ashrae indoor air quality guide · 2013-04-10 · ashrae indoor air quality guide presented for:...

ASHRAE Indoor Air Quality Guide

Presented For:

Chicago ASHRAE

By:

James Livingston, Regional Sales Manager,

Ruskin Company

1

Purpose of Presentation• Comment on ASHRAE IAQ

Guide topics as related to air

control devices

• Provide information on the

function and benefits of these

devices

• Provide advice on their

application

2

Presentation Agenda

3

IAQ Guide Basics

Objectives

1 Design & Construction

2 Control Moisture

4 Moisture in HVAC

6 Capture/Exhaust Contaminants

7 Reduce Contaminants

8 Advanced Ventilation Approaches

Purpose of IAQ Guide• Provide advice on how provide good IAQ

via means that are:

– Cost effective

– Practical

– Currently available

– Technologically sound

– Sustainable

– Goal: Increased usage & IAQ!

4

Guide Approach• 8 “Objectives”

• Objectives address components of

building IAQ

• Each Objective contains individual

“Strategies” to help achieve the Objective

• Benefits designers, constructors, owners

and facility managers

5

Scope of IAQ Guide• Buildings covered:

– Commercial & institutional

• Office

• Retail

• Educational

• Lodging

• Public assembly

6

Scope of IAQ Guide• Buildings not covered:

– Kitchens

– Medical procedure rooms

– Natatoriums

– Cold buildings

– Laboratory

– Industrial

– Residential

– Chemical storage

7

Why IAQ?• Health & well being of occupants

• Financial success & sustainability of

building

8

Common Sources of Poor IAQCommon Sources of Poor IAQ

• Two Basic Categories– Gaseous

• Radon, C02, chemical vapors, etc.

– Biological (with 2 subcategories)

• Microbial– Bacteria, molds, mildews, viruses, dust

mites, animal dander, etc.

• Particulate – Dust, pollen, building material fibers,

process byproduct (such as saw dust), etc.

“THE SOLUTION TO “THE SOLUTION TO “THE SOLUTION TO “THE SOLUTION TO

POLLUTION IS DILUTION”POLLUTION IS DILUTION”POLLUTION IS DILUTION”POLLUTION IS DILUTION”W. K.W. K.W. K.W. K.

Health Issues• Increased allergy & asthma symptoms

• Colds & infections

• Carbon monoxide poisoning

• Legionnaires’ disease

• Lung cancer from Radon exposure

10

Financial Impact

• Repairs or modifications to correct issues

• Potential temporary building closure

• Difficulty in renting spaces

• Legal action due to sick building or other

issues

11

A Different Way Of Thinking• Traditional high priority features include

cost, space, aesthetics, etc.

• Make IAQ a priority in the beginning!

• Early discussions & strategies by all parties

• Improving IAQ after the fact is difficult and

sometimes impossible

12

Objective 1 Manage the Design &

Construction Process to Achieve

Good IAQ• Strategy 1.1 Traditional Design

13

Objective 1

• Strategy 1.1 Integrated Design

14

Objective 1

• Strategy 1.2 Commissioning

– Not just post-construction

– Employ a Commissioning Authority (CxA) for

pre-design and during construction

– Ensure the design meets owners

requirements and is being constructed

correctly

15

Objective 1

• Strategy 1.3 Selecting HVAC Systems

– Use environmentally-friendly & energy efficient

systems when possible

– Displacement ventilation

– If conventional means are used (CV, VAV, etc.),

be sure good IAQ practices are used (62.1

ventilation for example).

16

Objective 1

• Strategy 1.5 Effective Operation &

Maintenance

– O&M can be just as important as design &

construction

– Expected level of owner’s O&M efforts?

– Consider O&M during design & construction

– Provide documentation & training

17

Objective 2 Control Moisture in

Building Assemblies• Moisture is a common cause of IAQ problems and

responsible for the most costly litigation and

remediation

• Thermal bridging enables interior frost build-up &

condensation

• Condensation liquid can travel through capillary

action to inaccessible locations

18

Objective 2• Strategy 2.2 Limit Condensation of Water

Vapor within the Building Envelope and on

Interior Surfaces

– Use Thermally Efficient (Insulated) Control

Dampers at outside air intakes

19

Strategy 2.2

• Why use Thermally Efficient

Dampers?

– Reduce condensation to

prevent bacteria, mold,

mildew

– Thermally broken to prevent

frost build-up

– Lessen leakage into or out of

space

• Generally Class 1 leakage – 4

cfm/ft² at 1” w.g.

