Underfloor Air Distribution UFAD Systems: Design Issues, Principles and Practices

1
Underfloor Air Distribution (UFAD)
SystemsDesign Issues, Principles and Practices
Sponsored by National Energy Management Institute
By James E. Woods, Ph.D., P.E 25-26 September
2003
Building Diagnostics Research Institute
2
Seminar Overview and Purpose

• The purpose of this seminar is to explore the
  use of Building Diagnostics principles and
  procedures (i.e., protocol) for evaluating the
  expected performance of underfloor air
  distribution (UFAD) systems as alternative to
  conventional air distribution (CAD) systems
  during design.

3
Objectives

• The objectives of this seminar are to provide
• Valid and reliable information on the advantages
  and disadvantages of UFAD systems compared to CAD
  systems,
• A protocol that can be used to evaluate the
  appropriateness of a UFAD system for a specific
  project, and
• Obtain feedback for subsequent revisions to the
  Protocol and to this Training Manual.

4
Educational Outcomes

• Increased understanding of advantages and
  disadvantages of UFAD systems.
• Increased ability to predict, through diagnostic
  procedures, the performance of UFAD systems for
  site-specific applications.

5
Seminar Content

• Session 1 Introduction and Overview (1 hour)
• Session 2 Design Issues (1 hour)
• Session 3 Principles of Psychrometrics, Air
  Distribution, and Energy and Mass Balances (4
  hours)
• Session 4 Principles and Procedures of Building
  Diagnostics and Commissioning (Define a Set of
  Evaluation Criteria) (3 hours)
• Session 5 Practice evaluating the Performance of
  UFAD as Alternative to CAD systems during Design
  (4 hours)
• Session 6 Discuss results of Practice Session
  and provide feedback (2 hours)

6
Team Organization
Team 1 1. 2. 3. 4. 5.
Team 2 1. 2. 3. 4. 5.
Team 3 1. 2. 3. 4. 5.
Team 4 1. 2. 3. 4. 5.
7
Introduction of Example Problem

• Project Description
• Program Objectives
• Problem Statement
• Sketch of Floor Plan
• General Characteristics

8
Example Problem Project

• A general office area for a mid-level floor of a
  new speculative building in Washington, DC

9
Example Problem Program Objectives

• Provide an office environment that is
• Conducive to high expectations of human response
  and occupant performance
• Protective of exposures from contaminants that
  are naturally occurring (e.g., mold), accidental
  (e.g., spills, fire and smoke), and intentional
  (e.g., chemical, biological, radiological)
• Energy Efficient and Cost Effective

10
Example Problem Problem Statement

• Determine if CAD, UFAD, or a combination of
  systems is appropriate to meet the Program
  Objectives

11
Example Problem Sketch of Floor Plan
15
Perimeter 8,700 ft2
15
45
80
45
15
25
Interior 12,100 ft2
St
St
SW
Lobby
El
MER
40
M
Core 3,200 ft2
El
MER
W
SW
St
25
N
15
12
Example ProblemGeneral Characteristics
13
Focus of Session 1 Overview

• Current Drivers
• What is a UFAD System? How does it differ from a
  CAD System?
• Brief History
• Prior to 1900s (Heating and Ventilation)
• Cleanrooms and Computer Spaces (Cooling)
• Flexible Workspaces (Access to cabling, thermal
  and ventilation)
• Types and Variations of UFAD Systems
• Supply Air (positive or neutral pressure, ducted
  or unducted)
• Return Air (ceiling plenum or ducted, floor
  ducted or unducted)
• Methods of Evaluation
• Psychrometrics
• Building Diagnostics

14
Current Drivers and Balances
Environment

• Green Buildings
• Sustainability
• Global warming
• Moisture and Mold
• Weather and Seismic Protection
• Occupant Safety
• Environmental Security

Productivity

• Health and Comfort
• Occupant performance
• Health care costs
• Employee absences
• O M costs
• Value Engineering
• Fear of terrorism

Energy

• Reduced loads and capacities
• Advanced control strategies
• Changes in OM procedures
• Zero Energy Buildings

15
UFAD and CAD Systems
UFAD
CAD
Return
Relief
Relief
Return
Supply
Stagnant Zone
55 F
77 F
75 F
Induction Zone
Bypass
Uniform Mixed Zone
Recirculated
Recirculated
75 F
Uniform Mixed Zone
75 F
Mixing Zone
Supply
65 F
Plenum
OA
OA
Fan
Fan
SA Terminal
Filter
Coil
Coil
Filter
16
Brief History of UFAD Systems

• Prior to 1900s
• Heating and ventilation (Monticello, Houses of
  Parliament, Chicago Auditorium, Metropolitan
  Opera House)
• Cleanrooms and Computer Spaces (1960s - current)
• Cooling of sensible loads (floor return for
  contamination control, floor supply for thermal
  control)
• Flexible Workspaces (1990s - current)
• Heating, cooling, and ventilation of interior and
  perimeter zones

17
Types and Variations of Current UFAD Systems
Supply Air
Return Air

• Ceiling Plenum
• Ducted
• Partially Ducted
• Unducted

• Positive Pressure Plenum
• Unducted, Push Type
• Diffusers Grilles
• VAV Units

• High Sidewall Grilles
• Ducted or unducted to Ceiling
• Ducted to VAV or FCU in Floor

• Neutral Pressure Plenum
• Ducted to VAV or FC Units
• Unducted, Pull Type
• Fan-powered VAVs
• Fan Coil Units
• Fan-powered diffusers Grilles

• Floor Plenum
• Ducted from Kiosk to VAV or FCU
• Ducted from Grille to VAV or FCU
• Membrane to separate floor plenum for supply
  and return

