What electrical contractors should know about energy code requirements and their exemptions/allowances relating to lighting power density and control
Gradually — and sometimes not so gradually — building energy codes are getting tighter. While it may have been simple to comply with the less stringent energy codes in the past, it's not so easy anymore. As the lighting power density (LPD) and control requirements become stricter, even seasoned designers can become frustrated trying to balance the desires of the client with energy code stipulations. Building officials responsible for code compliance in the field may also feel the pinch of having to enforce complex codes with more requirements and lower allowances.
Fortunately, most energy codes and standards include a variety of exemptions and allowances for compliance with LPD and control requirements. In fact, as codes get tighter, additional exemptions and allowances will show up in the codes and standards to accommodate potentially impractical applications. These necessary provisions are becoming increasingly important as part of effective compliance; however, they are often misunderstood or not recognized. A better understanding of the available allowances and exemptions, as well as their intent, can make compliance go much more smoothly.
For anyone working in multiple states or jurisdictions, an additional complication in the code compliance process exists — the variety of energy codes and different versions adopted by states as well as the handful of states that have developed their own. (For information on state adoption of codes, visit http://www.energycodes.gov/states/.) The majority of states, however, have either adopted the American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers/Illuminating Engineering Society of North America (ANSI/ASHRAE/IESNA) 90.1 Standard or International Energy Conservation Code (IECC), both of which have similar requirements. But beware — in an effort to be more energy compliant, some codes allow fewer exemptions and allowances. So check your applicable code requirements carefully.
Interior lighting power limits
Because LPD allowances are tighter today than in years past (click here to see Fig. 1), it's important to make sure you apply the appropriate LPD so as not to shortchange your project. Codes and standards have historically offered both a building area (whole/entire building) and space-by-space (tenant area) compliance method.
The building area method is the simplest to apply, especially when just one building type is chosen and applied to the entire building's square footage. However, most code versions allow you to apply multiple building areas per completed building. This is especially important if you have a building with more than one primary function. For example, an office building with a small cafeteria for employees may be viewed as an office building because cafeterias can be a common part of such buildings. However, a “cafeteria” is a separate building area type that, because of its higher lighting needs, has a higher LPD than an office. Therefore, for significant cafeteria areas, apply this higher LPD to the specific cafeteria's square footage to more accurately represent the lighting needs of the building.
The space-by-space method requires more work up-front but can provide a more accurate basis for appropriate LPD allowance. For example, a post office facility could use the building area value for compliance, which represents the space type mix of a typical post office. However, a post office with a high percentage of sorting areas (i.e., regional sorting center) should consider the space-by-space method to account for the higher illuminance — and therefore higher LPD — for the specific sorting area. This will more realistically represent the higher-than-typical lighting need for that facility.
Interior lighting exemptions
Exemptions are critical to effective and meaningful application of LPD limits because it's difficult for any set of requirements to be generically written to cover all expected situations. The exceptions describe specific lighting uses that are not required to be counted as part of the allowed LPD.
This article discusses the list of exemptions provided in the latest version of the 90.1 Standard (2007) because it's the most complete — and covers what is found in most other codes. The IECC generally provides a shorter exemption list, so make sure you know the specific list in the code or standard you have to comply with before assuming an exemption. Exemptions from Standard 90.1 (2007) include:
Lighting within dwelling units. Note that a “dwelling unit” is not a hotel, motel, or dormitory room. It is intended to define only an apartment, condominium, or other similar primary living space with full living facilities.
Lighting that is integral to equipment, including open and glass-enclosed cases and food preparation/warming apparatus.
Lighting specifically designed for use only during medical/dental procedures. The general overhead or standard task lighting would not be exempted because it's there as part of the lighting for the room itself.
Lighting integral to advertising or directional signage. The lighting that is not part of a manufactured sign is not exempted.
Lighting for plant growth or maintenance. This refers only to the special grow lamps aimed at the plants, not any general room or area lighting.
Casino gaming areas. Here, the intent is to apply only to primary gaming areas in casinos with themed lighting, not other common areas that may include a few slot machines.
