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Chilled Beam and
Radiant Cooling Basics
Salt Lake City, UT ASHRAE Chapter
December 2013Nick Searle
Contents
• Radiant Ceilings & Chilled Beam Basics
• Energy & Space Savings
• First and Lifecycle Costs
• Maintenance
• Application Suitability
• Design Considerations
• Application Example # Laboratories
• Case Study – 250 S. Wacker, Chicago
Fan Energy Use in Buildings
“Energy Consumption Characteristics of Commercial Building HVAC
Systems” � publication prepared for U.S. Department of Energy
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Central VAV Central CAV Packaged CAV
Desig
n L
oad
KW
/SF
Chiller/Compressor
Supply & Return Fans
Chilled Water Pump
Condenser Water Pump
Cooling Tower Fan
Condenser Fan
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Central VAV Central CAV Packaged CAV
En
erg
y U
se K
Wh
/SF
Water = Efficient Transport
¾” diameterwater pipe
10”
1 Ton of Cooling
requires 550 CFM of air
or
4 GPM of water
Chilled Ceilings
Many buildings heated only
PC’s appearing on desks
Restricted ceiling cavity
1980 1990 2000 2010
Chilled Ceilings
Chilled Ceilings Radiant Effect
45%Radiant
55%Convective
CW Supply59�62°F
CW Return62�66°F
76°F Dry Bulb
74°F radiant
temperature
(black bulb)
Chilled CeilingsAdvantages Design Issues
• Low cooling output‒ 20 to 25 BTUH/ft2 100%
coverage‒ 14 to 18 BTUH/ft2 70% coverage
• High cost
• Separate air system required
• Excellent thermal comfort
• Reduced space requirements‒ Will fit into 6#8” cavity
• Self regulating‒ Simple controls
• Low noise
• Low maintenance
Chilled Sails
Chilled Sails
Advantages Design Issues
• Cooling output‒ 40 to 50 BTUH/ft2
• Separate air system required
• High cost
• Cannot heat
• Need good acoustic treatment to avoid hard spaces
• Many connections
• Aesthetics ?
• Good thermal comfort
• Reduced space requirements
• Freely suspended
• Self regulating
• Simple controls
• Low noise
• Low maintenance
Chilled Sails
Passive Chilled Beams
• Increased cooling loads‒ Equipment‒ Occupancy‒ Day#lighting
• Inadequate perimeter cooling
1980 1990 2000 2010
Chilled Ceilings
Passive Chilled Beams
Passive Chilled Beams 1 Operation Principle
Perforated tile
Water coil
Suspension rod
Soffit
Fabric skirt
Passive Chilled Beams 1 System Highlights
• Good thermal comfort
• Cooling capacity up to 40 BTUH/FT2 floor space‒ Up to 500 BTUH per LF of beam
• Reduced ductwork, riser and plant sizes‒ Water transports most of sensible cooling
• Self regulating‒ simple two position controls
• Low noise
• Low maintenance
Design Considerations
• Sensible cooling only‒ Latent gains must be controlled by air system
• High free area perforated metal ceiling required‒ 28% free area minimum‒ Exposed beams (no ceiling) are an option
• Beams cannot be installed tight against slab‒ Typically 40% of beam width required above beam
• Separate heating system must be installed
• Separate air system must be installed
Passive Chilled Beams 1 Airflow Pattern
Passive Chilled Beams 1 Recessed Type
Passive Chilled Beams 1 Exposed Type
Active Chilled Beams1980 1990 2000 2010
Chilled Ceilings
Passive Chilled Beams
Active Chilled Beams
• Higher space loads
• Higher occupant densities
• Combined ventilation/cooling preferred
• Integration into fiber tile ceilings required
Active Chilled Beam 1 Operation Principle
Suspended ceiling
Primary air plenum
Primary air nozzles
Heat exchanger
