New Outside Air Control Solutions to Cut Your

Carbon Footprint & Save Energy

Gordon P. SharpChairman

Aircuity, Inc

Case Study Example: Bank of America

Tower, NYC

Session OverviewSession Overview

Review of issues concerning outside air control

Demand Control Ventilation

Multiplexed sensing

Differential enthalpy control

Lab applications

Case studies

IEQ – Energy Dynamics of Green BuildingsIEQ – Energy Dynamics of Green Buildings

Contaminant sources: Human pollutants Non Human Pollutants

Outside Air Ventilation: Source dilution

Control Approaches: Furnishings selection Green cleaning, etc. Filtration

Control Approaches: Demand Control

Ventilation (DCV)

Economizer control

What do current standards and research say about optimum outside air ventilation performance?

IEQ & Energy Efficiency Performance

What do the Guidelines Say About Outside Air?What do the Guidelines Say About Outside Air?

ASHRAE 62.1 – 2004 & 2007 rates versus 2001 Uses area & person component: ~ 5 cfm/person & ~.06 cfm/sq ft

Generally lowered O.A rates, sometimes significantly– Office rooms changed from 20 to a range of ~14 to 17 cfm/person

– Conference rooms & classrooms: 15/20 to ~ 5 to 7 cfm/person.

From Trane “Co2-Based Demand Controlled Ventilation

with ASHRAE Standard 62.1-2004” Engineers Newsletter 34-5

What do the Guidelines Say About Outside Air?What do the Guidelines Say About Outside Air?

Why did 62.1 reduce O.A. so much for conf. & educ? ASHRAE 62.1 changed: legal code vs. just a guideline

– Ventilation rates went from “Acceptable” to “Minimum”

New criteria used for “minimum” O.A. rates– 80% satisfaction of “adapted occupants” vs. “unadapted” (visitors)

ASHRAE 62.1 for dense spaces can be problematic Lower ventilation levels will create sensed odors Brief sensed odors: a perception of poor IAQ

– Complaints and even increased O.A. over prior rates

What Does the Recent O.A. Research Say?What Does the Recent O.A. Research Say?

William Fisk, LBNL 2004 ASHRAE Journal articleSurveyed results from many studies:

– 21 CO2 ventilation studies: over 30,000 subjects, over 400 bldgs

Consensus of studies indicated that:– Occupant health & perceived IAQ worsened w/ <20 cfm/person

– Unclear whether specifying outside air/person or per area better• Most studies were based on cfm/person

So What Outside Airflow Should be Used?So What Outside Airflow Should be Used?

For certain spaces 62.1 min airflows can be too low

In other conditions 62.1 allows airflow to be reduced

Ventilationwants more outside air

Energy Savingswants morereturn air

Ventilationwants more outside air

Energy Savingswants morereturn airFacilities

Env. Health &

Safety

ASHRAE 62.1-2004

Recent Research

In reality, there is no one best ventilation level!

….The “best” level varies over time, so what can be done?

What about Demand Control Ventilation?What about Demand Control Ventilation?

Measures the rise of CO2 in the buildingMeasures amount of ventilation

CO2 is a good proxy for human pollutants

Reduces ventilation when occupancy dropsCan save substantial energy when loading varies

Even optimizes the ventilation for constant loading– Most buildings are designed with more air than normally needed

Is DCV a good approach then for saving energy while also improving and validating IEQ?

Unfortunately, Experience w/ DCV is often poor:Unfortunately, Experience w/ DCV is often poor:

DCV CO2 sensors have had problemsSensor drift and loss of accuracy

Lack of periodic sensor calibrationASHRAE 62.1 standard: Should check twice annually

Accuracy issues w/ differential sensing Indoor to outside air differential measurements

Demand Control Ventilation when used, is often disabled!

LBNL* COLBNL* CO22 Field Sensor Study Paper Results Field Sensor Study Paper Results10% Dead

81% Read High(avg. 39%!)

