BASC Search | Building America Solution Center

Ducts are properly insulated and supported without compressing the insulation

Ducts are insulated but strapping is compressing the insulation therefore reducing the R-value

Duct and HVAC Insulation

Author(s)

North American Insulation Manufacturers Association

Organization(s)

NAIMA

Publication Date

January, 2010

Information sheet with HVAC duct insulation, testing, maintenance and performance information.

Sealed and Insulated Metal Ducts

Guide describing how to air seal and insulate metal ducts.

Sealed and Insulated Flex Ducts

Guide describing how to air seal and insulate flex ducts.

Mechanical Insulation Design Guide - Installation

Author(s)

National Mechanical Insulation Committee

Organization(s)

NMIC

Publication Date

January, 2017

Web resource that lays out the pre-work considerations, methods and finishes for installing mechanical insulation.

Ducts Buried in Attic Insulation and Encapsulated

Guide describing approaches to burying and encapsulating ducts in unconditioned attics to increase the overall R-value of duct insulation.

Air seal and insulate flex ducts

Publication Date

Fri, 10/28/2011 - 12:00

Duct insulation is installed over boot

Insulation does not cover boot and is not sealed

Duct is located in unconditioned space and is not insulated

Sealed and Insulated Fiber Board Ducts

Guide describing how to air seal and insulate fiber board ducts.

Insulation does not cover boot and is not sealed

No insulation installed in cavity and not air sealed

Duct is located in unconditioned space and is properly insulated

Measure Guideline: Sealing and Insulating Ducts in Existing Homes

Author(s)

Aldrich Robb,

Puttagunta Srikanth

Organization(s)

Consortium for Advanced Residential Buildings,

CARB,

National Renewable Energy Laboratory,

NREL,

Steven Winter Associates,

SWA

Publication Date

December, 2011

Report describing the sealing and insulating of HVAC duct systems in existing homes.

Exterior Insulation Implications on Heating and Cooling in Cold Climates

Author(s)

Herk Anastasia,

Poerschke Andrew

Organization(s)

Integrated Building and Construction Solutions,

IBACOS

Publication Date

April, 2015

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings.

Prescriptive Path: Supply ducts in unconditioned attic have insulation ≥ R-8. Performance Path: Supply ducts in unconditioned attic have insulation ≥ R-6

Pull the insulation and outer liner of the flex duct over the collar to come in full contact with the liner and insulation of the trunk line or fitting and tape in place

Boot has been covered with insulation and sealed with mastic

Publication Date

Fri, 10/28/2011 - 12:00

Inadequate amount of insulation installed with compression, misalignment, and voids

Trunk to duct connections are properly insulated and have been sealed with mastic

Right – An insulated space is provided in the home’s attic to house the HVAC equipment.

Publication Date

Mon, 09/30/2019 - 12:00

Spray foam insulates and air seals the underside of the attic roof and walls.

Publication Date

Thu, 09/01/2011 - 12:00

Wrong - Flex duct resting on floor compressing insulation and causing condensation

Seal all joints and seams in the metal ductwork with mastic before installing insulation

Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

Publication Date

Thu, 09/30/2021 - 12:00

Cleaning Fibrous Glass Insulated Duct (Ductboard / Duct Board) Systems - Recommended Practices

Author(s)

North American Insulation Manufacturers Association

Organization(s)

NAIMA

Publication Date

June, 2019

Manual showing duct cleaning contractors how to identify the different types of insulated air ducts, how to open each type for access by cleaning equipment and personnel, how to close and seal openings after cleaning.

Wrong - Duct insulation and vapor barrier do not cover all of the flex duct.

Publication Date

Fri, 12/07/2018 - 12:00

Wrong - Flex duct insulation is overly compressed in 3 ways; Zip-tie fastener is over the insualtion not under the insulation at the duct boot collar, duct turning radius is too tight, and support strap is too tight.

Publication Date

Sat, 01/19/2019 - 12:00

Right – Flex ducts are properly supported with straps that don’t pinch the insulation; closed-cell spray foam will be applied to the underside of the roof deck of this hot-humid climate home to provide an insulated attic space for the HVAC ducts.

Publication Date

Thu, 09/30/2021 - 12:00

Cavity used for return is not insulated and is not air sealed, which will pull in air from outside

Wrong- A tie strap should not be used over the duct outer liner because it can compress the insulation. Tuck in the fibrous insulation and seal the outer liner to the connecting duct with mastic or foil tape (Steven Winter Associates 2013).

All other supply ducts and all return ducts in unconditioned space have insulation ≥ R-6

Publication Date

Fri, 10/28/2011 - 12:00

Right - Insulating sleeve for small through-the-wall HRV unit with sealing gasket; 3 of 14.

Publication Date

Wed, 08/26/2020 - 12:00

A nylon draw band and tensioning tool are used to secure the inner coil of the pre-insulated flexible duct

Publication Date

Wed, 11/21/2012 - 12:00

A nylon draw band and tensioning tool are used to secure the inner liner of the pre-insulated flexible duct

Baffles are installed to protect airflow from the soffits to the ridge vents before the ceiling drywall and attic insulation are installed.

