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Air Sealing Recessed Light Fixtures Below Unconditioned Space

    Scope
    Scope Images
    Image
    Air seal around recessed can light fixtures that are installed through ceilings to keep conditioned air from leaking into unconditioned space.
    Scope

    Air seal around recessed can light fixtures that are installed through ceilings to keep conditioned air from leaking into unconditioned space.

    • Using a saw, cleanly cut a hole that is no more than 1 inch larger in diameter than the diameter of the can.
    • Install ICAT-labeled recessed lighting fixtures.
    • Seal around the can with caulk before installing trim or install a trim kit with a gasket.

    See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Single-Family New Homes, and ENERGY STAR Multifamily New Homes.

    Description
    Description

    Recessed “can” ceiling fixtures, or downlights, are the most popular home lighting fixture in the United States. However, recessed can fixtures can be energy intensive in the following ways:

    • If they are not approved for insulation contact and are installed in an insulated ceiling, insulation has to be kept at least 3 inches from the fixture all the way around, leaving about 1 square foot of uninsulated ceiling space.
    • Many homeowners and contractors install incandescent bulbs or R-lamps in the fixtures; these use four times the electricity of fluorescents and six times the electricity of LEDs, as well as generating heat that adds to air-conditioning loads.
    • If the cans are not airtight, they allow conditioned air to escape from the living area into unconditioned spaces such as the attic.

    Leaky recessed cans are an even greater issue than a hole in the ceiling. A non-airtight recessed can with an incandescent bulb can draw 3 to 5 times as much air as a hole the same size, thanks to the stack effect (Figure 1). When the light inside the can is turned on, the heat it generates turns the can fixture into a chimney, pulling air from the house up into the attic (McCullough and Gordon 2002).

    Non-ICAT-rated recessed lights waste energy.
    Figure 1. Typical non-airtight recessed can light fixtures waste energy in several ways (Source: Improving Recessed Lighting 2011).

     

    Recessed downlights that are installed in insulated ceilings are now required by code to be rated for insulation contact (IC) so that insulation can be placed over them. The housing of the fixture should also be rated airtight to prevent conditioned air from escaping into the ceiling cavity or attic, and unconditioned air from infiltrating the conditioned space. The fixture should bear a label showing it meets the ASTM E 283 requirement of ≤ 2.0 cfm of air movement from the conditioned space to the ceiling cavity when tested at 75 Pa, and the housing should be caulked or gasketed where it meets the ceiling (Lstiburek 2009). Some brands of can lights designated ICAT may still leak air. Check the fixtures you intend to use to see whether they appear to be well designed to be air tight. See the guide Insulating and Air Sealing Existing Non-ICAT Recessed Lights for more information.

    If recessed lights are installed in insulated cathedral ceilings, there must be insulation with an R-value of R-10 or greater above the can in IECC climate zones 4 and higher to minimize condensation potential. Extra caution should be taken to ensure the recessed can is airtight in unventilated cathedral ceilings. Leaky light fixtures can allow moisture-laden indoor air to enter the roof assembly. If the moisture encounters cold roof sheathing, it can condense, leading to moisture accumulation and rot (Holladay 2011).

    Some building scientists recommend against putting recessed can lights in cathedral ceilings (see for example Holladay 2011) and some recommend against putting recessed can lights in any insulated ceiling (for example, Bailes 2011). Other alternatives are to install the recessed cans in an air-sealed dropped soffit or to limit use of recessed cans to only ceilings of rooms that have conditioned space above them such as a second floor. Another option is to avoid recessed can fixtures all together and use surface-mounted or pendant fixtures instead. LED surface-mounted kits that look similar to recessed can lights are now available.

    How to Air Seal Recessed Can Lights in Insulated Ceilings

    1. Choose fixtures that are labeled ICAT, meaning they are approved for insulation contact and are airtight as determined by the ASTM E 283 air leakage test.
    2. Install according to the manufacturer’s instructions. Before installing the decorative trim, caulk the housing to the ceiling, or install the fixture using a manufacturer-supplied gasket (Figure 2). 
    Use ICAT-rated recessed lights and caulk the housing to the ceiling.
    Figure 2. Look for recessed lighting fixtures that are ICAT-rated with sealed cans. Install the manufacturer-supplied gasket or caulk around the fixture housing before installing the decorative trim (Source: Sealing Air Barrier Penetrations, Info-405 2009). 

     

    Success
    Ensuring Success

    Inspect and verify that recessed can light fixtures installed in ceilings below unconditioned space are rated insulation-contact, air-tight (ICAT). Blower door testing may help indicate whether the recessed can lights are sufficiently air sealed. An infrared camera used in conjunction with the blower door testing may assist in detecting leakage. Experienced contractors can also detect air leakage with a smoke stick or by hand.

