Category: Lighting Design

UL’s Adam Lilien Talks The New UL Design Guideline for Circadian Lighting

In December 2019, UL published Design Guide 24480, which provides guidance on how to design lighting systems that support circadian entrainment. To learn more, I talked to Adam Lilien, Global Business Development Manager, Lighting, UL, LLC. The resulting interview informed an article I wrote for the May issue of ELECTRICAL CONTRACTOR.

In December 2019, UL published Design Guide 24480, which provides guidance on how to design lighting systems that support circadian entrainment. To learn more, I talked to Adam Lilien, Global Business Development Manager, Lighting, UL, LLC. The resulting interview informed an article I wrote for the May issue of ELECTRICAL CONTRACTOR.

DiLouie: Please describe the new UL Design Guideline 24480: What is it? Who was involved in its development? What was the process of development? When was it published?

Lilien: The title of the document is: Underwriters Laboratories Inc. 24480 Design Guideline for Promoting Circadian Entrainment with Light for Day-Active People. I’ll refer to it in this interview as DG 24480. It was published in December of 2019. Underwriters Laboratories, Inc. is the not-for-profit entity. UL, LLC. Is the for-profit entity. As an employee of UL, LLC, with industry experience as a lighting manufacturer, lighting designer, and manager of electrical contractors, I served on the Task Force.

DG 24480 is a science-based design guideline, intended for use by those who design and specify lighting in buildings and wish to provide light for vision and for non-visual circadian entrainment for typical day-active and night-inactive people. As we have specified indoor lighting for vision for over 100 years, designing for health and wellbeing is a new practice that will take some getting used to. This document is a start. It intersects with Well Building Institute lighting guidelines, and as organizations such as IES and CIE prepare to publish their viewpoint on circadian lighting, this document will become one of the important tools for the industry.

In the end, DG 24480 is important as it introduces design guidelines based on the Circadian Stimulus (CS) method for lighting specifiers, manufacturers, electrical contractors and building owners to understand.

Underwriters Laboratories formed a task force, Chaired by Mark Rea, Ph.D, of the Lighting Research Center. Mark is a Professor of Architecture and Cognitive Sciences at the Lighting Research Center (LRC), and served as LRC Director from 1988 to 2017. Dr. Rea is well known for his research in circadian photobiology, mesopic vision, psychological responses to light, lighting engineering, and visual performance. He is the author of more than 250 scientific and technical articles related to vision, lighting engineering, and human factors and was the editor-in-chief of the 8th and 9th editions of the Illuminating Engineering Society (IES) Lighting Handbook. He has been elected Fellow of the Society of Light and Lighting (UK) and Fellow of the IES. In addition, he is recipient of the IES Medal.

The makeup of the Industry Task Force developing the Design Guidelines relied on a cross section of expertise from SSL industry, academia, medicine, the US government, the military and more. Diverse industry participation and feedback enabled the Task Force to produce an industry-leading document that lighting designers can use as an option in their design work. Underwriters Laboratories managed the Task Force procedures, including two Public Comment processes where lighting design professionals, facility owners, lighting manufacturers, sleep scientists, academia, scientists and other industry stakeholders from around the world provided constructive input.

While this is an evolving field, it should be emphasized that the recommendations in this document have been tested in field studies, and those studies have demonstrated that light that promotes entrainment will lead to better sleep, mood and behavior.

As a design guideline, now lighting designers and building owners and operators can pursue healthier spaces through lighting. Healthier spaces attract businesses to properties, and employees to businesses. This is due to the common understanding that spaces that are healthier are good: good for our wellbeing; good for our communities; good for business.

Perhaps a note, as this is a document published by Underwriters Laboratories. This is an optional design guideline… optional in that it’s not a UL Safety Standard. UL Safety Standards often become requirements when adopted by municipalities or states.

DiLouie: What was the general rationale for UL’s interest? Did UL do any market analysis indicating current or future adoption? Did UL see a problem that needed to be solved?

