Understanding the impact of IECC updates on lighting controls
The International Energy Conservation Code (IECC) is revised periodically to stay up-to-date on current technology and practices. Interior lighting plays an impactful role in the electricity usage of commercial buildings, and the 2012 IECC recognizes this by including various major updates to lighting control systems for energy conservation.
Energy conservation is an important aspect of building design in today's society. The International Code Council (ICC) has developed standards to encourage energy conservation through efficient design and installation of building envelopes and mechanical, lighting, and power systems. These standards are compiled in the International Energy Conservation Code (IECC), which is revised periodically to stay up-to-date on current technology and practices.
The code is implemented at the state and/or local levels, so depending on where a project is located, the design could have to adhere to the 2015, 2012, or 2009 IECC-or even no code at all. Although the 2012 IECC is not the most recent edition, it increases energy efficiency noticeably from the previous years' versions and has been adopted by nearly half of the states.
Interior lighting plays an impactful role in the electricity usage of commercial buildings, and the 2012 IECC recognizes this by including various major updates to lighting control systems for energy conservation. It is important for design and construction teams to be aware of and understand the updated requirements and solutions for achieving these standards.
Lighting control updates
One of the biggest changes with the 2012 IECC is that it requires automatic lighting controls to be used in all buildings, not just those larger than 5,000 sq ft. In addition, in all projects where more than 50% of the lighting is being modified, either the total wattage is increased or the number of required fixtures is increased to meet the current code. This is in an effort to prevent the need to rely on people to manually turn off the lights.
In previous codes, commissioning was not strongly enforced, so another important update mandates that all projects require commissioning, which ensures that the lighting controls are designed according to code and perform as intended. Engineers must submit an energy-compliance form (COMCheck) that documents the lighting-power density (watts per square foot) as well as the lighting controls that are required. Then, each project needs to be inspected upon completion of construction and signed off to ensure it meets the IECC commissioning regulation. These measures increase the likelihood that the code is properly implemented in both the design and construction processes, and energy efficiency is realized.
Options for complying with the updates
Fortunately, there are multiple options available to ensure lighting design meets code requirements.
- Occupancy/vacancy sensors are useful for small spaces; however, in larger spaces they can become a nuisance if the lights automatically shut off when others are present in the general vicinity. Proper coverage design is critical. The architecture/engineering team is wise to require the sensor manufacturer to provide coverage-map shop drawings to ensure proper design.
Interestingly, occupancy and vacancy sensors are the same physical pieces of equipment, but they differ in how they are programmed. With an occupancy sensor, the lights turn on and off automatically. Per the code, these are required in classrooms, conference rooms, lunch and break rooms, private offices, restrooms, storage rooms and janitor closets-no matter what. A vacancy sensor, on the other hand, requires that the lights be turned on manually, but shuts them off automatically.
If opting for occupancy sensors, the lights can be turned on automatically to only 50%. The other 50% must be turned on manually by the occupant. This requires dual switching either through step-dimming ballasts, two ballasts per fixture, or a checkerboard switching pattern. With vacancy sensors, lights need to be turned on manually, but they can be turned on to 100%.
The bottom line in choosing between occupancy and vacancy sensors is how the client wants the controls to behave based on operations and users. Vacancy sensors, for example, have the advantage of not turning on unnecessarily if someone enters a room, even very briefly.
- Timer panels allow the lights to turn on and off automatically on a timed schedule. Though the upfront cost may be a little higher, it ultimately translates to energy savings and cost savings. It's also important to note that automatic switches and controls need an override switch that turns the lights back on for a maximum of 2 hours, per the code. This is a good solution for larger buildings and institutions where occupancy sensors may not be cost-effective or appropriate in every area of the building.
- Daylighting helps lower energy usage by using natural ambient light to reduce the amount of artificial light required in a space. As part of the 2012 energy code updates, daylighting must be used in any space that has a window, and the daylighting zone extends 2 ft beyond the window edges and 15 ft into the space. However, it is not required in spaces with two or less lighting fixtures, such as a private office. There are two options when it comes to daylighting: automatic and manual.
With automatic daylighting, a sensor is installed in the ceiling that senses how much natural light is coming in and dims the lights accordingly. This is the most effective control method because it does not rely on people to remember to turn off the lights. Additionally, there is a less noticeable change when the artificial lighting is dimmed. It's important to keep in mind that standard fluorescent lights are not dimmable, so when retrofitting a project with fluorescent lights, a dimming ballast will need to be installed along with the daylight sensor and controller. To avoid installing another piece of equipment, LED lights, which are dimmable in a standard model, can be used as a substitute. LEDs offer additional energy savings because they consume less power and may be eligible for utility rebates.
The other option is to simply employ a manual daylighting method, which involves using a traditional toggle switch to shut off the artificial lights when there is enough sunlight. This is by far the more cost-effective option, especially in retrofit projects. It requires no controller, sensor, and most important, can be used with standard fluorescent ballasts. However, it requires a person to be conscientious enough to remember to shut off the lights for that area. In practice, this method results in far less actual energy savings.
Regardless of the daylight-harvesting method chosen, occupants must be educated about the system, how it works, and why it is used. This will prevent complaints and unnecessary maintenance calls for dim or burnt-out lights. It may take some time to adjust, but education and positive reinforcement will expedite this process.
Beyond the 2012 IECC
The 2015 IECC further demonstrates the importance of lighting controls by employing even stricter metrics to the 2012 updates, but many states and local jurisdictions have been slow to implement this version. Examples of updates include:
- If only 10%-instead of 50% in the 2012 code-of lighting fixtures are altered, then the entire space is required to meet the 2015 code.
- Automatic daylighting is required within the daylighting zone rather than having an option between automatic and manual.
-This article originally appeared in an RTM white paper. RTM Engineering Consultants is a CFE Media content partner.