18
Methods of Evaluation
Psychrometrics
Building Diagnostics
Psychrometrics deals with determining
thermodynamic properties of moist air, and using
these properties to analyze conditions and
processes involving moist air (ASHRAE HOF)
A process in which a skilled expert draws on
available knowledge, techniques, and
instrumentation in order to predict a buildings
likely performance over time (BRB 1985)
19
Focus of Session 2 Issues

• Fundamental Purposes of Buildings
• Fundamental Objectives of Environmental Control
• Four Objectives of Design
• Seven Steps for Design of Healthy Buildings
• Revisit Current Drivers
• Summary of Literature Review
• Health, Safety and Environmental Security
• Occupant Performance, Productivity, Energy
  Utilization, and other Economics

20
Purpose of Buildings

• Provide secure, safe, and healthy conditions
• Facilitate well being and productivity of
  occupants, owners, and managers
• Four functional categories
• Residential
• Educational
• Health Care
• Commercial/Public Assembly

21
Fundamental Objectives of Environmental Control

• Prevent adverse health and safety effects
• Provide for desired conditions
• Human Response
• Occupant Performance
• Productivity
• Achieve by simultaneous control of exposure
  parameters
• Thermal
• IAQ

• Lighting
• Acoustics

22
Four Principles for Design of Healthy Buildings

• Design to provide for Wellness rather than to
  prevent Illness
• Design to achieve Functional Requirements rather
  than just to meet codes and standards
• Design for the Last Day of Occupancy rather than
  for Initial Occupancy
• Verify with Building Diagnostic Methods for
  virtual and actual buildings

23
Seven Steps for Design of Healthy Buildings

• Establish design requirements and criteria
• Determine the design loads
• Determine the system capacities
• Design control system for partial loads
• Assemble the design documentation
• Commission the system or building
• Periodically re-evaluate system performance

24
Current Drivers and Balances
Environment

• Green Buildings
• Sustainability
• Global warming
• Moisture and Mold
• Weather and Seismic Protection
• Occupant Safety
• Environmental Security

Productivity

• Health and Comfort
• Occupant performance
• Health care costs
• Employee absences
• O M costs
• Value Engineering
• Fear of terrorism

Energy

• Reduced loads and capacities
• Advanced control strategies
• Changes in OM procedures
• Zero Energy Buildings

25
Summary of Literature Review

• Background and Issues of Concern
• Procedures
• Preliminary Literature Search
• Evaluation and Classification Criteria
• Subsequent Literature Search
• Findings
• Discussion and Interpretation
• Conclusions and Recommendations

26
Background and Issues

• UFAD systems are not new
• Demands for flexible work environments have
  increased interest
• Millions of sq ft of office space with UFAD are
  being designed
• Concerns include
• Latent cooling capacities
• Accumulation of particulate matter and moisture
• Pressurized floor plenums
• TAB difficulties
• Compartmentalization and Isolation during
  incidents

27
Procedures

• Preliminary Literature Search
• 13 occupied facilities with UFAD
• Initial functional characteristics identified
• Systems installed within the last 15 years
• Characteristics used as basis to modify the BDRI
  Evaluation Criteria for comparison of UFAD and
  CAD systems Characteristics used to define
  keywords for subsequent literature search

28
Procedures

• Evaluation and Classification Criteria
• Basic set used as integral part of Building
  Diagnostics Protocol
• Criteria classified in three categories and 8
  classes
• Healthy H1 and H2,
• Marginal M3, M2, M1
• Problematic P3, P2, P1
• Evaluation Criteria
• Defined for each classification
• Modified by Preliminary Literature Search for
  UFAD and CAD comparisons

29
Procedures

• Subsequent Literature Search
• Search engine found 2990 citations
• Analysis of 500 of these yielded 9 general review
  articles
• Four additional articles were added from our
  library

30
Findings

• Preliminary Literature Search
• Size from 20K to 290K sq ft, but UFAD generally
  less than total floor area
• Climatic conditions did not represent high dew
  point or latent load conditions
• None reported to have ducted supply air to floor
  or desk outlets
• Plenum supply air temp ranged from 55 70 F
• Period of occupancy ranged from 1 5 years
• More than half had thermal and draft complaints
• Other complaints included noise, dirt in
  diffusers, and air distribution and TAB problems
• Energy savings were claimed but not validated
• In several cases, hard or flex conduit was
  required for wiring and cabling in plenums

31
Findings

• Subsequent Literature Search
• 65 buildings identified with UFAD systems
• 33 in western/northwestern US (e.g., light
  latent loads)
• 47 in midwestern/eastern US (e.g., large heat
  losses and large sensible heat loads in summer)
• 18 in southern US (e.g., light sensible heat
  losses and large sensible and latent heat loads
  in summer)
• Size from 2K to 3M sq ft, but UFAD generally
  less than total floor area
• 30 were installed as part of new construction
• No P1 or P2 reported but the author has
  investigated such complaints
• Occupant discomfort, P3, reported for thermal,
  lack of air movement/drafts, noise, dust and dirt
• Non-compliance with relative humidity and air
  movement frequently reported, while gas and
  particulate concentrations were more frequently
  in compliance, M1
• System problems included insufficient latent heat
  capacity, lack of controllability of temperature,
  pressurization, and compartmentalization, M2
• Energy and first cost justifications were not
  validated, M3

32
Discussion and Interpretation

• UFADs are attractive alternatives to CADs, but
  more limited than marketing suggests
• Many variations of UFADs preclude simple
  characterization of their advantages and
  disadvantages
• Claims of superior performance of UFADs over CADs
  are probably meaningless
• Frequency of non-compliance with evaluation
  criteria expected to be similar for UFADs and
  CADs
• More specific design guidance being provided
  regarding the use of UFADs (e.g., LEED 2.1 and Ch
  5 mods to GSA PBS-P100)

