1 Meeting ASHRAE Fundamentals, Standard 55 & 62.1 with Chilled Beams Displacement Ventilation

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Meeting ASHRAE Fundamentals, Standard 55 & 62.1 with Chilled Beams Displacement Ventilation.

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ASHRAE Standard 62.1-2009Space Ventilation for Non-residential Occupancies

Ventilation

for Acceptable

Indoor Air Quality• Classifies occupied spaces

• Sets ventilation requirements based on size and occupancy

• Sets guidelines for demand control ventilation

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Conventional Method• Ventilate the space according to ASHRAE 62-2009

• Use Ventilation Rate or IAQ Procedure to determine OA requirements using table 6-1

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Conventional Method• Ventilate the space according to ASHRAE 62-

2009 • Use Ventilation Rate or IAQ Procedure to

determine OA requirements using table 6-1

• Make Corrections for Zone Air Distribution Effectiveness using Table 6-2

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• Make Corrections for Multiple-Zone Recirculating System using Table 6-3

Zp=Voz/Vpz

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• Make Corrections for Multiple-Zone Recirculating System using Table 6-3

Zp=Voz/Vpz

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Conventional MethodOur Goal is to Reduce the Amount of Treated Air Traveling Through theBuilding• 62.1 Dynamic Reset a.k.a. CO2

Ventilation• How does the Outdoor Air know

where to go?

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Goal: Reduce the Amount of Conditioned Air Traveling Through the Building

-So how else can we reduce the treated air???

Free Cooling Hours for 54F & 69F

0

500

1000

1500

2000

2500

3000

54F 69F

5am-4p

m Mon-

Fri

Displacement

18“ x 18“

Air Duct

1“ diameter

Water Pipe

Chilled Water

(above the dew point)

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Goal: Reduce the Amount of Conditioned Air Traveling Through the Building

-So how else can we reduce the treated air???

Displacement

Displacement Terminal QLI Disp. Term w/ Coil Active Chilled Beam

Chilled Water

(above the dew point)

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Ideally get to a…

DOAS• The system is simplified.

• Constant Volume

• No return air.

One Step Further…

DOAS w/ CO2 Sensor• The Fresh Outside Air goes where

it’s need.

• More Complicated due to VAV

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Implementing ASHRAE Standard 62.1While Not Abusing ASHRAE Standard 55 &

Fundamentals

Near/Adjacent Zone

No comfort zone

High Airflow / Draft

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ASHRAE Standard 55-2009Thermal Comfort Guide

• Defines “Occupied Zone”

• Factors affecting thermal comfort

– Metabolic rate– Clothing (insulation)– Air temperature and speed– Radiant effects– Humidity

• Defines acceptable conditions

• Goal is occupant satisfaction levels 80% or higher

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ASHRAE Standard 55-2009Occupied Zone


Occupied zone definition– Not within two (2) feet of a wall

– Between the floor and the head level of the predominant space occupants

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Occupant Thermal ComfortBasic principles

SHG = Metabolic RateClothing

Convective transfer to surrounding airRadiant transfer to cooler surfaces

Dependent on temperature of surfaces

Independent of air conditions

Dependent on orientation of surfaces

Effected by air speed

Dependent on air conditions

Thermal comfort achieved when heat out is equal to heat generatedThermal comfort achieved when heat out is equal to heat generated

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ASHRAE Standard 55-2009Cooling Operation Comfort Range

65 70 75 80 85

0.012

0.014

0.013

0.011

0.010

0.009

0.008

0.007

50

55

60

57

Operative Temperature, °F

Hu

mid

ity

Ra

tio

, L

bs

Wa

ter

pe

r L

b D

ry A

ir

Sp

ac

e D

ew

Po

int

Te

mp

era

ture

, °F

50%

RH

45%

RH

55%

RH60%

RH

Cooling Operation Comfort Window

Cooling Operation Comfort Window

Assumes 1.0 Clo, 40% Tu and ≤ 40 FPM mean velocity

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ReturnReturn

Ankle Level

Displacement Supply Air

Near Zone

Neck Level

Thermal Plume

ASHRAE Standard 55-2009 & Fundamentals

Lets Start with Displacement Ventilation

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Near/Adjacent ZoneAdjacent zone is defined as the region adjacent to the terminal discharge in which terminal velocities exceeding 0.2 m/s (40 FPM) may be found that are 71F or below.

It is indicated by the dimension L0.2 as shown.

To avoid draft complaints, stationary space occupants should not be located within this region.