Publication Date

Wed, 01/01/2014 - 12:00

When wrapping metal ducts with insulation allow two inches of overlap and staple along the seam with outward clinching staples

If HVAC duct must be installed in an exterior wall, separate it from the exterior with at least R-6 of continuous rigid insulation

Right – Rigid foam is installed behind HVAC ducts to provide additional insulation to the ducts which are installed within the conditioned space.

Publication Date

Mon, 09/30/2019 - 12:00

Wrong: open wall cavity connected to this return air plenum is allowing cellulose attic insulation to be pulled into the furnace

Publication Date

Sun, 06/01/2014 - 12:00

A ducted central return brings air from central return registers back to the air handler through insulated, air-sealed ducts

Publication Date

Thu, 03/09/2017 - 12:00

To attach the flex duct to a main trunk duct or any other connection, the flex duct is pulled over the connecting collar at least 2 inches past the raised bead, then the insulation is pulled back

Wrong – These flex ducts are pulled taut, which is correct but they are inadequately supported with straps that are spaced too far apart and are too tight causing pinching of the insulation and turns are sharp rather than gradual.

A 5,000- 6,000 Btu/hr air conditioner drawing about 500 watts can be installed in one window of a designated cool room (it is important that the installation is insulated and well-sealed

HVAC ducts, cavities used as ducts, and combustion inlets and outlets may pass perpendicularly through exterior walls but shall not be run within exterior walls unless at least R-6 continuous insulation is provided on exterior side of the cavity

The mechanical room in the insulated basement houses the water heating equipment, including the storage tank for the solar thermal system and the wall-hung boiler as well as the air handler for the hydro coil and high-efficiency (16 SEER) air conditioner.

Right - The precast insulated concrete walls of the basement provide a conditioned space for the high-efficiency (18 SEER, 9.5 HSPF) air-source heat pump, with its variable-speed fan, five-stage compressor, and MERV 11 filter.

Building Science Introduction - Heat Flow

Information guide providing background information about heat flow in residential buildings.

Ducts in Raised Ceiling Sections

Guide describing method for designing and installing ducts in a raised ceiling chase.

Encapsulated Ducts

Guide that illustrates how and when to encapsulate ductwork in unconditioned attics, increases the R-value of duct insulation, mitigating condensation issues and reducing air leakage.

Support at Intervals for Flex Ducts

Guide describing how to hang ducts with supporting straps or saddles to adequately support ducts so they do not sag and are not pinched or compressed in a manner that would cause damage to the ducts, the duct insulation, or the duct air barrier covering.

Sufficient Cavity Space for Flex Ducts

This measure guide describes how to correctly install ducts, ensuring enough cavity space to avoid compression.

Burried and encapsulated ducts in a ceiling plane

Publication Date

Fri, 02/01/2013 - 12:00

Bedford Farmhouse High Performance Retrofit Prototype

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

April, 2010

Case study describing a retrofit project in the cold and very-cold climate zones.

Builders Challenge High Performance Builder Spotlight: Ecofutures Building Inc., Boulder, Colorado

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

December, 2009

Case study describing a building project in the coldclimate.

High Performance Builder Spotlight: G.W. Robinson, Gainesville, FL

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

January, 2011

Case study describing a new home construction project in the hot-humid climate.

HVAC Ducts Shall Not Be Run within Exterior Walls

Guide describing the use of building cavities as supply or return ducts.

Home Performance Assessment

Information guide describing how to apply a whole-house approach to home improvement with energy efficiency upgrades, improved indoor air quality, and increased comfort.

Show Home Targets Energy Efficiency in Hot-Humid Climates

Author(s)

U.S. Department of Energy

Organization(s)

DOE

Publication Date

November, 2004

Case study describing the New American Home project.

Best Practices Case Study: S&A Homes, East Liberty, PIttsburgh, PA

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

December, 2010

Case study describing a building project in the cold and very-cold climate zones.

Builders Challenge High Performance Builder Spotlight: Ferrier Custom Homes, Dallas, Texas

Author(s)

U.S. Department of Energy

Organization(s)

DOE

Publication Date

October, 2009

Case study describing a building project in hot-dry and mixed-dry climates.

Existing Whole-House Solutions Case Study: Consortium for Advanced Residential Buildings (CARB), Washington, D.C.

Author(s)

Pacific Northwest National Laboratory,

Steven Winter Associates

Organization(s)

PNNL,

CARB,

SWA

Publication Date

September, 2009

Case study describing a retrofit project in Maryland.

Measure Guideline: Reducing Thermal Losses and Gains With Buried and Encapsulated Ducts in Hot-Humid Climates

Author(s)

Mantha Pallavi,

Zoeller William,

Shapiro Carl

Organization(s)

Consortium for Advanced Residential Buildings,

CARB,

Steven Winter Associates,

SWA

Publication Date

August, 2013

Document covering the technical aspects of buried and insulated ducts (BEDs), as well as the advantages, disadvantages, and risks of BEDs compared to alternative strategies.

