Hvac Insulation- One of the Keys to a Healthy Building

7/31/2019 Hvac Insulation- One of the Keys to a Healthy Building

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Glenn Brower

ASHRAE Technical Comm. MemberKnauf Fiber Glass


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Indoor Environmental Quality

AIR

PURITY THERMAL

COMFORT

ACOUSTICAL

COMFORT

LIGHTING

QUALITY

AESTHETICS


3/41

THE ROLE OF HVAC INSULATION

IN IEQ Thermal - helps to deliver air at the design

temperature, save energy and minimize

condensation

Acoustical - helps to reduce sound down the

ducts, breakout noise, crosstalk

ventilation - can insulate withoutcontributing to indoor pollution

aesthetics - depending on application, can

be finished to blend in


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5/41

THERMAL PERFORMANCE OF

DUCT INSULATIONS Both internal and external insulations candeliver required R-values

R-values should be specified based on installed

thickness

Duct Wraps are installed with 25% compression

Most codes specify R-values based on ASTM

C518 or C177 testing no air film benefits are allowed

Radiant barrier insulations tested at high delta Ts

will not deliver R-value in duct applications


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7/41

DUCT THERMAL PERFORMANCE

Condensation Control - eliminating

sweating as a contributor to mold growthREQUIRED R-VALUE FOR 0.1 EMISS

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

20 25 30 35 40

AMBIENT TEMPERATURE (C)

R-VALUE

60% RH

70% RH

80% RH

90%RH REQ'D R-VALUE FOR 0.9 EMISS

0.00

0.50

1.00

1.50

2.00

2.50

21.1 26.7 32.2 37.8

AMBIENT TEMPERATURE

R-VALUE

60% RH

70% RH

80% RH

90% RH


8/41

AIR FLOW CONSIDERATIONS WITH

INTERNAL LINED SYSTEMS

The use of any type of material on the

inside of a sheet metal duct will have some

type of associated friction loss

friction loss can be calculated from surface

absolute roughness factors

galvanized steel, 1.22 m joints 0.091 mm

galvanized steel, 0.61 m joints 0.152 mmfg liner with mat-faced airstream 0.914 mm

fg liner with coated airstream 3.048 mm


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COMPARISON OF FRICTION

FACTORS FOR DIFFERENT

ABSOLUTE ROUGHNESS

Pressure loss is linear with friction factor

Pressure loss is linear with Hydraulic Diameter 4A/P

Pressure loss is the square of velocity, a factor of 2 in f = 30% velocity loss

FRICTION FACTOR

0.01

0.015

0.02

0.025

0.03

0.035

0 0.5 1 1.5 2 2.5 3 3.5

Absolute Roughness (mm)

f(dimensionless

)

305x610

610x610

610x1220

BARE

METAL

LINER

W/ MAT

COATED

MAT OR

FLEX DUCT


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ACOUSTICAL

COMFORT

Duct

Attenuation

Loss

Duct Rumble

Duct

Breakout &

Breakin


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Air Ducts Are Speaking Tubes

Direct energy through a very focused area.

Carry equipment noise, damper noise, and other

duct noise.

Can generate their own noise through expansion,

contraction, or air velocity.

Carry office noise from interconnected spaces.


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COMPARISON OF ASHRAE

ATTENUATION DATA FOR

RECTANGULAR DUCTS

DUCT LINER

SIZE (mm) THICKNESS 125 Hz 250Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

305x305 0 0.66 0.33 0.20 0.20 0.20 0.2025 1.31 2.62 6.23 13.12 13.45 9.19

51 1.64 5.25 11.48 16.41 13.45 9.19

610x610 0 0.66 0.33 0.10 0.10 0.10 0.10

25 0.66 1.64 4.59 9.19 7.22 5.91

51 0.98 2.95 8.20 11.48 7.22 5.91

305x610 0 0.66 0.33 0.16 0.16 0.16 0.16

25 0.98 1.97 5.58 11.48 10.50 7.55

51 1.31 4.27 9.84 14.11 10.50 7.55

ATTENUATION LOSS dB/meter


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ASHRAE ATTENUATION DATA FOR

RECTANGULAR ELBOWSRECTANGULAR ELLS - NO TURNING VANES

DUCT LINER

WIDTH (mm) THICKNESS 125 Hz 250Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

305 0 0.0 1.0 5.0 8.0 4.0 3.0

25 0.0 1.0 6.0 11.0 10.0 10.0

610 0 1.0 5.0 8.0 4.0 3.0 3.0

25 1.0 6.0 11.0 10.0 10.0 10.0

RECTANGULAR ELLS - WITH TURNING VANES

DUCT LINERWIDTH (mm) THICKNESS 125 Hz 250Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

