Lighting by Layers

By James R. Benya, PE, FIES, FIALD

“As in architecture and interior design, the extent to which aesthetics in lighting matters varies from project to project. There is hardly any aesthetic concern, for example, in designing lighting for an ordinary office using inexpensive lay-in troffers. However, the type and location of every luminaire in a cathedral is critical in the appearance of the space itself, not just the lighting. Even though many real-world projects require simple (and often economical) lighting designs, it is still beneficial to tackle each with a common approach that permits an appropriate result.”

I wrote this with co-author Mark Karlen for the first edition of Lighting Design Basics.(1) The book was written as a classroom text mostly because, at the time, Mark was a professor in the interior design program at Moore College of Art and Design in Philadelphia. Our intent was to share a design approach that could help students and entry level architects, interior designers, electrical engineers, contractors and lighting designers to understand how to approach the problem better and allow them to achieve good results, even on everyday projects. The driving reason for the approach is to ensure, in the end, that the space will be well composed to reach both its functional and aesthetic intents.

The core philosophy is to differentiate between layers of lighting and techniques of lighting. A layer identifies a general use for light in a space, and includes the ambient layer, the task layer, the focal layer, and the decorative layer. Each layer plays a specific role in the visual composition of the space. In simple terms, while one layer may serve to light the common uses of a space, other layers may be needed to make the space more appealing, interesting, or functional. Once layers are identified and the overall concept reconciled, then for each layer a technique can be chosen. Dimmable lighting controls are used to balance the relationship among layers.

• The ambient layer choice establishes the character and atmosphere of an interior space. The amount of ambient light is important; if significantly lower than the task light, the space will have greater luminance contrasts and appear more dramatic, whereas if similar to the task light levels, the room will be brighter, cheerier and perhaps, more relaxing. The technique could be direct lighting, indirect lighting, or a combination of both. I prefer indirect lighting for work environments and direct lighting for more finished spaces like private offices, living and entertainment venues. Ambient lighting might include indirect lighting such as wallwashing, scalloping or grazing. Direct lighting is often as simple as downlighting, being careful to avoid scallops and glare. Direct/indirect lighting has served me well as a go-to solution in many instances as a “best of both worlds” for moderate cost projects.

• The task layer is usually the brightest and produces the light that enables the space to be used for its intended purpose. The luminance ratio of task to ambient light determines the general ambience of the space. In extreme conditions like retail stores and museums, very high luminance ratios are often used to raise the drama and importance of the displays, and task lighting employs monopoints and track. In everyday conditions, the luminance may be less pronounced, but still noticeably brighter than the ambient lighting. The technique in offices and workspaces is often a linear light source, such as undercabinet lighting, or portable task lights. Track lighting and other adjustable methods are, for obvious reasons, used in stores and museums.

A high luminance ratio is used to highlight the display.

Photo credit: Clark Street Mercantile

• The focal layer is like the task layer, but especially significant in that it uses brightness, spectrum, direction and shadow to make a specific visual emphasis, such as on a sculpture, painting or exceptional architectural feature. Adjustable lighting, such as recessed multiples or track lighting, are generally used. However, in certain project types, a sculptural chandelier or lamp might become a focal element.

A decorative chandelier serves as the lighting focal point.

Photo credit: Victor Huynh

• The decorative layer introduces lighting as ornament, such as pendant lights, portable lamps or sconces. In certain project types, there is a theme carried out by the decorative layer that is an important part of the interior architecture or interior design.

The first two editions of the book were before LEDs became practical. I have recently served as a judge in several lighting design awards programs, and in reviewing the entries, I asked myself what differences LEDs make in this theory of design. Certainly, there must be something LEDs accomplish that was not practical or even possible with older sources. I concluded that linear lighting effects, exposed lighting effects and outlining, which were generally either imperfect, expensive, and/or unmaintainable with legacy lighting, stood out as a family of techniques that were indeed new.

In his book Perception and Lighting as Formgivers for Architecture (2), the late William M.C. Lam (3), one of the most prominent early architectural lighting designers, provides basic theoretical information on environmental objectives and the process of visual perception and human needs as they relate to lighting design. Bill passed away in 2012 before LED lighting could fully take over. Now that it has, in his remembrance I would like to add another layer to my system: the formgiver layer. The techniques involve all manner of shape and form accentuation, both exposed and in coves or niches.

Next, I reflected on daylighting designs that I had created on several projects. In at least four cases in recent years, I was able to work with architects to create significantly daylit buildings – buildings in which electric lights were generally not needed most of the time, especially schools. Daylight design requires the lighting designer to become involved in the early stages of the project, as the key to success is a combination of solar orientation, building shape and massing, floor plan, fenestration, ceiling design, energy management, interior surface finishes and glare control. Daylighting is not only key to energy efficiency, but also prominent in occupant well-being and an important asset in both the LEED and WELL programs. I probably should have discussed daylighting more in the book, but I guess I needed to learn a lot more and enjoy some measurable success before promoting the daylighting layer.

Daylight is becoming a popular source of light, given an increased focus on energy efficiency and occupant well-being.

Photo credit: Chastity Cortijo

Finally, I considered the dimension of time. When the first edition was published, the science behind human circadian lighting considerations was just being discovered. Now, almost two decades later, with the encouragement of programs like WELL and the many other special considerations for light and living beings, the integration of lighting effects, intensities and spectrum are now part of the professional practice of lighting design. Not only does this affect choices of daylighting, luminaires and all other aspects of the light sources, it also affects their controls and makes lighting controls far more important than switching and dimming. I’d like to call this new layer the controls layer as it may not always be tuned to a circadian purpose, but even its everyday capabilities need to be a fundamental part of the design solution.

I believe that the layer system serves at least three important purposes. To the student, it provides a foundation to understand lighting standards, methods and techniques and how to apply them. To the new professional, it is derived from a normal intuitive approach to lighting and serves as a reminder of the alternatives without unnecessarily prejudicing choices. And to the experienced professional, it serves as a reminder of the alternative approaches to a problem, perhaps even as a nudge to make sure every practical alternative has been considered.

Mark Karlen, PhD, Architect, Professor, Author

In memory and gratitude to my Lighting Design Basics co-author, Mark Karlen (1930-2022). ■

1. Mark Karlen and James Benya, Lighting Design Basics, Wiley 2004. A free download is available from https://epdf.pub/lighting-design-basics.html . Chapters 8 and 9 are the basis of this article. Christina Spangler joined as co-author for a second edition in 2012 and a third edition in 2017 and under her leadership the layer pedagogy was moved to Chapter 2.

2. McGraw-Hill, 1977

3. https://wmclam.com/ (1924-2012) A pioneer and intellectual powerhouse, Bill often walked the line among modernist architect, lighting product manufacturer and lighting designer. His lighting design legacy continues with the firm Lam Partners with offices in Cambridge, Pittsburgh and Washington, D.C.