Decoding IECC 2018

In 2017, the International Code Council published the 2018 version of the International Energy Conservation Code (IECC), which has been updated every three years since 2000. This 2018 version reduces lighting power allowances, broadens mandatory controls requirements, and issues clarifications.

Commercial building energy codes regulate the energy-efficient design of buildings. Today, a majority of states base their commercial building energy codes on the IECC model energy code, while the remainder base it on the ASHRAE/IES 90.1 energy standard, developed their own code, or have no statewide code.

On February 27, 2018 the Department of Energy recognized 90.1-2016 as the national energy reference standard. By February 27, 2020, all states must adopt a code at least as stringent as 90.1-2016 or justify non-compliance. The IECC recognizes 90.1 as an alternative compliance standard. Specifically, 90.1-2016 is considered equivalent to the 2018 IECC.

The IECC contains both prescriptive and mandatory provisions focused on lighting power allowances, lighting controls and commissioning. The scope covers new construction and alterations. This article focuses on controls.

As occurred with the 2015 IECC, the 2018 version includes significant changes to the mandatory control requirements. Note exceptions may apply for each. For interpretations, consult the authority having jurisdiction.

Luminaire-level controls: Possibly the biggest change in the mandatory controls requirement section is a new choice of two compliance paths. The code now includes an alternative path in which luminaire-level lighting controls (LLLC) are installed alongside manual controls and controls for specific applications such as accent and supplemental task lighting.

The IECC defines LLLC as a system in which luminaires feature embedded intelligence, occupancy and light sensors, wireless networking capability, and where required, local override switching capability. The code requires the luminaire to be independently capable of occupancy sensing, dimming to maintain a desired light level, and configurability including dimming set-points, timeouts, fade rates, sensor sensitivity, and wireless zoning.

Interior automatic lighting shutoff: Interior lighting must be turned OFF when it is not being used. The basic choice is occupancy- or time-based control.

The 2018 IECC specifically requires occupancy sensors in a range of applications from classrooms to private offices to warehouses. The sensor must feature manual-ON or auto-ON-to-maximum-50-percent-power operation and provide manual-OFF override capability to occupants.

A significant change here is the sensor must turn the lights OFF within 20 minutes of the space becoming vacant, a reduction from 30 minutes.

In open areas and aisles in warehouses, the sensor must reduce lighting power by at least 50 percent after the aisle becomes vacant. The sensor must be zoned to a single aisle and not control any lighting aside the aisle.

With the 2018 version, the IECC now calls out open offices with special control requirements, a major change in the code.

Specifically, if the open office is smaller than 300 sq.ft., the usual occupancy sensor provisions apply. If larger than 300 sq.ft, the sensors must control general lighting up to a 600-sq.ft. control zone and reduce lighting power by at least 80 percent when the zone is vacant, while providing a reasonably uniform illumination pattern. If all occupants leave the space, the sensors must turn OFF all general lighting within 20 minutes. Any daylight-responsive controls in the space will activate general lighting only if occupancy is detected in the same area.

Where occupancy sensors are not installed, time-switch controls provide a suitable alternative. The control must feature a minimum seven-day clock, backup capability in the event of power interruption, and “holiday” programming. Users must be given override capability via a switch.

Manual override switches: These switches give users the option to override automatic shutoff while providing local ON/OFF lighting. The switch must be readily accessible to users. The controlled lighting must be in view from the switch’s location, though remote switches are allowable if they identify the location and status of the controlled lighting.

The 2018 IECC limits the override area to 5,000 sq.ft. and the override period to two hours, which may be restarted by resetting the switch. For some larger applications such as industrial buildings and mall concourses, the 2018 IECC permits an override zone up to 20,000 sq.ft., with the override time limit extendable beyond two hours if a captive key device is the override.

Switches must be capable of light reduction control. Using the switches, users can reduce lighting power by at least 50 percent in a reasonably uniform illumination pattern. Multilevel switching and continuous or step dimming are typical light reduction strategies.

Daylight-responsive interior lighting controls: The 2018 IECC requires installation of these controls in applicable sidelighted (e.g., window) and toplighted (e.g., skylight) spaces. Specifically, in the daylight zones around the daylight aperture as defined by the model code.

The daylight-responsive controls must feature automatic operation and be capable of turning the lights completely OFF. In offices, classrooms, laboratories and library reading rooms, they must be capable of continuous dimming to 15 percent or less full light output. The controls must be capable of being calibrated where installed, with easy access to the means of calibration.

Special applications: The 2015 IECC designated control requirements for special applications. For example, independent control must be provided for display and accent lighting, and supplemental task lighting must be controlled by an integral control device or readily accessible wall-mounted control.

The 2018 version changes this to specifically require manual control plus a means of automatic shutoff, which may be a time switch or occupancy sensor, for these applications. Lighting for nonvisual applications such as plant growth or food warming must be controlled by a time switch.

Exterior lighting control: Automatic shutoff of all exterior lighting in response to daylight is required. This requires a light sensor. Curfew control (lights turning OFF at a certain time afterhours, depending on business hours) is required for building façade and landscape lighting. Dusk-to-dawn lighting must be reduced by at least 30 percent afterhours on a scheduled basis or in response to an occupancy sensor.

Additional energy efficiency options: Buildings complying with the 2018 IECC must enhance energy efficiency by implementing one of eight options. These options cover on-site renewable energy production, HVAC/hot water enhancements, etc. Two cover lighting and controls.

For lighting, lighting power density (LPD) must be achieved that is at least 10 percent below the model code’s maximum LPD values.

For lighting controls, digital controls must be implemented. The digital lighting control system must be capable of continuous dimming, individual luminaire addressability, load shedding, reconfiguration, and individual occupant control of overhead lighting in open offices.

Commissioning: All lighting controls must be set up in accordance with approved documents and manufacturer instructions, and performance verified through testing. This ensures that the project team delivers a lighting and control system that operates as specified. Specific functional testing is indicated for different control types.

At the conclusion of the project, the owner must be given certain documentation about the lighting and control system so that they can maintain it. This is in addition to documentation provided by the functional testing party that the installed controls meet or exceed specified performance criteria. Documentation requirements include a lighting and control narrative, operating and maintenance manuals, submittal data indicating all selected options for lighting and controls, a schedule for inspecting and recalibrating lighting controls, and more.

2018 IECC decoded

Commercial building energy codes continue to become increasingly restrictive in regards to lighting and controls. Designers in jurisdictions likely to implement the 2018 IECC should start becoming familiar with its requirements, as there are some significant changes, particularly in regards to controls.

For more information, consult the 2018 IECC.