Lilien: The rationale for our involvement in this design guideline was directly related to our mission of working for a safer world.

UL employs exacting scientific processes and the highest ethical principles to help accomplish this. As technology challenges and concerns expand to include sustainability, well-being, connected technologies and security, we provide broad leadership, deep expertise and vital services to guide these transformations. Fueled by our mission of working for a safer world, we are trusted partners in solving our customers’ and stakeholders’ most critical challenges. We believe that when choices are empowered by insight and opportunity, the potential to realize responsible innovation and better living is endless. To fulfill our mission, UL delivers business solutions and our nonprofit conducts independent research and shares scientific knowledge broadly.

The opportunity here was to advance the market place’s understanding of the non-visual effects of illumination, and its impact on human circadian systems. UL does not see this document as an “end goal”; rather, we see this as a critical starting point where achieving the design goals will predictably improve building occupants health an wellbeing.

Over time, as other organization publish their positions on the science and the practice of circadian-effective lighting, the field will evolve based on deeper learning from case studies.

DiLouie: What does UL hope will be achieved with this publication?

Lilien: Through this deeper understanding of these design guidelines and the science behind them, we know that several stakeholders will see opportunities:

• Property owners will see healthier indoor spaces as an opportunity to distinguish their properties, increase property values and provide a meaningful improvement to building occupants’ lives;
• Lighting specifiers will see an opportunity to have a deeper impact on the ultimate users of the spaces that they design, and will have an opportunity to advance their careers in meaningful ways;
• Electrical contractors will see an opportunity for deeper partnerships with lighting specifiers and building owners to ensure that the designs are implemented properly, while growing their business
• Building occupants will see greater alertness, less reliance on stimulants, better sleep quality, and the resulting improvements in health.

DiLouie: Why did UL publish this guideline rather than wait for the Illuminating Engineering Society to produce an ANSI publication?

Lilien: Through the process of UL’s task force developing these design guidelines, our collaborative discussions with IES, CIE and WELL Building institute have deepened.

Through those discussions, we understand that the goals that we defined —to explore an optional design guideline that delivers benefits that are backed by scientific studies — employ a different approach and methodology. For example, IES has stated that they committed to an ANSI-based process. UL’s Design Guideline is not based on American National Standard Institute’s requirements. Multiple approaches are beneficial, and the industry should look forward to the upcoming options that other organizations provide.

While not all organizations agree, it is difficult to argue that creating a baseline for delivering more light during the day, and less light at night, is too early given the current understanding of the science.

UL looks forward to the work that associations, institutes, commercial entities and non-profit organizations can do collaboratively to advance the understanding of science-based illumination, especially as it related to human centric lighting and its impact on health and wellbeing.

DiLouie: The WELL Building Standard uses a different metric and possibly a different resulting design objective. How should designers reconcile the UL guidance with WELL?

Lilien: We believe that WELL Building Standard and UL’s resulting design approach — more light during the day and less light at night — are very consistent.

According to WELL, “WELL is a performance-based system for measuring, certifying, and monitoring features of the built environment that impact human health and well-being, through air, water, nourishment, light, fitness, comfort and mind.” Their website further states: “Light: Minimize disruption to the body’s circadian rhythm. Requirements for window performance and design, light output and lighting controls, and task-appropriate illumination levels are included to improve energy, mood and productivity.”

DG 24480 Design Guideline focuses specifically on promoting circadian entrainment with light for day-active people.

One difference is the method. By focusing on the Circadian Stimulus (CS) method, UL was able to define six specific steps to achieve the resulting design objective. These appear in the Design Guideline as a two-page “Quick Guide”.

As found on the WELL website: “WELL uses EML as a metric to evaluate the circadian impact of both natural and artificial light. Equivalent Melanopic Lux (EML) is a measurement of the effect of light on the human circadian rhythm. It is similar in concept to the more widely-used Circadian Stimulus metric, but computed in a different manner.”

