Commercial Duct Systems: The Current State of … Commissioning Group AIA Provider Number 50111116 Commercial Duct Systems: The Current State of Regulatory Compliance, Design & Best

AABC Commissioning GroupAIA Provider Number 50111116

Commercial Duct Systems: The Current

State of Regulatory Compliance,

Design & Best PracticesCourse Number: CXENERGY1622

Neal Walsh

Aeroseal LLC

April 13, 2016

Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.

This course is registered with 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.

This presentation will review key updates to the

ASHRAE 62.1 standard for ventilation and indoor

air quality, the SMACNA duct design manual for

energy efficiency and other related industry

guidelines. We will look at recent study results

that highlight the size and the scope of the

problems associated with building ventilation and

the direct correlation between duct leakage rates,

energy efficiency and indoor air quality.

CourseDescription

LearningObjectives

1. Regulatory compliance and air duct leakage standards associated with ASHRAE

62.1, the SMACNA duct design manual and other industry guidelines.

2. Current research on the prevalence of duct leakage in commercial buildings today

and the implications that this has for energy efficiency and indoor air quality.

3. Best practices for duct system testing and remediation.

4. Real-world examples of duct deficiencies and strategies used to mitigate the

energy inefficiencies that result.

At the end of the this course, participants will be able to:

Overview

• Air duct tightness and testing standards

• The Hole Truth about air duct tightness

• Best practices in air duct remediation

Air duct tightness and testing standards

ASHRAE 62.1 and Duct Leakage

Key to maintaining correct

building pressurization

Duct tightness effects

zone air quality

Minimum discharge air

calculation must include

duct leakage


ASHRAE 90.1, IECC, IGCC and Duct Leakage

Test ducts operating at >3 inWG

Test no less than 25% of the

surface area of the duct


IAPMO Guidance

Test 20%

Recommended procedure:

-- If fail: retest + additional 20%

-- If 2nd fail: 100% test


SMACNA and Duct Leakage

Formula for calculating maximum permissible leakage:

Leakagemax = CL X P0.65 X SA

• Leakagemax = maximum leakage expressed in CFM

at test pressure

• SA = duct surface area expressed in units of 100 sqft

• P = test pressure expressed in units of inWG

• CL = leakage class specified by design engineer


SMACNA Test Manual Inferences

Engineer must specify amount of duct to be tested

• Testing all the ductwork is too costly

• Little benefit from testing low pressure ducts

• Not required to test ducts operating < 3 inWG

Engineer must specify leakage class• Use the recommended values

• Assume an operating pressure of 2 inWG for

VAV high pressure systems and 1 inWG for CV

systems if not specified

A 10% difference between fan and diffusers is not

necessarily excessive


Europe Test Criteria

Testing required on duct pressure

classes above 0.8 inWG (200 Pa)

• UK: no testing required on low

and medium pressure ducts

Recommended procedure:

• If fail: retest + additional 10%

• If 2nd fail: 100% test

Test 10%

EU 12337 strength and testing of circular metal ducts


Emerging Trends

Less allowable leakage

Higher percentage of duct tested

- low and medium pressure testing

- 25 - 50 - 100

Part II

The Hole Truth

About Air Duct Tightness

The Hole Truth aboutair duct tightness

What Happens When Ducts Leak

• Supply duct leakage short circuits system

• Longer to satisfy temperature

• Building and zone pressurization

impact air quality

T


Top Ten Building Faults: By Cost

Source: Building Commissioning: A Golden Case For Reducing Energy Costs , E Mills, 7/09


By The Numbers

• 30% - the average rate of leakage

in light commercial buildings1

• 10% to 20% - average amount of air

provided by supply fan that

never reaches the occupied

space2

• 75% - percentage of commercial duct

systems that leak 10% to 25%3

(1) Florida Solar Energy Center, California Energy Commission Studies

(2) Lawrence Berkeley Nat’l. Laboratory Studies

(3) ASHRAE Handbook, Duct Design Manual


More Facts & Figures

• System leakage significantly increases building energy leakage1

• A leaking VAV system uses 20% to 35% more fan energy than a

tight system2

• A fan exhaust system with 20% leakage causes fan power to

increase 95%2

(1) ASHRAE Handbook, Duct Design Manual

(2) ASHRAE SPC 215P: MOT to Determine Leakage

Airflows and Fractional Leakage of Operating

Air Handling Systems



55% find leakage

rates of 15% or

more somewhat

common.

Part III

Best Practices

Air Duct Remediation

Best practices:Air duct remediation


Infrared photo of

typical air duct


Licking Heights School District

• 5 school buildings

• 4,000 students


West K-2 Elementary School

• 7 year-old building

• 20% higher energy

consumption than

sister building 3 miles

away

• Severe comfort issues

• New AHU and boilers

• 20,000 sqft expansion


Diagnosis

• Dual 40 HP motor

continuous operation

• Ceiling plenum

positive pressure

• Many rooms had no

supply air flow

• Existing leakage 55%

• Internal duct

insulation torn


Constraints

• No disruption to students or staff

• Guarantee result

• Project completion over winter break

• Safe for application with staff in building

• Proof of repair


Alternatives

External manual repair

• 12 weeks

• $350,000

• Repair main ducts only

• Demolish ceiling

• No verification

• No guarantee

Internal aerosol sealing

• $180,000

• 2 weeks

• No demolition

• Repair main and branches

• Performance verified

• Guaranteed results


Results

• Completed during 2 week winter break

• Reduced leakage by 95%

• Ended comfort complaints

• $45,000 annual energy savings

• Operating on night setback

• AHU VFD operating at 65% winter;

85% in summer


Federal rating of top energy saving strategies



Process Overview

1. Connect equipment

2. Isolate AHU

3. Block registers

4. Pre-seal: benchmark

5. Seal: inject sealant

6. Post-seal: measure final leakage

7. Present certificate


Process Overview


Certificate of completion

When we arrived

YOUR DUCTS HAD:

3,317 CFM of Leakage equivalent

After we finished

YOUR DUCTS HAVE

178 CFM of Leakage equivalent

This corresponds to a 95%

Reduction in Duct Leakage


Sealant FAQsVinyl Acetate Polymer

- base of chewing gum, hair spray

- remains rubbery

Certified in accordance with UL 1381

- surface burning

- mold growth and humidity

- interior duct burning

- leakage reduction

- durability

Low VOC content

2 hours to cure

3-year guarantee


Next Steps

• Tighter leakage standards

• Increased testing/verification

• 75% of existing buildings

have excessive leaks

• Duct leaks are a low-

hanging

opportunity

• Aerosol sealing is an

efficient

and effective method

This concludes The American Institute of Architects Continuing Education Systems Course

For More Information contact:

Neal Walsh, [email protected]

mailto:[email protected]

Documents

Commercial Duct Systems: The Current State of … Commissioning Group AIA Provider Number 50111116 Commercial Duct Systems: The Current State of Regulatory Compliance, Design & Best