1 Part Primary Air
4 Parts Room Air
Heat Removal Ratio
70% of sensible heat removed by chilled beam
water coil
Airflow requirement
reduced by 70%
Active Chilled Beam 1 Airflow Pattern
Active Chilled Beams 1 System Highlights
• Very high cooling capacity‒ Up to 100 BTUH/FT2 floor space‒ Up to 1500 BTUH per LF
• Integrated cooling, ventilation and heating‒ All services in the ceiling cavity
• Suitable for integration into all ceiling types‒ Reduces ceiling costs compared to Passive Beams
Active Chilled Beams 1 System Highlights
• Significant space savings‒ Smaller ductwork saves space in shafts, plant rooms and ceiling
• Can be installed tight up against the slab‒ Reduced floor to floor heights‒ Reduced construction costs on new buildings
• Low noise levels
• Low maintenance‒ No moving or consumable parts
Energy Savings 1 Compared to VAV
Source Technology Application % Saving*
US Dept. of Energy Report (4/2001) Beams/Radiant Ceilings General 25#30
ASHRAE 2010 Technology Awards Passive Chilled Beams Call Center 41
ACEE Emerging Technologies Report (2009) Active Chilled Beams General 20
ASHRAE Journal 2007 Active Chilled Beams Laboratory 57
SmithGroup Active Chilled Beams Offices 24
*Compared to VAV
“Energy Consumption Characteristics of Commercial Building HVAC
Systems” � publication prepared for U.S. Department of Energy
Active Chilled Beams 1 First Costs
• Office Building, Palo Alto, CA
• 80,000 ft2
• Thermostat in each office for beam design
*HPAC Engineering Article “European Technology Taking Hold in the U.S.: Chilled
Beams, Peter Rumsey, PE, CEM, FASHRAE, FRMI
“costs were in line with VAV”*
Active Chilled Beams 1 First Costs
• Office Building, Denver, CO
• 600,000 ft2 design/build renovation
• Elimination of two air handlers per floor due to beams
*HPAC Engineering Article “European Technology Taking Hold in the U.S.: Chilled
Beams, Peter Rumsey, PE, CEM, FASHRAE, FRMI, January 1st 2010
“the chilled�beam system was equal
to the VAV system”*
Active Chilled Beams 1 Lifecycle Costs
• 100,000 ft2 Office Building, Cincinnati, OH
• 15 year lifecycle study
• 15% Energy Savings Compared to VAV‒ $0.79 versus $0.93 ft2
• 22% reduction in mechanical installation costs‒ $19.50 versus $25.00 per ft2
• Lifecycle costs analysis over 15 years‒ Favored chilled beam system by 20%‒ $32 ft2 versus $40 ft2
HIXSON ARCHITECTURAL INTERIORS � Spring 2009
LEED Certification 1 LEED NC V3.0
• Optimize Energy Performance# up to 48% (new) or 44% (existing)
more efficient than ASHRAE 90.1(EA Credit 1) # up to 19 points
• Increased Ventilation# 30% more outdoor air than
ASHRAE 62(IEQ Credit 2) # 1 point
• Controllability of Systems# individual temperature control(IEQ Credit 6.2) # 1 point
• Thermal Comfort# meet ASHRAE 55(IEQ Credit 7.1) # 1 point
(Minimum 40 points needed for certification
out of 100 maximum)
Maintenance
• No moving parts
• No filter
• No condensate pumps
• No consumable parts
• Up to 4 year inspection & clean
• Easy maintenance access
Cleaning Access
Active Chilled Beams 1 Typical Installation
Active Chilled Beams 1 Typical Installation
Active Chilled Beams 1 Typical Installation
Concealed Active Beams
Bulkhead Active Chilled Beams
ACTIVE CHILLED BEAM DESIGN
CONSIDERATIONS
Building Suitability
Building Characteristics that favor Active Chilled Beams
• Zones with moderate#high sensible load densities‒ Where primary airflows would be significantly higher than needed for
