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a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
1
© 2006 American Standard All rights reserved
HVAC Systems and Airside Economizers
anEngineers Newsletter Live telecast
“Trane” is a Registered Provider with The American Instituteof Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members available on request.
This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, ordealing in any material or product.Questions related to specific materials,methods, and services will be addressedat the conclusion of this presentation.
© 2006
Am
erican Standard Inc.
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
2
© 2006
Am
erican Standard A
ll rights reserved
Copyrighted MaterialsThis presentation is protected byU.S. and international copyright laws. Reproduction, distribution, display, and use of the presentation without written permission of Trane or American Standard is prohibited.
© 2006 American Standard All rights reserved
© 2006
Am
erican Standard A
ll rights reserved
AIA continuing educationLearning ObjectivesParticipants will learn the following about airside economizers:
ASHRAE/IESNA Standard 90.1-2004 requirements
How issues, such as building pressurization, affect economizer operation
Ways to control airside economizer systems based on HVAC system type and location
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
3
© 2006
Am
erican Standard A
ll rights reserved
airside economizersToday’s Topics What an airside economizer is
Reasons and exceptions for use
Types of control
Performance in constant- vs. variable-air-volume systems
Implementation in different systems
Application considerations
© 2006
Am
erican Standard A
ll rights reservedToday’s Presenters
Brian Fiegenmanager, applicationsengineering
Dennis Stankestaff applicationsengineer
John Murphysr applicationsengineer
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
4
© 2006 American Standard All rights reserved
What Is an Airside Economizer?
HVAC systems andairside economizers
© 2006
Am
erican Standard A
ll rights reserved
definitions Airside Economizer“1. Device that, on proper variablesensing, initiates control signals oractions to conserve energy …
“2. Control system that reducesthe mechanical heating and cooling requirement … ”
ASHRAE Terminologyof Heating, Ventilation,Air Conditioning & Refrigeration
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
5
© 2006
Am
erican Standard A
ll rights reserved
definitionsAirside Economizer“A duct-and-damper arrangement and automatic control system that togetherallow a cooling system to supply outdoorair to reduce or eliminate the need for mechanical cooling during mild orcold weather”
ASHRAE/IESNAStandard 90.1-2004
SAOA
RA
RL
space
T
Single Zone, Constant Air Volume (CAV)©
2006Am
erican Standard A
ll rights reserved
Supply-air temperaturevaries to match cooling load
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
6
© 2006
Am
erican Standard A
ll rights reserved
0
heating mechanical cooling
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min outdoor air
CAV systemOperating Modes
heatingcapacity
© 2006
Am
erican Standard A
ll rights reserved
CAV system without economizerOperating Modes
0
heating mechanical cooling
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min
coolingcapacity
outdoor air
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
7
© 2006
Am
erican Standard A
ll rights reserved
CAV system with economizerOperating Modes
0
heatingmodulated
econ
outdoorair
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min mech clgcapacity
© 2006
Am
erican Standard A
ll rights reserved
CAV system with economizerOperating Modes
0
heatingintegrated
econ
outdoorair
modulatedecon
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min
mech clgcapacity
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
8
© 2006
Am
erican Standard A
ll rights reserved
CAV system with economizerOperating Modes
0
mechcoolingheating
integratedecon
outdoorair
modulatedecon
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min
mech clgcapacity
CAV system with economizerOperating Modes
mechanical coolingmin OA
heatingmin OA
modulatedeconomizermin to100% OA
integratedeconomizer100% OA
high-limit shutoff
© 2006
Am
erican Standard A
ll rights reserved
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
9
© 2006 American Standard All rights reserved
Why Use anAirside Economizer?
HVAC systems and airside economizers
© 2006
Am
erican Standard A
ll rights reserved
airside economizerWhy Use It?