9% Low(½ by 50%)

No trends observed with 44 sensors vs site, mfg, or age!

* Lawrence Berkeley National Laboratory Paper, recently presented at ASHRAE 2009 Winter Conference

Typical DCV Performance Based on LBNLTypical DCV Performance Based on LBNL

-100%

-50%

0%

50%

100%

150%

200%

250%

300%

350%

400%

>20% OA Error ≤20% OA Error Average Over-Ventilaton

Outside Air CFM Error % of Required

64%

27%7%

CO2 Sensor Study Results from Iowa Energy CenterCO2 Sensor Study Results from Iowa Energy Center

Traditional Sensors Not Up to DCV TaskTraditional Sensors Not Up to DCV Task

Differential sensing needed due to outside air changes

Using two sensors doubles error on smaller diff. signal

±75PPM + ±75PPM = ±150PPM

ASHRAE says: Ventilation control needs differential CO2 measurement

ReturnAir

OutsideAir

Even w/calibrated sensors, avg outside air can be 67% high!Result: Significant energy penalty

OSA CO2

300

400

500

600

Midnight 6:00 AM Noon 6:00 PM Midnight

PPM

400

600

500

Unfortunately Conventional DCV is Also FlawedUnfortunately Conventional DCV is Also Flawed

DCV only solves half of the problem DCV varies O.A. based only on number of people in bldg

DCV does not react to non-human pollutants Odors, particles, CO, and formaldehyde

As a result: DCV can create complaints Nonhuman pollutants can rise when DCV reduces O.A.

– New bldg, recent renovation, cleaning materials, vacuuming

Typical response: Disable DCV & increase O.A.

RESULT: Increased Energy Costs

Solution: Multi-parameter DCV or “Healthy” DCVSolution: Multi-parameter DCV or “Healthy” DCV

The goal is dilution of all pollutants in building:Human based pollutants (odors, virus, bacteria, etc.)Non human pollutants (TVOC’s, particles, CO, etc.)

Control O.A. based on multiple parameters:Use CO2 as a proxy for human based pollutants EPA & LEED specify levels for non-human pollutants

– TVOC’s, particles, & carbon monoxide

Sensing humidity also helpful to prevent mold

Vary outside air rates based on actual air cleanliness!

ASHRAE Support of Sensing More Than CO2:ASHRAE Support of Sensing More Than CO2:

ASHRAE Emerging Technologies Article on DCV, 7/2003: “Although CO2 levels tend to correlate well with human

occupancy and human-generated pollutants, they do not reflect the buildup of pollutants not related to occupancy…,

“Currently, most buildings do not use DCV because of concerns about nonhuman indoor pollutants mentioned previously.”

ASHRAE’s Standard 62.1 User Manual: The contaminants in indoor spaces that ventilation is

intended to dilute are generated primarily by two types of sources:

– Occupants (bioeffluents) and their activities …

– Off-gassing from building materials and furnishings.

“There is little doubt or controversy about the existence of these two sources...”

Benefits of Varying Outside Air based on IEQBenefits of Varying Outside Air based on IEQ

Doesn’t dilute clean air w/ clean air

Provides better IEQ

Increases fresh air when needed

Maximizes energy savings

Operates at lowest possible O.A.

Effectively validates bldg IEQ

Measures multiple air parameters (not just CO2)

Sounds great, but can it be done cost effectively?

VAV VAV VAV VAV

Room 101 Room 102 Room 103 Room 104

RH

CO

CO2 P

V

T RH

CO

CO2 P

V

RH

CO

CO2 P

V

T T RH

CO

CO2 P

V

T

Ctrlr CtrlrCtrlr Ctrlr

CF

M

Bldg Ctrlr

Conventional Sensing with Many SensorsConventional Sensing with Many Sensors

Disadvantages High first cost High maintenance costs Lack of accuracy, particularly

differential measurements

A New Approach: Multiplexed Sensing A New Approach: Multiplexed Sensing

Routes multiplexed air samples to central sensors Multiplex one set of sensors over 20 locations