AMCA 500-D Section 6.9

• Thermal Efficiency Test

• Test setup Figure 5.10

• Damper tested in both

airflow directions

• ±2°F Steady State

Temperature for a period of

10 minutes

• Applied torque

AMCA 500-D

• V-groove reference damper

• 9 cfm per square foot at 1” w.c.

• How much more efficient is the test damper when compared to the reference damper?

• Insulated & thermally

broken blades

• Blade & jamb seals for

low leakage

• Thermally broken

frames

• Non-metallic bearings

Thermally Efficient Damper Features

• AMCA Standard 500-D– AMCA certified leakage

– AMCA certified performance

– AMCA certified Thermal Efficiency

Thermally Efficient Damper Performance

Objective 2• Strategy 2.3 Maintain Proper Building

Pressurization

– Building pressure affects moisture infiltration

and exfiltration

– Negative pressure in hot, humid conditions

promotes moisture infiltration into spaces

– Positive pressure in humid spaces increases

condensation buildup within envelope

25

Strategy 2.3

• Pressurization often is not consistent

throughout building due to:

– Stack effect

– Wind speed & direction

– Temperature

– HVAC supply & exhaust rates

26

Strategy 2.3• Airflow measuring stations can assist with

pressurization

27

Pick the Product for the Application

• Use Electronic Air Flow Measurement for

very low velocities and large openings

• Use Velocity Pressure Measurement for high

velocities or small openings.

Electronic Airflow Measuring

• Thermistors, heated mass flow sensors,

hot film anemometers, etc.

– Measures energy to heat element

– Low velocities – as little as 0 fpm

29

Pv = Pt - Ps

PsPt

Total Pressure Chamber

Static Pressure Chamber

Velocity Pressure Airflow Measuring

• Differential Pressure

– Minimum 300 fpm

Locations For Airflow Measuring Stations

Suggestions for Measuring Outside

Air

32

VAV & CV Systems

• Air measuring

station w/ control

damper built-in

• Damper control is

manual or by BAS

DCV Systems

• Air measuring

station with built-in

control damper and

control system

• Control system

maintains CFM set

point as fans scroll

up and down

Any system, limited

space

• Air measuring

combined with

outside air louver

• Can be as little as

4” total depth

Suggestions for Measuring Supply

Air

33

Fan inlet

• Highest velocity

point in the system

• Total system supply

airflow

Retrofit – single floor

or pressure area

• Probes or stations

• Can install as close

as 4” in front of

existing dampers

New construction –

single floor or pressure

area

• Air measuring

station w/ control

damper built-in

• Damper control is

manual or by BAS

Suggestions for Measuring Return

Air

34

Retrofit – single floor

or pressure area

• Probes or stations

• Can install as close

as 4” in front of

existing dampers

New construction –

single floor or pressure

area

• Air measuring

station w/ control

damper built-in

• Damper control is

manual or by BAS

Suggestions for Measuring Exhaust

Air

35

Use velocity pressure probes

or stations

• Works well with high

velocity exhaust airflow

• Much less expensive than

electronic airflow stations

Objective 4 Control Moisture &

Contaminants Related to

Mechanical Systems• Strategy 4.1 Control Moisture and Dirt in Air-

Handling Systems

– Fungi & bacteria are normally present on building

interior surfaces, including HVAC components

– Microorganism growth in HVAC system results in

malodors, nasal & throat irritation and building-

related illnesses

36

Strategy 4.1

• Outside air louvers can prevent rain

penetration

37

Louvers

Louvers With Plenum Behind

38

Water Penetration

39

Sloped Plenum Detail

40

Strategy 4.1• Traditional louvers provide protection

from non-storm rain

• Wind Driven Rain Resistant louver provide

storm condition protection

• Let’s look at the differences…

41

Strategy 4.1

• Traditional Louvers:

– Horizontal blades

– Drain Gutters

– Wide Spacing

– High Free Area

– Low Cost

– Stops some rain

– Not effective in storms

42

Strategy 4.1• Traditional louver sizing

– AMCA Water Penetration test – Beginning

Point of Water Penetration free area velocity

(FAV)

– Determine design FAV considering AMCA test

data

– CFM/FAV = Total Free Area required

– Reference louver Free Area Guide to

determine appropriate louver size

43

Air ExhaustWater

Droplets

Waterdrop Manifold

Wetted Wall Manifold

Test Unit

Air Entrained into chamber

through louver

Air FlowMeasurement

CollectionZone

ExhaustFan

“Still Air” Condition!

