HVAC Systems and Airside Economizers • 3 May 2006

a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

HVAC Systems and Airside Economizers

an Engineers Newsletter Live telecast

“Trane” is a Registered Provider with The American Institute of 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, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 06American Standard Inc. © 2006

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 1 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Copyrighted Materials

This presentation is protected by U.S. and international copyright laws. Reproduction, distribution, display, and use of the presentation without written permission of Trane or American Standard is prohibited. 06American Standard Allrights reserved © 2006

AIA continuing education Learning Objectives

Participants will learn the following about airside economizers:

 ASHRAE/IESNA Standard 90.1-2004 requirements

 How issues, such as building pressurization, affect economizer

 Ways to control airside economizer systems based on HVAC system type and location

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 2 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

airside economizers Today’s Topics

 What an airside economizer is

 Reasons and exceptions for use

 Types of control

 Performance in constant- vs. variable-

 Implementation in different systems

 Application considerations

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 3 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

What Is an Airside Economizer?

HVAC systems and airside economizers

definitions Airside Economizer

“1. Device that, on proper variable sensing, initiates control signals or actions to conserve energy …

“2. Control system that reduces the mechanical heating and cooling

ASHRAE Terminology of Heating, Ventilation, Air Conditioning & Refrigeration

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 4 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

definitions Airside Economizer

“A duct-and-damper arrangement and automatic control system that together allow a cooling system to supply outdoor air to reduce or eliminate the need for mechanical cooling during mild or cold weather” 06American Standard Allrights reserved © 2006 ASHRAE/IESNA Standard 90.1-2004

Single Zone, Constant Air Volume (CAV)

Supply-air temperature varies to match cooling load

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 5 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system Operating Modes

heating mechanical cooling 100

OA intake flow, % OA min outdoor air

0 coldOA temperature hot

CAV system without economizer Operating Modes

heating mechanical cooling 100

0 coldOA temperature hot

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 6 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system with economizer Operating Modes

modulated heating econ 100

OA intake flow, % OA min mech clg capacity 0 coldOA temperature hot

CAV system with economizer Operating Modes

modulated integrated heating econ econ 100

outdoor air

0 coldOA temperature hot

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 7 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system with economizer Operating Modes

modulated integrated mech heating econ econ cooling 100

outdoor air

0 coldOA temperature hot

CAV system with economizer Operating Modes

integrated economizer 100% OA

modulated economizer min to 100% OA

high-limit shutoff

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 8 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Why Use an Airside Economizer?

HVAC systems and airside economizers

airside economizer Why Use It?

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 9 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

U.S. climate zones* *Alaska = Zones 7, 8 Hawaii = Zone 1a 7a 6b 4c 7b 6a 5a 5b 4a

3c 4b warm, 3a humid 3b 2a

Climate zones of cities Canada listed in Table B-2, climate zone examples ASHRAE 90.1-2004

5 cool Inuvik 8 6 cold 7 very cold 8 subarctic 8 Whitehorse

Ft. Nelson 8 8 Ft. Smith

Goose Bay 7 Prince George 7 06American Standard Allrights reserved © 2006 Kamloops St. John’s 5 Saskatoon 6 5 7 7 Kapuskasing Québec Vancouver Calgary 7 7 7 7 Halifax Regina Montreal 6 Winnipeg 6 6 Toronto

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 10 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Mexico climate zone examples

1 very hot 2 hot 3 warm 4 mixed 3 Monterrey

Climate zones of cities listed in Table B-3, ASHRAE 90.1-2004

Std 90.1’s economizer requirements Exception (a) System  135,000 Btu/h? Economizer required

c b a marine dry moist

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 11 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

airside economizer use Std 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 cleaning to meet ASHRAE Standard 62

(d) Systems with condenser heat recovery

airside economizer use Std 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

(i) Systems with high mechanical cooling efficiency ( Table 6.3.2 requirements)

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 12 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

airside economizer Why Use It?

