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2021 IECC Section R404 and R408

Lesson 8: Lighting and Additional Efficiency Options

IECC R404, R408.2, R403.10 (IRC N1104, N1108.2, N1103.10) · 14 practice questions

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Reading

This lesson closes out the prescriptive path's mandatory and required-elective provisions with two short but consequential sections: lighting, which is cheap to get right and easy for a rehab crew to get wrong by installing whatever bulb is on hand, and the additional efficiency package, a 2021 IECC addition that requires every prescriptive-path house to do something measurably better than the bare minimum envelope and equipment tables in Lessons 2 through 7. Neither section involves much math, but both show up on nearly every energy final GCHS performs.

High-efficacy lighting

R404.1 requires a minimum percentage of permanently installed lighting fixtures to contain only high-efficacy light sources. The 2021 IECC set that requirement at 100 percent, a ratchet up from 90 percent in the 2018 edition and 75 percent in the 2015 edition before that, which is exactly the kind of number that trips up anyone working from an older field guide or a memory of an earlier course. The requirement applies to permanently installed fixtures: the recessed cans, wall sconces, and ceiling fixtures that are part of the house, not table lamps or other portable fixtures a homeowner brings in after move-in. There is one narrow, specific exclusion: kitchen appliance lighting, such as the lamp inside a range hood, oven, or refrigerator, is excepted, because those are specialty products that are not generally available in high-efficacy form. General kitchen lighting, including the ceiling fixture over the counter, is fully covered by the 100 percent requirement.

Key numbers
  • High-efficacy lighting, permanently installed fixtures: 100% (2021 IECC), up from 90% (2018) and 75% (2015); kitchen appliance lighting excluded (R404.1)
  • Interior lighting controls: permanently installed fixtures require a dimmer, an occupant sensor control, or another control installed or built into the fixture, with exceptions for bathrooms, hallways, exterior lighting, and lighting designed for safety or security (R404.2)
  • Additional efficiency package: one option required on the prescriptive path (R401.2.5), from R408.2: total UA and SHGC at 95 percent or less of Table R402.1.2; 95 AFUE furnace with 16 SEER air conditioner, 10 HSPF/16 SEER heat pump, or 3.5 COP ground source heat pump; 0.82 EF fossil fuel, 2.0 EF electric, or 0.4 solar fraction water heating; 100 percent of ducts and air handlers inside the envelope; or 3.0 ACH50 with an ERV or HRV at 75 percent sensible recovery efficiency or better
  • Documentation for the additional efficiency package: the option selected is identified on the certificate required by R401.3
  • Pools and spas (R403.10): no continuously burning pilot on gas heaters; outdoor heated pools and spas need a vapor-retardant cover unless more than 75 percent of the heating energy comes from a heat pump or on-site renewable energy

Interior lighting controls

The 2021 IECC edition also added a lighting control requirement that did not exist in earlier editions: permanently installed interior lighting fixtures generally require a dimmer, an occupant sensor control, or a control that is integral to the fixture itself. The purpose is straightforward, to reduce the energy wasted by lights left on in an empty room, but the requirement is not universal. Bathrooms, hallways, exterior fixtures, and lighting designed for safety or security are excepted from the control requirement (R404.2), on the reasoning that those fixtures are either used briefly and repeatedly (a hallway) or need to stay available regardless of occupancy sensing (security lighting). A general living room or bedroom ceiling fixture is squarely inside the requirement and is one of the more commonly missed items on a lighting plan, since older lighting layouts assumed a simple wall switch and nothing more. Exterior lighting has its own control rule in R404.3: where the permanently installed exterior lighting totals more than 30 watts, it needs a manual on-off switch that permits automatic shut-off, and it must shut off automatically when daylight is present.

Gas pool heaters, pilot lights, and pool covers

R403.10, at the end of the mechanical provisions covered in Lesson 7 but grouped with lighting and efficiency here as an equipment-adjacent item worth knowing, controls the energy use of pools and permanent spas. Heaters need an on-off switch that is part of the heater and mounted on its exterior with ready access, or one located outside the heater within 3 feet of it, and using the switch must not change the thermostat setting. Gas-fired heaters may not be equipped with continuously burning ignition pilots (R403.10.1), which would burn fuel around the clock for no useful output. Heaters and pump motors also need time switches or other controls that turn them on and off on a preset schedule (R403.10.2). Outdoor heated pools and outdoor permanent spas must have a vapor-retardant cover or other approved vapor-retardant means, since evaporation is the dominant heat loss mechanism for a heated body of water sitting exposed to outdoor air (R403.10.3); the exception applies where more than 75 percent of the heating energy, computed over an operating season of at least three calendar months, comes from a heat pump or an on-site renewable energy system. Separately, R404.1.2 bars continuously burning pilot lights on fuel gas lighting systems. GCHS rarely scopes pool work directly, but a rehab or inspection that touches an existing pool heater should still flag a missing cover or a standing pilot as a code item, not just a comfort or cost suggestion to the homeowner.

