In 2015, the International Code Council published a new version of its International Energy Conservation Code (IECC). This model energy code provides states and jurisdictions code-ready language to adopt in whole or in part. It has been updated every three years since 2000.
Today, a majority of states base their commercial building energy codes on IECC. The rest adopted a code based on the ASHRAE/IES 90.1 energy standard, developed their own code, or have no statewide code at all.
The Department of Energy ruled that before October 2016, all states must adopt an energy code at least as stringent as 90.1-2013 or justify why they could not comply. According to EnergyCodes.gov, 10 states were in compliance as of January 2017. Seven of these specifically adopting a code based on IECC 2015: Illinois, Maryland, Massachusetts, New York, Texas, Utah and Vermont. IECC recognizes 90.1 as an alternative compliance standard. Specifically, 90.1-2013 is considered equivalent for the 2015 IECC.
IECC contains both prescriptive and mandatory provisions focused on lighting power allowances (maximum lighting power density expressed in W/sq.ft.), lighting controls and commissioning. The scope covers new construction and alterations (except where less than 10 percent of the luminaires are replaced and these new luminaires do not increase the installed lighting power).
The 2015 IECC contains significant changes in regards to lighting power allowances and notably lighting controls.
Lighting power allowances
The 2015 IECC features adjusted lighting power allowances, generally more restrictive. The Building Area Method lighting power allowances are similar to the 2013 version of 90.1. For example, the 2015 IECC adjusted the office building interior lighting power allowance from 0.9W/sq.ft. in the 2012 version to 0.82W.sq.ft.
The biggest changes in the 2015 IECC are in lighting controls. This article summarizes these requirements below. Note exceptions may apply for each and that the IECC may be implemented in some jurisdictions with amendments. For interpretations, consult the authority having jurisdiction.
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 2015 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. It must turn the lights OFF within 30 minutes of the space becoming vacant.
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.
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 2015 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 malls and industrial buildings, the 2015 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 2015 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: IECC 2015 designates 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.
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) 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 IECC 2015 must enhance energy efficiency by implementing one of six options. These options cover on-site renewable energy production, HVAC/hot water enhancements, and 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.
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, and a schedule for inspecting and recalibrating lighting controls.
Commercial building energy codes are becoming increasingly restrictive, particularly in regards to lighting and controls. ASHRAE/IES 90.1-2013 and the 2015 IECC contain extensive control requirements that are essentially similar due to harmonization but with some notable differences.
The most common thread is that lighting must be turned OFF or reduced when it is not used. Occupancy sensors are required in a broad range of spaces, and separate control is required for daylight areas. The standards impose commissioning requirements including functional testing and documentation. Finally, these standards incentivize installation of a more robust control system as either an enhanced efficiency option or as a method to achieve a higher interior lighting power allowance.
For more information, consult the 2015 IECC.