 Comply with ASHRAE 90.1-2004, Section 6.5.1 … or local energy code

airside economizer (Columbus) HVAC Energy Savings

100

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 13 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

airside economizer (Cincinnati) HVAC Energy Savings

100

airside economizer Why 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 Credit 1: Optimize energy cost

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 14 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Economizer Control Types

HVAC systems and airside economizers

Allowed Types of Economizer Control

Disable econ Enable econ (up to 100% OA) (minimum OA) Control type when OA is: when OA is:

Fixed dry bulb Warmer than Cooler than fixed setting fixed setting

Differential dry bulb Warmer than RA Cooler than RA

Fixed enthalpy Higher thermal Lower thermal energy than fixed energy than fixed setting setting

Electronic enthalpy Above fixed DB Below fixed DB

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,DP DP lockout) settings settings

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 15 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

economizer control type: Fixed Dry Bulb

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

high-limit shutoff

dry-bulb temperature, °F econ economizer econ OFF ON OFF

Prescribed High-Limit Settings for economizer shutoff

For Fixed DB, OA > 70°F

For Fixed DB, OA > 75°F

c b a marine dry moist

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 16 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

missed opportunities: Fixed Dry Bulb

wet-bulb temperature, °F air of dry ratio,humidity grains/lb high-limit shutoff 75°F DB possible increased cooling tons 55°F

dry-bulb temperature, °F econ economizer econ OFF ON OFF

economizer control type: Fixed Enthalpy

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

high-limit shutoff 28 Btu/lb

dry-bulb temperature, °F econ economizer OFF ON

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 17 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

missed opportunities: Fixed Enthalpy

wet-bulb temperature, °F air of dry ratio,humidity grains/lb 75°F possible missed CV economizer hours high-limit shutoff 28 Btu/lb

minimum 55°F OA intake

dry-bulb temperature, °F econ economizer OFF ON

economizer control type: Electronic Enthalpy

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

high-limit shutoff curve “A”

dry-bulb temperature, °F econ economizer OFF ON

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 18 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

missed opportunities: Electronic Enthalpy

wet-bulb temperature, °F air of dry ratio,humidity grains/lb missed 75°F economizer hours high-limit shutoff curve “A”

minimum 55°F OA intake

dry-bulb temperature, °F econ economizer OFF ON

economizer control type: Differential Enthalpy

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

high-limit shutoff range

dry-bulb temperature, °F econ economizer OFF ON

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 19 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

missed opportunities: Differential Enthalpy

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

high-limit 75°F shutoff range (hOA > hRA)

dry-bulb temperature, °F econ economizer OFF ON

economizer control type: Dew-Point and Dry-Bulb Temperatures

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

high-limit shutoff 55°F DP OA

minimum OA intake

dry-bulb temperature, °F econ economizer OFF ON

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 20 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

missed opportunities: Dew-Point and Dry-Bulb Temperatures

wet-bulb temperature, °F air of dry ratio,humidity grains/lb

possible missed economizer hours high-limit shutoff 55°F DP OA

minimum 55°F OA intake

dry-bulb temperature, °F econ economizer OFF ON

Limitations on Economizer Control Types

Any control type No fixed enthalpy

c b a marine dry moist

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 21 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

economizer control High-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

 Ask for a variance, or

 Use Energy Cost Budget Method (Section 11)

economizer control Integrated Economizer

 Extends economizer hours to save more cooling energy

 Must use everywhere—except almost anywhere

“Economizer systems shall be integrated with the

06American Standard Allrights reserved © 2006 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

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 22 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Integrated Economizer Exceptions

integrated economizer required  DX systems that reduce OA to prevent frosting  Small DX systems with capacities < 65,000 Btu/h  Any system in most climates 06American Standard Allrights reserved © 2006

c b a marine dry moist

economizer control Integrated Economizer

 Use in chilled water systems whenever possible—even if not required

 Use with care in built-up DX systems Low-load operation can lead to:

