2 - dcv 12.12.13 - maeep - dcv 12.12.13_1.pdf · ashrae 62.1-2010 written into the actual standard...

12/6/2013

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Demand Controlled Ventilation (DCV)

Ryan R. Hoger, LEED [email protected]


Comfort Is More Than Just The Right Temperature…

Comfort = Temperature + Ventilation

Ventilation Control

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The same way it was in 1930.

With Fixed Ventilation!

How is ventilation provided in buildings today?

Ventilation Control

Minimum Ventilation Rates

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Inefficient!

Building codes require ventilation rates based on cfm/person: (typically 20 cfm/person)

Max Occupancy: 25 people = 500cfmActual Occupancy: 5 people = 500cfmActual Occupancy: 1 person = 500cfm

Fixed Ventilation

Fixed Ventilation In a Multi-Zone VAV BuildingTotal cfm = Max occupants X 20 cfm

There Is No Control!

Ventilation Control

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Temperature Control InA Multi-Zone VAV Building

• Measure In Each Zone• Control Based On Actual Load

What if we did the same thing with ventilation?

Temperature SensorTemperature + Ventilation Sensor

Delivers

The RIGHT Amount of Fresh Air,

To The RIGHT Place,

At The RIGHT Time…

Great Idea!

But How Does It Work?

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Indoor Air Quality

FIRST ALARM (TWA)

SECOND ALARM (STEL)

SENSOR LOCATION

RADIUS OF DETECTION

Temperature & Humidity N/A N/A N/A N/A

Carbon Dioxide (CO2) 800-1200 ppm 5000 ppm5 ft. above floor 20 ft.

Oxygen (O2)19.5%

(O2 depletion)22%

(O2 saturation)

CO2 Basics

• CO2 is NOT a contaminant, it is a colorless, odorless gas found naturally in the atmosphere– Outdoor levels are fairly constant at 400 +/- 25

ppm– Typical indoor levels 400 to 2,500 ppm– Not harmful unless concentrations reach 30,000

ppm • Carbon Monoxide (CO) and Carbon Dioxide are

NOT the Same

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People exhale CO2 at concentrations of 4% (40,000 ppm)

Normal room concentrations are in the range of 400 - 1200 ppm

As a gas, CO2 diffuses and equalizes rapidly throughout a room (like humidity)

CO2 Basics

• CO2 production by people is very predictable based on activity level

• Doubling the people in a room will double CO2production

CO2 and Ventilation Rates

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Actual Occupancy 25 people = 500cfmActual Occupancy 5 people = 100cfmActual Occupancy 1 person = 20cfm

Ventilation based on actual occupancy!

Ventilation Control

Zone Ventilation Control

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Research & Studies

• Numerous Studies Confirm that Correct Ventilation:• Increases Productivity• Improves Occupant/Customer Satisfaction • Helps Prevent Sick Building Syndrome Health

Affects

DOE/Lawrence Berkeley LabsIndoor Environment In Schools

Pupils’ Health & Performance In Regard To CO2 Concentrations

A significant correlation was found between decreased performance and high CO2 levels (lower ventilation rates).

Research & Studies

“Air Quality and Ventilation” ranked very high (#2 of 25) on the list

of tenant retention issues in a recent survey conducted by

Real Estate Information Systems.


Affects

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Research & Studies

DOE/Lawrence Berkeley Labs Evaluation of

Sick Leave Statistics vs. Ventilation Rates

(3720 employees / 40 buildings):

Optimal ventilation reduces sick time costs. For every $1 spent on ventilation cost,

$2 are saved in sick time.


Affects

nChart compares ventilation usage throughout typical day using purple to represent “demand controlled” and green to represent “constant”nDifference between equates to significant savings

DCV Savings

Federal Energy Management Program Study

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Office Retail Restaurant School

Research FindingsDemand Control Ventilation

Energy required, DCV control applied

HUGE Savings

Energy wasted - no DCV

SCHOOL$6,910

Annual Savings15 mo. ROI

THEATRE$11,530


SCHOOL$20,051


THEATRE$17,603


RETAIL$18,729


OFFICES$7,112


OFFICES$3,448


Examples of Potential Energy Savings and ROI

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FEMP Study• 4 CO2 sensors per floor– Energy Model

$81,293 annually$3,000 per floor$0.22/ft2

– Actual saving for 6 months was $133,805

Application

Ratin

g

Application

Ratin

g

Application

Ratin

g

Correctional facilities Specialty shops Hospitals and medical Cells A Barber and beauty B Patient rooms BDining halls (Note 2) B Reducing salons B Medical procedure CGuard stations C Florists B Operating rooms C