The additional efficiency package

R408.2 is new to the 2021 IECC and is one of the edition's most consequential changes for anyone following the prescriptive path (R402 through R404): rather than stopping once every table in Lessons 2 through 4 and every equipment and lighting requirement in Lessons 6 through 8 is met, the prescriptive path now also requires the house to install one additional efficiency package option from a defined menu of five (R401.2.5 and R408.2). The menu is: an enhanced envelope, with total building UA and area-weighted glazing SHGC each at 95 percent or less of the Table R402.1.2 values (R408.2.1); more efficient HVAC equipment, meaning a 95 AFUE gas furnace with a 16 SEER air conditioner, a 10 HSPF/16 SEER air source heat pump, or a 3.5 COP ground source heat pump (R408.2.2); reduced-energy service water heating, meaning a fossil fuel system of 0.82 EF or better, an electric system of 2.0 EF or better (which a heat pump water heater can reach), or a solar system with a 0.4 solar fraction (R408.2.3); a more efficient duct system, meaning 100 percent of ducts and air handlers inside the building thermal envelope, a ductless or hydronic system inside the envelope, or ducts in conditioned space as R403.3.2 defines it (R408.2.4); or improved air sealing with efficient ventilation, meaning a measured 3.0 ACH50 or less together with an ERV or HRV of at least 75 percent sensible recovery efficiency (R408.2.5). The point for GCHS's purposes is that this requirement exists, that it applies to every prescriptive-path house, and that it is not satisfied automatically just because the rest of the prescriptive tables are met. A permit set that shows compliant insulation, fenestration, ducts, and equipment but never identifies which R408.2 option the house is using is missing a mandatory piece of the compliance package, not an optional bonus.

The other compliance paths carry their own version of the same requirement. Under R401.2.5, the 2021 edition's additional efficiency section applies to every compliance approach: a prescriptive house (including one using the total UA alternative) installs one R408.2 option; a house on the total building performance path under R405 either installs an R408.2 option without counting it in the model or shows an annual energy cost no more than 95 percent of the standard reference design; and a house on the Energy Rating Index path under R406 must score at least 5 percent below the ERI target in Table R406.5. The option selected is identified on the certificate required by R401.3. Lesson 9 covers how each performance path documents that extra step.

In the field

A recurring finding on a GCHS energy final is a handful of recessed cans in a kitchen or hallway still holding old incandescent or halogen lamps, left over from a partial remodel where the electrician swapped fixtures but a punch-list item to swap bulbs got missed. It is an easy, cheap fix, but it is still a code deficiency at final inspection under the 100 percent standard, and GCHS flags it the same way it would flag a missing duct insulation section: correct before sign-off, not noted and waived.

Lighting requirements and the R408 additional efficiency package A diagram showing a house's permanently installed lighting fixtures at 100 percent high-efficacy with an exception for kitchen appliance lighting, an interior fixture with a dimmer or occupancy sensor control, and a menu of five additional efficiency package options under R408.2 with one option required to be selected and documented. Lighting (R404.1) 100% high-efficacy fixtures Exception: kitchen appliance lamps Interior fixtures: dimmer, sensor, or integral control Exceptions: bath, hallway, exterior, safety R408.2 additional efficiency package Prescriptive path: one option required - Enhanced envelope - More efficient HVAC equipment - Reduced-energy hot water system - Improved thermal distribution - Air sealing (3.0 ACH50) + ERV/HRV Option is named on the certificate
Lighting is checked fixture by fixture; the R408.2 package is checked as a single selection, named on the certificate, that every prescriptive-path house must carry.

Practice questions

1. Under the 2021 IECC R404.1, what percentage of permanently installed lighting fixtures must contain only high-efficacy light sources?

  1. 75 percent
  2. 90 percent
  3. 100 percent
  4. There is no fixed percentage

2. Which lighting is excluded from the high-efficacy requirement under R404.1?

  1. All bathroom lighting, since bathrooms are excepted from the lighting controls rule
  2. Kitchen appliance lighting, such as range hood and oven lamps
  3. All exterior lighting on the dwelling, including porch and garage fixtures
  4. All hallway lighting, since hallways are excepted from the lighting controls rule

3. An energy final finds several permanently installed recessed cans in a living room fitted with incandescent lamps. The correct finding is:

  1. Acceptable, since lighting is only checked at rough-in and not at the final inspection
  2. Acceptable, since only exterior lighting is regulated by the energy code
  3. Acceptable if fewer than five fixtures are affected in the room
  4. A deficiency, since living room fixtures are not excepted from R404.1