DiLouie: In a nutshell, what does UL DG 24480 encourage as a guideline for designing circadian-friendly lighting systems?

Lilien: The process, perhaps oversimplified here but well thought out in the DG 24480 Design Guideline, has six steps:

1: Select a circadian-effective lighting design goal. Deliver a Circadian Stimulus of 0.3 (the rationale is found in the Design Guideline)
2. Select a luminaire type with the desired horizontal distribution. A higher vertical to horizontal ratio delivers a higher CS result
3. Select a light source Spectral Power Distribution (SPD). The amount of illumination across the spectrum of visible light in considered here
4. Perform CAD software measures of the light delivered in the plane of the occupant’s eyes
5. Calculate Circadian Stimulus (CS) using the calculator
6. Ensure that the CS is equal or greater than 0.3. If not, consider other luminaires or more local lighting near the work station

These rationale for these six steps are best understood after reading DG 24480, which is comprised of over 50 pages of worked examples, research overviews, and calculation procedures.

DiLouie: What are typical design approaches and equipment used to achieve DG 24480, and how do they different from typical current approaches?

Lilien: The approach requires the industry to not only consider the visual effect of lighting (the horizontal measure of illumination at the task level, such as a desk), but to newly consider the vertical illumination delivered to the eye.

As mentioned here, designing with knowledge of the vertical to horizontal ratio, SPD, and the resulting Circadian Stimulus are all new to this approach.

The use of a spectroradiometer capable of measuring SPD in the field is suggested here, which is also new to the lighting specifier.

The use of CAD software is a common tool for the lighting specifier.

The new practice that we have to get used to is that more lighting is required during the day, and less lighting during the night. Where a space is measured and falls short of the desired goal of 0.3 CS, the lighting designer would consider modifications to the existing system, and possibly adding layers of light. The DG 24480 Design Guideline provides direction and the scientific rationale throughout the document.

DiLouie: What are the market drivers for circadian-supportive lighting, and when is the market going to shift to these new practices?

Lilien: We already see the shift taking place.

Speaking with Gayathri Unnikrishnan, Director, Standard Development at WELL Building Institute, over 800 WELL Building projects are underway.

Since a lot of the circadian research has been conducted in healthcare facilities, we are seeing movement in healthcare spaces first.

Attending events like LightFair, it’s amazing to see how many lighting manufacturers are addressing circadian-effective solutions, or “human-centric lighting” as some call it.

We see lighting designers learning the principles of DG 24480.

We see building owners and operators seeking ways to distinguish their properties competitively wanting to learn more, and ready to consider a test.

Building owners will look for the ROI to justify the expense. As case studies are published, and the costs to implement are positively compared to the results, adoption will follow.

DiLouie: Circadian lighting may involve higher light levels than may be possible with today’s strictest energy codes. What can designers do?

Lilien: With DG 24480 Design Guideline, designers can now do a lot.

Addressing this question is rather complex, as one needs to be aware of the nature of building energy codes, how they are formed, how they are adopted, and how they are updated.

My comments here are focused on the energy codes in the 2018 IECC Commercial Electrical Power and Lighting Systems. The section of the codes your question refers to is: Interior Lighting Power Allowances, measured in watts/ft2.

Today, the lighting power allowances make no specific accommodation for projects addressing circadian-effective lighting in, for example, office buildings.

In the meantime, let’s look at the current requirements for energy conservation, as well as how exceptions to these requirements have been handled.

For office spaces, the Lighting Power Density ranges from .93 to .81 w/ft2 for enclosed and open floor plans, respectively. While my observations are over simplified, where a fluorescent space in the past might use 1.2 w/ft2 an upgrade to LED would typically reduce this 50%, to .6 w/ft2. Occupancy sensors or advanced controls would reduce this even further, say by 33% to .4 w/ft2.

Following this mathematical logic, a circadian lighting design that employs an energy-conservative approach has some room to fall within the current energy requirements.