Comply with ASHRAE 90.1-2004, Section 6.5.1 …or local energy code
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
10
1a
2a
3a
4a
7a
2b3b
3c
*Alaska = Zones 7, 8Hawaii = Zone 1a
U.S. climate zones*
4c6b
7b
5b5a6a
7 very cold8 subarctic
5 cool6 cold
3 warm4 mixed
1 very hot2 hot
cmarine
bdry
amoist
© 2006
Am
erican Standard A
ll rights reserved
warm,humid
4b
© 2006
Am
erican Standard A
ll rights reserved
6
6
6
77
Halifax
8
Vancouver
Prince George
Ft. Nelson
Whitehorse
ReginaWinnipeg
St. John’s
Inuvik
Ft. Smith
Calgary
Saskatoon Kapuskasing
Montreal
Goose Bay
Toronto
8
8 8
57
5
7
6777
7Kamloops
Canadaclimate zone examples
Climate zones of citieslisted in Table B-2,ASHRAE 90.1-2004
7 very cold
8 subarctic
5 cool
6 cold
Québec
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
11
© 2006
Am
erican Standard A
ll rights reserved
11
1
43Mexico City
Monterrey
Tampico
Guadalajara
Veracruz
Mérida
3
Mexicoclimate zone examples
Climate zones of citieslisted in Table B-3, ASHRAE 90.1-2004
3 warm
4 mixed
1 very hot
2 hot
4b
cmarine
bdry
amoist
© 2006
Am
erican Standard A
ll rights reserved
System 65,000 Btu/h?Economizer required
System 135,000 Btu/h?Economizer required
EconomizerNOT required
Std 90.1’s economizer requirementsException (a)
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
12
© 2006
Am
erican Standard A
ll rights reserved
airside economizer useStd 90.1’s Exceptions(a) Individual fan-cooling units with
less-than-minimum capacities installed in specific climate zones
(b) Systems with gas-phase outdoor air cleaningto meet ASHRAE Standard 62
(c) Systems with > 25% of supply airserving spaces humidified above35°F DP for process needs
(d) Systems with condenser heat recovery
© 2006
Am
erican Standard A
ll rights reserved
airside economizer useStd 90.1’s Exceptions(f) Residential space systems with capacities
< 5× limit in Exception (a)
(f) Space sensible cooling load transmission+ infiltration load at 60°F
(g) Systems that operate < 20 hr/wk
(h) Supermarket applications, where outdoor air for cooling affects open refrigerated cases
(i) Systems with high mechanical cooling efficiency ( Table 6.3.2 requirements)
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
13
© 2006
Am
erican Standard A
ll rights reserved
airside economizerWhy Use It?
Comply with ASHRAE 90.1-2004,Section 6.5.1 …or local energy code
Reduce operating costs
© 2006
Am
erican Standard A
ll rights reserved
airside economizer (Columbus)HVAC Energy Savings
base VAV CAV75
80
85
90
95
100
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
14
© 2006
Am
erican Standard A
ll rights reserved
airside economizer (Cincinnati)HVAC Energy Savings
CAVVAVbase75
80
85
90
95
100H
VA
C e
ner
gy
con
sum
pti
on,
% o
f b
ase
© 2006
Am
erican Standard A
ll rights reserved
airside economizerWhy Use It?
Comply with ASHRAE 90.1-2004,Section 6.5.1 …or local energy code
Reduce operating costs
Earn LEED-NC v2.2 certification EA Prerequisite 2: Must comply
with ASHRAE 90.1-2004 EA Credit 1:
Optimize energy cost
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
15
© 2006 American Standard All rights reserved
EconomizerControl Types
HVAC systems and airside economizers
Disable econ Enable econ(up to 100% OA) (minimum OA)
Control type when OA is: when OA is:
Fixed dry bulb Warmer than Cooler thanfixed setting fixed setting
Differential dry bulb Warmer than RA Cooler than RA
Fixed enthalpy Higher thermal Lower thermalenergy than fixed energy than fixedsetting setting
Electronic enthalpy Above fixed DB Below fixed DBvs. DP curve vs. DP curve
Differential enthalpy Higher thermal Lower thermal(comparative enthalpy) energy than RA energy than RA
Dew point & dry bulb Warmer or wetter Cooler and drier(fixed DB with than fixed DB,DP than fixed DB,DPDP lockout) settings settings
Allowed Types of Economizer Control©
2006Am
erican Standard A
ll rights reserved
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
16
humidity ratio, grains/lb of dry air
dry-bulb temperature, °F
© 2006
Am
erican Standard A
ll rights reserved
wet-bulb temperature, °F
minimumOA intake
high-limitshutoff
econOFF
econOFF
economizerON
economizer control type:Fixed Dry Bulb
4b
cmarine
bdry
amoist
© 2006