Lighting in retail display windows enclosed by ceiling-height partitions. If the window is not enclosed, the lighting is not exempted.
Lighting that is for sale or is part of a lighting-related educational system.
Lighting for theatrical purposes, including performance as well as film/video production. This covers lighting that is in place solely for putting on the production, not used at other times.
Lighting for TV broadcasting in sports activity areas. This is intended only for lighting that is turned on to support televising events but is off at other times.
Furniture-mounted task lighting that is separately controlled, including automatic shutoff. If the task lighting is not of this type, then it must be counted along with other general lighting.
Other exemptions may not be as clear, leading to greater difficulties in their application. It's important to remember that the ultimate interpretation and application of the requirements rest with the local AHJ. However, some practical guidance on the intent of these more involved exemptions may be useful to ensure you're claiming all of the exemptions you're entitled to:
Display or accent lighting for galleries, museums, and monuments. This applies to the essential display/accent elements in these applications, even if they are a part of another building. For example, a gallery or collection display in an office would be able to claim this exemption for the appropriate display/accent lighting.
Lighting in spaces specifically designed for use by occupants with special lighting needs. The intent here is to exempt lighting designed specifically to accommodate higher lighting needs for medical conditions. This could apply to various spaces in hospitals/clinics and some elderly care facilities. However, it's not intended to provide a blanket exemption for any spaces that may be used by elderly occupants or patrons.
Lighting in interior spaces that have been specifically designated as a registered interior historic landmark. The term “historic” as defined in the standard refers primarily to listing on the National Parks Service “National Register of Historic Places” or a building that has been determined to be eligible for such listing (a facility can be found eligible per the Secretary of Interior without officially registering). The AHJ or building official can accept other historic registries, such as those of state and regional organizations.
Decorative lighting allowance
The decorative lighting allowance provides additional wattage for any decorative or lighted architectural elements in your design. It is a use-it-or-lose-it provision, so you can claim only the wattage actually used for these elements — and only up to 1W per square foot of the area that includes these elements. The allowance applies to purely decorative elements, such as chandeliers, decorative wall sconces, cove lighting, architectural accent lighting, and other lighting design elements that provide sparkle and accent.
It's not always perfectly clear when you can consider specific design elements decorative. The intent is clear, however, that lighting designed to contribute to the general illumination of the space to meet desired task-related light levels is not considered decorative for code application purposes. Some design elements can provide both general illumination and decorative accent, but it is only purely decorative design elements that can claim the allowance.
Retail display/accent lighting allowances
If you are using the space-by-space method of compliance for any retail lighting project, you may have some important additional allowances available for merchandise display lighting. Most codes and standards recognize the importance of display lighting and its potential variability between different retail operations, and allow additional wattage to ensure its critical function is not unduly restricted. This is lighting that is not part of the general illumination of the space, is separately switched, and installed specifically and only to highlight merchandise.
The allowance has historically been difficult to interpret and apply, given the variations in retail display formats. The most recent versions of the 90.1 and IECC standards and codes provide a base allowance plus individual allowances based on the type of merchandise highlighted, but check your applicable code for specifics. As with the decorative allowance, this is a use-it-or-lose-it provision, so you can only claim the wattage actually used for the specific display lighting.
In applying the retail display allowances, it's easy to overlook a base allowance because it may not be tied to a specific merchandise type. This is critical to include, particularly for smaller retail spaces. Make sure you are accurately applying the allowances by specific merchandise type, and note that you are not restricted to just one type. For each clearly defined merchandising area, apply the appropriate allowance(s) based on each merchandise type's square footage. Of course, not all specific merchandise types are listed in the standard. In these cases, document for the building official what category it should fall in based on the merchandising area's illumination needs.
Exterior lighting application
Similar to the interior lighting compliance paths, exterior requirements are based on a set of lighting power limits and some mandated controls. The limits are divided into tradable and non-tradable applications. The tradable applications work in full trade-off mode such that the total sum of all tradable application allowances can be used in any distribution across all applications.