What’s unique about DG 24480 Design Guideline is that it informs the lighting specifier how they would address solving for circadian entrainment with both a fixed, as well as a dynamic lighting system. Fixed is, for example, fluorescent lighting on a light switch. Dynamic includes color-shifting (typically 2700K to 6500K) luminaires or lamps that could be on IoT controlled systems.

In both cases, the document points out that solving for circadian entrainment using color-shifting luminaires on IoT controls is more efficient.

Regarding today’s strict energy codes not addressing circadian effective projects, my personal opinion is that this is likely to change soon. Why? With documents like DG 24480, the committees considering updates to the energy codes can now include the research approach, the findings, and the design guidelines as a factor in upcoming updates.

Just one way that this might be accomplished in the short term is for an exception allowance, like today’s code requirements make for the following project types:

• Retail spaces
• Lighting for occupants with special needs (visual impairment and other medical and age-related issues)
• Casino gaming areas
• Task lighting for medical and dental purposes
• Display lighting for exhibits in galleries, museums and monuments
• Plant growth or maintenance
• Approved because of safety considerations

Perhaps we can anticipate an addition such as: Lighting that addresses Circadian Entrainment

DiLouie: What’s in it for electrical contractors? Why should they care? Why should they get behind this?

Lilien: This is a great question.

Building owners and operators rely on their internal expertise as well as trusted partners when considering if a technology advancement is “ready” or “just a trend”.

While Return On Investment is critical to the building owner, if the service providers are not convinced that they can deliver the result, the decision maker is not going to move forward.

For new buildings, designing for circadian effectiveness will likely be adopted quickly.

For existing spaces, it’s more challenging.

While lighting designers need to take the lead and be able to ensure a prospect that their current space can be modified successfully, electrical contractors who learn about circadian-effective projects will add a level of certainty to the decision-making process.

For these firms, establishing a circadian lighting book-of-business for both new construction and retrofits will move them to the top of the list, as this reduces the uncertainty of the project costs related to delays and re-work.

DiLouie: Is there anything else that contractors should do or know concerning DG 24480?

Lilien: Other organizations have chosen to pursue an ANSI-based process for publishing new lighting standards related to health and wellbeing.

With over a century of experience in the development of more than 1,500 Standards, UL is an accredited standards developer in the US and Canada.

When the situation calls for it, Underwriters Laboratories (the not-for-profit) also publishes documents such as Outlines of Investigation (OOI), Technical Guidance Documents (TGD), Recommended Practices (RP) and Design Guidelines (DG).

DiLouie: If you could tell all electrical contractors just one thing about circadian-supportive lighting and DG 24880, what would it be?

Lilien: As a lighting industry, we have provided illumination for vision for over 100 years. Over the past several decades, we have come to know that we are under-illuminating our indoor spaces during the day, and over-illuminating them at night.

While there is certainly more for us to understand, science-based studies concur that new lighting design practices can improve human health and wellbeing today.

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The Lighting Practice’s Evan Wilson Talks Photometrics

Because it’s impractical to mock up every design element in a project, lighting designers often rely on photometric reports and computer-generated renderings to predict the distribution and effects of light after lighting is installed. In this LinkedIn article, The Lighting Practice’s Evan Wilson explains what’s involved.

Because it’s impractical to mock up every design element in a project, lighting designers often rely on photometric reports and computer-generated renderings to predict the distribution and effects of light after lighting is installed. The Lighting Practice’s Evan Wilson explains what’s involved in a recent LinkedIn article.

He writes:

Lighting professionals study photometrics for the same reason a meteorologist studies the weather or an economist studies statistics, we want to deliver the most accurate information to our clients. In a perfect world, we would be able to determine precisely what every light fixture will do in a space before it is specified, purchased and installed. While a mock-up or a pilot install can provide insight, it is impossible and impractical to mock up every single design element on any given job. Instead, we turn to photometric models, or calculations, to understand what we are recommending to our clients. Like a weather professional or economist uses each of their respective models to make a prediction, photometric calculations can be used to make an educated guess as to how light will perform in a space.