Am
erican Standard A
ll rights reserved
Prescribed High-Limit Settingsfor economizer shutoff
For Fixed DB,OA > 75°F
For Fixed DB,OA > 70°F
For Fixed DB,OA > 65°F
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
17
© 2006
Am
erican Standard A
ll rights reserved
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °F
minimumOA intake
econOFF
econOFF
high-limit shutoff75°F DB
economizerON
55°F
missed opportunities:Fixed Dry Bulb
possible increasedcooling tons
© 2006
Am
erican Standard A
ll rights reserved
economizer control type:Fixed Enthalpy
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °FeconOFF
economizerON
high-limit shutoff28 Btu/lb
minimumOA intake
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
18
© 2006
Am
erican Standard A
ll rights reserved
missed opportunities:Fixed Enthalpy
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °FeconOFF
high-limit shutoff28 Btu/lb
minimumOA intake
55°F
75°F
economizerON
possible missed CVeconomizer hours
possible increasedcooling tons
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °F
© 2006
Am
erican Standard A
ll rights reserved
econOFF
minimumOA intake
economizer control type:Electronic Enthalpy
high-limit shutoffcurve “A”
economizerON
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
19
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °F
© 2006
Am
erican Standard A
ll rights reserved
econOFF
minimumOA intake
high-limit shutoffcurve “A”
missed opportunities:Electronic Enthalpy
75°F
55°F
missedeconomizerhours
economizerON
possible increasedcooling tons
© 2006
Am
erican Standard A
ll rights reserved
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °FeconOFF
minimumOA intake
high-limitshutoff range
economizer control type:Differential Enthalpy
economizerON
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
20
© 2006
Am
erican Standard A
ll rights reserved
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °FeconOFF
minimumOA intake
high-limitshutoff range(hOA > hRA)
missed opportunities:Differential Enthalpy
75°F
55°F
economizerON
© 2006
Am
erican Standard A
ll rights reserved
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °FeconOFF
minimumOA intake
high-limitshutoff55°F DP OA
high-limitshutoff75°F DB OA
economizer control type:Dew-Point and Dry-Bulb Temperatures
economizerON
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
21
© 2006
Am
erican Standard A
ll rights reserved
humidity ratio, grains/lb of dry air
wet-bulb temperature, °F
dry-bulb temperature, °FeconOFF
minimumOA intake
missed opportunities:Dew-Point and Dry-Bulb Temperatures
high-limitshutoff55°F DP OA
55°F
possible missedeconomizer hours
high-limitshutoff75°F DB OA
economizerON
cmarine
bdry
amoist
Limitations on Economizer Control Types©
2006Am
erican Standard A
ll rights reserved
No fixedenthalpy
Any control type
No differentialdry bulb
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
22
© 2006
Am
erican Standard A
ll rights reserved
economizer controlHigh-Limit Shutoff It’s an enable/disable point,
prescribed by control type and climate (see Table 6.5.1.1.3B)
“Right” limit setting should yield largest energy-use reduction
If analysis shows a “better” setting: Ask for a variance, or Use Energy Cost Budget Method
(Section 11)
© 2006
Am
erican Standard A
ll rights reserved
economizer controlIntegrated Economizer Extends economizer hours to save
more cooling energy
Must use everywhere—except almost anywhere
“Economizer systems shall be integrated with the mechanical cooling system and be capable of providing partial cooling even when additional mechanical cooling is required to meet the remainder of the cooling load”
ASHRAE/IESNA Std 90.1-2004, Section 6.5.1.3
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
23
cmarine
bdry
amoist
Integrated Economizer Exceptions
© 2006
Am
erican Standard A
ll rights reserved
DX systems that reduce OA to prevent frosting
Small DX systems with capacities < 65,000 Btu/h
Any system in most climates
integratedeconomizerrequired
© 2006
Am
erican Standard A
ll rights reserved
economizer controlIntegrated Economizer Use in chilled water systems whenever
possible—even if not required