Environmental data sent to BMS for control & to web to view

Room 101 Room 102 AHU 2 -1

Sensor Suite

BMS

Web based data access

Area Summary - Accounting cubicles Historical Summary

Test Dates

Start Dates

Hours Tested

12/16/2001 6:53:00 AM 22:28

Comfort and Ventilation - Assessment This category applies to those parameters normally associated

with comfort, but are not necessarily health related. Temperature,

relative humidity and carbon dioxide are included. Carbon

dioxide in this case is used as an indicator of ventilation in the

building since the primary source is occupants, and is not

normally considered a pollutant.

CO2 (ppm)

Temperature (°F) Relative Humidity (%)

CFM (Outdoor Air PP)

Average Values 593 69 26

36

Extreme Values 686 67-71 22-29 N/A

Typical/Comfort < 1012 71 - 74 20 - 60 > 15

Recommended < 1012 68 - 78 20 - 60 > 15

Summary

Under the conditions of this test, and based on carbon dioxide levels, the amount of outdoor air to this area

meets or exceeds the currently accepted guideline and no action is required.

During this testing period, the area temperature was outside of Typical/Comfort guidelines as well as being

outside of recommended guidelines and should be reviewed. (Percentage of time outside of recommended

guidelines = 8%; Median of values outside recommended guidelines is 67.14).

o The control system (thermostat sensor, controller, and controlled device) settings, or programmed

parameters may not be optimized for accurate temperature regulation.

The test area thermostat may not be set or calibrated correctly.

The test area thermostat may be poorly located.

During this testing period, the area relative humidity was within recommended guidelines and does not require

attention.

Comfort and Ventilation Ratings Outside guidelines, requires attention Outside guidelines, should be reviewed Within guidelines, improvement possible Within guidelines, No action required

0 | | | | | 25 | | | | 50 | | | | 75 | | | | | 100 |

CO2

Temperature 45

Relative Humidity

Recommended Actions

The following recommendations are suggested to improve temperature in the area:

Building Data Summary Test Area Highlights

Within guidelines - no action Within guidelines - improvement possible

Outside guidelines - Review suggested

Outside guidelines - Review required

Average Values - Occupied Hours The data gathered by the Optima™ system during the building’s occupied hours is summarized below. The average

values are shown for each area tested (please note that the carbon dioxide reported value is not the average), and are

compared to typical values seen in similar buildings to those recommended by industry guidelines and standards. Values

outside these guidelines are highlighted and are further explained in each area analysis section. Data collected during

unoccupied hours is also screened by the expert system and is noted where appropriate on the individual area sections of

the report.

* CO2 (Carbon Dioxide) values expressed as 90th percentile ppm during occupied hours - see Test Methods and Background Information

* CFM (Outdoor Area) refers to Cubic Feet per Minute of Outdoor Air per Person as calculated using ASHRAE guidelines

* CO (Carbon Monoxide) * TVOC (Total Volatile Organic Compounds)

* PM 2.5 (Particulate Matter 2.5 microns and less in size)

* PM 10 (Particulate Matter 10 microns and less in size)

Comfort and Ventilation

Air Cleanliness Building Pollutants

CO2 Temperature Relative Humidity Particles (PM 10) Particles (PM 2.5) TVOC CO

Radon Ozone

Accounting cubicles

Lara office

Marketing

Comfort and Ventilation Air Cleanliness

Building Pollutants

CO2 (ppm)

Temperature (°F) Relative Humidity (%) CFM (Outdoor Air PP) PM 10

(µg/m3) PM 2.5 (µg/m3) TVOC (index) CO

(ppm) Radon (pCi/l) Ozone

(ppm)

Accounting cubicles 593 69 26

36 14

9 0

0 0.3

0

Lara office 531 74 20

46 6

4 0

0 0.5

0

Marketing 480 69 27

59 5

4 0

0 0.3

0

Typical/Comfort < 1012 71 - 74 20 - 60

> 15 < 40

< 20 < 10 < 3 < 2

< 0.1

Recommended < 1012 68 - 78 20 - 60

> 15 < 40

< 20 < 35 < 9 < 4

< 0.1

Executive Summary

Headquarters - Building Overview The following table presents the reader with a very high-level view of the building performance in three performance

categories. Any review suggested at this level refers to further reading within this report. A complete listing of individual

area and sensor ratings can be found in the Results Summary immediately following this section.