The non-tradable allowances are use-it-or-lose-it for that specific application. You cannot use non-tradable wattage for a different application. The lighting power limits are provided based on appropriate application metrics, including square footage, length, or location/application quantity. To take full advantage of the allowances, you must apply the correct category to the area or function being illuminated. A few notes will help guide you:
The table of exterior applications can't cover everything. Unlisted applications should typically be applied under “Special Feature Areas” or “Plaza Areas.”
Building entrances and exits can often also have a canopy or overhang. In these cases, you will want to apply the one that provides the most wattage, but note that only one or the other is applied — not both.
Drive-through windows, although only noted for fast food restaurants, are meant to apply to any drive-up window, including those at pharmacies and banks.
Also note that an additional allowance of 5% of the total of all lighted tradable and non-tradable applications is provided, and it can be used for any exterior application.
Exterior lighting exemptions
Like the interior compliance provisions, the exterior section also includes a list of lighting applications and uses that are exempted and do not need to be counted. Many are similar to the exemptions for interior, but a few additions could use some clarification:
Lighting for athletic playing areas. This covers the lighting used to illuminate playing surfaces, including fields, tracks, ranges, rinks, and courts. It does not cover other common areas, such as walkways, seating areas, etc.
Lighting for industrial production, material handling, transportation, and associated storage. This covers the lighting needed to support the specific process needs, but is not intended to cover common areas that might be associated with any business exterior.
Theme elements in theme/amusement parks. This would not cover any lighting for common exterior applications found in typical commercial exteriors.
When a compliance path is not clear
Let's be realistic. The requirements in energy standards are not perfect. As such, there will be cases where compliance with the written requirements may seem impractical to nearly impossible, given the variety in building design.
A further reality is that some building officials or departments may seem hard-nosed, leaving you to find compliance unforgiving and restrictive. In other cases, there seems to be little interest in energy codes and what you are doing to comply. In the end, final application and interpretation authority rests with these local building officials, who can be just as confused as the builder or designer.
Most codes and standards organizations offer interpretation services that can provide the most direct application guidance or official interpretation (see the ASHRAE Web site at http://www.ashrae.org/technology/page/121 or the ICC Web site at http://www.iccsafe.org/cs/Pages/opinions.aspx). Other resources, such as the Building Energy Codes Web site at http://www.energycodes.gov/help/ can provide clarification, background, and intent related to code requirements that are useful in working with building officials to resolve issues.
If you find yourself struggling with a particular issue, addressing it with the local official or department can often be the most timely and effective path to resolution. A few additional approaches can also be effective:
If you have an application that requires a control or LPD limit that seems impractical, explore the application of newer code versions. Different exemptions or allowances in newer code versions may have addressed your specific issue. If this is the case, convey this to the building official, documenting how this is a rational application of the newest energy code to your situation.
If you have a case that isn't covered in the standard, propose a resolution that meets the intent of the requirements and document how you are meeting — or perhaps exceeding — requirements in some cases.
The bottom line is that if you have an unusual application or situation, look hard at all the allowances and exceptions in the standard — and when all else fails, work with the building official to agree on a rational application of the standard.
Richman is an engineer at Pacific Northwest National Laboratory, Richland, Wash., and is the chair of the ASHRAE/IES 90.1 Lighting and Power subcommittee. He can be reached at email@example.com.
Sidebar: Evolution of Energy Code Requirements
Energy codes, including lighting requirements, are a necessary part of most commercial building construction and remodeling projects. This is mostly a result of the regulations in the Energy Conservation and Production Act (ECPA), as amended by the Energy Policy Act (EPAct) in 1992 and 2005, that require states to adopt an energy code/standard that meets or exceeds the level set by the Department of Energy. Energy standard and code development began in the mid-1970s with early versions of Model Energy Codes and the 90.1 Standard.
As interest in energy efficiency and sustainability continued to rise, energy codes and standards became more stringent, and the minimum code adoption level set by DOE increased. At the same time, there are other non-regulation and above-code-based systems and programs being considered by states, local jurisdictions, municipalities, and corporate entities, which also support tighter energy code requirements. Currently, states have a variety of versions of the 90.1 Standard, IECC, and some state-specific codes on the books. See http://www.energycodes.gov/states/ for additional information on energy code adoption.