Use with care in built-up DX systemsLow-load operation can lead to: Very cold coil temperatures and frosting Compressor flooding and excessive
cycling, and possible premature failure Out-of-control space relative humidity
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
24
© 2006
Am
erican Standard A
ll rights reserved
CAV-system operating modesIntegrated Economizer
0
mechcoolingheating
integratedecon
modulatedecon
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min
high-limitshutoff
outdoor air
© 2006
Am
erican Standard A
ll rights reserved
CAV-system operating modesNon-Integrated Economizer
0
heatingmechanical
cooling
outdoorair
modulatedecon
OA
inta
ke f
low
, %
OA temperaturecold hot
100
min
mech clgcapacity
low-limitenable
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
25
© 2006 American Standard All rights reserved
Performance in a Constant-Volume System
HVAC systems and airside economizers
© 2006
Am
erican Standard A
ll rights reservedEconomizer Performance Compare:
Economizer control types High-limit shutoff settings
Assess impact on: Energy use Space humidity
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
26
© 2006
Am
erican Standard A
ll rights reserved
Building Analysis ToolsTRACE™ 700HVAC load design and analysis software
Comprehensive energy andeconomic analysis for virtuallyany building
Also tracks space humiditylevels
© 2006
Am
erican Standard A
ll rights reserved
TRACE™ 700Space Humidity Profile
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
27
5a
cmarine
bdry
amoist
warm,humid
Retail storeConstant-volume system
Office buildingVAV system
Columbus, Ohio
SA
OA
RA
EA
space
© 2006
Am
erican Standard A
ll rights reserved
T
High-limit shutoff:
55°F 70°F 65°F 75°F
single-zone CAV system
economizer control type:Fixed Dry Bulb
MA
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
28
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Energy: Fixed Dry Bulb
8%
15%13%
75
80
85
90
95
100
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
none 55°F 65°F 70°F 75°Fhigh-limit shutoff setting (fixed DB)
13%
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
60
5550
4540
3530
wet-bulb temperature, °F
OA
RA
70°F high-limitshutoff setting
75°F high-limit shutoff setting
MA
SA
© 2006
Am
erican Standard A
ll rights reserved
*Single-zone CAV system: Mild, rainy day in Columbus, Ohio
fixed dry bulb:Example at Part Load*
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
29
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Humidity: Fixed Dry Bulb
0
50
100
150
200
250h
ours
wit
h s
pac
e R
H >
58
% 206
nonehigh-limit shutoff setting (fixed DB)
206 208228218
55°F 65°F 70°F 75°F
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
OA
RA
MA
SA
RASA
70°F high-limitshutoff setting
75°F high-limit shutoff setting
© 2006
Am
erican Standard A
ll rights reserved
*Single-zone CAV system: Mild, rainy day in Columbus, Ohio
fixed dry bulb:Example at Part Load*
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
30
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Energy: DP Lockout
8%
13%15%
13% 14%
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
none 55°F 65°F 70°F 75°Fhigh-limit shutoff setting (fixed DB)
75°F DB,55°F DP
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Humidity: DP Lockout
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250206 206 208
228218 206
none 55°F 65°F 70°F 75°Fhigh-limit shutoff setting (fixed DB)
75°F DB,55°F DP
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
31
SA
OA
RA
EA
space
© 2006
Am
erican Standard A
ll rights reserved
h
single-zone CAV system
High-limit shutoff:
23 Btu/lb 32 Btu/lb 28 Btu/lb
economizer control type:Fixed Enthalpy
MA
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Energy: Fixed Enthalpy
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
none 70°Ffixed DB
75°F DB,55°F DPlockout
23Btu/lbfixed h
28Btu/lbfixed h
32Btu/lbfixed h
15% 14%16%
11%
14%
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
32
© 2006
Am
erican Standard A
ll rights reserved
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
OA
RA
MASA
*Single-zone CAV system: Hot, dry day in El Paso, Texas
SA
fixed enthalpy:Example at Part Load*
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Humidity: Fixed Enthalpy
