Below is a short news piece I wrote for the July issue of tED Magazine. Reprinted with permission.
On September 26, 2014, the U.S. Department of Energy (DOE) named the ASHRAE/IES 90.1-2013 energy standard as the new national energy reference standard, superseding the 2010 version.
What this means: Before October 2016, all states in the country must implement a commercial building energy code at least as stringent as 90.1-2013, or justify why they can’t comply. States may adopt 90.1 in whole or part, the 2012 version of the International Energy Conservation Code (IECC), or develop their own code. Roughly one-half of the states complied with the last DOE ruling. As of January 2016, only six states had achieved early compliance.
The 90.1 standard provides code-ready language jurisdictions can use to implement commercial building energy codes. Updated every three years since 2001, the lighting requirements have become increasingly complex and strict over the years. The 2013 version goes further while attempting to simplify application.
The major changes include tougher controls requirements, adjusted maximum allowable lighting power densities (LPD, expressed as W/sq.ft.), and a new tabular format for implementing LPD and control requirements in specific space types.
Most of the LPDs were adjusted, some up, some down. For example, the maximum allowable LPD for office buildings was adjusted up to 1.01W/sq.ft. from 0.9, while the LPD for hospitals was adjusted down to 1.05W/sq.ft. from 1.21. These modified LPD values were prompted by new light level recommendations published in the Tenth Edition of the IES Lighting Handbook.
Mandatory requirements for lighting controls received a number of significant changes. Occupancy sensors must turn OFF controlled lighting within 20 minutes after the space is vacated, not 30. Partial-OFF is required for occupancy sensors in certain spaces such as stairwells and corridors. Automatic independent control is required for secondary sidelighted daylight zones, not just the primary zone. Daylight harvesting step dimming requires two control points between full ON and OFF to increase flexibility. More-detailed functional testing requirements are included.
ASHRAE/IES 90.1-2013 features a new table for determining LPD allowances and control requirements using the Space by Space Method and control requirements using the Building Area Method. The idea is to make things simpler, but the tables may take some getting used to. For the Space by Space Method, there are actually two tables, one listing space types found in multiple building types, the second listing spaces generally found in one building type. The standard contains language applicable to these tables that must be referenced separately.
Let’s look at open offices as an example. If using the Space by Space Method, an LPD of 0.98 is prescribed. The room cavity (RCR) threshold is 4, which means an additional lighting power allowance of 20 percent can be used if the actual RCR (2.5 x room cavity height x room perimeter length / room area) is greater than the threshold. Choices of controls are then listed. In open offices, space controls are required for users, and all lighting must be bi-level. If daylight is available, daylight zone lighting must be automatically and independently controlled. The lights may be manual-ON (“ADD1”) or partial-automatic-ON (“ADD1”), and they must turn OFF automatically based on either occupancy (“ADD2”) or a schedule (“ADD2”).
Lighting is steadily getting more complicated; increasingly complex and stringent energy codes are part of the mix. For more information, consult the ASHRAE/IES 90.1-2013 standard or the state and/or other jurisdictional energy offices to determine local energy code requirements.