Profiles in design: Lighting designer Toby Lewis

Starchitects aside, we hear little about the individuals whose cumulative decisions shape the built environment. To peer behind the curtain of today’s design field, we’re asking engineers, architects, policymakers, and others about their personal experiences and opinions.

Toby Lewis, a senior lighting designer in Arup’s San Francisco office, spoke with us about art, circadian rhythm, and Edison bulbs.


Why did you decide to become a lighting designer?

I probably started in that direction back in elementary school. I wanted to take as many art classes as I could, and when I started saying, “Oh, maybe I want to be an artist,” my parents might have subtly signed me up for fewer art classes. I don’t remember it ever being a point of contention, though. At the same time I started to excel in math and science, and got interested in engineering.

For college I picked the University of Colorado Boulder based on the engineering program. In your first year you’re required to take a sampling of different disciplines, and the class I loved the most was Intro to Lighting Design. It really represented the best of both worlds for me — it builds on the math and science of hard engineering but also draws on psychology, perception, and art.

I deviated from lighting when I became the construction manager of UC Boulder’s entry in the 2007 Solar Decathlon.

Toby Lewis in construction hat

That led to helping two professors launch a company building solar homes in the Middle East, so I went and lived in Israel for a couple years. That experience was incredibly valuable. Understanding how buildings go together is something most lighting designers need to learn through project work, so I was really fortunate to gain this experience while running a construction crew for two years.

Toby Lewis in Israel

What do you do on a day-to-day basis now? What does it mean to be a lighting designer?

It means juggling a lot of different tasks all day long, with many projects in different phases of design and construction. Because lighting is a relatively small discipline compared to, say, structural or mechanical engineering, our fees are smaller and our timeline of involvement on a project is shorter. We have to be able to jump between conceptual design, where we generate the big ideas, to design development — building computer models, conducting research, creating physical mock-ups, et cetera — to construction documentation and construction administration. On a given day I might do all of these things — sometimes while standing on a ladder during a site visit.

The work involves a lot of computer-oriented tasks, but also a lot of interfacing with architects, owners, and builders to come up with the right approach and make sure the design is executed as intended.

Light fixture

Toby’s design for a custom light fixture in Israel

How does innovation apply to lighting design?

Well, the great thing about lighting design is that each project requires fresh eyes, because the architecture and end user needs are different each time.

But the actual innovation comes from identifying and applying new technologies. Like, LEDs have been on the market for a long time, but it’s only in the last three to five years that we’re seeing commercially available products catering to the field of human health and circadian rhythm.

What does that mean?

So, research coming out of universities like Rensselaer Polytechnic and Thomas Jefferson over the last 15 years has really advanced our understanding of how human biology has adapted to the sun. It’s very exciting to think that designers could apply information about how light affects the brain to improve people’s quality of life. The studies suggest that commercially available technology could make a difference for issues like productivity, quality of sleep, patient recovery time, dyslexia, and dementia.

Lighting designers aren’t physicians, of course, and there’s still a lot the medical field doesn’t know about how light affects human health. But people have been experimenting with electric light sources in our built environment for a long time. There’s never been an exhaustive study into whether using electric lights after sundown is actually good for people, for example. So the kind of experimentation we’re seeing now doesn’t seem overly reckless.

Illustration of 1878 demonstration of electric light

1878 demonstration of new electric light technology (alternated with gas light for comparison) in London

But yeah, our team is very proactive about keeping a finger on the pulse of current research in general. We’ve partnered with institutions like Lawrence Berkeley National Laboratory to test new technologies.

How rapidly does lighting technology evolve?

It’s changing all the time, especially with LEDs. They’re evolving almost as fast as computer chips, because an LED is a computer chip, basically. We now have the ability to integrate all sorts of sensors for reporting and recording data onto LED chips, although this hasn’t really been applied widely in buildings just yet.

Do these products reach the professional market way before the consumer market? How many more options do you have compared to what’s at Home Depot?

Way more. Lighting designers spend a lot of time meeting with manufacturers to learn about the new technologies and products coming onto the market. Staying on the cutting edge of what’s commercially available is a constant reeducation process.

Staying on the cutting edge of what’s commercially available is a constant reeducation process.

Arup likes to push the envelope of commercial availability. This happens across disciplines, of course, but our lighting group was designing around circadian lighting before, well… there still aren’t standard approaches to the implementation of this technology, but we started designing with dynamic white sources five years ago in patient rooms on the Kaiser San Diego hospital project. And back in 2007 our London lighting team altered the color temperature of fluorescent lamps in their workspace over the course of about a year, documenting the subjective effects on the team throughout. We’ve also partnered with manufacturers like iGuzzini to develop products around specific needs.

I should clarify: lamp is the technical term for light bulb. As one of my college professors, David DiLaura, always told us, a bulb is what gets planted in the ground!

Do most new lighting technologies eventually trickle down, or is there a lot that just stays in the professional realm?

Well, like many things, it comes down to cost. Right now your basic LED retrofit lamp with an Edison screw base from Home Depot can cost nearly 10 times more than an incandescent lamp, but you can’t compare just the initial cost: an LED could last you 50 years and cost one-tenth in operating costs. The trickle-down effect happens, but there’s also a real need to educate the end user in order for these technologies to be adopted.

Some other technical factors also come into play. The public really needs a basic understanding of issues like color temperature, color rendering, and efficacy — light output per energy consumed — to make educated decisions.

A great example is the consumer backlash when the compact fluorescent lamp [CFL] was introduced to the market in the ’80s. The cheapest CFLs emitted really poor light quality; people looked unhealthy under them. This had to do with color rendering. To get into the weeds for a second, every light source emits wavelengths in the spectrum of visible light, but daylight emits wavelengths across every single nanometer of the visual spectrum. We use a metric called the color rendering index, or CRI, to quantify this. Daylight has a CRI of 100, and all other light sources are measured against that.

Now there’s a new metric for describing color rendering called TM-30 that’s more complex and more accurate. It will overtake CRI in no time.

Anyway, CFLs are capable of rendering colors almost as well as your typical incandescent lamp, but in the ’80s the industry hadn’t set any standards. Some manufacturers were just churning out lamps as cheaply as possible, and those models had particularly low CRIs. It was possible for consumers to pay way more and get a CFL with a high CRI, but a lot of people who were disappointed the first time just didn’t bother trying again.

The industry has learned from this, luckily. The standards have been set high for consumer LED products — the CRI has to be 90 or above.

A question on the consumer front. Edison bulbs are everywhere! They look great, but they’ve become sort of a clichéd signifier for a certain kind of lifestyle in the past few years. Why do you think this is?

Well, from a technical perspective, what we think of as an Edison bulb today is just a twist on the standard incandescent lamp — which Edison, building on the foundational work of so many others, invented — with extra filaments for looks. One reason that we’re stuck on incandescent lamps in general as a culture is because their color rendering capability is almost as good as daylight.

Edison bulbs

Color temperature comes into play as well. We all intuitively notice the color temperature based on how warm or cool the light source appears — whether it seems red or blue, in other words — and incandescent light is quite warm and relaxing.

And with the Edison bulb style, the clear lamp shows the filament, which is a visually appealing feature.

But some people are replacing this style of lamp with LEDs made to appear as though they have a filament. These are sold with a warm color temperature and they look attractive. I guarantee most people wouldn’t notice the difference.

So hopefully hipster taste will evolve.


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