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While observing lines of dirt and debris frozen in a glacier, the British physicist, John Tyndall noted in 1860 that more light on an object did not necessarily increase its visibility. Despite this observation, cheap and abundant electricity led to lighting design in the mid twentieth century that meant little more than sizing branch circuits large enough to safely deliver power to the light bulbs. A philosophy of, "More light, better sight" summarized the approach to architectural lighting. Lighting control was unnecessary as illuminated (but empty) buildings defined the nighttime city skylines.
Recognizing perhaps what John Tyndall observed over 150 years ago, the relatively new lighting design profession takes a more refined approach to providing visibility for the occupants and enhancing architectural forms rather than flooding a space with light. The approach also represents an enormous business opportunity in the form of energy savings in new and retrofit construction. The Energy Information Administration estimates that electricity used for lighting in US commercial buildings totaled 297 billion kWh in 2010. This represents about 22% of total commercial building electricity use in the United States. Ironically, much of this commercial building occupancy takes place during daytime hours when daylight could provide for some or all of the lighting requirements without any electricity use at all. Contemporary electric lighting design captures this electricity savings opportunity while improving visibility in the built environment.
Role of Professional Lighting Designer
A lighting designer brings knowledge and expertise of a quickly expanding array of available lighting equipment and technology. Because a designer neither sells nor installs lighting equipment, the design is based on an objective understanding of the project goals and budget. While electrical engineers can design a lighting system, that design is most likely based on electrical requirements and code standards but may lack the aesthetic sensitivities to the overall architectural design.
Art and Science
Lighting design requires a technical understanding of electricity, light sources, and vision while also a sensitivity to architectural and aesthetic issues. The end design needs to meet the visual requirements for human eyes performing an endless array of tasks while also illuminating the architectural forms and immediate environment.
Lighting designers understand that most building occupants do not necessarily want LEDs or wireless control—they want to comfortably see what they are doing. How to provide for this visibility summarizes the role of the lighting designer. How to provide this while enhancing the architecture, integrating with the available daylight, minimizing building energy use, and aligning with the overall construction process and budget summarizes the role of the lighting designer in a whole building design process.
Lighting in Whole Building Design
In the whole building design process, effective lighting design integrates with many other building systems and design disciplines.
Probably the largest impacts on electric lighting requirements and design come from the architectural orientation, massing, ceiling height, and section profiles that determine daylight availability in the building. Typically, south facing orientations, narrow floor plates, high ceilings, and open sections tend to bring more usable daylight into the building and correspondingly reduce the electric lighting use. Lighting designers should be brought onto the project team early in the design process so that they might have an impact on these early siting and massing decisions.
Lighting systems should illuminate the architectural forms and surfaces and needs to be well integrated. It may take the form of coves that uplight the ceiling or walls. Or it may be carefully selected luminaires that respond to the architectural elements or style.
Designers must understand the use of each space and the tasks that need to be lighted. The criteria for both quantity and quality of light depend on the type of task performed in each space and work area.
Interior design choices, such as surface finishes, can have a dramatic impact on the lighting system and how much light is required to make a space feel bright. Dark wood finishes require more light (and electricity) to brighten a space than light colored surfaces. The visual elements of lighting equipment must also coordinate with the interior design. Lighting designers need to work with interior designers so that both understand the impact of the other's design decisions.
Lighting designers have control over one of the largest energy consuming services in the building. As mentioned previously, visibility does not always increase with more light and more electricity. While much attention focuses on minimizing power density, total energy usage also depends on the total time that lighting is activated.
Lighting designers have the opportunity to not only reduce the electric energy use of lighting system, but in turn reduce the cooling load on the HVAC system. Coordination between the lighting and mechanical designers can capture this opportunity. Keeping plenum space low and avoiding conflicts between luminaires and ductwork also requires extensive coordination. Without this coordination, HVAC systems may be oversized and miss energy saving opportunities.
Lighting designers must understand how a lighting system might be incorporated into structural elements: coves, beams, and columns; as well as what structural components may become lighted surfaces.
Effective Design (Sustainability)
As part of a whole building design process, lighting designers develop an electric lighting solution that addresses:
Daylighting—the design should supplement the available daylight.
Task / Ambient / Accent systems—a lighting system that layers these components provides flexibility in its use and comfort.
Control of systems—with daylight, occupancy, vacancy, schedule, time, and user preference.
Efficient and effective luminaires—making the best use and distribution of the light source.
Efficacious light sources—designer should choose the most efficacious (lumens of light per watt of power) that still accomplishes the design goal for that source and luminaire.
Exterior Lighting—while enough light needs to be provided for nighttime visibility, too much can cause glare, adaptation problems, and light trespass.
