ASHRAE/IES 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, was developed as a model commercial building energy code that jurisdictions can adopt in whole or in part. It is updated every three years; as of the time of writing, the 2013 version was expected to be published this month.


Today, most states have adopted either ASHRAE/IES 90.1 or the International Code Council’s International Energy Conservation Code (IECC) as their commercial building energy code, have a code based on one of them, or publish a state-specific code with similar requirements. The IECC references ASHRAE/IES 90.1 as an alternative reference standard, providing a choice.


In October 2011, the Department of Energy recognized the 2010 version as the new national energy reference standard for commercial buildings. All states are required to put in place a commercial building energy code at least as stringent as this model energy code or justify why they could not comply by Oct. 18, 2013.


That time has arrived. So what has changed?


More than 35 states were predicted to comply by October or afterward. States that cannot comply, such as Colorado, which has a home rule constitution, may see adoption at the local government level.


In terms of lighting, the new ASHRAE/IES 90.1 standard is far more comprehensive, stringent and complicated than previous iterations. Lighting systems designers in states with a code based on ASHRAE/IES 90.1 2010 will recognize lower lighting power densities, expanded mandatory lighting control requirements and new commissioning requirements. Depending on the project, the electrical contractor may be responsible for some or all elements of compliance, particularly functional testing and certain commissioning documentation requirements.


First, note the standard’s scope has changed. ASHRAE/IES 90.1 2010 now covers lamp and ballast retrofits if 10 percent or more of the connected lighting load is replaced. For these projects, the standard’s lighting power density and automatic shutoff requirements apply.


As with past versions, for interior lighting design compliance, ASHRAE/IES 90.1 2010 provides a choice of building area method (whole-building power allowance expressed in watts per square foot) or space by space method (power allowances allocated by individual space types, with potential additional and tradable allowances for greater flexibility). A majority of these power allowances are reduced. There are now two power adjustment credits that can be earned if using the space by space method: a credit for odd room geometries and a credit for using recognized advanced lighting controls.


For exterior lighting, ASHRAE/IES 90.1 2010 expanded the scope of applications and based power allowances on five lighting zones covering outdoor environments in order of increasing population density. The greater the density, the higher the power allowance.


Lighting controls have a starring role in ASHRAE/IES 90.1 2010. The standard requires automatic shutoff of indoor and outdoor lighting when it is not in use (eliminating the exemption for buildings smaller than 5,000 square feet). Occupancy sensors are mandated for a broader range of interior applications. The requirements for exterior lighting control changed to require a photosensor plus an astronomical time switch enabling curfew control of building facade and landscape lighting within specified time periods. Daylight harvesting is required in spaces adjacent to windows or with toplighting. Automatic controls must feature manual-on or auto-on-to-50-percent operation. All lighting systems controlled by a manual switch must be circuited for bilevel lighting. Automatic bilevel control is required in certain stairwell, parking garage and other spaces.


Furthermore, all lighting controls must be functionally tested, bringing elements of ASHRAE Guideline 0 2005, The Commissioning Process, into the lighting part of 90.1 for the first time. All specified lighting controls and associated software must be calibrated, adjusted, programmed and ensured to operate in accordance with construction documents and manufacturer installation instructions. Specific requirements are identified for occupancy sensors, programmable schedule controls and photosensors. For example, at a minimum, the party conducting the testing must confirm that the placement, sensitivity and time-out settings of any installed occupancy sensor must perform in an acceptable way—the lights must turn off only after the space is vacated. 


Finally, new documentation requirements in ASHRAE/IES 90.1 2010, also related to commissioning, require that the owner be given, within 90 days of acceptance, as-built drawings of the lighting and control system, operating and maintenance manuals for all lighting equipment, recommended relamping program, schedule for inspecting and recalibrating lighting controls, and a complete narrative of how each lighting control system is supposed to operate, including its recommended settings.


The major changes in ASHRAE/IES 90.1 2010 are expected to challenge lighting system designers to provide energy-efficient and well-lighted spaces; ensure that automatic shutoff control is included in retrofits; and provide a stronger role for electrical contractors able to provide functional testing and the required documentation.