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250
none 70°Ffixed DB
75°F DB,55°F DPlockout
23Btu/lbfixed h
28Btu/lbfixed h
32Btu/lbfixed h
206 218 206 206 216207
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
33
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
shutoff setting
© 2006
Am
erican Standard A
ll rights reserved
*Single-zone CAV system
economizer control type:Electronic Enthalpy (h)*
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Energy: Electronic Enthalpy
16%15% 14% 15%
none 70°Ffixed DB
75°F DB,55°F DPlockout
28Btu/lbfixed h
electronicenthalpy
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
34
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Humidity: Electronic Enthalpy
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250207 207206206 218
none 70°Ffixed DB
75°F DB,55°F DPlockout
28Btu/lbfixed h
electronicenthalpy
SA
OA
RA
EA
space
© 2006
Am
erican Standard A
ll rights reserved
h
single-zone CAV system
hRA
economizer control type:Differential Enthalpy
MA
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
35
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Energy: Differential Enthalpy
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
none 70°Ffixed DB
75°F DB,55°F DPlockout
28Btu/lbfixed h
electronicenthalpy
differentialenthalpy
16%16%15% 14% 15%
© 2006
Am
erican Standard A
ll rights reserved
CAV system (Columbus)Humidity: Differential Enthalpy
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250206 218 206 211207 207
none 70°Ffixed DB
75°F DB,55°F DPlockout
28Btu/lbfixed h
electronicenthalpy
differentialenthalpy
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
36
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
OA
75°F DB50%RH
*Single-zone CAV system: Mild, rainy day in Columbus, Ohio
differential enthalpy:Example at part load*
© 2006 American Standard All rights reserved
Performance in a Variable-Volume System
HVAC systems and airside economizers
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
37
© 2006
Am
erican Standard A
ll rights reserved
VAV system (Columbus)Energy: Fixed Dry Bulb
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
none 55°F 65°F 70°F 75°Fhigh-limit shutoff setting (fixed DB)
8%
11%10%9%
75°F DB,55°F DP
11%
© 2006
Am
erican Standard A
ll rights reserved
VAV system (Columbus)Humidity: Fixed Dry Bulb
nonehigh-limit shutoff setting (fixed DB)
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250
29
55°F 65°F 70°F 75°F
319 2619
75°F DB,55°F DP
8
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
38
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
OA
RA
MA
SA
RASA
75°F high-limit shutoff setting
© 2006
Am
erican Standard A
ll rights reserved
*VAV system: Mild, rainy day in Columbus, Ohio
55°F SAtemperature
fixed dry bulb:Example at part load*
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
OA55°F
SA setpoint70°F economizershutoff setting
RA
MA
MA/SA
RASA
*VAV system: Columbus, Ohio
© 2006
Am
erican Standard A
ll rights reserved
VAV system:Economizer Effect on Space Humidity*
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
39
© 2006
Am
erican Standard A
ll rights reserved
VAV system (Columbus)Energy: Fixed Enthalpy
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
11%10% 9% 8%11% 11%
none 70°FfixedDB
75°F DB,55°F DPlockout
23Btu/lbfixed h
28Btu/lbfixed h
32Btu/lbfixed h
electronicenthalpy
© 2006
Am
erican Standard A
ll rights reserved
VAV system (Columbus)Humidity: Fixed Enthalpy
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250
none 70°FfixedDB
75°F DB,55°F DPlockout
23Btu/lbfixed h
28Btu/lbfixed h
32Btu/lbfixed h
electronicenthalpy
1919 1929 19 8 2
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
40
© 2006
Am
erican Standard A
ll rights reserved
none 70°Ffixed DB
75°F DB,55°F DPlockout
28Btu/lbfixed h
electronicenthalpy
differentialenthalpy
VAV system (Columbus)Energy: Differential Enthalpy
11%10% 11% 12%11%
HV
AC
en
erg
y co
nsu
mp
tion
,%
of
bas
e
75
80
85
90
95
100
© 2006
Am
erican Standard A
ll rights reserved
VAV system (Columbus)Humidity: Differential Enthalpy
29 19 8 19 1819
hou
rs w
ith
sp
ace
RH
> 5
8%
0
50
100
150
200
250
none 70°Ffixed DB
