The Energy Policy Act of 1992 mandated minimum efficiency standards for many popular lamps and deregulated the $300 billion electric power industry. It also amended the Energy Conservation and Production Act (ECPA) by establishing ASHRAE/IESNA 90.1-1989, Energy-Efficient Design of New Buildings Except Low-Rise Residential Buildings, as the federally mandated minimum design and construction standard for commercial buildings nationwide. ECPA also gave the U.S. Department of Energy (DOE) the authority to review any updates to Standard 90.1 and adopt new versions as their new minimum standard.
The original standard was revised and reissued in 1999 as 90.1-1999. Subsequently, the DOE agreed to accept it in July 2002. Once the DOE accepted the new standard, this triggered a two-year time frame under which all 50 states would be required to certify that they had commercial energy codes in place that were at least as stringent as the 1999 version or provide justification for their non-compliance by July 15, 2004. The Figure at right shows which states have complied and which have applied requirements from other standards.
The effect on lighting systems. Standard 90.1-1999 was designed to be easier to use than 90.1-1989, so it's written in clearer, enforceable language for both new construction and renovations. While its standards for HVAC aren't much higher, it's much more strict with regards to lighting.
The 1999 version of the standard mandates the calculation procedure for fixture wattage to prevent under-calculation, and includes a much broader range of building categories. The 1989 version of the standard provided single-value whole building lighting power densities for only 11 building types, while 90.1-1999 provides power density levels for 31 building types. In addition, a number of exemptions in the 1989 standard, such as process facilities, aren't present in the 1999 version. However, the 1999 version does include a number of narrowly targeted exemptions, such as for safety lighting.
Standard 90.1-1999 is largely prescriptive, setting lighting power allowances for both interior and exterior applications. Interior applications are addressed using either the whole building method or space-by-space method. It also provides power limits for exit signs. To address special lighting needs, the 1999 standard provides specific allowances for decorative, merchandise, display, and accent lighting, and lighting used to reduce glare on computer screens in certain spaces.
For exterior applications, power allowances are prescribed for building entrances, exits, and highlighting. Mandatory tandem wiring requirements are provided to reduce the use of single-lamp ballasts. The lighting power allowances are generally more strict based on advancements in commercially available lighting technologies over the last decade.
For changes in lighting power allowance levels using the space-by-space method, see the Table.
It's assumed that light levels in these spaces will be maintained at IESNA-recommended values, which were used in development of the power allowances in Standard 90.1-1999. Compliance will require more efficient technology, mostly more efficient lamps and ballasts. For more sophisticated or alternative approaches, engineers can use the energy cost budget method (computer calculations) to demonstrate that load reduction values fall within limits of the new energy code.
90.1-1999 and lighting controls. Standard 90.1-1999 includes broad mandatory provisions with regards to lighting controls. The 1989 code required minimum controls and covered their accessibility. Automatic controls were addressed in the form of credits for higher power allowances if occupancy sensors, lumen maintenance controls, or daylight controls were included in the design.
Facility-wide lighting. Standard 90.1-1999 mandates that either scheduling or occupancy sensing automatic shut-off strategies be used for buildings larger than 5,000 square feet. The only exception is lighting operated 24 hours/day. The control device can be:
A programmable time scheduling control system for shut-off that's based on time of day when spaces are predictably unoccupied. A minimum of one schedule is required per floor, and each control zone is not to exceed 25,000 square feet.
An occupancy sensor that turns the lights off no longer than 30 minutes after the space is vacated.
An unoccupied/shut-off control signal from another control or alarm system.
Individual spaces. In addition, each space that's enclosed by ceiling-high partitions must have at least one control device that independently controls the general lighting in the space. Each control device is activated either by an automatic motion sensor or manually by an occupant.
For spaces equal to or less than 10,000 square feet, each control device is limited in coverage area to a maximum of 2,500 square feet.
For spaces greater than 10,000 square feet, each control device is limited in coverage area to 10,000 square feet.
No control device can override the time-scheduled automatic shut-off for more than four hours.
Each control device must be readily accessible and located so the occupant can see lights from the controlling switch, with an exemption for controls located remotely for safety or security purposes.
Exterior lighting. Exterior lighting not exempt from the standard must be controlled by a photocell or astronomical timeclock.
Tandem wiring. Light fixtures in the same space and on the same control device and that use one or three linear fluorescent lamps greater than 30W each must use two-lamp tandem-wired ballasts in place of single-lamp ballasts.
Other controls required.
