Displacement and Chilled Beams in Healthcare

Copyright Price Industries, Inc. 2012 1

Jerry Sipes, Ph.D., P.E.Vice President of Engineering

Displacement and Chilled Beams in Healthcare

Introduction – Health Care Ventilation Standards

Displacement1. Overview2. Theory and Design Considerations3. Patient Room Example

Chilled Beams1. Overview2. Theory and Design Considerations3. Patient Room Example

Outline


Emerging Health Care Design TrendsHealth Care Ventilation Standards

ASHRAEStandard 170 – 2008

AIA 2006(Adopted by 42 States)

AIA 2010(Includes ASHRAE 170)


Recently published ASHRAE 170 addendums:

• Addendum G – Further definition of Air Diffusers for Patient Rooms (Displacement)

• Addendum H – Further definition of Recirculating Room HVAC units (Chilled Beams)


Single bed patient rooms Group A, Group D, or Group E

All other patient care spaces

Group A or Group E

All other spaces No Requirement

ASHRAE standard 170


Table 7 – 1, Notes(s) For single bed patient rooms using Group D diffusers, a minimum of six total air changes per hour shall be provided and calculated based on the volume from finished floor to six feet above the floor 6’- 0”

ASHRAE standard 170, Addendum G




ASHRAE standard 170, Addendum H

Table 7 – 1, Notes(a) The portion of the ‘Minimum Total ach’ required for a space that is greater than the ‘Minimum Outdoor ach’ required component may be provided by recirculating room HVAC units. Such recirculating room HVAC units shall:

(1) Not receive non-filtered, non-conditioned outdoor air,(2) Serve only a single space,(3) Provide a minimum MERV 6 filter for the airflow passing over any surface

that is designed to condense water….

DISPLACEMENT VENTILATION


History of Displacement Systems:

• Utilized in Europe for over 30 years

• Origins in industrial facilities

• #1 choice for industrial facilities in Europe

• Applied to commercial market in the 1980’s

• Becoming popular in North America

Displacement Ventilation

Review of Mixing systems:

• 55°F Supply Air

• Mix the entire space

• Diffusers drive air motion

• High velocity supply



Displacement Systems:

• 65-68°F supply air

• Low velocity

• No mixing in space

• Heat sources drive air motion

• Stratified heat, contaminants

• Only conditions the occupied zone



Benefits• Air Quality (IAQ)

– More efficient contaminant removal

– High Ventilation Effectiveness

– Outdoor air can be reduced

• Local code permitting

• Thermal Comfort

• LEED & CHPS

• Quiet


Common Applications:

• Schools

• Theaters

• Casinos

• Airports

• Healthcare

• Halls & Conference Rooms

• Offices & Lobby Areas

• Restaurants & Cafeterias

• Industrial Spaces


Thermal Plumes:

• Create temperature stratification

• Carry contaminants from breathing zone

• Improve air quality in occupied zone



Thermal Plumes:

• Heat sources drive air motion


Layout:

• Air is drawn to heat sources

• Cool supply air flows around:

- Complex geometries

- Furniture

- Obstructions



2-10 °F Cooling 0‐5 °F Heating 5 °F+ Heating

Heating with Displacement:


Heating with Displacement:• Perimeter Radiation

• Diffusers with Integrated Heat

• Radiant Ceiling Panels

• Fan Coil Units



Installation examples:

Commercial Cafeteria


Worship Space


Factory

OfficeDisplacement Ventilation

School



Theater Office Meeting Room


Displacement Ventilation Velocity Profile

Displacement Ventilation – HealthcarePatient Room


Hospital Mockup• IAQ testing

• Tracer gas injected

• Test for:

• Ventilation effectiveness

• Contaminant exposure


Hospital Mockup• IAQ testing

• Tracer gas injected

• Test for:

• Ventilation effectiveness

• Contaminant exposure



Patient RoomOutsideCondition

Supply Type Airflow VentilationEfficiency

Summer

Low Sidewall DV 80 1.28

Overhead DV 80 1.14

Square Cone 80 0.65

Winter

Low Sidewall DV 80 1.14

Overhead DV 80 1.06

Square Cone 160 0.92


AIR DISTRIBUTION METHOD OverheadDisplacement

Ventilation(low)


(high)

Supply Air Volume 290 190 190

Corresponding ACH 6 4 4

VENTILATION EFFECTIVENESS

1.24 1.41 1.27



Waiting Room

Supply Type CFM ACH VE

Square Cone 1800 12 0.90

Overhead DV 1200 8 1.09

Low Sidewall DV 900 6 1.04

Displacement Ventilation – HealthcareHospital Waiting Room

HYDRONIC SYSTEMS (CHILLED BEAMS)


Hydronic SystemsHistory and Introduction

• Started in Europe ~ 60 years agoo Metal ceilingso Radiant systems

• Seeking more capacityo Passive chilled beams

• Integration of ventilation systemo Active chilled beams

Legend:

■ Application of radiant products

is natural

■ Additional care to control building moisture

■ Humidity must be carefully considered

Hydronic Systems


Why water?• Water holds ~ 3400 x more energy than air• Pumps more efficient than fans

Note: Ventilation air still required

Hydronic Systems

CBS Newsletter, Fall 1994 http:/eetd.lbl.gov/newsletter/CBS_NL/n14/RadiantCooling.html

The GOAL: Reducing Energy Required for Air Transport/Removal of Heat

Hydronic Systems


Thermal Comfort

• Three basic human comfort factors are:o Radiant comfort (40 to 50% of the human comfort factor)

o Fresh air/ air movement (30%)

o Humidity control (10 to 15%)

• Operative temperature is what a person will feel based on the interaction of radiant and convective

temperatures

Hydronic Systems

Hydronic System Concerns

• Potential for higher first costo What is the reference system?o Chiller requiredo Additional plumbingo Additional costs associated with

tighter envelopes

• Humidity control more importanto Condensation is a slow processo Transient spikes in humidity can be tolerated

as long as they are not more than a few hours and not a massive volume of moisture.