 Out-of-control space relative humidity

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 23 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV-system operating modes Integrated Economizer

modulated integrated mech heating econ econ cooling 100

0 coldOA temperature hot

CAV-system operating modes Non-Integrated Economizer

modulated mechanical heating econ cooling 100 low-limit enable outdoor air

0 coldOA temperature hot

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 24 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Performance in a Constant-Volume System

HVAC systems and airside economizers

Economizer Performance

 Compare:

 Economizer control types

 High-limit shutoff settings

 Assess impact on:



 Space humidity

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 25 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Building Analysis Tools

TRACE™ 700 HVAC load design and analysis software

 Comprehensive energy and economic analysis for virtually any building

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 26 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Columbus, Ohio

warm, humid

c b a  Retail store marine dry moist Constant-volume system  Office building VAV system

economizer control type: Fixed Dry Bulb

SA T space

High-limit shutoff:  55°F  70°F single-zone CAV system  65°F  75°F

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 27 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system (Columbus) Energy: Fixed Dry Bulb

100

95 8%

90 13% 13% 15%

fixed dry bulb: Example at Part Load*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 OA 120

100 MA 60 80 55 RA 60 50 SA 45 40 40 06American Standard Allrights reserved © 2006 35 30 70°F high-limit 75°F high-limit 20 shutoff setting shutoff setting 0 30 40 50 60 70 8090 100 110 dry-bulb temperature, °F

*Single-zone CAV system: Mild, rainy day in Columbus, Ohio

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 28 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system (Columbus) Humidity: Fixed Dry Bulb

228 250 218 206 206 208

200

150

fixed dry bulb: Example at Part Load*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 OA 120 70 100 65 MA SA 60 RA 80 55 RA 60 50 SA 45 40 40 06American Standard Allrights reserved © 2006 35 30 70°F high-limit 75°F high-limit 20 shutoff setting shutoff setting 0 30 40 50 60 70 8090 100 110 dry-bulb temperature, °F

*Single-zone CAV system: Mild, rainy day in Columbus, Ohio

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 29 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system (Columbus) Energy: DP Lockout

100

95 8%

90 13% 13% 15% 14%

CAV system (Columbus) Humidity: DP Lockout

228 250 218 206 206 208 206

200

150

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 30 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

economizer control type: Fixed Enthalpy

SA h space

High-limit shutoff:  23 Btu/lb  32 Btu/lb single-zone CAV system  28 Btu/lb

CAV system (Columbus) Energy: Fixed Enthalpy

100

11% 90 14% 15% 14% 16% 85 % of base % of 06American Standard Allrights reserved © 2006 80 HVAC energy consumption, 75 none 70°F 75°F DB, 23 28 32 fixed DB 55°F DP Btu/lb Btu/lb Btu/lb lockout fixed h fixed h fixed h

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 31 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

fixed enthalpy: Example at Part Load*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 70 100 65

0 30 40 50 60 70 8090 100 110 dry-bulb temperature, °F

*Single-zone CAV system: Hot, dry day in El Paso, Texas

CAV system (Columbus) Humidity: Fixed Enthalpy

250 218 216 206 206 206 207

200

150

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 32 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

economizer control type: Electronic Enthalpy (h)*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 70 100 65

0 30 40 50 60 70 8090 100 110 dry-bulb temperature, °F

*Single-zone CAV system

CAV system (Columbus) Energy: Electronic Enthalpy

100

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 33 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system (Columbus) Humidity: Electronic Enthalpy

250 218 206 206 207 207

200

150

economizer control type: Differential Enthalpy

EA RA h

SA h space

single-zone CAV system

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 34 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

CAV system (Columbus) Energy: Differential Enthalpy

100

90 15% 14% 15%  16%  16% 85 % of base % of 06American Standard Allrights reserved © 2006 80 HVAC energy consumption, 75 none 70°F 75°F DB, 28 electronic differential fixed DB 55°F DP Btu/lb enthalpy enthalpy lockout fixed h