Standard 500-L Louvers5.6 Water Penetration

Test Conditions

• 48” x 48” size

• 15 minute intervals

• Manifold (raindrops) - 4” per hour (3.15 gal/15 min)

• Wetted wall - .25 gpm (3.75 gallons/15 min)

• Ventilation airflow only – no wind

• 1250 fpm max free area velocity

Standard 500-L Louvers

AMCA “Still Air” Water Test

Water Penetration GraphBeginning Point Of Water Penetration: .01 oz/ft² at 1,023 fpm Free Area Velocity

.01 oz./ft² of free area

“Still Air” Test with Non-drainable Louver

Traditional Louvers• Where to use:

– Properly drained applications

• Sloped plenums & ductwork

• Floor drains

– Protected areas (overhangs, barriers, interior,

non-prevailing wind elevations)

– “Screen” applications (vision barriers)

• Sizing

– Use Safety Factor (15% to 20% min)

• Does NOT stop storm rain

Traditional Drainable Louver

29 mph wind, 3”/hr rain, 1,000 fpm intake velocity

New Louver Technology

• Wind Driven Rain Louvers

– Horizontal or Vertical blades

– Drain Gutters on horizontal

– Hooks on vertical

– Close spacing

– Lower Free Area

– Higher Velocity

– Effective in storms

51

52

Wind/RainMachine

Test Louver

Wind DrivenRain plus

Air EntrainedInto Chamber

Through Louver

Air Exhaust

Exhaust FanCollection Zone

Rain WaterDischargeNozzles

Std 500-L Wind Driven Rain Test

5.11 Water Rejection Wind Driven Rain

• Rejection Effectiveness Classes

A 99% to 100%

B 95% to 98.9%

C 94.9% to 80%

D below 80% (std. louvers)

• 3” rain/29 mph wind

• 8” rain/50 mph wind

53

Std 500-L Wind Driven Rain Test

Wind Driven Rain Louver

29 mph wind, 3”/hr rain, 2,000 fpm intake velocity

Rear view, 29 mph wind, 3”/hr rain, 2,000 fpm intake velocity

How Much Water Is Applied?• 3” Per Hour Rain On 1m X 1m

• 21 Gallons Applied Over 1 Hr.

– Class A (99% or better) allows 27 fl. oz penetration

– Class D (80% or worse) allows over 4 gallons

– Std Louvers (60% or lower) - over 7 gallons

Wind Driven Rain Louver Benefits• Prevent rain infiltration

– Lessens interior water damage & mold growth

– Helps keep walls & floors dry

– Helps keep filters dry

– Excellent for Penthouses

• Allow higher intake velocities

– Use smaller louvers!

• Reduce future problems & liability

Wind Driven Rain LouversHorizontal blade models Vertical blade models

58

40% - 50% free area

2” to 8” deep

Class A @ 800 to 1200 fpm

Moderate ∆p

Traditional appearance

40% - 45% free area

3” to 7” deep

Class A @ 1500 to 2100 fpm

Low ∆p

Best performance

Sizing Example• 48” x 48” & 7,000 cfm

• 6” Traditional• 710 fpm• .07” ∆p• 60% Wind Driven Rain Effectiveness (29 mph)

• Cost 1.0

• 5” Horizontal WDR• 1,002 fpm• .16” ∆p• 99.8% Wind Driven Rain Effectiveness (29 mph)

• Cost 1.7

• 6” Vertical WDR• 1,030 fpm• .09” ∆p• 99.8% Wind Driven Rain Effectiveness (50 mph)

• Cost 2.7

• 48” x 36” (25% smaller)• 1,488 fpm• .18” ∆p• 99.8% Wind Driven Rain Effectiveness (50 mph)

• Cost 2.3

Rooftop Intakes

Traditional style, allows rain penetration

Wind Driven Rain Design, prevents rain penetration

What About Snow?

61

Suggestion for Stopping Snow Penetration

• Heated screen behind louver

• Prevents snow blowing into

ductwork

• Reasonable pressure drop

• Relatively slow airflow - 350 FPM

Face area velocity.