Click here to check it out.

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Stantec’s Sarah Dreger on How Lighting Designers Can Master Digital Technology

LD+A recently published an informative piece by Sarah Dreger, the global leader of Digital Practice for Stantec’s Buildings practice, about how lighting designers can efficiently stay up to date on current digital technology, from software and apps to VR and AR.

LD+A recently published an informative piece by Sarah Dreger, the global leader of Digital Practice for Stantec’s Buildings practice, about how lighting designers can efficiently stay up to date on current digital technology, from software and apps to VR and AR.

She writes:

While there is no “silver bullet,” I’ve found a few solutions over the years that are worth a look and, best of all, they’re scalable—accessible regardless of tech-savvy or firm size. I’m not in software sales nor am I particularly vendor loyal; I’m a practitioner with over a decade of experience that has and does face the same day-to-day challenges you do, so perhaps you can benefit from my experience and have an easier go of it.

One of our industry’s biggest inefficiencies, risks and potential opportunities is in our ability to actively manage and leverage data. There are four key categories within a design “tool kit” and each firm, regardless of size, should have some combination of these solutions to accommodate and anticipate client and market demand. What follows is an overview of the four categories as well as ideas for how to leverage each to elevate your lighting design practice.

Click here to check it out.

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Lighting Maintenance Checklist

The Northwest Energy Efficiency Alliance recently published an infographic describing lighting maintenance best practices, which can help maintain the integrity of a new lighting design over the long term.

The Northwest Energy Efficiency Alliance recently published an infographic describing lighting maintenance best practices, which can help maintain the integrity of a new lighting design over the long term.

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Focal Point’s Mark D’Ambrosio on the WELL Building Standard

I recently had the opportunity to interview Mark D’Ambrosio, Senior Project Engineer – New Technology Strategy, Focal Point on the topic of how lighting fits into the WELL Building Standard. The interview informed an article I wrote for tED Magazine’s September 2019 issue. Here’s the transcript.

I recently had the opportunity to interview Mark D’Ambrosio, Senior Project Engineer – New Technology Strategy, Focal Point on the topic of how lighting fits into the WELL Building Standard. The interview informed an article I wrote for tED Magazine’s September 2019 issue. Below is the transcript.

DiLouie: What is the WELL Building Standard and how would you describe lighting’s role in it?

D’Ambrosio: The WELL Building Standard™ (WELL) was created using scientific and medical research and articles on behavioral and health factors that suggest a correlation between productivity and health benefits as they relate to building design, construction, and management. It is the premier standard for buildings, interior spaces and communities seeking to implement, validate and measure features that support and advance human health and wellness.

Now more than ever, designers are diving deeper into how they can create environments that maximize occupants’ comfort by addressing elements such lighting in commercial spaces. WELL provides guidelines that help promote visual, mental and biological health grouped under Features. The Features address key areas of lighting: circadian lighting design, visual lighting design, glare control, color quality, daylighting, automated shade and dimming control and more, that contribute to enhancing productivity, support quality sleep and deliver visual comfort.

DiLouie: Where is WELL being adopted now? How much traction is it getting?

D’Ambrosio: According to the International WELL Building Institute, 1541 WELL projects (153 certified projects and 1388 registered projects) with 311 million square feet in 48 countries have been completed. It has become the premier standard for buildings, interior spaces, and communities seeking to implement, validate and measure features that support and advance human health and wellness.

Currently, two versions of WELL are available for buildings seeking certification, WELL v1 and WELL v2 which is in pilot phase.

As a manufacturer of architectural lighting solutions, we continue to receive inquiries from designers about how our lighting and acoustical solutions support the WELL Building Standard™ even if the building is not applying for a WELL certification or registration. Specifiers are designing toward the standard, seeking products that help support the creation of more human-centric environments.

DiLouie: Does WELL follow lighting design practices, extend them, or contradict them?

