No Sweat Radiant Cooling Case Studies

Ryan Westlund – REHAUDevin Abellon – Uponor

Barry Stephens – Ventacity

Definition:

A radiant system is a sensible cooling and heating system that provides more than 50% of the total heat flux by thermal radiation.

Note: Active chilled beams do not fit this definition due to added forced convection portion.

Basic Physical Phenomena

Heat emission from the human body occurs through four modes of transfer:

– Conduction (~5%)– Evaporation (~20%)– Convection (~30%)– Radiation (~45%)

Humans feel most comfortable when they can regulate at least 45% of their heat emission through radiation

Image courtesy of RPA

Hydronic Radiant Cooling Types

1. Embedded Thermal Masses

2. Ceiling Panels

3. Capillary Tube Mats

Hydronic Radiant Cooling Types

1. Embedded Thermal Masses

2. Ceiling Panels

3. Capillary Tube Mats

Hydronic Radiant Cooling Types

1. Embedded Thermal Masses

2. Ceiling Panels

3. Capillary Tube Mats

Hydronic Radiant Cooling Types

1. Embedded Thermal Masses Requires High Mass Control Strategy

2. Ceiling Panel Requires Low Mass Control Strategy

3. Capillary Tube Mats

Basic Components:• Cross-linked polyethylene (PEX) pipes• Distribution manifolds

Common Hydronic Applications:- Radiant Heating and Cooling- Snow and Ice Melting Systems (SIM)- Turf Conditioning- Anti-Frost Heave Systems

(Below commercial freezers)

Radiant Systems: “Embedded Thermal Masses”

In a radiant heating system, warm fluid circulates through PEX pipes which are integrated in the floor structure- Heat radiates outward from the warmed floor- Additional natural convection

A radiant cooling system works with the reverse energy transfer process by absorbing heat from the space- Heat transferred through the floor is removed

from the space via the circulating fluid- In cooling mode, the same network of pipes is

used as in heating mode- In some applications pipes can be embedded

into the ceiling or even the wall

WARMED CONCRETE SLAB

Floor Covering

PEX Pipe

COOLED CONCRETE SLAB

COOLED CONCRETE SLAB

Radiant Systems: Heat Transfer

• 74°F ≤ TAIR ≤ 78°F

• TSURFACE ≥ 66°F

• 55°F ≤ TSUPPLY ≤ 60°F • Minimum allowable supply temperature

based on max dew point

• 5°F ≤ ΔT ≤ 8°F

• 0-30% PG in fluid

• PEX diameter (usually 5/8” for cooling applications)

• PEX spacing (usually 6” OC for cooling applications)

Typical Radiant Cooling Parameters

From years of adjusting thermostats, we have been conditioned to believe that air temperature alone translates to comfort, but this is not necessarily true.

We have to consider:1. Air temperature

Space’s air temperature, monitored by thermostat as “set point temperature”

2. Mean radiant temperature (MRT)Average temperature of surrounding surfaces

3. Operative room temperatureWeighted average of mean radiant temperature and the conditioned space’s air temperature

The operative temperature is what we perceive on our skin in a room and what is most important to consider when specifying a radiant system.

Higher air temperature set points during the cooling season and lower set points during the heating season are possible with radiant systems.

Temperature… Which Temperature?

Pink area = approximate comfort zoneRadiant coolingForced air

MRT comfort graph originally published in Architectural Forum, January 1939

Temperature… Which Temperature?

Why Radiant Cooling is Relevant?

Energy savings through “decoupling and optimizing”

Radiant Floor Heating & Cooling• With insulation underneath to

condition the space above • Heated/cooled floor surface• Uni-directional radiant exchange

Thermally Activated Building System (TABS)- No insulation- Upper and lower surfaces of slab

heated/cooled- Bi-directional radiant exchange

Types of In-Slab Radiant Systems

Earth Rangers: Woodbridge, Ontario

Pond Road Residence, York University:Toronto, Ontario

Campus North Residential Commons, University of Chicago

Campus North Residential Commons, University of Chicago

Richard J. Klarchek Information Commons, Loyola University:Chicago, Illinois

VAV Cooling Radiant Cooling

Infosys SDB 1: Hyderabad, India

Infosys SDB 1: ASHRAE Journal

Infosys SDB 1: HVAC Energy

CBE post-occupancy survey results

Infosys SDB 1: Thermal Comfort

Colorado Army National Guard High Altitude Aviation Training Site (HAATS), Gypsum, Colorado

Modeled Cost Savings for Radiant Heating Hangar

Devin Abellon – Uponor

Introductions

• Devin Abellon, PE is an ASHRAE Distinguished Lecturer and a registered professional engineer with 23 years of experience in the HVAC industry

• Devin earned his B.S. degree in mechanical engineering from the University of California at Santa Barbara in 1993

• As a business development manager for Uponor North America, Devin works closely with engineers, contractors, and building owners throughout the country to incorporate energy-efficient and cost-effective building solutions