Objective 7 Reduce Contaminant

Concentrations through Ventilation,

Filtration and Air Cleaning• First goal is to reducing contaminant sources,

then capturing & exhausting

• Remaining contaminants should be

– Diluted with ventilation air, or

– Reduced by filtration and gas-phased air cleaning

(FAC)

63

Strategy 7.2 Continuously Monitor

and Control Outdoor Air Delivery

• Fixed minimum outdoor air dampers may not

provide optimum control of intake CFM,

particularly in VAV systems

• Over-ventilation is common now – estimated

30% annual savings in U.S. building energy costs

if ventilation per standards is maintained

64

Suggestion for Maintaining Proper

Outdoor Air Intake Levels

• Use air measuring station with built-in control

damper and control system to maintain CFM set

point

65

Air Measuring & Control Stations

• Advantages

– System automatically modulates

damper to maintain CFM

– Can be used as minimum outside air

damper only (overridden when

economizer damper opens), or

– Can be used as entire outside air

damper

66

� Air Measuring & Control Damper

Documentation I/O Chart

� Provided w/ unit

� Calibration Certificate

� 0 - 10 VDC Input - CFM Setpoint

� 0 – 10 VDC Output - Measured CFM

� Alarm when CFM falls below setpoint

Pressure Signal Chart

text

Strategy 7.2 Continuously Monitor

and Control Outdoor Air Delivery

• Proper placement of airflow stations is critical

• Installing too close to an elbow or other

disrupting feature can affect performance

68

Air Measurement Station Placements for Acceptable Installations

Air Measurement Station Placements for Acceptable Installations

Air Measurement should be in the Mechanical Spec!

Air Measurement Station Placements for Acceptable Installations

90° DEGREE UNVANED ELBOW

5D 1D

Strategy 7.2 Continuously Monitor

and Control Outdoor Air Delivery

• Consider using airflow

measuring sensors

between fixed louver

blades

– Higher velocity, better

accuracy

20,000 CFM supply air measured

±±±±1,000 CFM @ 5% accuracy (S.A.)

16,000 CFM return air measured

±±±±800 CFM @ 5% accuracy (R.A.)

THE DIFFERENCE

Could be off by ±±±±1,800 CFM

Versus measurement at the intake

4,000 CFM @ 5% accuracy (O.A.)

±±±±200 CFM @ 5% accuracy (O.A.)

Air Flow Sensing Stations

Accuracy Considerations:Outside Air Measurement Advantage

Outside Air

Objective 8 Apply More Advanced

Ventilation Approaches

• Strategy 8.2 Use Energy Recovery Ventilation

Where Appropriate

– Required by ASHRAE 90.1 2007 & 2010 in some

cases

74

Code Driven Requirements

ASHRAE 90.1 2007 Energy StandardEnergy recovery is required on individual fan systems that are:

5000 cfm or greater, and

Outside air accounts for 70% or more of the design supply air quantity

Energy recovery system shall have 50% effectiveness:

Change in enthalpy equal to 50% of the difference between outdoor air and return air at design conditions

Status of Code Adoption: Commercial

www.energycodes.gov/adoption/states

As of February 2013

Most States are Expected to Adopt 90.1 2010 by End of 2013!

DOE Climate Zone Map – for 90.1

Miami FL

Houston, TX

Phoenix, AZ

San Francisco CA

Baltimore MD

Salem, OR

Chicago, ILBoise, ID

Burlington, VT

Helena MTDuluth, MN

El Paso, TX

Albuquerque, NM

Memphis TN

Figure B-1

How do Climate Zones affect ERV?

ASHRAE 90.1 2010 states:6.5.6.1 Exhaust Air Energy Recovery. Each fan system shall have an energy

recovery system when the system’s supply air flow rate exceeds the value listed

in table 6.5.6.1 based on the climate zone and percentage of outdoor air flow rate

at design conditions.

• Stretch standard for energy efficiency

• “Glimpse” of the future of 90.1

• Currently being specified for some

government buildings

• Requires even more energy recovery

• As low as 10% outside air requires energy

recovery in some cases

• The energy recovery effectiveness shall be

60%

ASHRAE 189.1 Standard

Energy Recovery

• ERV – Latent Recovery

– Energy Recovery Wheels

– Fixed Plate w/ Latent Transfer

• HRV – Sensible Only (no latent)

– Fixed Plate

– Heat Pipe

– Runaround Loops

80

Wheel ERV’s – How They WorkWheel Rotates between the

Return Air and the Outdoor Air

Airstreams

Return Air Temperature and

Humidity is absorbed onto the

Desiccant Wheel

Outdoor Air is tempered

(Heated/Cooled) as it flows

across the Wheel

Outdoor Air Humidity

Decreases or Increases as air

flows across the Wheel

Exhaust Air Transfer Ratio

EATR is the % of air being exhausted from

the occupied space that leaks around the

ERV wheel and re-enters occupied space.

Importance: Per ASHRAE 62.1……

Dedicated Duct System

Ducted to Rooftop Unit

Common ERV Configurations

UnitizedStand Alone

Typically 300 to 12,000 CFM

Small ERV’s – 150 to 1000 CFM

Only 18” to 22” tall!

Example of small ERV application

Small ERV Installation

Questions?

89

90

Thank You!