75°F DB,55°F DPlockout
28Btu/lbfixed h
electronicenthalpy
differentialenthalpy
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
41
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
OA
SA
55°FSA setpoint
60°FSA setpoint
RA
RA
*VAV system: Columbus, Ohio
© 2006
Am
erican Standard A
ll rights reserved
VAV system:SA Temperature Reset*
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
wet-bulb temperature, °F
55°FSA setpoint
modulatedeconomizer
integratedeconomizer
55°FSA setpoint
Traditional VAV System©
2006Am
erican Standard A
ll rights reserved
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
42
180
160
140
120
100
80
60
40
20
0
humidity ratio, grains/lb of dry air
11030 40 50 60 70 80 10090dry-bulb temperature, °F
85
80
75
70
65
60
5550
4540
3530
48°FSA setpointreset
Cold-Air VAV System
© 2006
Am
erican Standard A
ll rights reserved
wet-bulb temperature, °F
integratedeconomizer
modulatedeconomizer
© 2006
Am
erican Standard A
ll rights reservedEnergy/Humidity Effects Control strategy and high-limit shutoff
setting impact energy use AND indoor humidity levels
TRACE 700 can aid in analyzing various economizer control strategies
SA temperature reset can save cooling and reheat energy, BUT …increases supply fan and preheat energy, and raises space humidity
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
43
© 2006 American Standard All rights reserved
ImplementingAirside Economizers
HVAC systems and airside economizers
© 2006
Am
erican Standard A
ll rights reserved
ImplementingAirside Economizers Single-zone systems
Multiple-zone systems
Dedicated outdoor-air systems
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
44
© 2006
Am
erican Standard A
ll rights reserved
single-zone systemsPackaged DX Rooftop
OA
RRA SA
Size OA intake hood for design airflow of system
© 2006
Am
erican Standard A
ll rights reserved
single-zone systemsIndoor Air Handler
Size OA duct for the air handler’s design airflow
SA
OA
RRA
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
45
© 2006
Am
erican Standard A
ll rights reserved
single-zone systemsUnit Ventilators
OA
RRA
SA
minimum = 1 ft
Size OA intake forthe unit ventilator’sdesign supply airflow
© 2006
Am
erican Standard A
ll rights reserved
multiple-zone systemsOutdoor Air Handler
RRA
SA
VAV terminals
Measure and controloutdoor airflow to maintainproper airflow rates
OA
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
46
© 2006
Am
erican Standard A
ll rights reserved
VAV terminals
multiple-zone systemsIndoor Air Handler
RRA
OA SA
Measure and control outdoor airflowto maintain proper airflow rates
alt
Options include flow-sensing dampersand airflow measurement stations
© 2006
Am
erican Standard A
ll rights reserved
multiple-zone systemsCommercial Self-Contained
RRA
RRA
minimumOA
RRA
SA
SA
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
47
© 2006
Am
erican Standard A
ll rights reserved
multiple-zone systems (central AHU)Commercial Self-Contained
DX coil
condensers
economizer coil
cooling tower
© 2006
Am
erican Standard A
ll rights reserved
dedicated outdoor-air systemsCentral Air Handling
RRA
RRA
SA
minimumOA
conditionedOA
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
48
© 2006
Am
erican Standard A
ll rights reserved
dedicated outdoor-air systemsWater-Source Heat Pumps
minimumOA
SARRA
conditionedOA
SARRA
Water-Source Heat Pumpwith waterside economizer coil
economizer coil
3-way valve
refrigerant-to-waterheat exchanger
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
49
© 2006
Am
erican Standard A
ll rights reserved
dedicated outdoor-air systemsFan-Coils
minimumOA
SA
RRA
conditionedOA
SASA
closed ineconomizermode
typicalcooling
coil
heatexchanger
Plate-and-Frame Heat Exchangeras waterside economizer
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
50
© 2006
Am
erican Standard A
ll rights reserved
terminal unit systemsPackaged Terminal ACs
Opening the windowlets in “economizer” air
SA
RRA
© 2006 American Standard All rights reserved
Application Considerations
HVAC systems and airside economizers
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
51
© 2006
Am
erican Standard A
ll rights reserved