• Email: Devin.Abellon@uponor.com• Website: www.uponorengineering.com

Acknowledgements

• Peter Simmonds, B&S Analytics• Robert Bean, RET P.Eng• Michelle Dionello, Genentech• Michael Talbot, Talbot & Associates Consulting Engineers

“No Sweat Radiant Cooling Case Studies”

Learning Objectives:

1. Discuss three radiant cooling case studies in different climate zones

2. Understand different control strategies for ensuring that surface condensation does not occur

• 18 million square feet under roof and a total of 67 acres,

• $8.5 billion. • Six of its properties (ARIA, Vdara,

Crystals, Mandarin Oriental, Las Vegas and Veer Towers) have achieved LEED Gold certification from the U.S. Green Building Council.

• And two properties — Crystals and Veer Towers — feature radiant heating and cooling.

• Goal 30% more efficient

CityCenter

Crystals at CityCenter

• 6" on-center tube spacing for exterior zones

• 9" on-center tube spacing for interior zones

• Cooling only for interior zones• Heating and cooling for exterior

zones• 25 total zones on three levels• LEED® Gold

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Radiant cooling design parameters

• Minimum surface temperature: 66°F

• Average water temperature:

55°F to 58°F

• Spacing: 6" on center

(maximum 9" on center)

• Loop lengths: 300 to 500 feet

• Size of pipe: ½", ⅝", ¾" typical

• Design differential temperatures: 5°F to 8°F for

cooling36

Human comfort

ASHRAE Standard 55

Six Factors:

AIR MOVEMENT

AIR TEMP

HUMIDITY

CLOTHING

RADIANT TEMP

METABOLISM

Four Factors:

Human comfort

Direct solar heat gain

Akron Art MuseumAkron, OhioRadiant Heating and Cooling45,000 square feet

Energy Efficiency

7.5%

9.4%

1.9%

34.4%

Fan andmotor

Load from lights

Air transport load

Other loads

ConventionalHVAC system

Radiant coolingHVAC system

37.5%

18.8%

9.3%

34.4%

Chiller62.5%

100% peak power

57.7%

7.5%

9.4%

1.9%

34.4%

Fan andmotor

Load from lights

Air transport load

Other loads

ConventionalHVAC system

Radiant coolingHVAC system

37.5%

18.8%

9.3%

34.4%

Chiller62.5%

100% peak power

Source: LBNL

1.5% - Pumps

Depending on the climate, a radiant cooling system in conjunction with a dedicated outside air system (DOAS) could save between 17% to 42% over the baseline VAV system.

Lawrence Berkley National Laboratory Report:

Commercial radiant heating and cooling case studies

NREL Research Support Facility, Golden, ColoradoLEED Platinum / Net Zero

David Brower Center, Berkeley, CaliforniaLEED Platinum

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Commercial radiant heating and cooling case studies

Western Science Center, Hemet, CaliforniaLEED Platinum

Cooper Union, New York, New YorkLEED Platinum

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Commercial radiant heating and cooling case studies

The Chartwell School, Seaside, CaliforniaLEED Platinum

Manitoba Hydro Place, Winnipeg, ManitobaLEED Platinum

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Commercial radiant heating and cooling case studiesSuvarnabhumi Bangkok Airport, Bangkok, Thailand30.5% Energy Savings

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Suvarnabhumi Bangkok AirportBangkok, Thailand

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• Completed in 2006• 2,150,000 SF• Radiant Area – Approx.

1,615,000 SF• Challenges

– Outdoor Conditions– Internal Gains

• Design Temperatures:– 99 deg. F dry bulb– 85% relative humidity– Average dew point – 77.1

deg. F

Suvarnabhumi Bangkok AirportBangkok, Thailand

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• Nearly 2M feet of tubing (approx. 370 miles)

• 7500 circuits• Combined with

displacement ventilation diffusers

• System Temperatures:– Setpoint 75 deg F / 50-

60% RH– Dew Point – 60 deg F– Surface Temperature –

69deg F.

Suvarnabhumi Bangkok AirportBangkok, Thailand

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• Condensation Control Strategy:– Minimize loads with high

performance envelope– Maintain airport’s

required indoor conditions of 75 deg F and 50-60% RH with displacement ventilation system

– Operate radiant slab to provide sensible cooling per ASHRAE Standard 55

Clemson University Lee HallSchool of Architecture – Clemson, South Carolina

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Clemson University Lee HallSchool of Architecture – Clemson, South Carolina

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• Completed in 2011• 53,000 SF• Challenges

– Outdoor Conditions– Internal Gains– Natural Ventilation

• Design Temperatures:– 90 deg. F dry bulb– 90% relative humidity

Clemson University Lee HallSchool of Architecture – Clemson, South Carolina

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• Concrete slabs combined with radiant heating & cooling, and night time free cooling

• Natural ventilation interlocked with the HVAC system thru building automation

• Dedicated outdoor air systems allow for dry air to be introduced to the space either at a neutral temperature or a low temperature to provide supplemental cooling

• Lowest energy use building on Clemson’s campus-exceeds ASHRAE 90.1-2007 by 50 percent

• Geothermal water to water heat pump system• Radiant cooling/heating system integrated with geothermal• Natural ventilation system• Dedicated outside air system• Net zero energy building• Green roof• Daylighting/controls• Building dashboard with web-interface

HEB Austin Mueller Grocery StoreAustin, Texas

HEB Austin Mueller Grocery StoreAustin, Texas

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• Completed in 2013• 75,000 SF• Radiant Area – Approx.

