Energy codes and lighting in smart buildings
Lighting is an integral component of smart buildings and is one of the variables that is affected by—and in some cases drives—a design team’s decision to follow ASHRAE 90.1-2010 or IECC 2012 energy codes.
In October 2011 the Dept. of Energy adopted ASHRAE 90.1-2010 as the national reference standard. Overall, ASHRAE Standard 90.1-2010 has theoretically reduced energy consumption by slightly less than 20% in comparison to ASHRAE 90.1-2007. Further, the federal government mandated that all states update their energy codes to meet or exceed ASHRAE 90.1-2010 by October 2013. While many states have so far ignored this injunction, a handful has already complied and several more are expected to follow within the next year. The majority of these states have adopted International Energy Conservation Code (IECC) 2012 with an alternate to follow ASHRAE 90.1-2010.
Both IECC 2012 and ASHRAE 90.1-2010 include significant changes to the lighting sections compared to previous versions, including but not limited to the scope, lighting power density, and controls requirements. While IECC and ASHRAE are similar in overall intent, small differences exist. Many designers believe that IECC may be a less expensive design alternative, and certainly the lighting sections uphold that theory. For example, ASHRAE is more stringent in regard to scope as well as lighting controls. However, it may offer greater flexibility in other areas such as lighting power density in combination with the related allowances.
A design team typically considers up to four criteria when choosing a code to follow.
- Will all disciplines be able to meet the code requirements? For example, the building envelope section of IECC 2012 may be too stringent or the mechanical requirements too unrealistic. Conversely, the receptacle control requirements under ASHRAE 90.1-2010 may be unamenable to a client.
- Is the project new construction or an alteration? Compared to ASHRAE 90.1-2010, IECC 2012 appears less stringent in the lighting section for existing buildings than new. For example, the lighting scope for alterations is much tighter in ASRHAE 90.1-2010 than IECC 2012. Under ASHRAE 90.1-2010, lamp plus ballast replacement is considered an alteration, whereas under IECC 2012 it is considered maintenance.
- Will the project benefit from the allowances and exemptions offered by one code or the other? For example, in ASHRAE 90.1-2010, retail spaces are exempt from the daylight harvesting requirements.
- Is U.S. Green Building Council LEED certification being pursued? LEED 2009 follows ASHRAE 2007, while LEED v4 follows ASHRAE 90.1-2010.
Ultimately the decision to follow IECC 2012 or ASHRAE 90.1-2010 is based on a cost and design implication breakdown. In many ways this can act like a mini design charrette to accelerate early communication.
Extraordinary advancements in lighting technology also affect the way a project meets or exceeds the code, particularly in smart buildings. The LED market has boomed in the past 7 years, providing more cost-effective, efficacious, and aesthetically pleasing solutions. At the same time, many linear fluorescent lamps have made significant strides in their lamp life, in some cases more than tripling the standard fluorescent lamp life.
The lighting controls market likewise has grown. It is becoming routine to provide a building-wide network control system. A broad variety of control protocols are available and selection is typically based on lamp choice, programmatic requirements, and budget. Many spec-grade LED luminaires come standard with 0 to 10 V dimming drivers. Thus, 0 to 10 V dimming control has made a resurgence. For high-performing buildings, digital control protocols are frequently selected; two of the more common are DALI (digital addressable lighting interface) and DMX (digital multiplex).
On a smaller scale and often because of code requirements, many occupancy sensors are being set to function as vacancy sensors or 50% occupancy sensors, under which the luminaires will still shut off automatically. When using a vacancy sensor, a manual control is required to turn on the lighting. However, the 50% occupancy sensors allow up to half of all lamps or 50% illumination to come on automatically.
Exterior lighting controls also have made substantial improvements. Integrated occupancy sensors, photocells, time clocks, and dimming are becoming common place, depending on the lamp source. Beyond the lamp source, the selection of the exterior controls may depend on the code the project is following, the initial budget, and programmatic requirements.
These new lamp and controls technologies, in conjunction with scientific discoveries, have given rise to new luminaire aesthetics and design concepts. Edge-lit LED and organic LED (OLED) luminaires have created luminous planes and floating forms. New knowledge of how photosensitive retinal ganglion cells interact with the body’s circadian system has created a field of new design concepts. Employing color-changing or dynamic white LED luminaires with DMX or DALI controls allows the lighting to change color or tone throughout the day to enhance circadian rhythms, which may improve health and well-being. These same technologies are often applied to wayfinding, with luminaire types or colored light employed to help occupants move through a complex building.
The ever-increasing complexity of smart building systems and architecture make it imperative for the design and construction team as well as ownership to have open communication and documented coordination.
Unfortunately, energy and budget goals and their implications often are not well understood by all parties.
According to the national commissioning manager of one large engineering firm, both ASHRAE and IECC require projects to be commissioned to prove energy performance. The IECC, however, allows the registered design professional to commission the HVAC systems but not the lighting controls. This system must be commissioned by an independent party, a requirement that provides another challenge when determining which code a project will follow.
Clearly there is no one-size-fits-all approach to energy codes and lighting in smart buildings. However, the following in-process projects illustrate how some design teams are proceeding. Each project is employing new luminaire and control technologies as well as design concepts to not only meet but go above and beyond the requirements of the energy code being followed.
Shanna Olson is Senior Lighting Designer for KJWW Engineering Consultants. She is NCQLP certified and experienced in creating lighting designs for municipal, health care, educational, commercial, and residential clients.