application considerationsBuilding Pressure ControlStandard 90.1 requires:
Low-leak dampers Some method for controlling
building pressure
“Systems shall provide a means to relieve excess outdoor air during air economizer operation to prevent overpressurizing the building. The relief air outlet shall be located to avoid recirculation into the building”
ASHRAE/IESNA Std 90.1-2004, Section 6.5.1.1.5
return airRA
OAoutdoor(intake) air
space
© 2006
Am
erican Standard A
ll rights reserved
Building Pressure Terminology
relief airRL
RRArecirculated
return air
SAsupply air
EAlocalexhaustair
exfiltration
infiltration
mixed-airplenum
return-airplenum
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
52
© 2006
Am
erican Standard A
ll rights reserved
system configurationsNatural Relief
return airRA
OAoutdoor(intake) air
spaceRRA
recirculatedreturn air
SAsupply air
EAlocalexhaustair
exfiltration
infiltration
mixed-airplenum
return-airplenum
Only works forsmall buildings
© 2006
Am
erican Standard A
ll rights reserved
system configurationsLocal Barometric Relief
return airRA
OAoutdoor(intake) air
spaceRRA
recirculatedreturn air
SAsupply air
EAlocalexhaustair
exfiltration
infiltration
mixed-airplenum
return-airplenum
Works okay, butisn’t accurate
localrelief air
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
53
© 2006
Am
erican Standard A
ll rights reserved
system configurationsCentral Barometric Relief
return airRA
OAoutdoor(intake) air
spaceRRA
recirculatedreturn air
SAsupply air
EAlocalexhaustair
exfiltration
infiltration
mixed-airplenum
return-airplenum
Doesn’t workvery well
centralrelief air
return airRA
OAoutdoor(intake) air
space
© 2006
Am
erican Standard A
ll rights reserved
relief airRL
SAsupply air
EAlocalexhaustair
exfiltration
infiltration
mixed-airplenum
return-airplenum
system configurationsRelief Fan
Works well formost buildings
P
RRA
recirculatedreturn air
P
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
54
return airRA
OAoutdoor(intake) air
space
© 2006
Am
erican Standard A
ll rights reserved
relief airRL
RRArecirculated
return air
SAsupply air
EAlocalexhaustair
exfiltration
infiltration
mixed-airplenum
return-airplenum
system configurationsReturn Fan
Works well withducted return
© 2006
Am
erican Standard A
ll rights reserved
application considerationsDynamic Reset“The system may be designed to reset thedesign outdoor air intake flow (Vot) and/orspace or zone airflow as operating conditions change. These conditions include but are not limited to:
Variations in occupancy … Variations in the efficiency … A higher fraction of outdoor air …”
ASHRAE Standard 62.1–2004
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
55
© 2006
Am
erican Standard A
ll rights reserved
application considerationsDynamic Reset Control“These conditions include … Variations in occupancy or ventilation airflow in one or more individual zones for which ventilation airflow requirements will be reset.
“Note: Examples of measures for estimatingsuch variations include: occupancy scheduled by time-of-day, a direct count of occupants, or an estimate of occupancy or ventilation rate per person using occupancy sensors such as those based on indoor CO2 concentrations.”
ASHRAE Standard 62.1–2004
0
mechcoolingheating
integratedecon
outdoorair
modulatedecon
flow
, %
maxheating
load
maxcoolingload
100
80
60
40
20
application considerationsDynamic Reset
chilledwater
mincoolingload
high-limitshutoff
returnair
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
56
© 2006
Am
erican Standard A
ll rights reserved
dynamic reset controlMinimum Intake Airflow
intake
exhaust
=exfiltr’n
resetlimit
relief
For positive pressure …intake exfiltration + exhaust
design
design
exhaust=intake
dynamic reset
allowable reset
exfiltr’n
© 2006
Am
erican Standard A
ll rights reserved
dynamic reset controlMinimum Intake Airflow
intake
exhaust
=
infiltr’n
resetlimit
design
For negative pressure …intake + infiltration exhaust
relief
exhaust=intake
dynamic reset
allowable reset
infiltr’n
design
a Trane Engineers Newsletter Live satellite broadcastHVAC Systems and Airside Economizers • 3 May 2006
© 2006 American Standard All rights reserved
Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional.