Hydronic Systems


Sensible only applicationDesign to avoid condensation – how?

Design:•Dew point + 2°F•Avoid or design for high latent load applications•Use dry air – DOAS

Hydonic Systems

Mumma, Stanley; 2002; Chilled Ceilings in Parallel with Dedicated Outdoor Air Systems: Addressing the Concerns of Condensation, Capacity, and Cost; ASHRAE Transactions 2002, Vol

108, Part 2; pp220-231

Exceeding dew point limit•Condensation process begins at dew point > surface temperature•Speed of process depends on environmental conditions

Sensible only applicationDesign to avoid condensation – how?

Sensing:Room humidity sensorsCondensation detection on piping

StrategiesWater on/offEntering water temperature resetSupply air water content

Hydronic Systems (Chilled Beams)


Hydronics Systems (Chilled Beams)

Benefits• Improved healing environment / low noise < NC 30

• Reduced plenum height• Reduced footprint (equipment or duct riser)

• Improved comfort• Superior humidity control• Superior room air velocity

Maintenance requirements are very low

• No filter – no filter changes

• Low velocity & dry coil minimizes dirt build up• Wide fin spacing reduces dust

bridging.

• Dry coils prevent dust from sticking

• Recommended cleaning by vacuum once every 1 to 5 years



Chilled Beams Operating Conditions


Cooling Heating

SAT 55 – 65°F 60 – 90°F

Airflow Rate 3 – 25 cfm/ft

EWT Dew point + 2°F 90‐140°F

Water ΔT 2 – 6°F 10‐20°F

Water Flow Rate min – 0.4 gpmmax – 2 gpm

Water ΔP 0 ‐ 10’

Air ΔP 0.2 – 0.75”target 0.4”‐0.6”

Design Recommendations• Select and position based on throw similar to a supply diffuser

• < 50 fpm air velocity in the occupied zone

• Select cooling EWT 2°F space dew point

• Keep hot water EWT < 140°F



Reduced primary air quantity• From 6 ACH to 2 ACH (100% OA)• Reduces fan power• Significantly reduces reheat requirement• Chilled beam chilled water return (62°F to 65°F)

can be used to provide reheat

Eliminates common return • Reduce hospital associated infection

Provides lower noise level & better healing environment

Active Beams in Health Care

Theory and Design Considerations

Patient Room• 300 ft²• 2 ACH = 90 cfm, 6 ACH = 270 cfm• Internal Cooling Load: 6,000 btu/hr sensible, 400 btu/hr latent

Item Chilled Beam VAV

Required Airflow 90 CFM 270 CFM

Outside Airflow 90 CFM 90 CFM

Supply Temp 55 54

Required Pressure .52” 1.0”

Coil LAT 50 54

CHWS Temp 57° F to 62° F 45° F to 55° F


Patient Room Energy Example


Patient Room• Active Beam Selection

• 2’x8’ ‐ 6000 Btu/hr

Condition Result

Airflow 90 cfm

Sound NC 21 (@5”)

Pressure drop 0.55”

Water flow rate 1.35 gpm

Water head loss 6.9’



Energy Comparison

Notes: 1 kw per hp, 1 kw per ton, $0.10 per kwh, $1.00 per therm

Item Chilled Beam VAV

Fan Power per Room 0.103 bhp 0.308 bhp

Reheat per year 20.2 therms 159.3 therms

Overcooling per year 129 ton hours 1017 ton hours

Fan heat savings 291.6 btu/hr 874.8 btu/hr

Energy Savings 3,110 kwh & 139 therms per year

Cost Savings per Room $450 per year





Jasper Memorial Hospital – Jasper, IN

Pharmacy section of hospitalHigh thermal comfortExpected to be used again in the

hospitalRenovation with low ceiling

heights



• Laboratories

• Commercial Construction

• Owner occupied buildings

• Hospitals

• Educational facilities

• Historical Retrofits

Hydronic Systems

Radiant Panels

• Primarily radiant heating/cooling – no airflow

• Quick response to load demand

• Used along perimeters or spot cooling interior

• 2 types: Linear & Modular

Hydronic Systems


Hydronic Systems

Chilled Sails

• Radiant and convective cooling

• Increased performance over panels

• Profiles and free area encourage convection

• Architectural integration

Hydronic Systems


Laboratory Office Conference Room

Hydronic Systems

Chilled Beams

• Convective heating and cooling

• Higher capacities than panels and sails

• Integrated airflow for Active Beams

• 2 types:o Passive Chilled Beam

o Active Chilled Beam

Hydronic Systems


Laboratory AUDI Museum

Passive Beams

Hydronic Systems

Chilled Beam – Active, 2-way supply

Hydronic Systems


Active Beams

Hydronic Systems

Woods Lab, TN Bourne School, MA

Active Beams

Hydronic Systems


Suspended from slab Quick connect fittings

Hydronic Systems

Questions?

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Displacement and Chilled Beams in Healthcare