ventilation‒ Sensible Heat Ratio’s (SHR) of 0.8 and above
• Buildings most affected by space constraints‒ Hi – rises, existing buildings with induction systems
• Zones where the acoustical environment is a key design criterion
• Laboratories where sensible loads are driving airflows as opposed to air change rates
• Buildings seeking LEED or Green Globes certification
Building Suitability
Characteristics that less favor Active Chilled Beams
• Buildings with operable windows or “leaky” construction
‒ Beams with drain pans could be considered‒ Building pressurization control should be used
• Zones with relatively low sensible load densities
• Zones with relatively low sensible heat ratios and low ventilation air requirements
• Zones with high filtration requirements for the re#circulated room air
• Zone with high latent loads
APPLICATION EXAMPLE:
LABORATORIES
Laboratory Design Issues
• Sensible heat gains of up to 70 BTUH/ft2
• Space ventilation requirements of 6 to 8 ACH
• Laboratories where chemicals and gases are present require 100% outdoor air
• Air systems require 15 to 20 ACH of outside air to
satisfy sensible load
Cooling Load and ACH
Benefits of Active Beams in Labs
• Eliminated or reduced reheat‒ Reheat can account for 20% or more HVAC energy costs
• Water more efficient transport medium‒ Reduces fan energy costs
• Smaller space requirements‒ System sized for 6 ACH instead of 15 ACH
Active Chilled Beam DesignCooling Load = 65 BTU/H ft2
Ventilation Rate = 6 Air Changes
VAV Solution = 15 Air Changes
Chilled Beam Solution = 6 Air Changes
Active Chilled Beam Solution = 6 x 6’ Long, 130 CFM each
Reheat ReductionVAV System ACB System
• Minimum Airflow‒ 6 ACH = 760 CFM
• Cooling Load‒ 65 BTU/H ft2
‒ 41,000 BTU/H Peak
• Maximum Airflow‒ 760 CFM
• Minimum Cooling without reheat‒ 6 ACH @ 65°F
‒ 8,300 BTU/H
• Turndown without reheat‒ 8,300/41,000‒ 80%
• Minimum Airflow‒ 6 ACH = 760 CFM
• Cooling Load‒ 65 BTU/H ft2
‒ 41,000 BTU/H Peak
• Maximum Airflow‒ 1,860 CFM (15 ACH)
• Minimum Cooling without reheat‒ 6 ACH @ 55°F‒ 16,600 BTU/H
• Turndown without reheat‒ 16,600/41,000‒ 59%
CASE STUDIES
250 South Wacker
Chicago, IL
250 S. Wacker, Chicago 1 Case Study
• 16#story tower –215,000 sq. ft. 1st floor retail2 – 16th floor offices
• Separate HVAC systemsfor 1st and 16th floors
• Perimeter induction systemwith floor#mounted unitsserving 2 # 15th floors
• Interior constant volume/variable temperaturesystem serving 2 – 15th floors
250 S. Wacker, Chicago – Case Study
Building Renovated with 1
• 100% glazing with E#glass (190 Btuh/Ln.ft. heat loss)
• Single duct cooling only VAV interior system
• Evaluated fan#powered VAV oractive chilled beamperimeter system
• Seeking LEEDcertification
250 S. Wacker, Chicago – Case StudyPerimeter SystemType
Existing
Induction System
Proposed
Fan#powered
VAV System **
Proposed
Active Chilled Beam System **
Design Cooling Load
262 tons(382 sq.ft./ton)
156 tons(641 sq.ft./ton)
156 tons(641 sq.ft./ton)
Primary Airflow 25,600 cfm(0.5 cfm/sq.ft.)
86,270 cfm
(1.7 cfm/sq.ft.)
15,880 cfm(0.3 cfm/sq.ft.)
Fan Energy at Design
64 kW 182 kW 22 kW
Fan Energy at 70% of Design
64 kW 116 kW 22 kW
Pump Energy 28 kW 8 kW 12 kW
Combined Fan & Pump Energy
92 kW 190 kW @ Design
124 kW @ 70%
34 kW
** Required larger ductwork/risers ** Used existing ductwork/risers
250 S. Wacker, Chicago – Case Study
25 250 S. Wacker, Chicago – Case Study
QUESTIONS?
