U.S. Department of Energy U.S. Department of Energy Energy Efficiency and Renewable Energy

Recessed Light Fixtures Below Unconditioned Space

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Recessed lighting fixtures adjacent to unconditioned space ICAT labeled and fully gasketed. Also, if in insulated ceiling without attic above, exterior surface of fixture insulated to ≥ R-10 in CZ 4 and higher to minimize condensation potential

Scope


Air Sealing

 

Recessed lighting fixtures adjacent to unconditioned space ICAT labeled and fully gasketed. Also, if in insulated ceiling without attic above, exterior surface of fixture insulated to ≥ R-10 in Climate Zone 4 and higher to minimize condensation potential.

  1. Install ICAT labeled recessed lighting fixtures.
  2. Seal all gaps and holes to unconditioned space with caulk or foam.
  3. Install a proper trim kit with a gasket.

 

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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 three 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. Second, many homeowners and contractors install incandescent bulbs in the fixtures that use 4 times the electricity of fluorescents and add to air-conditioning loads. Third, 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 like a hole in the ceiling, only worse. 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.” 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 Reference

 

 

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 leak air; check the fixtures you intend to use to see whether they appear to be well designed to be air-tight (EPA 2010). 

 

If recessed lights are installed in insulated cathedral ceilings, there must be at least R-10 of insulation 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.

 

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. 

 

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 Reference



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, which is conducted as part of the whole-house energy performance test-out, 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


ENERGY STAR Version 3, (Rev. 6)

Thermal Enclosure Checklist, Air Sealing. If in insulated ceiling without attic above, exterior surface of fixture insulated to ≥ R-10 in CZ 4 and higher to minimize condensation potential.

 

climate zone map

International Energy Conservation Code (IECC) Climate Regions



Right and Wrong Images



Presentations

None Available



Videos

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CAD Images




Compliance


ENERGY STAR Version 3, (Rev. 6)

Thermal Enclosure Checklist, Air Sealing. Penetrations to unconditioned space fully sealed with solid blocking or flashing as needed and gaps sealed with caulk or foam. Recessed lighting fixtures adjacent to unconditioned space ICAT labeled and fully gasketed. Also, if in insulated ceiling without attic above, exterior surface of fixture insulated to ? R-10 in CZ 4 and higher to minimize condensation potential.



DOE Challenge Home

Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3.



2009 IECC

Section 402.4.5 Recessed lighting. Recessed lights in the building thermal envelope are 1) type IC rated and ASTM E283 labeled and 2) sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.*

 

2009 IRC

Section N1102.4.5 Recessed lighting. Recessed lights in the building thermal envelope are 1) type IC rated and ASTM E283 labeled and 2) sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.*



2012 IECC

Table R402.4.1.1 Air Barrier and Insulation Installation, Recessed lighting: Recessed light fixtures installed in the building thermal envelope are IC rated, airtight labeled at air leakage rate <= 2.0 cfm, and sealed to the drywall with gasket or caulk.* 

 

2012 IRC

Table N11402.4.1.1 Air Barrier and Insulation Installation, Recessed lighting: Recessed light fixtures installed in the building thermal envelope are IC rated, airtight labeled at air leakage rate <= 2.0 cfm, and sealed to the drywall with gasket or caulk.* 

 

 

*Due to copyright restrictions, exact code text is not provided.  For specific code text, refer to the applicable code.



Case Studies

None Available


References

  1. 2009 IECC—International Energy Conservation Code

    2009 IECC, International Energy Conservation Code. International Code Council, Washington, D.C.

  2. 2009 IRC—International Residential Code for One and Two Family Dwellings

    2009 IRC, International Residential Code for One and Two Family Dwellings. 2009. Fifth Printing. International Code Council, Washington, D.C. 

  3. 2012 IECC—International Energy Conservation Code

    2012 IECC, International Energy Conservation Code.  International Code Council, Washington, D.C.

  4. 2012 IRC—International Residential Code for One and Two Family Dwellings

    2012 IRC, International Residential Code for One and Two Family Dwellings. 2012. Second Printing. International Code Council, Washington, D.C.

  5. Building America Best Practices Series Volume 12: 40% Whole-House Energy Savings in the Cold and Very Cold Climates

    Baechler MC, TL Gilbride, MG Hefty, PC Cole, and PM Love.  2011.  Building America Best Practices Series Volume 12: 40% Whole-House Energy Savings in the Cold and Very Cold Climates. PNNL-20139. Prepared by Pacific Northwest National Laboratory for the U.S. Department of Energy, Building America Program.

  6. Building America Best Practices Series, Volume 10: Retrofit Techniques and Technologies: Air Sealing

    Baechler MC, TL Gilbride, MG Hefty, PC Cole, JL Williamson, and PM Love. 2010. Building America Best Practices Series, Volume 10: Retrofit Techniques and Technologies: Air Sealing. PNNL-19284. Prepared by Pacific Northwest National Laboratory for the U.S. Department of Energy's Building America Program.

  7. DOE Challenge Home National Program Requirements

    DOE. 2012. DOE Challenge Home National Program Requirements (Rev. 02). Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, Washington, D.C.

  8. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements

    EPA. 2012. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements. U.S. Environmental Protection Agency, Washington, D.C.

  9. Guide to Attic Air Sealing

    Lstiburek, J. 2010. Guide to Attic Air Sealing. Prepared by the Building Science Corporation for the U.S. Department of Energy, Building America Program.

  10. High Hats, Swiss Cheese, and Fluorescent Lighting?

    McCullough, Jeff J. and Kelly L. Gordon 2002. “High Hats, Swiss Cheese, and Fluorescent Lighting?” Proceedings of the 2002 ACEEE Summer Study, prepared by the Pacific Northwest National Laboratory. 

  11. How to Build an Insulated Cathedral Ceiling

    Holladay, M. 2011. How to Build an Insulated Cathedral Ceiling. Green Building Advisor, Newton, Connecticut. 

  12. Improving Recessed Lighting

    PNNL. 2011. Improving Recessed Lighting. PNNL-SA-82688. Prepared by Pacific Northwest National Laboratory for the U.S. Department of Energy, Building America Program. 

  13. Kick the Can! No Recessed Lights in the Building Envelope

    Bailes, A. 2011. Kick the Can! No Recessed Lights in the Building Envelope. Energy Vanguard, Decatur, GA. 

  14. Sealing Air Barrier Penetrations

    Lstiburek, J. 2009. Sealing Air Barrier Penetrations. Information Sheet 405. Prepared by the Building Science Corporation for the Department of Energy's Building America Program.

  15. Technical Guidance to the Indoor airPLUS Specifications

    EPA. 2012. Technical Guidance to the Indoor airPLUS Specifications. U.S. Environmental Protection Agency, Washington, D.C. 

  16. Thermal Enclosure System Rater Checklist Guidebook

    EPA. 2011. Thermal Enclosure System Rater Checklist Guidebook. U.S. Environmental Protection Agency, Washington, D.C.



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