D’Ambrosio: WELL is the next generation of design objectives for future-proofing buildings. The WELL standard references requirements for lighting design, while also extending beyond luminous thresholds. WELL is putting a greater emphasis on the people who inhabit the spaces and the future of the environment.

DiLouie: How practical or simple is it to implement WELL’s lighting provisions?

D’Ambrosio: WELL v2 is more practical and attainable than WELL v1. Its new parameters provide various methods to achieve a Feature while still supporting and advancing human health through better buildings.

DiLouie: How well does WELL work with LEED, which might be described as a cousin of the standard?

D’Ambrosio: LEED and WELL work alongside one another to ensure that buildings and communities preserve energy and resources and promote initiatives that enhance the human experience in spaces that are better for the inhabitants, and for the planet. LEED focuses on sustainability by addressing energy management and materials among others, while WELL encourages a human-centric approach to the built environment. Both standards are striving to enhance human health, well-being, and performance.

Both standards address four key elements of lighting: daylight, glare, controls, and light quality. However, the approach to addressing each of these elements is different. WELL emphasizes circadian rhythm as it relates to daylight while LEED uses daylight as a method for energy conservation. According to both standards, solar and electrical glare should be managed. WELL has more stringent standards around controllability while they both place great value on light quality.

DiLouie: How well does WELL work with prevailing commercial building energy codes and standards such as 90.1, IECC, and Title 24?

D’Ambrosio: IECC, Title 24, and ASHRAE 90.1 all focus on energy efficiency. IECC and ASHRAE are now harmonized, concentrating on overall building energy consumption and the fundamental impact on people’s lives to further address the economic well-being of the nation. IECC focuses on lighting power density (LPD) of the overall space using control and dimming systems.

While Title 24 does have some environmental “well-being” type requirements, its primary goal as with IECC/ASHRAE is energy consumption reduction and efficiency. Title 24 also addresses flicker. Although WELL does not address energy efficiencies in terms of limits or thresholds, there are complimentary sections, in particular in WELL V2, Light, Feature 05 enhancing daylight which would reduce energy consumption via daylight harvesting.

Also, if a space were to undertake the Innovation Feature 105 section of WELL, and pursued the ILFI Zero Energy Certification (which is approved by WELL), most if not all energy codes could be met as ILFI Zero Energy entails 100% of the buildings energy needs are renewable.

DiLouie: Some lighting designers have stated WELL addresses and promotes quality lighting. What is your take?

D’Ambrosio: The point of WELL is to address quality of building elements to enable human comfort and well-being. Feature L07 of WELL v2 explicitly addresses electric light quality. The feature contains two parts: Part 1 ensures color rendering and color quality and Part 2 focuses on managing flicker. More importantly, WELL states that light sources with features similar to daylight can improve comfort and well-being of users within a space, creating a healthier environment. The metrics specified as minimum requirements under Part 1 align with recent independent studies that have converged to identify a light spectrum preferred by humans.

DiLouie: What are disadvantages or shortcomings of the lighting provisions in the current version of WELL?

D’Ambrosio: From WELL v1 to WELL v2, there were many changes. However, even the latest version still fails to address the outdated metrics used in assessing glare.

DiLouie: What approach should a distributor take with a client that is adopting WELL but is reluctant to implement the lighting provisions? What provisions in WELL are the easiest and which are the hardest? Which are most influenced by design and which by product?

D’Ambrosio: A distributor should begin by addressing the impact of a WELL certified environment – a positive outcome on one’s health and well-being through design. There should be emphasis placed not only on the benefits for the users of the space but also that of the owner of the facility. Studies have shown employees who feel more comfortable achieve improved productivity, engagement, and retention, reduced absenteeism, and ultimately cost savings.