33
Conclusions and Recommendations

• Each of the initial issues of concern has been
  validated in the literature search
• Both UFAD and CAD systems will require more care
  in design, installation and operation as
  consequences become more apparent
• TAB, commissioning, and building diagnostic
  techniques continue to improve and provide
  greater assurance of system performance
• Recommend that NEMI continue to develop and
  validate methods and procedures to assure system
  performance

34
Schematic of UFAD Systems Specified by GSA
50FWB/70RH
50FWB/70RH
To other perimeter zones
H/C
Filter
Filter
OA
H/C
To other interior zones
Min Stop for Vent/press
Dedicated 100 OA Vent/Press System
Dedicated 100 OA Vent/Press System
VAV
Ceiling Plenum
Glazing
RAG
TEG
RAG
CD
?P
80 ADPI
?P
P
Interior Zone
Toilet
Finned-tube radiation
Perimeter Zone
T
T
o
FD
FD
FD
RA
100 Shut off
RA
VAV
VAV
Floor Plenum
To other perimeter zones
Min Stop for Vent/press
50 FWB/ gt 64FDB
H/C
OA
Filter
Filter
H/C
OA
Economizer
Economizer
To other interior zones
Perimeter H/C System
Interior H/C System
35
Focus of Session 3 Principles

• Rational and Extended Models for Environmental
  Control
• Psychrometrics for Thermal and IAQ Control
• Principles of Air Distribution for Occupied
  Spaces
• Energy and Mass Balances

36
Rational Models for Building Diagnostics of
Virtual and Actual Buildings

• Relational Model of Sources, Systems, Human
  Responses and Economics
• Objective Model for Building Energy Efficiency
• Extended Model for Human Responses, Occupant
  Performance and Productivity

37
Sources or Loads
Human Responses
Systems
Exposures
Thermal Contaminants Lighting Acoustics
Structure Envelope Services Enclosures
Thermal Air Quality Illumination Acoustics
Envir-Percep Pers-Percep Envir-Affective Pers-Affe
ctive
First Costs
Operating Costs
Energy Use
Productivity
Economics
38
Energy Efficiency Definition
Energy Waste
Heating/Cooling
Solar radiation
Indoor Exposures Thermal Air Quality Illumination
Acoustics
Ventilation
Infiltration/Exfiltration
Lighting
Natural ventilation
Processes
Conduction
Energy Requirement
Convection
Envelope Load
Internal Load
Outdoor Conditions Dry bulb temp Dew point
temp Wind vel dir Contaminants Insolation
Occupancy
Energy Consumption
Energy Requirement
Building Energy Efficiency
Energy Resources Oil, Coal, Natural
gas, Biomass, Other

Energy Consumption
39
Forcing Functions
Response Functions
Physical Factors
Cost Factors
First costs O M costs Other costs
Sources Building Systems Exposures
Human Responses
Human Factors
Personal Factors
Objective Perceptive Affective
Intrinsic Adaptive Psychological- Environmental
Risk Perception
Occupant Performance
Productivity
Motivating Factors
Social Factors
Economic Motivators Other Motivators
Secular Trends Soc. Factors in Minienvironment
Extended Model
40
Psychrometrics for Thermal and IAQ Control

• One-compartment Model
• Air Quality Control
• Thermal
• Chemical
• Particulate
• Two-compartment Model
• Non-dimensional Parameters
• Energy, Air, and Contaminant Balances

41
Air Conditioning
Air Conditioning is the control of the humidity
of air by either increasing or decreasing its
moisture content. Added to the control of the
humidity is the control of temperature by either
heating or cooling the air, the purification of
the air by washing or filtering the air and the
control of the air motion and ventilation. -
Willis H. Carrier
42
Basic Control Concepts

• Three control mechanisms
• Three control methods
• Extension of psychrometrics
• Thermal
• Chemical
• Particulate

43
Three Control Mechanisms
Exposure
Control Mechanism
Thermal
Acoustics Vibration
IAQ
Lighting
Sensible Heat
Latent Heat
Mass
Energy
Energy
?
?
Conduction
?
?
?
Radiation
?
?
?
?
Convection
44
Three Methods of Control

• Source (N)
• Removal (E)
• Dilution (Vo )

45
Co - Ci ( N - E ) / Vo
Blower
Vr
Ci
Co
N (Net Generation Rate or Loads from Sources)
Vo (Dilution Rate)
Air Cleaner
?
Ci Cu
Cd (1 - ? ) Cu
Ci
Occupied Space (Indoors)
E Vr ? Cu (Removal Rate)
46
Air Quality Control

• Air quality control is a natural
• extension of psychrometrics

47
Psychrometrics

• Psychrometrics deals with determining
  thermodynamic properties of moist air, and using
  these properties to analyze conditions and
  processes involving moist air.
• ASHRAE Handbook-Fundamentals

48
Moist and Dry Air

• Moist air is a binary mixture of dry air and
  water vapor
• Dry air exists when water vapor and contaminants
  have been removed from atmospheric air
• ASHRAE Handbook-Fundamentals

49
Atmospheric Air

• Atmospheric air contains a large number of
  gaseous components as well as water vapor and
  miscellaneous contaminants (for example, smoke,
  pollen and gaseous pollutants not normally
  present in free air far from pollutant sources)
• ASHRAE Handbook-Fundamentals

50
Water Vapor

• Water vapor in moist air varies from zero (dry
  air) to a maximum which depends on temperature
  and pressure (saturated air)
• ASHRAE Handbook-Fundamentals

