How energy codes affect lighting design

Engineers have many resources when designing energy-efficient lighting in nonresidential buildings. Lighting designers do not have to sacrifice quality or reduce lighting levels just to meet energy codes.


This article has been peer-reviewed.Learning objectives:

  • Learn the three parts of a building’s energy-efficient lighting system.   
  • Understand how to create energy efficiency goals for lighting design.
  • Use an example to illustrate how to design energy-efficient lighting in nonresidential buildings.

Electrical engineers and lighting designers tackle many challenges as they strive to create design solutions that enrich the built environment. One leading challenge is energy management of electric lighting in buildings. Electric lighting in buildings is a prime target for reducing energy, as it is the largest end use of electricity in commercial buildings, according to the U.S. Energy Information Administration.

There are many motives for advancing energy reduction of electric lighting in buildings, such as sustainable responsibility and lowering ongoing expenses. All of these goals result in less energy consumed for the same lighting deployed in a building.

Effective lighting energy management involves three essential parts of a building’s overall lighting system:

  • Daylighting.
  • Electric lighting.
  • Lighting controls.

Building energy codes and standards provide prescriptive or performance requirements for the building’s lighting system with regard to its energy use. Lighting design guidelines, like the Illuminating Engineering Society (IES), “The Lighting Handbook, 10th Edition” provide prescriptive requirements for a building’s lighting system for the quantity (illuminance) in each area; the guidelines are written to inform the designer how to adequately light the space. The engineer needs to ensure that the requirements set forth do not inhibit the quality of the building’s lighting system and its positive influence on the built environment.

Figure 1: The lighting for a combined health care and research facility not only meets code, but also showcases lighting techniques applied to challenging environments. All graphics courtesy: CannonDesignWhile many lighting systems are available to help the engineer comply with energy codes and adequately light the space, only some will accomplish this while also enhancing the quality of the built environment. It is the engineer’s responsibility to evaluate all criteria of the application and then select the lighting system that supports both energy reduction and lighting quality.

The primary challenge for the engineer is to ensure that critical tasks are adequately lit. However, the simplest solution, uniformly lighting the entire space to the critical-task illuminance, does not enhance the quality of the built environment nor does it allow for the most energy-efficient strategy. By defining and confining the multiple critical tasks to their respective areas and providing multiple layers of lighting to ensure that illumination of critical tasks is targeted while not over-lighting adjacent areas, the engineer can achieve a non-uniform, layered lighting layout that maximizes both energy management and lighting quality.

The engineer can achieve an effective energy-management strategy that satisfies energy codes and increases lighting quality by performing the following process:

  1. Determine applicable code requirements.
  2. Establish energy-management goals:
    a. Illumination targets.
    b. Lighting-power density (LPD) limits.
  3. Develop strategies to meet goals:
    a. Non-uniform, layered lighting layout.
    b. Evaluate efficacy of luminaires.
  4. Document methods and results.

The energy challenge

Figure 2: This graphical comparison illustrates average energy use in buildings over time when comparing energy codes, U.S. Green Building Council’s LEED, and the AIA 2030 Commitment. ASHRAE Standard 90.1 energy requirements increased 30% between 2004 and Building energy codes were created in response to the first world energy crisis of 1973. Long lines at gas stations, brownouts, and closing of public buildings created demands for more equitable sharing and distribution of energy supplies. As a result, ASHRAE published Standard 90-1975: Energy Conservation in New Building Design, the first professional consensus standard to address building energy efficiency. Around the same time, new legislation in the form of the Energy Policy and Conservation Act of 1975 and the National Energy Conservation Policy Act of 1978 were enacted, which began to require states to adopt an energy standard for nonresidential buildings in exchange for federal support.

In the early 1970s, there were few if any energy efficiency measures for building construction. By midway through the 1970s, a minority of states had adopted an energy-conservation standard. Beginning in the early 1980s, more than half of the United States had adopted energy-related building requirements. A “lighting power budget” was introduced in 1980, which limited lighting energy. By the end of the decade, most states had adopted some form of energy efficiency requirement for buildings.

ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings (1989 edition) included the first use of LPD as a measure of lighting energy use in a building. The passage of the U.S. Energy Policy Act of 1992 was a milestone in energy code history, effectively making ASHRAE 90.1 the law of the land and requiring all states to enforce an energy code at least as stringent, if not more, than the 1989 edition of ASHRAE Standard 90.1 . In 2000, the first version of the International Energy Conservation Code (IECC) was published. The Energy Policy Act of 2005 further elevated energy efficiency by once again requiring states to adopt a new energy code as stringent as ASHRAE 90.1-2004.

This timeline reveals a shift from an industry with few energy-conservation requirements in the 1970s to one where energy efficiency requirements are affecting every way engineers light a building today. A little more than half of the U.S. is still following a code less stringent than ASHRAE 90.1-2010. This is important to note because, between the 2004 and 2010 code cycles, the energy use of a standard building is expected to be 30% less—a significant jump. The jump in energy efficiency is quite large in comparison to the early history of energy codes. In just this past decade, the industry has seen commercial-building energy codes’ efficiency requirements increase by 45%. Contrast this to the 14% improvement over the previous 25 years.

The most current model code for commercial construction calls for energy efficiency levels approximately 37% above those required by the same code 10 years ago. Current policy discussions reveal a similar trend moving forward. A trend toward more rigorous code requirements, more performance-based requirements, more enforcement and auditing, and more post-occupancy building energy performance reporting.

Throughout all of these seismic shifts in the rules governing design and construction, there is a big question: What can engineers do to stay on top of energy code requirements?

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