ASHRAE/IES 90.1 Energy-Efficient Design of New Buildings Except Low-Rise Residential Buildings was first published in 1975 and updated in 1980, 1989, 1999, 2001, 2004 and 2007. After 2001, the intention is to update the Standard every three years.
Applicability: Today, most states have adopted either 90.1 or the International Energy Conservation Code (IECC) as their commercial energy code, have a code based on one of them, or a state-specific code with similar requirements.
Click here for a list of states and which commercial building energy codes are in effect.
What’s based on 90.1: In addition to some state-specific codes, the Commercial Buildings Deduction’s Interim Lighting Rule is based on exceeding the lighting power density requirements of 90.1-2001 by 25-50% while meeting its mandatory lighting control requirements where applicable. The Leadership in Energy & Environmental Design (LEED) for New Construction v.2.2 green building rating system requires/rewards meeting and exceeding the requirements of 90.1-2004. ASHRAE’s green building standard still in development—189.1—is also partly based on 90.1.
90.1 as alternative to IECC: Most versions of IECC recognize 90.1 as an alternative compliance standard, with flexibility to choose either version by section (mechanical, lighting, etc.). This means a project’s mechanical engineer could use IECC, while the lighting designer could use 90.1, which offers some additional flexibility in lighting compliance.
IECC 2009 changes that, however, by requiring the design team to choose one standard or the other for all building systems. This will mean the lighting designer will need to lobby upfront with other project design elements for which code or standard will be used, in some cases meaning they ultimately get less design flexibility.
What’s New: Two interesting developments have occurred recently that will affect use of 90.1:
A new national energy standard—90.1-2004: Right now, 90.1-1999 is the national energy standard of record for state code adoption requirements in the United States. As of July 2004, all states were required to implement a commercial energy code that is at least as stringent as 90.1-1999. As of the time of writing, thirty-seven states and significant jurisdictions in other states have complied.
On December 30, 2008, the U.S. Department of Energy determined that switching to 90.1-2004 would generate site energy savings of about 12%, and recognized 90.1-2004 as the new national energy standard effective two years later, on December 30, 2010. The Federal Register notice can be found here.
Twenty-four states already have a building energy code in place that meets or exceeds 90.1-2004, meaning 13 states will likely catch up in 2010 and 13 will not comply for various reasons, such as “home rule” state constitutions.
“The 90.1-2004 Standard includes some minor text clarifications and additional exceptions throughout, and it incorporates three major changes compared to the 1999 version,” says Eric Richman, LC, senior research engineer at Pacific Northwest National Laboratory and a member of DOE’s Building Energy Codes Program. “The first is a completely updated set of interior lighting power densities (LPD) that are much more stringent than previous versions. A second major change is an expanded set of exterior lighting requirements covering effectively any exterior application encountered in exterior lighting. The previous 90.1 Standard only placed limits on a few applications—entrances, exits and facades. The third major change is a set of initial requirements for installing occupancy sensors in specific space types.”
Stimulus package encourages adoption of 90.1-2007: Under the stimulus package enacted into law in February, DOE is offering $16.8 billion to the states for a variety of measures related to production of renewable energy, energy and conservation research, and other programs. For a state to qualify for the money, its governor is required to work towards implementation of a commercial energy code that is at least as stringent as 90.1-2007 and to develop a plan for achieving 90% compliance with the code, including provisions for training and enforcement. (Meanwhile, the state must implement and enforce a residential energy code at least as stringent as IECC 2009.) Interestingly, 2007 offers several significant refinements and improvements over 2004, but otherwise does not change the lighting power density limits.
Federal construction based on 90.1: Federal construction is governed by an energy code that is based on 90.1-2004. EPAct 2005 and Presidential Order requires all Federal facilities to exceed 90.1-2004 by 30%.
Combining opportunities: By going 30% beyond 90.1-2004/2007 and meeting its mandatory controls and other provisions, a designer could contribute to a building’s LEED rating, earn the Commercial Buildings Deduction, and help a Federal building comply with the energy efficiency Executive Order.
Differences between 90.1-1999 and 90.1-2004: Below are descriptions of the significant differences in the lighting section of the Standard. For more information, take EE203. Lighting and Commercial Energy Codes, a course offered by Lighting Controls Association via its Education Express program.
• Change to recognized methods for automatic lighting shutoff and new exceptions.
• Addition of occupancy sensor requirements for classrooms, meeting and lunch rooms.
• New exit sign wattage requirement.
• Complete replacement of interior lighting power density allowances.
