Cost Factors
No Cost
• Structural Slab already part of the construction budget
• Chilled water source typically already part of the budget
Additional Cost
• Cost of tubing, manifolds, fittings, circulators
• Insulation
• Increased Labor
Reduced Cost
• Smaller air handling units, ductwork, diffusers, etc.
• Reduced ceiling space requirements may allow for reduced
floor to floor heights
• Potential to reduce electrical service size
Reduced Maintenance Cost
• Less airside equipment to maintain

36. COST
Typical Cost Factors
Pacific Northwest National Laboratory
Study
• Average cost of the radiant system, including central plant
• $9.31/ SF (7-8 year payback)
2010 R.S. Means Cost Data
• Average cost of materials & labor (excluding chilled water
source)
• $4.25 - $5.43/ SF
Innovations for Reduced Cost
• Big Box Retailer
• 2-1/2 year payback

37. RADIANT COOLING
Summary
Benefits
• Can be used to dramatically reduce overall building energy use
• Superior Human Comfort
• Improved architectural freedom
Performance
• 12-14 BTUH/SF Sensible, up to 25-32 BTUH/SF with direct solar for
radiant floor installations
Important Considerations
• Controls
• Installation Methods
• Installation and Life-Cycle Costs

38. Questions?