305 0 0.0 1.0 4.0 6.0 4.0 4.0

25 0.0 4.0 4.0 7.0 7.0 7.0

610 0 1.0 4.0 6.0 4.0 4.0 4.0

25 4.0 4.0 7.0 7.0 7.0 7.0

ATTENUATION LOSS dB

ATTENUATION LOSS dB


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COMPARISON OF ASHRAE

ATTENUATION DATA FOR ROUND

DUCTSDUCT LINER

SIZE (mm)THICKNESS 125 Hz 250Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

152 0 0.10 0.16 0.16 0.33 0.33 0.3325 1.94 3.05 5.02 7.12 7.58 6.69

51 2.62 4.49 7.38 7.12 7.58 6.69

305 0 0.10 0.10 0.16 0.23 0.23 0.23

25 1.51 2.66 4.78 7.15 6.27 4.86

51 2.20 4.10 7.15 7.15 6.27 4.86

610 0 0.07 0.07 0.10 0.16 0.16 0.16

25 0.82 1.87 4.20 5.61 4.07 2.79

51 1.51 3.31 6.56 5.61 4.07 2.79

ATTENUATION LOSS dB/meter


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ASHRAE ATTENUATION DATA FOR

ROUND ELBOWS

DUCT

WIDTH (mm) 125 Hz 250Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

152 0.0 0.0 1.0 2.0 3.0 3.0

305 0.0 1.0 2.0 3.0 3.0 3.0

610 1.0 2.0 3.0 3.0 3.0 3.00

ATTENUATION LOSS dB


18/41

IF ATTENUATION IS THE GOAL,

HOW DO YOU SPECIFY WHAT YOU

WANT? Unless all duct sizes are the same, dont

specify internal liner by dB/meter or dBs at

the targetchanges for every duct dimension change

does the contractor include ells and other

fittings? Specify internal liner by sound absorption

gives an easy way to compare materials


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SOUND ABSORPTION TESTING

Uses the Reverberation Room (ASTMC423) method, which measures ability to

absorb random incidence sound

6.69 square meters of test material in the room

The mounting method plays a large part in

the values obtained

for repeatability, duct liners should be testedusing the Type A mounting

Test yields absorption values for each freq.

band, also calculates an average, NRC


20/41

HOW CAN SOUND ABSORPTION

CAN BE RELATED TO DUCT

ATTENUATION?Sound Absorption vs Attenuation for 305x610mm

0

5

10

15

0 0.2 0.4 0.6 0.8 1 1.2

Absorption Value

Attenuation(dB/m)

500 Hz

1000Hz250 Hz

2000 Hz

Sound Absorption vs Attenuation for 610x610 mm

0

2

4

6

8

10

12

14

0 0.2 0.4 0.6 0.8 1 1.2

Absorption Value

Attenuation(dB/m)

500 Hz

1000Hz

250 Hz

2000 Hz

Relationship between

absorption & attenuation isnearly linear ~ 10

Relationship between

absorption & attenuation

is nearly linear ~ 7.5


21/41

DUCT RUMBLE, BREAKOUT &

BREAKIN NOISE Thermal insulations do not have enough

mass to be effective over most frequencies

Flexible insulations in combination withmass can be helpful

for round ducts, can be directly attached, for

rectangular, both the insulation and the massshould be physically separated from the duct


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NOISE CONTROL FOR EQUIPMENT

AND PIPING Rigid insulation materials tend to pass the

majority of vibrating energy right through with

minimal attenuation. Fibrous insulation is a much better attenuator. In

specific applications one may have to install

fibrous insulation over rigid insulation.

For extra attenuation, use multi-layered fibrous

insulation with hard septums between layers.


23/41

INSERTION LOSS (dB) INTO 6" IPS SCHEDULE 40 PIPE

TEST SPECIMEN 500 Hz 1000 Hz 2000 Hz 4000 Hz

4" MIN WOOL + 2 PSF ACOUSTI-JAC 12 21 34 37

4" FIBERGLASS + 2 PSF ACOUSTI-JAC 17 30 36 42








24/41

Combining Decibel Levels

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13

dB Difference Between Two Sources

dBToAddToLargerLevel

THE DILEMNA OF REDUCING

NOISE FROM MULTIPLE SOURCES


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AIR PURITY

PARTICULATEMATTER BIOLOGICAL

CONTAMINANTS

VOCEMISSIONS


26/41

PARTICULATE MATTER - THE

ROLE OF INSULATIONS

External duct insulations should not

contribute to dust levels in the occupied

space

Internal duct insulations are designed to be

non-contributors when properly installed

FG duct liners are tested at 2.5 times rated

velocity, including an elbow without vanes, toassure that they can withstand air velocity

abuse

numerous studies have shown fiber levels to be

at background levels


27/41

TOUGHNESS OF INTERNAL

INSULATIONS The Surfaces of FG Liners will also take

normal abuse from cleaning procedures

soft brushes or air washes will not damage theairstream surface

cutting into the duct should be done carefully so

as not to damage the insulationclosing the duct after cleaning is also critical for

future integrity


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1994 BUILDING CONSTRUCTION

INDUSTRY ADVISORY

COMMITTEE STUDY

Evaluated duct cleaning methods for

effectiveness in cleaning the duct surface

and improving indoor air quality

contact method (conventional vacuum cleaning)

air sweep method (compressed air through a

nozzle)

mechanical brush method (rotary brush in

combination with vacuum collection)