51
Composition of Dry Air
Concentration at
Standard Component Symbol Volume () Conditions
(a)

• Nitrogen N2 78.084 894 g/m3 (b)
• Oxygen O2 20.948 274 g/m3
• Argon Ar 0.934 15 g/m3
• Carbon dioxide CO2 0.0314 565 mg/m3
• Neon Ne 0.00182 15 mg/m3
• Helium He 0.000524 428 ?g/m3
• Methane CH4 0.000200 1309 ?g/m3
• Hydrogen H2 0.000050 41 ?g/m3
• Trace gases (c) 0.000006 123 ?g/m3 (d)
• Total 100.00

52
Focus of Air Quality Control

• Air quality control focuses on the interactions
  between moist air and contaminants

53
ASHRAE Psychrometric Chart
Humidity Ratio
Dew Point Temp
Enthalpy
Wet Bulb Temperature
Specific Volume
Dry Bulb Temperature
Relative Humidity
54
Thermal Psychrometrics
55
IAQ Extension of Psychrometrics
56
ASHRAE Standards 55a-1994, 62-1999, and 62.1-2001
Std. 62.1-2001
Std. 55P 4(2003) (0.012 HR)
Std. 62-1999
57
Psychrometrics of CAD System
Design Dry Bulb Temp with Coincident Wet Bulb
Temp
Return
Relief
2
2
Supply
6
55 F
75 F
Induction Zone
Recirculated
1
4
75 F
Uniform Mixed Zone
3
SHRs
SHRr
2
1
5
6
4
5
OA
Fan
Coil
Filter
3
58
Psychrometrics of CAD System
Design Dew Pt. Temp with Coincident Dry Bulb
Return
Relief
2
2
Supply
6
55 F
75 F
Induction Zone
Recirculated
1
3
4
75 F
Uniform Mixed Zone
SHRs
SHRr
2
1
5
6
4
5
OA
Fan
Coil
Filter
3
59
Psychrometrics of UFAD System
Design Dry Bulb Temp with Coincident Wet Bulb
Temp
Relief
Return
3
Stagnant Zone
77 F
Bypass
2
Uniform Mixed Zone
Recirculated
1
75 F
4
5
3
Mixing Zone
9
3
3
1
2
6
7
8
9
Supply
65 F
8
Plenum
5
6
OA
Fan
SA Terminal
7
4
Filter
Coil
60
Psychrometrics of UFAD System
Design Dew Pt. Temp with Coincident Dry Bulb
Relief
Return
3
Stagnant Zone
77 F
Bypass
2
Uniform Mixed Zone
Recirculated
4
75 F
1
5
3
Mixing Zone
9
1
2
3
3
6
7
8
9
Supply
65 F
8
Plenum
5
6
OA
Fan
SA Terminal
7
4
Filter
Coil
61
Psychrometrics for Thermal and IAQ Control
62
Room Acceptability Factor, K2, vs Room
Contamination Factor, Q2
K2 x2 H(1-e2)MQ2 xo H(1-e2)Me2
63
Micro Acceptability Factor, K1 vs Micro
Contamination Factor, Q1
K1 x1 (1-e1)Q1 x2
64
Ventilation Effectiveness

• Ventilation Effectiveness can be determined from
  Two-Compartment Model
• K1 vs Q1

65
Optional Systems
Central System
Distributed System
66
Energy Strategies
Heat Recovery (Plates, Heat Pipes)
Economizers (Air, water)
67
Air Distribution Strategies
Single/Dual Duct?
PI or PD?
Fan-Powered (S/P) or Induction?
Reheat?
Filter?
Min Pinchdown?
CAD or UFAD
Diffusers (ADPI)
Ventilation Efficiency
Ducted or Plenum Return?
Local Exhaust or Relief Fans?
Return Air Fans?
68
Pressurization Strategies
Draw- or blow-through?
In same pressurization zone
W
PI or PD?
Location on Roof
Optimum Filtration Location?
Reheat?
Filter?
(Exfiltration to adjacent press zones)
Min Pinchdown?
Ceiling Diffusers (ADPI gt 80)
From room or plenum (UFAD)
Ventilation Efficiency
Ducted or Plenum Return?
Local Exhaust or Relief Fans to Outside
Return Air Fans?
69
Conclusions

• IAQ is a part of IEQ.
• Control of IAQ can be evaluated with
  psychrometrics.
• Complete energy and mass balances must be
  achieved to assure system performance.
• System preparedness can also be evaluated with
  psychrometrics.

70
Air Distribution for Occupied Spaces

• Zonal Air Distribution
• Physical Boundaries
• Functional Zones or Boundaries
• Thermostatic Zones
• Moisture, Contaminant and Pressurization Zones
  (Health, Fire-Safety, Environmental Security)
• - Supply, Return, and Exhaust Airflow Rates
• Air Distribution in Occupied Spaces
• CAD Systems (Supply ADPI, Return Ventilation
  Efficiency)
• UFAD Systems (Supply ?T vs V/A, Return ?)