Existing Whole-House Solutions Case Study: Evaluation of a Multifamily Retrofit in Climate Zone 5, Boulder, Colorado

Author(s)

Steven Winter Associates

Organization(s)

CARB,

SWA

Publication Date

November, 2013

Case study describing a multifamily retrofit project in a cold climate.

New Whole-House Solutions Case Study: The Performance House: A Cold Climate Challenge Home, Old Greenwich, Connecticut

Author(s)

Steven Winter Associates

Organization(s)

CARB,

SWA

Publication Date

November, 2013

Case study describing a high performance test home incorporating best practices for energy efficiency.

Existing Whole-House Solutions Case Study: Deep Energy Retrofit of 1910 House, Portland, Oregon

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

December, 2011

Case study describing a deep energy renovation of a home in the marine climate.

The New American Home 2011 Orlando, Florida

Author(s)

IBACOS,

National Renewable Energy Laboratory

Organization(s)

IBACOS,

NREL

Publication Date

December, 2010

Case study describing innovative technologies, construction techniques, products, and design trends in new home construction.

Existing Whole-House Solutions Case Study: Green Home Solutions by Grupe, Lodi, California

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

September, 2009

Case study describing a retrofit project in the hot-dry and mixed-dry climate zones.

New Whole-House Solutions Case Study: Fort Devens: Cold Climate Market-Rate Townhomes Targeting HERS Index of 40, Harvard, Massachusetts

Author(s)

Steven Winter Associates

Organization(s)

CARB,

SWA

Publication Date

November, 2013

Case study describing a new townhome construction project designed to achieve a HERS score of 40.

New Whole-House Case Study: Transformations, Inc. Net Zero Energy Communities, Devens, Easthampton, Townsend, Massachusetts

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

November, 2013

Case study describing a new construction net zero energy home.

Building America's Optimized Solutions for New Homes: Mixed-Humid Climate

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

March, 2015

Case study describing Building America's Optimized Solutions for energy efficient home construction in a mixed-dry climate.

New Whole-House Solutions Case Study: Lancaster Live/Work Townhome Prototype

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

April, 2010

Case study describing a building project in the marine climate.

Building America's Optimized Solutions for New Homes: Cold Climate

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

March, 2015

Case study describing Building America's Optimized Solutions for energy efficient home construction in cold and very cold climates.

New Whole-House Solutions Case Study: Tommy Williams Homes Initial Performance of Two Zero Energy Homes, Gainesville, Florida

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

November, 2013

Case study describing two new construction projects in Florida built to be net zero energy homes.

Existing Whole-House Solutions Case Study: Build San Antonio Green, San Antonio, Texas

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

June, 2013

Case study describing one of three deep energy renovations of occupied affordable homes.

Case Study: Rural Development, Inc., Wisdom Way Solar Village, Greenfield, MA

Author(s)

Pacific Northwest National Laboratory,

Oak Ridge National Laboratory

Organization(s)

PNNL,

ORNL

Publication Date

December, 2010

Case study describing a 20-unit community of energy-efficient duplexes in Massachusetts incorporating solar water heating and photovoltaics.

Building America's Optimized Solutions for New Homes: Hot-Humid Climate

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

March, 2015

Case study describing Building America's Optimized Solutions for energy efficient home construction in a hot-humid climate.

Existing Whole-House Solutions Case Study: National Grid Deep Energy Retrofit Pilot Program - Clark Residence

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

March, 2010

Case study describing a retrofit project in the cold and very-cold climate zones.

No Excessive Coiled or Looped Flex Ducts

Guide outlining how to correctly install flex ducts without excessive coils or loops.

Building America's Optimized Solutions for New Homes: Hot-Dry Climate

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

March, 2015

Case study describing Building America's Optimized Solutions for energy efficient home construction in hot-dry and mixed-dry climates.

Boot is uninsulated

Publication Date

Fri, 10/28/2011 - 12:00

Duct work is uninsulated and not sealed at seams

HVAC duct layout

No Kinks or Sharp Bends in Flex Duct Installation

Guide outlining how to correctly install flex ducts without kinks or sharp bends.

Seams are being properly sealed with mastic and mesh tape

Trunk to duct connections are only mechanically fastened and not sealed

Assembled section of fiber board duct

Publication Date

Fri, 01/11/2013 - 12:00

Use only Underwriters Laboratory UL-181 approved tape

The tape is covered with mastic to ensure an airtight seal between the duct and the fitting

Fiber board sheets are available with pre-cut shiplapped ends

After securing the inner coil, cover the draw band and the seam with a generous amount of mastic

Collars that are specifically made for flexible duct have a raised bead to prevent the duct from slipping off

Fiberglass duct board typically comes in sheets 4 foot wide by 10 foot long

New Whole-House Solutions Case Study: Tindall Homes: The Legends at Mansfield, Columbus, NJ

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

April, 2012

Case study describing a new construction building project of 20 luxury homes in northern New Jersey that were more energy efficient than ENERGY STAR and met the 50% energy savings requirements of the federal tax credit for new homes.