CAV system (Columbus) Humidity: Differential Enthalpy

250 218 206 206 207 207 211

200

150

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 35 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

differential enthalpy: Example at part load*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 70 100 65 OA 60 80 55 60 50 75°F DB 45 40 50%RH 40 35 30 20

0 30 40 50 60 70 8090 100 110 dry-bulb temperature, °F

*Single-zone CAV system: Mild, rainy day in Columbus, Ohio

Performance in a Variable-Volume System

HVAC systems and airside economizers

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 36 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

VAV system (Columbus) Energy: Fixed Dry Bulb

100

95 8% 9% 10% 11% 11% 90

VAV system (Columbus) Humidity: Fixed Dry Bulb

250

200

150

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 37 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

fixed dry bulb: Example at part load*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 OA70 100 65

temperature shutoff setting 0 30 40 50 60 70 8090 100 110 dry-bulb temperature, °F

*VAV system: Mild, rainy day in Columbus, Ohio

VAV system: Economizer Effect on Space Humidity*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 70 100 65 60 RA 80 55SA MA 60 50 45 RA 40 40

*VAV system: Columbus, Ohio

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 38 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

VAV system (Columbus) Energy: Fixed Enthalpy

100

95 8% 9% 10% 11% 11% 11% 90

85 % of base % of 06American Standard Allrights reserved © 2006 80 HVAC energy consumption, 75 none 70°F 75°F DB, 23 28 32 electronic fixed 55°F DP Btu/lb Btu/lb Btu/lb enthalpy DB lockout fixed h fixed h fixed h

VAV system (Columbus) Humidity: Fixed Enthalpy

250

200

150

100 06American Standard Allrights reserved © 2006 50 29 19 1919 19 8 2 hours space with RH > 58% 0 none 70°F 75°F DB, 23 28 32 electronic fixed 55°F DP Btu/lb Btu/lb Btu/lb enthalpy DB lockout fixed h fixed h fixed h

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 39 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

VAV system (Columbus) Energy: Differential Enthalpy

100

10% 11% 11% 11% 12% 90

VAV system (Columbus) Humidity: Differential Enthalpy

250

200

150

100 06American Standard Allrights reserved © 2006 50 29 19 19 19 18 8 hours space with RH > 58% 0 none 70°F 75°F DB, 28 electronic differential fixed DB 55°F DP Btu/lb enthalpy enthalpy lockout fixed h

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 40 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

VAV system: SA Temperature Reset*

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

*VAV system: Columbus, Ohio

Traditional VAV System

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 70 100 65

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 41 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Cold-Air VAV System

85 180 wet-bulb temperature, °F 160

80 air of dry ratio,humidity grains/lb

140 75 120 70 100 65

Energy/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

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 42 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

Implementing Airside Economizers

HVAC systems and airside economizers

Implementing Airside Economizers

 Single-zone systems

 Multiple-zone systems

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 43 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

single-zone systems Packaged DX Rooftop

Size OA intake hood for design airflow of system

RRA SA

single-zone systems Indoor Air Handler

Size OA duct for the air handler’s design airflow

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 44 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

single-zone systems Unit Ventilators

Size OA intake for the unit ventilator’s design supply airflow

minimum = 1 ft RRA

multiple-zone systems Outdoor Air Handler

Measure and control OA outdoor airflow to maintain proper airflow rates

VAV terminals

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 45 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

multiple-zone systems Indoor Air Handler

RRA alt

Options include flow-sensing dampers VAV terminals and airflow measurement stations

multiple-zone systems Commercial Self-Contained

minimum OA SA

RRARRA

RRA

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 46 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

multiple-zone systems (central AHU) Commercial Self-Contained

economizer coil

cooling tower

dedicated outdoor-air systems Central Air Handling

minimum OA conditioned OA

RRA

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 47 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

dedicated outdoor-air systems Water-Source Heat Pumps

conditioned OA minimum OA

Water-Source Heat Pump with waterside economizer coil

3-way valve

economizer coil

refrigerant-to-water heat exchanger

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 48 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

dedicated outdoor-air systems Fan-Coils

conditioned OA minimum OA

RRA

Plate-and-Frame Heat Exchanger as waterside economizer

closed in economizer mode heat exchanger

typical cooling coil

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 49 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

terminal unit systems Packaged Terminal ACs

Opening the window lets in “economizer” air

Application Considerations

HVAC systems and airside economizers

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 50 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

application considerations Building Pressure Control

Standard 90.1 requires:

