Integrating Radiant Cooling Systems for Energy Efficiency
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The document discusses the advantages of integrated radiant cooling systems for energy efficiency in buildings, highlighting their ability to save significant energy while providing improved human comfort and architectural flexibility. Various LEED certification points are associated with the systems, as well as detailed specifications, cost factors, and performance metrics for radiant cooling installations. Key benefits include energy savings of up to 53% compared to traditional HVAC systems and the effective management of sensible cooling loads under diverse environmental conditions.
Integrating Radiant Cooling Systems for Energy Efficiency
- 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.
- 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
- 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?