71
Pressurization Zones
Pt Pv ?Pv f(?t), and Pv ?UH2/2g
Ps Pt sin ? or Ps Cp Pv
Pt
?
Lowest Positive Pressure Zone
Psl Ps gt 2.5 (Pa)
?
Ps Pt cos ? or Ps Cp Pv
Intermediate Pressure Zone
Pt
Psll Psl gt2.5 (Pa)
Highest Positive Pressure Zone
?
Pslll Psll gt2.5 (Pa)
Ps
Negative Pressure Areas
Psn Ps X (Pa)
Ambient Air Pressure
72
Schematic of UFAD Systems Specified by
GSAThermal, Ventilation, Pressurization Zones
50FWB/70RH
50FWB/70RH
To other perimeter zones
H/C
Filter
Filter
OA
H/C
To other interior zones
Min Stop for Vent/press
Dedicated 100 OA Vent/Press System
Dedicated 100 OA Vent/Press System
VAV
Ceiling Plenum
Glazing
RAG
TEG
RAG
CD
?P
80 ADPI
?P
P
Interior Zone
Toilet
Finned-tube radiation
Perimeter Zone
T
T
o
FD
FD
FD
RA
100 Shut off
RA
VAV
VAV
Floor Plenum
To other perimeter zones
Min Stop for Vent/press
50 FWB/ gt 64FDB
H/C
OA
Filter
Filter
H/C
OA
Economizer
Economizer
To other interior zones
Perimeter H/C System
Interior H/C System
73
Theoretical Basis for ADPI
80
Houghtens 80 Comfort Data
? (tx tc) 0.07(Vx 30)
70
60
? 0
? -3
? 2
50
Draft Velocity, FPM
40
? Effective Draft Temperature
30
20
10
0
-6 -5 -4 -3 -2 -1
0 1 2 3 4 5
6 Draft Temperature Difference (tx tc ) F
74
Air Diffusion Performance Index (ADPI)
T50 Throw, or axial distance an air stream
travels after leaving the outlet before the
maximum stream velocity is reduced to a terminal
value of 50 fpm.
Improved Performance with VAV
100
80
L Characteristic length for diffuser or grille.
In this case half the distance between diffusers
distance from diffuser to 6 ft above floor.
ADPI
60
40
ADPI is the percentage of locations within an
occupied space (floor to 6 ft, and 2 ft away from
exterior walls) that complies with Draft
Criteria -3 lt ? lt 2 where ? (tx tc )
0.07(V 30)
20
T50/L
75
Characteristics of CAD and UFAD Diffusers
UFAD
Characteristic
CAD
Turbulent Mixing
Displacement
All space loads
Most space loads
Max loads of 4 5 W/ft2
Heat Gains
Room Temp
Uniform in Occ. Space
Uniform from 4 ft above floor
Max gradient lt 6 F
Air Velocity
lt 50 fpm in Occ. Space
lt 50 fpm in Occ. Space
30 - 40 fpm in Occ. Space
ADPI
gt 80 for all space loads
NA
NA
Throw
From ADPI
lt 6 ft vertical
Minimum ( lt 2 ft vertical )
Clear Zone
No minimum
2 4 ft radius
1 2 radius
Supply Air Temp.
55 62 F
62 67 F
68 70 F
Occ.Sp. SAT
12 20 F
8 13 F
2 6 F
Ventilation Effectiveness
1.0 at 80 ADPI and Min. bypass to RAG
1.0 1.2 estimated
1.0 1.2 estimated
76
Characteristics of Return Air CAD and UFAD Grilles
UFAD
Characteristic
CAD
Turbulent Mixing
Displacement
Ceiling, High Sidewall, Low Sidewall, Floor
Ceiling, High Sidewall, High Kiosk
Ceiling, High Sidewall
Location
Uniform spacing to minimize plume instability
Spacing less critical for high bay areas
Minimize Bypass Losses
Spacing
lt 750 fpm or as limited by noise criteria
Limited to minimize plume instability
Inlet Velocity
Limited by noise criteria
77
Energy and Mass Balances for CAD and UFAD Systems

• Follow Steps 1 4 for Design of Healthy
  Buildings
• Step 1 Design Requirements and Criteria
• Steps 2 and 3 Steady or Quasi-steady State
  Analysis
• Determine Thermal, Lighting , Acoustic, and Air
  Quality Loads at Design Conditions
• Make Initial Selection of System Capacities and
  Configurations
• Step 4 Quasi-steady or Dynamic Analysis
• Determine System Controllability
• Calculate Energy Consumption

78
Seven Steps for Design of Healthy Buildings

• Establish design requirements and criteria
• Determine the design loads
• Determine the system capacities
• Design control system for partial loads
• Assemble the design documentation
• Commission the system or building
• Periodically re-evaluate system performance

79
Step 1 Establish Design Requirements and Criteria
Process
References
1.1 Define zones within HVAC systems to be
analyzed
Slides 70 72 Protocol (Session 4) Architectural
Program
1.2 Determine Exposure and other Design
Criteria for each zone (e.g., xo, x1, x2, xs,
C/L Ratio, ER, and BEE, first costs,
operating costs)
Slides 37 - 39, 61 63 Protocol (Session 4)
To 2.1
80
Step 2 Determine Design Thermal Loads for each
Zone
Process
References
2.1 Determine N1, N2, zNs, M for initial
selections of building components and HVAC
systems that service each zone
Slides 61 63 ASHRAE CLTD Method or other load
analysis program
2.2 Compare Sensible and Latent Loads for
compliance with with 1.2, modify selected
components, and reiterate 2.1
Slides 37 - 39, 61 63 Protocol (Session 4)
To 3.1
81
Step 3 Determine Zone and System Capacities (1)
Process
References
3.1 Perform psychrometric analyses for UFAD or
CAD systems
Slides 57 60 ASHRAE HOF
3.2 Determine z, mm, mo, xs, H, Q1, Q2, ?1, ?2,
a
From 2.2 and 3.1 Slides 61 63
From zmm in 3.2 Slides 67, 68, 73 76 ASHRAE HOF
3.3 Select SA Diffuser and RA Grille locations
To 3.4
82
Step 3 Determine Zone and System Capacities (2)
Process
References
3.4 For each contaminant of concern, define K1,
K2 calculate Q1 Q2 for Initial values of H,
?1, ?2
From 3.2 and 3.3 Slides 62 63 ASHRAE Std
62.1-2001
3.5 If K1 and K2 are not in compliance with 3.4,
modify design and iterate 3.1 3.4 for
compliance
To 4.1
83
Step 4 Design Control Systems for Partial Loads
(1)
Process
References
4.1 For systems selected In 3.5, determine
minimum thermal loads for occupied and unoccupied
conditions
See 1.2, 2.1 and 2.2 Slides 67, 68, 71, 72
4.2 Perform psychrometric analyses at minimum and
representative partial loads design control
strategies to achieve compliance with criteria
See 3.1 3.3
To 4.3
84
Step 4 Design Control Systems for Partial Loads
(2)
Process
References
4.3 At minimum loads conditions (4.2), calculate
Q1 Q2 if not in compliance with K1 and K2,
modify control strategies and iterate 4.2 and 4.3
See 3.4 and 3.5
4.4 Calculate ER, EC, and BEE compare with
compliance criteria for UFAD and CAD systems (1.2)
Slides 38, 85 (A response method can be used,
here, see Slide 85)
To Step 5
85
Criteria Excursion Time
Criteria Range
Area Outside Criteria Range
86
Focus of Session 4 Procedures