Within guidelines or recommended levels

Review required Review

suggested Improvement possible No action suggested

Comfort and Ventilation

Air Cleanliness

Building Pollutants

Comfort and Ventilation - This category applies to those parameters normally associated with discomfort, but are not

necessarily health related. Temperature, relative humidity and carbon dioxide are included. Carbon dioxide in this case is

used as an indicator of ventilation in the building since the primary source is occupants, and is not normally considered a

pollutant.

Air Cleanliness – This category includes those parameters to which standards do not necessarily apply, but which may

still be the source of occupant complaints within the building. These parameters include particles and Total Volatile

Organic Compounds (TVOC). In this case, values in the building are scored against values typically associated with

occupant discomfort based on documented case studies.

Building Pollutants - This category includes those parameters classified as potential pollutants within buildings, and are

scored against regulatory standards. They include carbon monoxide, radon and ozone. Most are typically found at low

levels in most buildings. When moderate to high levels are found, simple cost-effective solutions are typically available

to bring levels within guidelines. Operations Assessment This assessment uses the temperature and ventilation measurements during both occupied and unoccupied hours to

assess the potential for energy savings. Existing air quality issues are taken into account in this assessment. An onsite

building professional is required to determine whether an actual savings opportunity exists or is appropriate.

Savings likely Review suggested

Savings possible Review suggested Good Performance

Optimum Performance

Accounting cubicles

Lara office

Marketing

Multiplexed Sensing OperationMultiplexed Sensing Operation

Room 101 Room 102 Room 103Outdoor Outdoor Air Air

ProbeProbe

Web Based User Web Based User InterfaceInterface

ConnectivityConnectivity

Sensor Sensor SuiteSuite

Air Data Air Data RouterRouter

Room Room SensorSensor

Vacuum Vacuum PumpPump

ServerServer

Benefits of Multiplexed Sensing ConceptBenefits of Multiplexed Sensing Concept

Better total first cost Sensor cost spread over many locations

Single point digital integration w/ BMS

Lower operating costs Drastically reduced calibration cost

– One high quality sensor vs. many low cost units

– Sensors more accessible, can be swapped out

Improved Accuracy Provides “true” differential sensing

– Sensor errors cancel since one sensor used

– Reduces impact of RH & barometric pressure

Cost effective, accurate bldg data for ventilation control

Economizers – “Free Cooling” w/ More Outside AirEconomizers – “Free Cooling” w/ More Outside Air

Control MethodDry Bulb Temperature

– Outside air sensor versus fixed setpoint in design• ASHRAE Std 90-2004 has max values from 65-75

Differential Enthalpy Control– Same outside air and return air sensor for °F

– Relative Humidity sensor for outside and return air• Need High Quality or Expect Failure

Diff. Enthalpy Economizer Savings PotentialDiff. Enthalpy Economizer Savings Potential

Diff. enthalpy is best, yet is rarely used… Why??Humidity sensors typically fail in outdoor conditions If economizer fails, energy penalty is high (100% OA)

CityNo

Economizer70º

Dry-bulbSingle

EnthalpyDifferential Enthalpy

Madison, WI 0% 11% 11% 27%

Lake Charles, LA 0% 3% 3% 9%

New York, NY 0% 12% 11% 33%

Los Angeles, CA 0% 51% 33% 76%

Seattle, WA 0% 25% 35% 51%

Albuquerque, NM 0% 7% 14% 22%

Economizer Savings Study, ASHRAE No. 3200, 1989, P.C. Wacker, P.E.