4. Under R404.2, a permanently installed interior lighting fixture generally must be controlled with:

  1. A dimmer, an occupant sensor, or another control installed or built into the fixture
  2. A dedicated circuit with its own breaker in the panel for each fixture
  3. A mechanical timer switch as the only permitted control type
  4. No control of any kind, since interior lighting is not regulated

5. Which of the following is excepted from the interior lighting control requirement?

  1. A living room ceiling fixture
  2. A bedroom fixture
  3. A hallway fixture
  4. A den fixture

6. A gas-fired pool heater is installed with a continuously burning pilot light. Under the energy code (R403.10.1) this is:

  1. Permitted if the pool is heated year round and the heater has an on-off switch
  2. Not permitted; gas heaters may not have continuously burning pilots
  3. Permitted in Climate Zone 2 only, where freezing is rare
  4. Permitted if a timer on the gas supply shuts the pilot off overnight

7. Outdoor heated pools and outdoor permanent spas are generally required to have:

  1. A minimum water temperature of 90 degrees F, held by a thermostat lockout
  2. A vapor-retardant cover, unless a heat pump or renewables supply over 75 percent of heating
  3. Continuous filtration around the clock, whatever the season or use
  4. A dedicated backup generator so the heater can run during outages

8. R408.2, new to the 2021 IECC, requires a prescriptive-path house to:

  1. Meet only the R402 envelope table, with no further requirement beyond Table R402.1.3
  2. Install one option from the R408.2 additional efficiency menu and identify it on the certificate
  3. Run a full Energy Rating Index model in addition to complying with the prescriptive path
  4. Install rooftop solar panels sized to offset at least half the annual electric load

9. Which of the following is NOT generally among the R408.2 additional efficiency package options?

  1. An enhanced building envelope beyond the R402.1.3 minimums
  2. More efficient HVAC equipment than the code baseline
  3. A reduced-energy service hot water system
  4. A larger garage

10. A permit set shows compliant insulation, fenestration, ducts, and equipment on the prescriptive path but never identifies an R408.2 option. This submittal is:

  1. Incomplete; R401.2.5 requires one R408.2 option on the prescriptive path
  2. Complete, since R408 is an optional chapter that applies only to performance-path homes
  3. Complete, since meeting the R402 insulation and fenestration tables alone is sufficient
  4. Incomplete only in Climate Zone 3 and above, where the tightest envelope limits apply

11. Which compliance path must always install one of the R408.2 options, with no alternative under R401.2.5?

  1. The Energy Rating Index path
  2. The prescriptive path
  3. The total building performance (simulated) path
  4. All three paths equally

12. What does a code official look for to confirm the additional efficiency requirement has been met on a prescriptive-path house?

  1. A signed statement from the builder that the house exceeds code, with no option named
  2. The blower door report alone, since it shows the house is tighter than the code requires
  3. The selected R408.2 option, identified on the R401.3 certificate with its supporting specification
  4. Nothing further; the option is self-certifying once the house is permitted

13. A common way to meet the reduced-energy service hot water option under R408.2.3 (2.0 EF or better for an electric system) is:

  1. A heat pump water heater
  2. A larger conventional gas tank water heater
  3. Adding a second water heater
  4. Removing the water heater's insulation blanket

14. GCHS finds a partial remodel where an electrician swapped several recessed can fixtures but left old halogen lamps installed. At an energy final under the 2021 IECC, this is:

  1. Not a code item, since the code regulates fixtures, not the lamps placed in them
  2. Acceptable, since halogen lamps count as high-efficacy under the 2021 definitions
  3. Acceptable if the homeowner agrees in writing to change the bulbs after occupancy
  4. A deficiency; the fixtures must hold high-efficacy sources

Glossary

High-efficacy light source
A lamp type meeting the code's efficacy standard, generally LED or equivalent products in current residential practice; required in 100 percent of permanently installed fixtures under the 2021 IECC.
Permanently installed fixture
A lighting fixture that is part of the building, as distinct from a portable lamp a homeowner brings in after occupancy; only permanent fixtures are regulated by R404.1.
Additional efficiency package
The R401.2.5 and R408.2 requirement, new to the 2021 IECC, that a prescriptive-path house install one efficiency option beyond the base envelope, equipment, and lighting tables and identify it on the certificate.
Required elective
A code provision offering a menu of options where selecting at least one from the menu is mandatory, as distinct from a true optional item.
Vapor-retardant cover
A pool or spa cover that limits evaporative heat loss, required on outdoor heated pools and outdoor permanent spas unless more than 75 percent of the heating energy comes from a heat pump or on-site renewable energy (R403.10.3).
Simulated performance / Energy Rating Index paths
The performance-based compliance paths covered in Lesson 9. They do not have to install an R408.2 option, but R401.2.5 gives each its own additional-efficiency step.
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