• Concepts of Building Degradation and
  Accountability
• Distinction between Building Diagnostics and
  Commissioning
• Elements and Chronology of Building Diagnostics
• Principles for Setting Criteria
• Three Phases of Building Diagnostics
• Evaluation and Classification Criteria

87
Three Fundamental Concepts

• Continuous Degradation
• Continuous Accountability
• Building Diagnostics

88
Concept of Continuous Degradation
Non-industrial Buildings
Problem Buildings (20 - 30)
Buildings Without Known Problems (70 - 80)
BRI (5 - 10)
SBS (10 - 25)
UPB (10 - 20)
HB (50 - 70)
89
Types of Problem Buildings

• Sick Building Syndrome (SBS)
• Persistence of symptoms
• Substantial percentage affected
• Rapid relief on exit
• Causes Unknown
• Solve by System Performance

• Building Related Illness (BRI)
• Clinical signs
• More than one affected
• Linkages to indoor exposures
• Solve by Source Removal

90
Healthy Buildings

• Pragmatic (Woods, et al)
• Minimize occupant complaints
• Comply with acceptable criteria
• Exposures
• System performance
• Economic performance

• Ideal (Berglund, et al)
• Free from BRI and discomfort
• Promote well being and health
• Provide for
• Non-hazardous conditions
• Thermal comfort
• Pleasant air quality
• Illumination and acoustic
• satisfaction
• Social needs and
• productivity
• Distinguished aesthetic
• qualities

• Undetected Problems
• Some discomfort and symptoms
• Non-compliance with some
• acceptable criteria

91
The Healthy Building Cycle
Building Diagnostics
Intervention
Continuous Accountability
Healthy Building
Problem Building
92
Commitments needed forContinuous Accountability

• Accountable person must be
• Explicitly identified for each phase in
  buildings life
• Empowered with authority to assure building
  performance
• Educated and trained to assure adequate building
  performance and occupant protection

93
Planning Conceptual Design
Occupancy Functional Performance
Assure
Set
Owner Financier Planner Designer
Owner Manager Tenant Occupant
Healthy Building
Designer Builder
Owner Financier
Builder Designer Owner Tenant
Evaluate
Translate
Accountability
Detailed Design Construction
Commissioning Substantial Completion
Performance Criteria
94
Building Diagnostics (Dx) and Commissioning (Cx)
Dx is a process in which a skilled expert draws
on available knowledge, techniques and
instrumentation in order to predict a
buildings likely performance over time. (BRB
1985)
Cx is a quality-focused process for enhancing
the delivery of a project. The process focuses
on verifying and documenting that the facility
and all of its systems and assemblies are
planned, designed, installed, tested, operated,
and maintained to meet the owners project
requirements. (ASHRAE 2002)

• Dx is a process that tests for expected
  performance and leads
• to interventional decisions.
• Cx is a process that certifies attainment of the
  expected
• performance.

95
Elements of Dx
Four Essential Steps
Three Phases
1. Observation form preliminary hypothesis 2.
System Analysis test preliminary hypothesis 3.
Exposure Analysis validate or refute hypothesis
with quantitative data
1. Knowledge of what to measure 2.
Availability of appropriate instrumentation 3.
Expertise in interpreting measurements 4.
Capability of predicting likely performance

• Hypothesis relates 3 Ss
• Sources
• Systems
• Symptoms

Procedure Evaluate -- Classify
96
Chronology of Dx
Conceptual Design
Detailed Design
Prescriptive Criteria
Virtual Building (Commissioning)
Performance Criteria
Construction
Actual Building (Re-commissioning)
Operations
97
Diagnostic ObjectivesContingency Matrix

• Problem Buildings
• Maximize True Positive
• Minimize False Negative

Event Occurrence
No
Yes
False Positive
True Positive
Yes

• Healthy Buildings
• Maximize True Negative
• Minimize False Positive
• or False Negative,
• depending on consequences