• Revised exterior lighting power density allowances.
Lighting Alterations: ASHRAE 2004 does not change the requirements for the minimum level of alterations to the lighting system that would enact the code, but places it at the beginning of the lighting section of the Standard, which could affect compliance. This section basically says:
• If a lighting system is altered (light fixture replacement), then 90.1 is triggered and the building is owner is obligated to comply with the Standard’s lighting power density requirements.
• If a lighting system is altered and this alteration involves replacement of existing controls, then the building owner is obligated to comply with the Standard’s Space Control requirements.
• The exception to these requirements specifies that if a lighting system is altered and this alteration involves replacement of less than 50% of the light fixtures in a space, then the building owner is not obligated to comply with the Standard’s lighting power density requirements for that space.
Automatic Lighting Shutoff: In both versions, interior lighting must be shut off when it’s not being used in buildings larger than 5,000 sq.ft. The 1999 standard lists “by occupant intervention” as a method of control. This was an error in description that was corrected for the 2001 and beyond versions by replacing it with “a signal from another control or alarm system that indicates the area is unoccupied.” For example, the last person to leave the building could arm the security system, which would signal the lighting to turn OFF.
More, 90.1-1999 recognizes only one exception, which is lighting intended for 24-hour operation. The 2004 standard adds “lighting in spaces where patient care is rendered” and “spaces where an automatic shutoff would endanger the safety or security of the room or building occupant(s).”
Space Control: The 2004 standard changes the “space control” requirements by identifying three applications where an occupancy sensor is a required control to turn the lights OFF within 30 minutes of the occupant leaving the space:
• classrooms (but not including shop classrooms, laboratory classrooms, and preschool through 12th grade classrooms);
• conference/meeting rooms; and
• employee lunch and break rooms.
ASHRAE 90.1-2004 adds, “These spaces are not required to be connected to other automatic lighting shutoff controls.”
Says Richman: “With the availability of easy-to-install equipment of this type, this requirement should be of minimal installation impact but with potentially large energy savings. The use of these sensors will also meet the automatic shutoff requirement for these spaces and may make design easier and costs lower in some cases. Note that the more current 90.1-2007 and future versions of the Standard will include a requirement for sensors in even more space types, including offices and restrooms. Therefore, getting used to occupancy sensors as part of a typical lighting design and installation planning is likely a good idea.”
Exit signs: The 1999 standard mandates a light source efficacy of at least 35 lumens/W for exit signs larger than 20W. ASHRAE 2004 simplifies and further tightens this requirement to read, “Internally illuminated exit signs shall not exceed 5 watts per face.” Basically, this means LED.
Lighting power densities: “Lighting power density” describes the density of lighting power in a building or space based on the amount of connected lighting wattage and the space’s area, expressed as watts per square foot. ASHRAE 90.1 imposes caps on the maximum allowable lighting power density in building or space types depending on whether the Building Area Method or Space by Space Method is used.
What’s new: The lighting power densities in 90.1-2004 have been completely revised and are generally 13-50% lower than 90.1-1999, as shown in Table 1 below.
“The new interior lighting power density requirements are based on complete updates of all the inputs to the models used to develop the power limits for each space and building type,” says Richman. “These updates include IES-recommended light levels, equipment efficacy, light loss factors, and common design practice. These new values are on average 20% more stringent than previous values. However, this increased stringency is based on the reality of increased product efficiency and other design attributes, so compliance should not be adversely affected. Good design will already be meeting those levels.”
Exterior lighting power allowances: Exterior lighting power allowances are dramatically expanded in ASHRAE 2004.
Richman explains: “The new expanded set of exterior lighting power density requirements is intended to make sure that exterior lighting limits are incorporated into the code along the same manner as interior lighting. The new set of requirements covers 17 different applications, from parking lots to drive-up windows, and is intended to cover any outdoor application. The values are based on IES-recommended light levels, standard efficient technology and appropriate design characteristics. The requirements are split into “tradable” and “non-tradable” applications and like the interior requirements; power can be traded among the tradable applications for design flexibility. Because many of these applications have never had limits placed in the energy code, designers need to consider these new limits compared to their current design practice.”
Final word: “I encourage all electrical industry professionals to become familiar not only with what the current code requirements are for states/jurisdictions they work in but also any requirements of newer published code versions that may become applicable in their work locations in the future,” says Richman. “It is much easier to consider adopting new lighting technologies, controls, systems and design attributes now that will meet newer codes before they are mandated.”