ASHRAE Humidity Control Design GuideASHRAE Humidity Control Design Guide

“For outdoor use, use a rugged sensor and expect to calibrate frequently”

“Sensors in this location are notoriously inaccurate, because they are easily contaminated by pollutants, particles, condensation, and even frost”

“In general, do not expect these signals will always be reporting within the manufacturers tolerance”

Multiplexed Dewpoint Sensing for EconomizersMultiplexed Dewpoint Sensing for Economizers

Use multiplexed sensing for AHU Return & OA sensor Solves problems of high drift from outdoor temp., particles, etc.

– Sensors are inside and can be protected by HEPA filters

Allows economic use of high quality dewpoint/enthalpy sensor

Eliminates the high error sensitivity of differential measurement– If traditional sensor error is ±5%, total error of two sensors is ±10%

– For a 10% RH difference, measurement error is ±100%

– Multiplexed sensing cancels errors by using 1 sensor for both readings

Case Study – LEED ProjectCase Study – LEED Project

One Bryant Place – LEED Platinum

Also known as Bank Of America Tower

World’s largest & most green skyscraper

– Goal is platinum certification

2nd tallest building in NYC – 954’

$1.0 B, 2.1M s.f. building

Cost effective IEQ monitoring & DCV

– Sampling at many points. on each floor plate

– Total of over 800 locations monitored

Case Study – LEED & DCV ProjectsCase Study – LEED & DCV Projects

ASHRAE Headquarters Renewal – LEED CI Gold Goal

Humidity monitoring, DCV control

Sensing for AHU & Enthalpy wheel control

Helping ASHRAE realize its living laboratory goal

TVOC, particles, CO2, Dewpoint , T sensing throughout

Case Study: Large Energy Retrofit Case Study: Large Energy Retrofit UBS Financial – Stamford, Connecticut

World’s largest securities trading floor (100K sq. ft.)

Rapid payback for DCV retrofit funded 95% by CL&P Multiplexed sensing of 6 large AHU’s DCV control: 1.6 Yr Payback

Also installed in a nearby office tower renovation

Multi-parameter DCV Case Study: ArenaMulti-parameter DCV Case Study: Arena

New Jersey Devils – Prudential Arena, Newark, NJ 100,000 sq. ft. sports arena; $310M budget

Multi-parameter DCV control: CO2, CO, particles, & TVOC’s

Dewpoint sensing & control for “Best Ice in the NHL”

CO2 ~ 3 daysCO2 ~ 3 days

Concert

NHL Hockey

Indoor Soccer

The Controversy Around Air Change RatesThe Controversy Around Air Change Rates

Minimum air changes still fixed at 6-12 / 10-20 ACH

Far majority of time lab air is “clean”

However, there many times when more air is better Dilute vapors from a spill when lab is occupied or unocc.

Dilute vapors or particles caused by poor practices

– Working outside the hood, improper storage

– No localized exhaust for instruments

– Improper bedding changing

The “human” factor

There is no one ventilation rate that is right all the time!

Impact of Higher Air ChangesImpact of Higher Air Changes

Test Case– Teaching Lab

Acetone at 4 ACH

CFD courtesy of Glenn Schuyler’s ASHRAE Presentation

Relative contaminant level: 27 PPM (black)

Impact of Higher Air ChangesImpact of Higher Air Changes

Test Case– Teaching Lab

Acetone at 8 ACH

CFD courtesy of Glenn Schuyler’s ASHRAE Presentation

Relative contaminant level: 2.5 PPM (light blue):Factor of 10 improvement!

Lab Application: Dynamic Control of Lab ACHLab Application: Dynamic Control of Lab ACH

Lab Multi-parameter DCV: Dynamic control of min. ACH Now all three factors affecting lab airflow can be varied

Significantly cuts energy & first cost, while enhancing safety

Hoods Thermal Load

Ven

tila

tio

n r

ate

(cfm

)

2- 4 ACH 6-8 ACH*

6-12 ACH 10-20 ACH*

VAV VAV

Constant

ACH / Dilution Requirement

Significant energy waste

*vivariums

VAV

Dynamic ACH Control Saves Energy SafelyDynamic ACH Control Saves Energy Safely

There is no need to dilute clean air w/ clean air

99% of the time the air will be clean, no need to dilute

Set min dilution levels per OSHA or as desired

For high concern: 4 ACH occupied & 2 ACH unocc.