Measurement
False Negative
True Negative
No

• Enhanced Preparedness
• Maximize True Negative
• Minimize False Negative

98
Three Phases of Building Diagnostics
Building Client
Problem Building?
Enhanced Preparedness?
Stringent Criteria
No
Yes
No
Yes
Stringent Criteria
Diagnose All Vulnerable Areas
Diagnose Specific Areas
Lenient Criteria
Diagnose All Areas
Phase I Observational
Additional Diagnostics Needed?
Recommendations For Interventions
Assurance of Healthy Building
No
No
Yes
Phase II System Analysis and Phase III
Exposure Analysis, as needed
99
Phase 1 Protocol
Obtain Data on Human Responses, Exposures,
System Performance, Economic Performance
Define Performance Criteria
Analyze Data
Classify Facility Or Area?
No
Submit Report
No
Implement Interventions?
Yes
Yes
Formulate Preliminary Hypothesis?
No
Proceed to Phases 2 or 3
Make Recommendations
Yes
No
Predict Trends
Identify Feasible Interventions?
Establish Goal for Remediation Based on Risk
Assessment
Perform Preliminary Benefit-Cost Analysis
Yes
100
Phase 2 Protocol
Obtain Data on Human Responses, Exposures,
System Performance, Economic Performance
Analyze or Simulate Data
Define Performance Criteria
Classify Facility Or Area?
Select Zones Within Functional Areas
No
Submit Report
No
Implement Interventions?
Yes
Yes
Validate Preliminary Hypothesis?
No
Proceed to Phase 3
Yes
No
Make Recommendations
Predict Trends
Identify Feasible Interventions?
Establish Goal for Remediation Based on Risk
Assessment
Yes
Perform Benefit-Cost Analysis
101
Phase 3 Protocol
Obtain Data on Human Responses, Exposures,
System Performance, Economic Performance
Analyze or Simulate Data
Define Performance Criteria
Select Zones Within Functional Areas
Classify Facility Or Area
Submit Report
No
Implement Interventions?
Yes
Validate Hypothesis?
No
Modify Hypothesis
Yes
No
Make Recommendations
Predict Trends
Identify Feasible Interventions?
Establish Goal for Remediation Based on Risk
Assessment
Yes
Perform Benefit-Cost Analysis
102
Evaluation Criteria

• Set of measurable and controllable parameters and
  corresponding values
• Mandatory Criteria
• Directly affect occupants
• (Exposure Human Response criteria)
• Non-compliance failure
• Flexible Criteria
• Indirectly affect occupants
• (System and Economic Performance criteria)
• Non-compliance fault

103
Sources or Loads
Human Responses
Systems
Exposures
Thermal Contaminants Lighting Acoustics
Structure Envelope Services Enclosures
Thermal Air Quality Illumination Acoustics
Envir-Percep Pers-Percep Envir-Affective Pers-Affe
ctive
First Costs
Operating Costs
Energy Use
Productivity
Economics
104
Four Domains of Human Response
Aspects of Response
Object of Response
Perceptual
Affective

• External
• Sensory
• Responses

• Acceptability

Environmental

• Preference

• Internal
• Sensory
• Responses

• Comfort

Personal State

• Well being

105
Exposure Criteria

Continuous Exposure Parameters
Human Response Criteria Percent Acceptability
Thermal
IAQ
Lighting
Acoustics
Std 55
Std 62
Std 90
Ch 46 App
95
Feasible Max
95
95
95
Selected Percentage
?
?
?
?
Predetermined Min
80
80
80
80
106
System Performance CriteriaBased on exposure
criteria and loads

• At design loads, system capacity should
• maintain the exposure values within the specified
  limits

• At part loads, the system controls
• should
• maintain the exposure values within
• the same limits as at design loads

107
Energy and Economic Performance Criteria

• System energy efficiency of at least 70 should
  be achieved
• Selected system should incur minimum life-cycle
  cost, wherein comparison of alternatives includes
  weighting for productivity and preparedness
  improvements in the environment

108
Measures of Occupant Performance ( Ex Schools)
Exposed Occupants
Long-term
Short-term

• Teachers
• Librarians
• Faculty
• Students
• Staff

• Students
• Parents and visitors
• Faculty
• Inspectors
• Accreditors

Occupancy

• lost
• concentration
• achievement
• absentees
• medical visits/yr

• lost
• concentration
• medical visits/yr
• hampered
• performance

Figures of Merit
109
Measures of Productivity (Ex Offices)

• Cost of salaries and wages for substitute workers
  due to sick leave
• Lost revenue due to absence of workers
• Direct and indirect health-care costs due to
  worker illnesses
• Productivity Impact Factors
• Ratio of cost savings from intervention to costs
  at risk (I.e, salaries, health -care costs, etc.)

110
Measures of Preparedness (Ex Offices)

• Time to isolate impacted zone from other zones
• Time to compartmentalize and pressurize or
  de-pressurize zones
• Time of egress from impacted zone
• Effectiveness of removal control strategies
  (e.g., contaminant removal rate)

111
Classification Criteria

• Healthy Category
• H2 Compliance with all Evaluation Criteria
  (Enhanced Performance, e.g., productivity or
  preparedness)
• H1 Compliance with all Evaluation Criteria
  (Transparent Performance)
• Marginal Category
• M3 Non-compliance with Economic Criteria
• M2 Non-compliance with System Performance
  Criteria
• M1 Non-compliance with Exposure Criteria
• Problematic Category
• P3 Non-compliance with Discomfort Criteria
• P2 Non-compliance with Symptom Criteria
• P1 Non-compliance with Illness Criteria