Dry cleaners and laundries Clothiers B Recovery and ICU BCommercial laundry B Furniture B Autopsy rooms CCommercial dry-cleaner C Hardw are B Physical therapy AStorage and pickup B Supermarkets B Lobbies and w aiting areas ACoin-operated laundries A Pet shops C Hotels, resorts and Coin-operated dry C Sports and amusement Bedrooms B

Education and schools Spectator areas A Lobbies AClassrooms A Industrial facilities Conference rooms ALaboratories (Note 4) B Heavy manufacturing C Meeting rooms ATraining shops B Light manufacturing B Ballrooms and assembly AMusic rooms A Materials storage C Gambling casino BLibraries A Training facilities C Game rooms ALocker rooms C Painting and finishing C Ice arenas AAuditoriums A Food and meat processing C Sw imming pools CSmoking lounges (Note 3) B Office buildings A Gymnasiums A

Food and beverage service Retail stores Ballrooms and discos ADining rooms (Note 2) B Sales floors A Bow ling alleys ACafeterias (Note 2) B Dressing rooms A Theaters ABars, cocktail lounges B Malls and arcades A TransportationKitchens C Shipping and receiving C Waiting rooms A

Garages, repair and service C Warehouses C Platforms A

Rating Legend: A Recommended B Possible (Note 1) C Not Recommended

Determine if CO2 Control is Appropriate

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Control Setpoints

.

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

30 cfm/person25 cfm/person

20 cfm/person

15 cfm/person

10 cfm/person

8 cfm/person

6 cfm/person

5 cfm/personUnacceptable

Very Poor

Poor

Under Ventilated

Marginal

Ideal

Over Ventilated

Typical OutsideLevels

2,600

Vent

ilatio

n R

ate

Condition OfIndoor Air

Need ToIncrease

Outside AirVentilation

OpportunityTo Save Energy

By ReducingVentilation

Insi

de C

O2C

once

ntra

tion

(ppm

)

CO2 Control Point Depends on:• Outdoor CO2 Level (typically 450 ppm)• Required cfm/person ventilation rate

If OA CO2 is 400 ppm:20 cfm/person = 930 ppm CO215 cfm/person = 1,100 ppm CO210 cfm/person = 1,450 ppm CO2

• Proof of Compliance

Using CO2-based ventilation control ensures compliance to codes and standards

Benefits of Ventilation Control

Now Allowed by Most Mechanical Codes

International Mechanical Code (IMC)

Local Codes

ASHRAE Standard 62.1

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ASHRAE 62.1-2010

Written into the actual standard since ASHRAE

62-2004

Now Allowed by Most Codes

Commentary To The International Mechanical Code (IMC)Section 403.3.1

“The intent of this section is to allow the rate of ventilation tomodulate in proportion to the number of occupants. This canresult in significant energy savings. Current technology can permitthe design of ventilation systems that are capable of detecting theoccupant load of the space and automatically adjusting theventilation rate accordingly.

For example, carbon dioxide (CO2) detectors can be used to sensethe level of CO2 concentrations which are indicative of the numberof occupants. People emit predictable quantities of CO2 for anygiven activity, and this knowledge can be used to estimate theoccupant load in a space.”

Was written into the actual code for IMC 2006

Now Allowed by Most Mechanical Codes

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• Proof of Compliance

Also required in green codes such as ASHRAE 189.1, IgCC, and LEED

Benefits of Ventilation Control

Now Required by Most Energy Codes

International Energy Conservation Code (IECC)

Local Codes

ASHRAE Standard 90.1

ASHRAE 90.1-2007

This language is the same for IECC 2009

which is required by law in most states

IECC 2012 requires DCV at 25 people per

1000 ft2

DCV Now Required by Most Codes

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Why Now?

• Digital Control Systems– Integration of ventilation control

• Increased Ventilation Rates (ASHRAE/IMC)

• Increasing Energy Costs• Required by Energy Codes• Decreasing Sensor Costs (First & Life

Cycle) & Increased Sensor Reliability

Sensor Cost• Control system integration• Sensor technology and

integration (CO2 + Temp)• Volume increases

1992 1997 2003

$1500

$500 Installed CostPer Point

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Sensor Reliability• 15 Year design life• Non-interactive,

selective to CO2 only• Stable - lifetime

calibration

Self Calibration of a CO2 Detector

• Automatic Baseline Calibration (ABC Logic)

• Self calibrating algorithm

• Considers lowest CO2

level every 24 hrs

• Looks at long term changes in baseline

• Applies a correction factor for calibration

Slight Long Term Sensor Drift Calculated Over Number Of DaysTEMA Corrected Baseline

1000

900

800

700

600

500

400

300Days

Indo

or C

O2

Con

cent

ratio

n

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Self Calibration of a CO2Detector