22,000 SF• Challenges

– Outdoor Conditions– Internal Gains

• Design Temperatures:– 100 deg. F dry bulb– 88% relative humidity

• Solutions provided to optimize the radiant design or installation – Used dessicant wheel 100% OA units with radiant floor;

needed to add an additional cooling coil in the unit to supplement the radiant floor for peak cooling

– Installation of perimeter insulation– Used heat recovery from cooling tower condenser for

heating

Design Challenges and Solutions

• Goal: Use 50% less energy than a typical HEB store

• Goal using radiant was to have a low-energy design and be committed to occupant comfort in the space.

Radiant Advantages

99198

192

80

0 100 200 300

Austin Mueller Target

Typical HEB Store

CBECS 2003- 28 stores

ASHRAE Target (CZ2)

kBtu/SF

Committed to 50% energy reduction

Condensation control

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• “Although radiant cooling has been in successful use in Switzerland for about 15 years, very little, if any progress has been made in its use in America. The reason seems to be that many engineers believe that a radiant cooling system will necessarily carry with it objectionable and injurious condensation of water vapor on the cooling panels…”

— F.E. Giesecke, Ph.D.Founder of the Texas A&M University Architecture ProgramHot Water Heating and Radiant Heating and Radiant Cooling, 1946

Piping and controls

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Combination heating/cooling piping diagramMixing with heating/cooling switchover

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Combination heating/cooling piping diagram

Local secondary injection system

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Control scenariosScenario: High-humidity infiltration

• Radiant system is in cooling mode• Airside system is in operation for

latent load / ventilation• Main doors constantly open and

close, allowing warmer humid air to enter atrium space

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Contact Information

For a copy of this presentation, please contact:

Devin Abellon, Uponor• Email: Devin.Abellon@uponor.com• Website: www.uponorengineering.com

Thank You!

Barry Stephens – Ventacity

The Project

The Parts & Pieces

Factory• Heat Recovery From Powder Coat Oven• Radiant Panels • Backup Boilers

Offices• Tight, well insulated envelope• Low-E Windows & External Blinds• Geothermal WSHPs• Very High Efficiency HRV• Advanced Control System

The Factory

Air-to-Water Heat Recovery

• 400 F Powder Coat Oven Waste Heat

• 135 F AWT

• Two Boilers ProvideBackup and Heat During Oven Shutdown

Radiant Panels• Radiant design optimizes comfort at floor level

• AWT 130F

• 150,000 SF Factory

The Office

Build It Tight…..

• Tight, well insulated envelope

• External blinds, automatic operationwith minimum tempand max wind controls

Low-E, low U-valuewindows

The Loop Field

20,00 Feet of Pipe

• Buried at 10 Ft Depth

• Connected to 3 WSHPs

• Allows for “FreeCooling” and Pre-Heating of HRV Supply Air

Ventilate Right

• Provides fresh air

• Allows for controlof humidity

• Significant energysavings

• Leverage groundloop for maximumefficiency

DO AS I SAY!

Ground-Source Pre-Heat/Pre-Cooling

• Up to 99% ASE

• Up to 90+% SRE

• Pre-Cooling =Dehumidification

• Frost Free Operation

• COP up to 30+ at-15F

Post-Heating

• Tempering

• Re-Heat forDry Mode

Post-Cooling/Dehumidification

• Tempering raises Dew Point

Advanced Controls

Advanced Dehumidification

• DEHUMIDIFIER 300/850 CFM• CONDENSATION* 25 gal/day• POWER ABSORBED 1.15 KW• COOLED WATER SUPPLY 210 gal/h• WEIGHT 155 Lb• DIMENSIONS 54” x 28” x 14”

*At 78 ºF and 65% HR

DRS 1000

Dehumidification Neutral Air1. Pre-treatment2. Air condenser3. Evaporator4. Water condenser5. capillary6. C= Compressor7. Modulating valve8. A= Inlet chilled water9. B=Outlet chilled water

Dehumidification & Cooling1. Pre-treatment2. Air condenser3. Evaporator4. Water condenser5. capillary6. C= Compressor7. Modulating valve8. A= Inlet chilled water9. B=Outlet chilled water

Advanced Dehumidification