112
Healthy Category Examples of H2 and H1
Classifcations
Category
Classification
Evaluation Criteria
113
Marginal Category Examples of M3 Classification
Category
Classification
Evaluation Criteria
Annual costs of housekeeping services lt
(TBD)/ft2, including cleaning of floor
plenum. Annual costs of churn services lt
(TBD)/ft2, including modifications of CAD or
UFAD systems. Annual costs of maintenance
services lt (TBD)/ft2, including adjustments to
CAD or UFAD systems.
Selected system should incur minimum life-cycle
cost, wherein comparison of alternatives includes
weighting for productivity improvements in the
environment.
114
Marginal Category Examples of M2 Classification
Evaluation Criteria
Category
Classification
M2 Compliance with all Evaluation Criteria
except System Performance Criteria.
115
Marginal Category Examples of M1 Classification
Category
Classification
Evaluation Criteria
M1 Compliance with all Evaluation Criteria
except Exposure Criteria.
Thermal Operative Temperature 74 4 F
throughout occupied space Relative Humidity
45 15 throughout occupied space Air speed lt
50 fpm throughout occupied space Temperature
gradient lt 5 F from floor to 6ft above floor.
IAQ CO2 lt 800 ppm throughout occupied
space TVOC, lt 500 µg/m3 throughout occupied space
PM10 lt 50 µg/m3 throughout occupied space Indoor
(occupied space) to outdoor bioaerosol ratios lt
0.5 with similar I/O taxa.
116
Problematic Category Examples of P3, P2 and P1
Classifications
Category
Classification
Evaluation Criteria
117
Evolving ProtocolCompliance with Evaluation
Criteria
Start
Phase 1 - Phase 3 Procedures
Human Response Data?
Clinical Signs?
Yes
Yes
Yes
Discomfort?
Symptoms?
Yes
No
P1
P2
No
No
Exposure?
Problematic
Exposure?
No
No
No
M1
P3
Yes
Yes
M1
Systems?
Marginal
Systems?
No
M2
No
M2
M3
M3
Yes
Yes
Economics?
Economics?
No
No
Healthy
H1
H1
Yes
Yes
118
H1
Proactive Procedure
Degradation Rate
M3
Intervention Alternatives
M2
Building Performance Classification
M1
Reactive Procedure
Status
P3
P2
Bid
SC
W
X
Time in Buildings Life
119
Phase I Report
Phase II Report
Design and Initial Occupancy Period
Recorded Complaint Period
Prognosis Report
H
M3
M2
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
With Intervention
M1
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
?
BUILDING PERFORMANCE CLASSIFICATION
x
P3
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
P2
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
?
Without Intervention
P1
x
x
x
x
x
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
TIME
120
Commissioning
H2
H1
M3
Installed Interventions
Post-Intervention Measuring Period
Sustainability?
M2
Building Performance Classification
M1
Pre-Intervention Measuring Period
P3
P2
Bid
SC
W
X
Y
Time in Buildings Life
121
Conclusions

• Objective, measurable and controllable Evaluation
  Criteria are essential to Building Diagnostics
• Classification Criteria focus design and
  management decisions
• To provide assurance, criteria must be set before
  diagnostics are conducted

122
Focus of Session 5 Practice

• Discuss Problem Statement
• Select a set of Evaluation Criteria
• Conduct a Phase 1 Dx
• Form Preliminary Hypotheses and Recommendations
  for Discussion
• If needed, Conduct a Phase 2 Dx
• Validate, Refute or Revise Preliminary Hypotheses
• Revise Recommendations for Discussion

123
Example Problem Project

• A general office area for a mid-level floor of a
  new speculative building in Washington, DC

124
Example Problem Program Objectives

• Provide an office environment that is
• Conducive to high expectations of human response
  and occupant performance
• Protective of exposures from contaminants that
  are naturally occurring (e.g., mold), accidental
  (e.g., spills, fire and smoke), and intentional
  (e.g., chemical, biological, radiological)
• Energy Efficient and Cost Effective

125
Example Problem Problem Statement

• Determine if CAD, UFAD, or a combination of
  systems is appropriate to meet the Program
  Objectives

126
Example Problem Sketch of Floor Plan
15
Perimeter 8,700 ft2
15
45
80
45
15
25
Interior 12,100 ft2
St
St
SW
Lobby
El
MER
40
M
Core 3,200 ft2
El
MER
W
SW
St
25
N
15
127
Example ProblemGeneral Characteristics
128
Evaluation Criteria for Example Problem

• Human Response
• Exposures
• System Performance
• Energy and Economic Performance
• Healthy Building Performance

129
Human Response Criteria for Example Problem
Category
Classification
Evaluation Criteria
130
M1 Thermal Exposure Criteria for Example Problem
Evaluation Criteria
Comments
131
M1 Contaminant Exposure Criteria for Example
Problem
Evaluation Criteria
Comments
132
M1 Lighting and Noise Exposure Criteria for
Example Problem
Evaluation Criteria
Comments
133
M2 System Performance Criteria for Example
Problem
Evaluation Criteria
Comments
134
M3 Energy and Economic Criteria for Example
Problem
Evaluation Criteria
Comments
135
H1 and H2 Healthy Building Criteria for Example
Problem
Evaluation Criteria
Comments
136
Phase 1 Dx for Example Problem (90 min)

• Prepare and review system schematics and layouts
• Review zones and systems
• ADPI or Clear Area Zones
• Psychrometrics
• Energy and mass balances
• Formulate Preliminary Hypothesis
• Prepare Preliminary Recommendations

137
Preliminary Hypotheses
138
Preliminary Recommendations
139
Discussion
140
Phase 2 Dx for Example Problem (105 min)

• Verify loads, psychrometrics, energy and mass
  balances
• Validate or refute Preliminary Hypothesis
• Classify Building and System Performance
• Prepare Recommendations

141
Focus of Session 6 (120 min)

• Discuss Results of Practice Session and Future
  Directions
• Present Findings and Recommendations
• Discuss Differences in Preliminary and Final
  Hypotheses and Recommendations
• What additional information would be helpful in
  deciding on UFAD or CAD systems?
• What can be done to make this training course
  more useful?
• What additional seminars and short courses on
  these subjects would you recommend developing?

142
THE BUILDING DIAGNOSTICS RESEARCH INSTITUTE,
INC. 5630 Wisconsin Avenue, Suite 706 Chevy
Chase MD 20815-4455 Phone [phone] FAX
301.951.5953 www.buildingdiagnostics.org E-mail
jewoods3_at_aol.com
143
ASHRAE Psychrometric Chart