- Display/accent lighting
- Display case lighting
- Hotel and motel guest room lighting
- Task lighting
- Non visual lighting (such as for plant growth)
- Demonstration areas
Issues of compliance. As of January 2005, only 33 states were in compliance with ASHRAE 90.1-1999. On the other hand, a few have adopted even stricter energy codes. For example, California's Title 24 energy code also mandates bi-level switching to achieve 50% energy savings, except in corridors, storerooms, restrooms, public lobbies, guestrooms, areas with only one fixture, and spaces where occupancy sensors are used. Others, such as Arkansas, Georgia, Kansas, Maine, New Mexico, Nebraska, Utah, Pennsylvania, Montana, and Rhode Island, have adopted the 2003 International Energy Conservation Code (IECC) as the basis for their energy codes. “Over half the states in the country either have energy codes in place or soon to take effect that meet or exceed Standard 90.1-1999,” says David Weitz, executive director for the Building Codes Assistance Project (BCAP). “The majority of these states account for over 70% of new commercial construction in the United States. In addition, the trend seems to be for more states to climb on board with either adopting the energy code or updating to a more current version than the one they have in place. So the energy code is definitely having an impact.”
The biggest obstacle in meeting the DOE's mandate appears to be inherent in the constitutions of the “home rule” states of Nevada, Arizona, Colorado, North Dakota, Missouri, and Tennessee. In these states, it's exclusively up to local cities and towns to decide if they want to adopt the energy code or not. “One reason for states not complying with the July 15, 2004, DOE deadline is that some states simply have no mechanism to impose a state-wide energy code,” Weitz says. “However, there are many cities that have adopted the energy code in home rule states.” Other reasons for non-compliance include:
Lack of funding for the mandate.
The DOE isn't enforcing the requirement aggressively.
There are no clear penalties for non-compliance.
Another dimension of the situation is that ASHRAE released revisions to Standard 90.1 in 2001 and 2004. Although the 2001 revision appears to primarily correct errors and address procedural issues, the 2004 version is 20% to 25% more efficient than the 1999 version, so it includes significant savings in power allowances. The DOE has yet to decide whether to accept the 2001 or 2004 version. If it makes a positive determination on either, it would reset the two-year clock for states to certify that they have updated their energy codes.
What does it all mean? Energy codes can be viewed as a double-edged sword. On the positive side, Weitz says, a common standard makes doing business easier for design professionals who work nationwide because they'll essentially only have to know one code, even though they move from one state to the next.
He also points out that saving energy, which is the ultimate goal of the energy code, is good for the country. “From a national policy perspective,” he says, “saving wasted energy is becoming an increasingly important issue for the nation's economy, environment, and security. There are significant savings that can be garnered from buildings, which consume 37% of our country's total energy and 70% of our electricity.”
In addition, Weitz says, large-scale adoption of stricter energy codes increases demand for energy-efficient lighting technologies, which expands supply. “Codes can help to drive down the cost of efficient technologies by expanding markets and thereby increasing supply,” he says. “We saw this with T8 lamps and electronic ballasts, and it will apply to new technologies as they are introduced and proven in the market.”
On the negative side, Standard 90.1-1999's lighting requirements are about 50% more efficient than the 1989 Standard, which some lighting designers believe hinders creativity by limiting design choices. Part of this criticism is that the energy code doesn't recognize high-end applications that may require a more intensive level of lighting. Weitz understands this criticism of the energy codes, but essentially disagrees. “Many new buildings are being built with quality lighting designs that use even less energy than allowed by code,” Weitz says. “The writers of lighting energy codes recognize the need for flexibility in lighting design and incorporate additional lighting power allowances aimed directly at providing additional power for these purposes. It's important for designers to understand these allowances and make effective use of them. Creativity always has limits that are imposed on it — budget, time, and the practical needs of the occupants can be said to ‘inhibit’ creativity.”
Another criticism of the energy code is that the content of the code is only as good as the system for compliance. “This is indeed a problem, but it is one that is difficult to quantify,” Weitz says. “Many jurisdictions do a fine job in both plan review and inspection, but this is by no means universal.”
Overall, energy codes are positive for the country, but may cause headaches for designers. But as more and more states adopt Standard 90.1 or even more stringent codes, designers must adapt. Many will even thrive. In the end, energy codes are simply another design challenge to be accommodated through knowledge and creativity.
DiLouie is communications director for the Lighting Controls Association and principal of ZING Communications, Inc., Calgary, Alberta, Canada.