No comfort zone

L 0.2


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Occupied Zone

Ele

vati

on

Max. 5oF

TE

TS

Ankle Level TA

TR

Stagnation Layer

Stratification Zone

Supply Layer


Near/Adjacent Zone

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Occupied Zone

Ele

vati

on

Max. 5oF

TE

TS

Ankle Level TA

TR

Stagnation Layer

Stratification Zone

Supply Layer


Comfort Chart – Ankle Region

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Occupied Zone

Ele

vati

on

Max. 5oF

TE

TS

Ankle Level TA

TR

Stagnation Layer

Stratification Zone

Supply Layer


Comfort Chart – Neck Region

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Adjacent Zone Comparison (Face size of 24x48")Trox Titus Halton Price

0 2 4 6 8 10 12 14 16 18

150 cfm

225 cfm

300 cfm

370 cfm

Flow

Length (ft)

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So why is there such a difference between manufacturers? Nozzles VS

Perforated

Adjacent Zone Effect

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Tag Model Size CFM Max Adjacent Zone @ 10F DT-1 INC 24x48 225 6ftDT-2 INC 24x48 150 5ftDT-3 INC 24x48 300 8ft

Displacement Terminal Schedule

Include the Max. Allowable Adjacent

Zone in the Schedule

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Now Lets Look at Active Chilled Beams

Discharge to Room

Ducted primary air

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Room sees two slot linear diffusers, nothing more!

Room sees two slot linear diffusers, nothing more!


What is an Active Chilled Beam?

It‘s a Diffuser!

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ASHRAE Standard 55-2009






Now Lets Look at Active Chilled Beams

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Mixed Air SystemsMixed Air Systems

OCCUPIED ZONE

T150

T100

T50

T50

T100

T150


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ASHRAE FundamentalsCooling Operation Comfort Range

Acceptable to 80%

Dissatisfaction Criteria 5% to 15% recommended limit

15% for draft (mixed flow)

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Part 1 – Chilled Beam

The primary air via a diffuser (Beam)•Provides fresh air requirement•Controls temperature•Controls humidity

Room Airflow

Active Chilled BeamsActive Chilled BeamsMixed Room Air DistributionMixed Room Air Distribution

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What does a diffuser do? • Delivers fast cold (or hot) air to the space• It directs the discharge• Makes use of the Coandă effect• Reduced velocity by mixing• Changes temperature by mixing

What does a diffuser do? • Delivers fast cold (or hot) air to the space• It directs the discharge• Makes use of the Coandă effect• Reduced velocity by mixing• Changes temperature by mixing

Room Airflow


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Room Airflow


Beam vs. diffuser• Increases volume, Example: assume 60% water 40% air

• 100 cfm by diffuser, 40 cfm @ beam but with induction ratio of say 4:1, = total air discharged is 40 x 4 + Original 40 = 200 cfm

• If we work on 1cfm/SF and room Height of 10’• 100 cfm = 6 ac/hr, 200 cfm = 12 ac/hr (room air movement)

• The increased discharge temperature helps but the higher volume throws further in a ‘more active space’.

Beam vs. diffuser• Increases volume, Example: assume 60% water 40% air

• 100 cfm by diffuser, 40 cfm @ beam but with induction ratio of say 4:1, = total air discharged is 40 x 4 + Original 40 = 200 cfm

• If we work on 1cfm/SF and room Height of 10’• 100 cfm = 6 ac/hr, 200 cfm = 12 ac/hr (room air movement)

• The increased discharge temperature helps but the higher volume throws further in a ‘more active space’.


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36

Sel

ecti

on S

oftw

are

4 or 2 pipe beam

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Input Beam Length and Nozzle Type

Sel

ecti

on S

oftw

are

Input Primary air, Room and CWS Temperatures

Input Water Flow Rate (s)

Input Primary Airflow Rate

Input Beam Mounting Details for Local Velocity Predictions

Output: Sensible from Water, Air and

Total

Output Waterside,

Airside Pressure drop

and noise

Output: Sensible from

Water, Air & Total

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Room Airflow


Beams must be selected for comfort, not just BTU’s

The selection programs will also show you that as you increase the cooling but maintain the cfm volume, the throw increases.

Beware of any proposition that half the number of beams for a given design when no throw data or statement on comfort is offered.

Beams must be selected for comfort, not just BTU’s

The selection programs will also show you that as you increase the cooling but maintain the cfm volume, the throw increases.

Beware of any proposition that half the number of beams for a given design when no throw data or statement on comfort is offered.


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Active Chilled Beam Velocities

• ASHRAE and AHRI working to establish testing and rating standards– Sensible cooling capacities– Aerodynamic performance (throw data) – Acoustical performance

• Many manufacturers do not catalog throw or velocity data

• One proposes selections with discharge airflow rates > 100 CFM/LF – Results in T100 values of 20 to 25 feet– Requires minimum diffuser separation of 50 to 60 feet for ADPI ≥ 80

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ASHRAE Fundamentals & Standard 55

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ASHRAE Fundamentals & Standard 55

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Designing Chilled Beam Systems for Thermal Comfort

Thank You!

Documents

1 Meeting ASHRAE Fundamentals, Standard 55 & 62.1 with Chilled Beams Displacement Ventilation