 Low-leak dampers

 Some method for controlling building pressure

“Systems shall provide a means to relieve excess 06American Standard Allrights reserved © 2006 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

Building Pressure Terminology

return-air relief air plenum return air RL RA

exfiltration

RRA recirculated infiltration space return air

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 51 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

system configurations Only works for Natural Relief small buildings

return-air plenum return air RA

exfiltration

RRA recirculated infiltration space return air

system configurations Works okay, but Local Barometric Relief isn’t accurate

return-air plenum return air local RA relief air

exfiltration

RRA recirculated infiltration space return air

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 52 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

system configurations Doesn’t work Central Barometric Relief very well

return-air central plenum return air relief air RA

exfiltration

RRA recirculated infiltration space return air

system configurations Works well for Relief Fan most buildings

return-air relief air plenum return air P RL RA

exfiltration recirculated P return air RRA infiltration space

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 53 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

system configurations Works well with Return Fan ducted return

return-air relief air plenum return air RL RA

exfiltration

RRA recirculated infiltration space return air

application considerations Dynamic Reset

“The system may be designed to reset the design outdoor air intake flow (Vot) and/or space or zone airflow as operating conditions change. These conditions include but are not limited to:

 Variations in occupancy …

 A higher fraction of outdoor air …”

ASHRAE Standard 62.1–2004

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 54 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

application considerations Dynamic 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 estimating such variations include: occupancy scheduled by time-of-day, a direct count of occupants, or an 06American Standard Allrights reserved © 2006 estimate of occupancy or ventilation rate per person using occupancy sensors such as those based on

indoor CO2 concentrations.” ASHRAE Standard 62.1–2004

application considerations Dynamic Reset

modulated integrated mech heating econ econ cooling chilled 100 water return 80 air

flow, % 40 outdoor 20 air

max min high-limit max heating cooling shutoff cooling load load load

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 55 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

dynamic reset control Minimum Intake Airflow

design dynamic reset

design relief allowable reset intake = exfiltr’n exfiltr’n reset intake =

For positive pressure … intake  exfiltration + exhaust

dynamic reset control Minimum Intake Airflow

design dynamic reset

infiltr’n design relief allowable reset intake = infiltr’n reset

For negative pressure … intake + infiltration  exhaust

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 56 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. a Trane Engineers Newsletter Live satellite broadcast HVAC Systems and Airside Economizers • 3 May 2006

application considerations Dynamic 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

06American Standard Allrights reserved © 2006  A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooling or exhaust air makeup” ASHRAE Standard 62.1–2004

airside economizers What 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

 Application considerations (building pressurization)

Trane, in proposing these system design and application concepts, assumes no responsibility for the performance or desirability of any 57 resulting system design. Design of the HVAC system is the prerogative and responsibility of the engineering professional. Trane Engineers Newsletter Live satellite broadcast Bibliography

03 May 2006 Industry Standards American Society of Heating, Refrigeration, and Air-Conditioning HVAC Systems Engineers (ASHRAE). ANSI/ASHRAE IESNA Standard 90.1-2004: and Airside Energy Standard for Buildings Except Low-Rise Residential Buildings. Available at http://xp20.ashrae.org/ Economizers 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=193186 2672> 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 Trane. 2002. HVAC System Control (Trane Air Conditioning Clinic TRG- TRC017-EN). La Crosse, WI: Inland Label and Marketing Services, LLC.

Page 1 of 1 engineers newsletter live Presenter Biographies

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).