0

100

200

300

400

500

600

700

800

2000/12/2914:58'08

2000/12/3007:38'08

2000/12/3100:18'08

2000/12/3116:58'08

2001/01/0109:38'08

2001/01/0202:18'08

2001/01/0218:58'08

2001/01/0311:38'08

2001/01/0404:18'08

PPM

Sensor 1Sensor 2Sensor 3

Sensor Reliability

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

12/27 12/28 12/29 12/30 12/31 1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 1/9 1/10 1/11

Day

CO

2 C

once

ntra

tion

(ppm

)

1 2 3 4 5 6 7 8 9 11 12 13 14 1510

Self Calibration Over 14 Days

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Long Term Sensor Stability

0250500750

10001250150017502000

1

365

729

1093

TIME (DAYS)

PPM

(CO

2)

Test Gas: 980 ppm CO2 in Nitrogen

Stat, Econ, and DCV Energy Savings

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Vehicle Demand Controlled Ventilation

Up to 80% fan energy reduction!!!Parking garagesLoading docksVehicle bays

– Fire stations– Car dealershipsBus terminals

Case Study – Parking Garage

Ventilation fans ran 24/7– 1.5M kWh annually– $242,000 annually

Installed– 41 CO sensors– 8 VFDs

$160,000 install cost90% reduction in fan energy

– Saved 1.35M kWh annually– Saved $217,800 annually– Simply payback of 9 months

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Alarm Setpoints

Time weighted average (TWA):Concentration levels that nearly all workers can be exposed to, during an 8 hour workday or 40 hour workweek, without suffering adverse affects

Short-term exposure limit (STEL):Maximum concentration to which workers can be exposed for a period of 15 continuous minutes

Ceiling concentration level (CCL):Exposure limit that should not be exceeded even momentarily

Toxic Gases

Standards

EXPOSURE LIMITS– OSHA PEL - Occupational Safety and Health

Administration (OSHA) permissible exposure limit (PEL) for CO is 50 PPM as an 8-hour time-weighted average (TWA) concentration [29 CFR Table Z-1]

– NIOSH REL - National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for CO of 35 PPM as an 8-hour TWA and 200 PPM as a ceiling [NIOSH 1992]

– American Conference of Governmental Industrial Hygienists (ACGIH) has assigned CO a threshold limit value (TLV) of 25 PPM as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 15]

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CO – Carbon Monoxide GasA colorless, odorless, and tasteless gas. It is the product of the incomplete combustion of carbon compounds. Carbon monoxide is a major industrial gas with many applications in bulk chemical manufacturing.Carbon monoxide is a toxic gas

– TWA (8 hour): 25 ppm (2007 ACGIH)– Common type of poisoning– Attaches to hemoglobin more readily than

oxygen, impairing the ability to transport oxygenSymptoms of exposure include:

– Headaches– Flu-like effects– Toxicity of central nervous system and heart

(larger exposures)

NO2 – Nitrogen Dioxide

Reddish-brown gas (above 70°F) with a pungent, acrid odorResult of incomplete combustionReacts with water to form Nitric AcidExposure routes – inhalation, ingestion, skin and/or eye contact.Symptoms – irritation of the eyes, nose, & throat. Decreased pulmonary function, chronic bronchitis, breathing difficulty, & chest painTarget Organs – Eyes, respiratory system, cardiovascular system

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State of Gases in Ambient Air

The density of the gas determines where gas can be detected

At ceiling level:Lighter than air

At breathing level:Equivalent to air

At floor level:Heavier than air

Be Strategic About Locating Sensors

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Determining the Number of Sensors

The radius of operation of units defines the quantity of transmitters used within specific applications

*Sources of gas must be mobile

This determination is particular to each manufacturer.

Gas Radius of detection Area covered

CO*, NO2* 50 ft 10,000 ft2

Others 20 ft 1,600 ft2

Indoor Parking Garages

FIRST ALARM (TWA)

SECOND ALARM (STEL)

SENSOR LOCATION

RADIUS OF DETECTION

Carbon Monoxide (CO) 25 ppm 200 ppm 5 ft. above floor

50 ft.Nitrogen Dioxide

(NO2)0.72 ppm 2 ppm 1 ft. below ceiling

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Zoning

ZONE 1

ZONE 2

ZONE 3ZONE 1

ZONE 2

ZONE 3

Reduces energy costs• Average/compare gas levels• Control relay activation

Use energy only as needed, where needed!

Energy Savings Estimation Tools

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2 - dcv 12.12.13 - maeep - dcv 12.12.13_1.pdf · ashrae 62.1-2010 written into the actual standard...

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