    Climate
    Climate

    The map in Figure 1 shows the climate zones for states that have adopted energy codes equivalent to the International Energy Conservation Code (IECC) 2009, 12, 15, and 18. The map in Figure 2 shows the climate zones for states that have adopted energy codes equivalent to the IECC 2021. Climate zone-specific requirements specified in the IECC are shown in the Compliance Tab of this guide.

    Climate Zone Map from IECC 2009, 12, 15, and 18.
    Figure 1. Climate Zone Map from IECC 2009, 12, 15, and 18. (Source: 2012 IECC)

     

    Climate Zone Map from IECC 2021.
    Figure 2. Climate Zone Map from IECC 2021. (Source: 2021 IECC)

     

    Training
    Right and Wrong Images
    Image
    Wrong – This recessed light is not ICAT labeled.
    Wrong – This recessed light is not ICAT labeled.
    Image
    Right – This recessed light was installed with a trim kit and is ICAT labeled.
    Right – This recessed light was installed with a trim kit and is ICAT labeled.
    Image
    Wrong – The installed recessed light is not ICAT labeled.
    Wrong – The installed recessed light is not ICAT labeled.
    Image
    Right – This recessed light is ICAT labeled, but still needs a gasket.
    Right – This recessed light is ICAT labeled, but still needs a gasket.
    Image
    Wrong – This recessed can light has not been sealed to the drywall.
    Wrong – This recessed can light has not been sealed to the drywall.
    Image
    Right – The recessed can light penetration is sealed with caulk to the drywall.
    Right – The recessed can light penetration is sealed with caulk to the drywall.
    Image
    Wrong – This recessed light does not have a gasket installed.
    Wrong – This recessed light does not have a gasket installed.
    Image
    Right – This ICAT recessed light is sprayed with foam to act as gasket against the drywall.
    Right – This ICAT recessed light is sprayed with foam to act as gasket against the drywall.
    Image
    Right – Airtight boxes are installed for LED can lights.
    Right – Airtight boxes are installed for LED can lights.
    Image
    Right - Retrofit existing recessed lighting with LEDs.
    Right - Retrofit existing recessed lighting with LEDs.
    Image
    Wrong - Recessed can light is compressing duct work.
    Wrong - Recessed can light is compressing duct work.
    Videos
    CAD
    CAD Files
    Air sealing at recessed lighting in attic - site built
    Air sealing at recessed lighting in attic - site built
    Download: DWG PDF
    Air sealing at recessed lighting in attic - pre made
    Air sealing at recessed lighting in attic - pre made
    Download: DWG PDF
    Compliance

    Compliance

    The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

     

    ENERGY STAR Single-Family New Homes, Version 3/3.1/3.2 (Rev. 13)

    National Rater Field Checklist

    Thermal Enclosure System.
    4. Air Sealing (Unless otherwise noted below, “sealed” indicates the use of caulk, foam, or equivalent material). 
    4.2 Recessed lighting fixtures adjacent to unconditioned space ICAT labeled and gasketed. Also, if in insulated ceiling without attic above, exterior surface of fixture insulated to ≥ R-10 in CZ 4-8.8

    Please see the ENERGY STAR Single-Family New Homes National Rater Field Checklist for applicable footnotes and additional information. 

    Please see the ENERGY STAR Single-Family New Homes Implementation Timeline for the program version and revision currently applicable in your state.

     

    ENERGY STAR Multifamily New Construction, Version 1/1.1/1.2 (Rev. 04)

    National Rater Field Checklist

    Thermal Enclosure System

    4. Air Sealing (Unless otherwise noted below, “sealed” indicates the use of caulk, foam, or equivalent material). 
    4.2 Recessed lighting fixtures adjacent to unconditioned space ICAT labeled and gasketed. Also, if in insulated ceiling without attic above, exterior surface of fixture insulated to ≥ R-10 in CZ 4-8.10

    Please see the ENERGY STAR Multifamily New Construction National Rater Field Checklist for applicable footnotes and additional information. 

    Please see the ENERGY STAR Multifamily New Construction Implementation Timeline for the program version and revision currently applicable in your state. 

     

    DOE Zero Energy Ready Home

    Version 1, Rev. 07, Rev. 08, Rev. 09, and Version 2

    Exhibit 1 Mandatory Requirements.
    Exhibit 1, Item 2) (Item 1) in Version 1, Rev. 07 and Rev. 08) Certified under the ENERGY STAR Qualified Homes Program or the ENERGY STAR Multifamily New Construction Program.

     

    2009 International Energy Conservation Code (IECC)

    Residential Requirements

    Section 402.4.5 Specifies mandatory air leakage requirements for recessed lighting. 

    Commercial Requirements

    Section 502.4.8 Specifies mandatory air leakage requirements for recessed lighting. 

    2012, 20152018, and 2021 IECC

    Residential Requirements

    See Section R402.4.1.1 and Section R402.4.5 (R402.4.4 in 2012 IECC) for mandatory air leakage requirements that apply to recessed lighting. 