57
© 2006
Am
erican Standard A
ll rights reserved
application considerationsDynamic Reset“These conditions include … :
Variations in occupancy … Variations in efficiency with which outdoor
air is distributed to the occupants under different ventilation system airflows and temperatures
A higher fraction of outdoor air in theair supply due to intake of additional outdoor air for free cooling or exhaust air makeup”
ASHRAE Standard 62.1–2004
© 2006
Am
erican Standard A
ll rights reserved
airside economizersWhat We Covered ASHRAE 90.1 requirements, exceptions
(location/size, controls, integration)
Energy costs and humidity levels(constant- vs. variable-air-volume systems)
Economizer implementation in various system types
Application considerations(building pressurization)
Trane Engineers Newsletter Live satellite broadcast
Bibliography
Page 1 of 1
Industry Standards American Society of Heating, Refrigeration, and Air-Conditioning
Engineers (ASHRAE). ANSI/ASHRAE IESNA Standard 90.1-2004: Energy Standard for Buildings Except Low-Rise Residential Buildings. Available at http://xp20.ashrae.org/ frame.asp?standards/std90.html
American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE). Standard 90.1-2004 User’s Manual. Available at http://www.ashrae.org
American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE). ANSI/ASHRAE Standard 62.1-2004: Ventilation for Acceptable Indoor Air Quality. Available at < http://www.realread.com/prst/pageview/browse.cgi?book=1931862672>
American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE). Standard 62.1-2004 User’s Manual. Available at http://www.ashrae.org
Articles Brambley, M., Pratt, R., Katipamula, S. et al. 1998. “Diagnostics for
Outdoor Air Ventilation and Economizers.” ASHRAE Journal 40-10 (October), 49-55.
Taylor, S. 2000. “Comparing Economizer Relief Systems.” ASHRAE Journal 42-9 (September), 33-40, 42.
Trane Publications Stanke, D. “Keeping Cool with Outdoor Air: Airside Economizers.”
Engineers Newsletter 35-2 (2006). Available at <http://www.trane.com/commercial/ navigation/files/pdf/6/admapn020en_0406.pdf>
Trane. 2002. HVAC System Control (Trane Air Conditioning Clinic TRG-TRC017-EN). La Crosse, WI: Inland Label and Marketing Services, LLC.
03 May 2006
HVAC Systems and Airside Economizers
HVAC Systems and Airside Economizers
Brian Fiegen | manager, applications engineering & systems marketing | Trane
Brian has been with Trane for 23 years in a variety of product management and system development roles. Specifically, he has worked with Trane’s air handling and VAV product lines, including unit controls for that equipment. He is presently responsible for Trane’s applications engineering and systems marketing team, and is well-respected for his extensive knowledge in airside design and controls. Brian is a member of ASHRAE.
John Murphy | senior applications engineer | Trane
John has been with Trane since 1993. His primary responsibility as an applications engineer is to aid design engineers and Trane sales personnel in the proper design and application of HVAC systems. His main areas of expertise include dehumidification, air-to-air energy recovery, psychrometry, ventilation, and ASHRAE Standards 15, 62.1, and 90.1. John is the author of numerous Trane application manuals and Engineers Newsletters, and is a frequent presenter on Trane’s Engineers Newsletter Live series of satellite broadcasts. He also is a member of ASHRAE, has authored articles for the ASHRAE Journal, and is a member of ASHRAE’s “Moisture Management in Buildings” and “Mechanical Dehumidifiers” technical committees.
Dennis Stanke | staff applications engineer | Trane
Dennis, a mechanical engineer from the University of Wisconsin, has been with Trane since 1973 and is a specialist in airside systems and controls, ventilation, indoor air quality, and dehumidification. He’s authored numerous publications on these subjects, has appeared in several Engineers Newsletter Live broadcasts, and holds three U.S. patents related to VAV system control. An active ASHRAE member, Dennis currently serves as chair for SSPC62.1, the committee responsible for ASHRAE Standard 62, Ventilation for Acceptable Indoor Air Quality, and is a member of the editorial board for the ASHRAE publication, IAQ Applications. He combines his knowledge of ventilation system design and control with knowledge of IAQ-related issues and solutions to help designers meet IAQ, ventilation, and energy challenges in commercial, institutional, and high-rise residential buildings. In addition to his Trane responsibilities as staff applications engineer, Dennis also serves on research advisory boards at UC–Berkeley (Centers for the Built Environment) and Penn State University (Indoor Environment Center), and is an active member of the USGBC LEED® Technical Advisory Group for Indoor Environmental Quality (EQ TAG).
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