– OSHA guidelines have a minimum at 4 ACH (range of 4 to 12)

For normal to less severe applications, use 2 ACH as min

– ASHRAE fresh air min for science lab is .18 cfm/sq ft or 1.2 ACH

Set max dilution for 12 to 16 ACH for safest purge

System responds to great majority of contaminants with high ACH’s vs. a lower fixed ACH rate

2008 Lab IEQ Performance Monitoring Study 2008 Lab IEQ Performance Monitoring Study

Largest known study done to date Supersedes smaller 2007 study of 7 sites

18 different sites selected 6 East, 7 Central, 3 West, 2 Canada

Over 300 different lab areas Largest site: 67 areas,

Smallest site: 2 areas

Research: Life sciences, bio, physical chem, etc

Almost all low density labs w/ dynamic control

3 animal facility sites

Lab IEQ Performance Monitoring Study Lab IEQ Performance Monitoring Study

Covers over 1,500,000 lab operating hours

Data taken over 2 year period up to Jan. 2009Amount of data varies by site

Approx. 20 million sensor values recordedLab TVOC’s: Measured with PID type TVOC sensor

– Values shown are differential measurements vs. supply air

Particles: laser based particle counter - .3 to 2.5 u.– Values shown are differential measurements vs. supply air

CO2: Measured with lab grade NDIR sensor

Dewpoint: Lab grade infrared spectrometer

Average of TVOC Data for All Sites: 1.5M HrsAverage of TVOC Data for All Sites: 1.5M Hrs

Using LEED flush-out threshold of 0.18 PPM: Low ACH can be used 99.4% of time

Represents 1 hour or ~ 4 events week

Average TVOC Levels at 18 Different SitesAverage TVOC Levels at 18 Different Sites

At ~0.2PPM, site value range: ~ .05% to 2.25%

Average for all sites

Significant savings at all sites

Average Differential Particle Levels For All SitesAverage Differential Particle Levels For All Sites

Using threshold of 1.0M PCF: Lowest airflow 99.6%

On average each lab has 2 particle events per week

Avg. Differential Particle Levels at 18 SitesAvg. Differential Particle Levels at 18 Sites

At 1M PCF, Site value range:

~ 0% to 1.4%

Average Level

Data shows significant savings at all sites

Case Study: Arizona State UniversityCase Study: Arizona State University

Pilot Project for ASU Biodesign Institute Large life sciences retrofit at Biodesign Bldg B

One Sensor Suite, 11 lab rooms monitored

LEED NC Platinum, R&D 2006 Lab of the Year

Biodesign B Aircuity Pilot ProjectBiodesign B Aircuity Pilot Project

TVOC Performance Before & With Dynamic ACHTVOC Performance Before & With Dynamic ACH

Dynamic ACH control saved energy & reduced lab TVOCs!

Current Status of ASU ProjectCurrent Status of ASU Project

Project has moved forward into full building implementation for both Biodesign Bldgs A &B

ASU has estimated savings in excess of $1 million a year 330K gross sq ft total for both bldgs

Savings of $3 per gross sq. ft/year

Savings of ~$5 per net sq ft/year

Savings equivalent to: 4.5 MW solar array ~$31M cost

– ~ 450,000 sq ft of installed panels

Multiplexed Facility Sensing SummaryMultiplexed Facility Sensing Summary

Optimizes ventilation: Increased savings & IEQ

A building wide sensing infrastructure

For new & existing facilities

Cost effective LEED points

Applicable to many building types Office buildings

Classroom & Educational

Lab & Vivarium

Healthcare

Public Assembly & Arenas

Data Centers