    Commercial Requirements

    See Section C402.5.8 (C402.4.8 in 2012 IECC and C402.5.10 in 2021 IECC) for mandatory air leakage requirements that apply to recessed lighting. 

    Retrofit:  2009, 2012, 2015, 2018,  and 2021 IECC

    Section 101.4.3 (in 2009 and 2012). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)

    Chapter 5 (in 2015, 2018, 2020). The provisions of this chapter shall control the alteration, repair, addition, and change of occupancy of existing buildings and structures.

     

    20092012, 2015, 2018 and 2021 IRC

    See Section N1102.4.1 (N1102.4.2 in 2009 IRC) for air leakage requirements for recessed lighting. 

    See Section N1102.4.5 (N1102.4.4 in 2012 IRC) for air leakage requirements for recessed lighting. 

    Retrofit:  2009, 2012, 2015, 2018,  and 2021 IRC

    Section R102.7.1 Additions, alterations, or repairs. Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with the requirements of this code, unless otherwise stated. (See code for additional requirements and exceptions.)

    Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.

    ASHRAE 90.1 - 2010, 2013, 2016, and 2019

    See Section 5.8.1.6 for insulation and installation requirements for recessed light fixtures. 

    Retrofit
    Existing Homes

    For information on air sealing recessed can lights in existing homes, see the guide Insulating and Air Sealing Existing Non-ICAT Recessed Lights.

    For more information, see the U.S. Department of Energy’s Standard Work Specifications regarding general penetrations. 

    See Compliance Tab. 

    More

    More Info.

    Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

    References and Resources*
    Author(s)
    U.S. Environmental Protection Agency
    Organization(s)
    EPA
    Publication Date
    Description
    Guide describing details that serve as a visual reference for each of the line items in the Thermal Enclosure System Rater Checklist.
    Author(s)
    Pacific Northwest National Laboratory
    Organization(s)
    PNNL
    Publication Date
    Description
    Report providing information about techniques and approaches to improve the efficiency of recessed lighting.
    Author(s)
    Baechler Michael C,
    Gilbride Theresa L,
    Hefty Marye G,
    Cole Pam C,
    Williamson Jennifer,
    Love Pat M
    Organization(s)
    Pacific Northwest National Laboratory,
    PNNL,
    Oak Ridge National Laboratory,
    ORNL
    Publication Date
    Description
    Report identifying the steps to take, with the help of a qualified home performance contractor, to seal unwanted air leaks while ensuring healthy levels of ventilation and avoiding sources of indoor air pollution.
    Author(s)
    Baechler Michael C,
    Gilbride Theresa L,
    Hefty Marye G,
    Cole Pam C,
    Love Pat M
    Organization(s)
    Pacific Northwest National Laboratory,
    PNNL,
    Oak Ridge National Laboratory,
    ORNL
    Publication Date
    Description
    Guide describing measures that builders in the cold and very cold climates can take to build homes that have whole-house energy savings of 40% over the Building America benchmark with no added overall costs for consumers.
    Author(s)
    Van der Meer
    Organization(s)
    Pennsylvania Housing Research/Resource Center
    Publication Date
    Description
    Recessed lighting is here to stay. If installed incorrectly they may contribute to air leakage and compromise building integrity.
    Author(s)
    Holladay
    Organization(s)
    Green Building Advisor
    Publication Date
    Description
    Information sheet presenting the correct methods for building an insulated cathedral ceiling.
    Author(s)
    McCullough,
    Gordon
    Organization(s)
    Pacific Northwest National Laboratory
    Publication Date
    Description
    Report discussing the potential energy savings of new high-efficiency downlights, and the results of product testing to date.
    *For non-dated media, such as websites, the date listed is the date accessed.
    Contributors to this Guide

    The following authors and organizations contributed to the content in this Guide.

    Sales
    Building Science Measures
    Building Science-to-Sales Translator

    Tight Air Sealed Home = Comprehensive Draft Protection

    Image(s)
    Technical Description

    Poorly air-sealed homes are less comfortable and cost more to maintain because they provide a pathway for drafts, cold spots, moisture, and insects into the home. Comprehensive draft protection includes a continuous air barrier around the whole house along with caulking and sealing in all holes and cracks. This includes around wiring, plumbing, ducts, and flues; where wall framing meets flooring; around windows; where drywall meets top plates and sill plates; where rim joists meet foundation walls and subfloors; etc. Spray foam insulation can be used at rim joists, floors above unconditioned space, and in attics to insulate and air seal at the same time.

    Comprehensive Draft Protection
    Sales Message

    Comprehensive draft protection minimizes air flow that can undermine a complete high-performance insulation system. What this means for you is less wasted energy along with enhanced comfort, health, quiet, and durability. Wouldn’t you agree it would be a shame to only get a partial return on your investment in advanced insulation?

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