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BCIAC STUDY RESULTS

Studied 8 identical homes in a singleneighborhood, 2 homes for each method

and 2 controls

Results:particle count readings were higher during

cleaning than before or after cleaning

cleaning did not lead to higher indoor fiber

counts

air sweep method showed the greatest reduction

in bioaerosol concentration, although none

caused significant improvement


30/41

HVAC INSULATIONS AND

BIOLOGICAL CONTAMINANTS FUNGAL GROWTH

requires both moisture and nutrients

dirt and fungal spores are present almosteverywhere, therefore they will inevitably be

deposited on duct surfaces

this is true regardless of the nature of the duct

surface

the only way to minimize this deposition is through

the use of better filtration


31/41

THE ROLE OF WATER AND

FUNGAL GROWTH IN HVAC

SYSTEMS Moisture is the essential element required

for fungal growth

Studies in static environmental chambershave shown that fungal growth will initiate

at RH>=65%

Field studies in buildings where RH isregularly >65% show that fungal growth is

rare


32/41

DUKE UNIVERSITY STUDY

Duke University - extensively studied 6buildings in the Piedmont region

Heavy deposition of dirt and fungal spores on

all surfaces inspectedno fungal growth on fresh air intakes, hot deck

surfaces or hot deck air distribution surfaces

no evidence of fungal growth on the cold deck

of dual-deck systems wherever intake air was

preconditioned

it is the condensation of water on surfaces at

dew point that have fungal growth


33/41

USE OF BIOCIDES AND

ENCAPSULANTS WITH INTERNAL

INSULATIONS All FG internal insulations are already

treated to be fungal and bacterial inhibited

when dry, these products will not sustain fungalgrowth

It is very difficult to get significant

coverage of the air stream surface except

where it is directly applied and visually

confirmed

small areas of repair that can be directly

reached may be effectively coated


34/41

BIOCIDES AND ENCAPSULANTS

(CONT.)

Application of these materials could have

human health consequences

Fire safety consequences - none have been

tested in combination with the insulation,and quantity will be difficult to control

Long term effects - may degrade integrity of

air stream surface, definitely voids mfrswarranty

These treatments are not recommended for

FG except for very limited spot repairs


35/41

VOLATILE ORGANIC CHEMICAL

EMISSIONS

VOCs are increasingly recognized as

significant contributors to poor indoor air

quality

Insulation materials, including duct

insulations, have long been tested for VOC

emissions and shown to be very low

contributors

meet US EPA indoor emission requirements,

State of Washington, State of Alaska, and State

of California requirements


36/41

COMPARISON OF VOC EMITTERS

EMISSION RATES

0

200

400

600

800

1000

1200

1400

FLOORINGW/

POLYURETHAN

E

FINISH

PRESSEDWOO

D

CABINETS

PERMANENT

PRESSSHIRT

S

(NEW)

PERMANENT

PRESSSHIRT

S

(WASHED)

FIBERGLASS

INSULATIONMI

CROGRAMS/SQ

M/HR


37/41

DECAY OF EMISSIONS FROM

FIBER GLASS

Formaldehyde Air Concentrations - Large Scale

Chamber

0

0.05

0.1

0.15

0 5 10 15

Time, Hours

PPM


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HOW CAN A SPECIFIER ADDRESS


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HOW CAN A SPECIFIER ADDRESS

LOW VOC EMISSIONS?

Follow the guidelines of the US GreenBuilding Council

the LEED design system addresses low

emitting sources

There is a independent, recognized

certification body that addresses all type of

building materials and furnishings

Greenguard is very much like Underwriters

Laboratories

Greenguard is recognized by LEEDS for

maximum points


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SUMMARY

Thermal benefits

radiant effects are not applicable for most ducts

Acoustical benefits

tradeoffs to cellular non-fibrous materials carry

a severe acoustical penalty

Minimal air quality issues in well designed

systemswater is the issue, design to prevent it

filtration selection & maintenance will

minimize any need for cleaning


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REFERENCE RESOURCES ON ALL

ASPECTS OF INSULATION AND IEQ NORTH AMERICAN INSULATION

MFRS ASSOCIATION

www.naima.org

Knauf Fiber Glass - www.knauffiberglass.com

[email protected],

[email protected], 317-398-4434, x8801

ASHRAE Handbooks

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Hvac Insulation- One of the Keys to a Healthy Building

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