Lighting designers must show how their design affects the project budget and provide a cost-effective solution. In retrofit projects, which frequently involve lighting changes, an economic analysis should compare the various new options with the cost of doing nothing. It should also evaluate the net present value of design options and consider:
- Initial material costs
- Energy costs
- Maintenance costs (lamp life, light source replacement, labor costs to replace, disruption costs during maintenance)
- Ease of maintenance
- User satisfaction
Many historic luminaires were not designed for energy efficiency or to meet the glare and performance standards of contemporary lighting equipment. When addressing these design challenges, the designer attempts to improve the performance and efficiency of these luminaires while maintaining the original aesthetic. This may mean adding internal shielding to the light source or a reflector that in improves the distribution of the light. Historic preservation may also limit how lighting can be integrated with the building architecture such as coves and facades.
Safety and Security
Lighting energy use is often increased (especially in exterior applications) as a response to safety and security requirements. A lighting design that minimizes glare, reduces shadowing, and provides appropriate contrast addresses safety and security far better than a simple increase in wattage and light output.
Building owners, developers, and municipalities increasingly place more emphasis on security lighting. Designers have not only the responsibility to provide adequate, low glare lighting but also avoid overlighting. This responsibility also extends to working with the rest of the design team to coordinate all aspects of security design.
User Productivity and Non-Energy Benefits
Lighting designers also recognize the non-energy benefits that a well-designed lighting system can bring to the building project. Studies have shown positive correlations between daylight, views, and control of electric lighting with improved productivity, higher student test scores, faster patient recovery time, and overall comfort. Characteristics of a poor lighting system can have significant impacts on building occupants including headaches and fatigue.
To achieve these non-energy benefits, designers need to consider daylight and views as well as electric lighting integration with daylight availability; personal lighting control as well as automatic lighting controls that save energy; proper commissioning of lighting controls as well as the specification of photocells and occupancy sensors.
Professional Lighting Design Certifications
Today, professional lighting designers are not required to be licensed, but two credentials designate a certain level of experience and knowledge.
International Association of Lighting Designers (IALD) membership requires a certain level of experience and completed projects. It also signifies that the independent designer abides by a code of conduct that maintains an objective design practice. For example, IALD designers cannot both provide design services and sell lighting equipment.
The National Council for the Qualification of Lighting Professionals (NCQLP) provides a Lighting Certified (LC) certification. This requires a tested level of technical lighting knowledge, three years of experience, and continuing education credentials to keep the certification.
Emerging Issues and Industry Advancements
Solid State Technology
Solid state lighting such as LED and organic LEDs (OLED) products are quickly coming to market with a wide range of capabilities, performance, and quality. Not only do lighting designers require a thorough understanding of these technologies, but must also must be able to pair multiple components and assure their compatibility. Because solid state lighting is a non-linear load, it influences the building electrical system power quality with increased total harmonic distortion, poor power factor, and repetitive peak currents. Solid state lighting equipment must be specified to minimize these effects. To dim LED sources properly and prevent flickering of the system, solid state sources need to be paired with dimmable drivers and controls that make up a compatible system.
Better Understanding of Human Vision (white light effectiveness)
As our understanding of human vision evolves, so does the approach to lighting design. Light spectrum plays a significant role in overall visibility. In addition, the spectral distribution of light sources also has an effect on circadian rhythms. White light effectiveness factors have been developed for use in design under low exterior light levels. Exterior lighting designs should incorporate these factors when designing for these low light conditions.
Relevant Codes and Standards
- ASHRAE/IESNA 90.1
- Energy Independence and Security Act of 2007
- IALD Quality of Light Brochure
- IALD Why Hire a Lighting Designer?
- IDA/IES Model Lighting Ordinance
- IES The Lighting Library
- IES LP-10 Lighting Practice: Sustainable Lighting – An Introduction to the Environmental Impacts of Lighting
- IES LP-1 Lighting Practice: Designing Quality Lighting for People and Buildings
- IANSI/IES RP-1 Recommended Practice: Lighting Offices Spaces
- IES LP-2 Lighting Practice: Designing Quality Lighting for People in Outdoor Environments
- IES LP-11 Lighting Practice: Environmental Considerations for Outdoor Lighting
- IES TM-12 Spectral Effects of Lighting on Visual Performance at Mesopic Lighting Levels
- IES TM-18 Light and Human Heath: An Overview of the Impact of Light on Visual, Circadian, Neuroendocrine and Neurobehavioral Responses
- UFC 3-530-01 Interior and Exterior Lighting Systems and Controls
- Energy Star Program
- Federal Energy Management Program (FEMP)
- General Services Administration (GSA)
- Illuminating Engineering Society of North America (IES)
- International Association of Lighting Designers (IALD)
- International Dark Sky Association (IDA)
- International Association of Energy Efficient Lighting
- National Institute of Building Sciences (NIBS)
- New Buildings Institute (NBI)
- US DOE Energy Efficiency and Renewable Energy (EERE)
- GSA Sustainable Facilities Tool (SFTool)—SFTool's immersive virtual environment addresses all your sustainability planning, designing and procurement needs.