WELL v1 is comprised of seven Concepts: air, water, nourishment, light, fitness, comfort, and mind. WELL v2 has expanded to include ten Concepts: air, water, nourishment, light, movement, thermal comfort, sound, materials, mind, and community. As it relates to lighting, WELL v2 contains eight Features covering daylight, glare, control and light quality. Features L03 – Circadian Lighting Design, L06 – Visual Balance, and Feature 07 – Electric Light Quality, are driven by product design. Feature L07 Part 1 is the simplest to achieve, with its straightforward metrics (using CRI and IES TM-30-18) and thresholds which define an acceptable color rendering quality. To meet the requirements, one must simply select a luminaire that meets the provision.

Feature L04 is requires more than selecting a luminaire that meets required light levels. Since glare is influenced by design it is difficult to assess at a luminaire level. Influenced mainly by design, there are many variables within a space that could factor into measuring glare (i.e. location where a person is sitting or standing).

DiLouie: If you could tell the entire electrical industry just one thing about the lighting provisions in the WELL Building Standard, what would it be?

D’Ambrosio: Designers are finding new ways to enhance spaces and create environments that maximize occupants’ comfort. Now is the time to familiarize yourself with the standards that help to deliver more human-centric environments. These standards may appear overwhelming at first, but their benefits will be felt from organizations, building owners, and users alike. WELL allows designers to make small adjustments to obtain a large impact in a space.

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Survey: Majority of Europeans Want Better Workplace Lighting

Results from a pan-European survey reveal that current lighting in the workplace is not satisfying end-users and their needs, while at the same time it is regarded as an influence on productivity and human well being.

Results from a pan-European survey reveal that current lighting in the workplace is not satisfying end-users and their needs, while at the same time it is regarded as an influence on productivity and human well being.

The survey, conducted as part of the Repro-light project, engaged with 1,100 workers across Germany, Spain, Italy and Austria. Participants were asked to consider their working environment’s lighting and what changes they would like to see that could improve their productivity, mood, and performance.

56% of end users said they would like the better work place lighting. Occupants would like to control their own light levels and for the lighting to automatically change color when it becomes dark outside.

Click here to learn more.

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Focal Point’s Matthew Blakeley on Quantifying Lighting Quality (Part 2)

This is the second of a two-part article addressing advances in light sources and light quality, authored by Matthew Blakeley, Vice President – Product and Business Development for Focal Point as an exclusive contribution to LightNOW. This article highlights recent research, which provides a baseline definition of a quality light source that’s preferred by humans, independent of cultural background and familiarity with the habitual built environment.

This is the second of a two-part article addressing advances in light sources and light quality, authored by Matthew Blakeley, Vice President – Product and Business Development for Focal Point as an exclusive contribution to LightNOW. This article focuses on the evolution of light sources and measurement tools that can accurately describe the quality of the color rendition in a space. This second article highlights recent research, which provides a baseline definition of a quality light source that’s preferred by humans, independent of cultural background and familiarity with the habitual built environment.

Click here to read Part 1

Several recent research studies, conducted by Pacific Northwest National Laboratories (PNNL) and Penn State University (PSU) in the United States, as well as Zhejiang University in China, come to similar conclusions when attempting to define a light quality that is preferred by humans.

Interestingly, the fidelity of the light source to a blackbody radiator, as would be measured by CRI – the Color Rendering Index – was not found to be the key determining factor when assessing the pleasance of a light source to the human eye. Rather, saturation, especially in the red spectrum, was a key attribute that was universally preferred in North America as well as in Asia.

Published in 2016, the first PNNL study showed participants various light scenes, all at 3500K. Participants entered a room filled with common items such as fruits, clothing, and consumables and outfitted with a mirror so that changes in skin tones could be observed. Similar to an eye doctor test, they were exposed to various spectral power distributions and asked to rate each scene, which varied from low to high fidelity and from undersaturated to oversaturated.

When the research team ran the results against statistical models a very interesting trend emerged. Rather than fidelity being linked to preference, they found a strong correlation between saturation and preference. They further identified that saturation in red was key, which is consistent with some requirements for R9 when using CRI. This research culminated in a simple equation:

Preference = Fidelity + Red Saturation

Where fidelity should be greater than 74 and the red spectrum should be oversaturated by 2 to 16 percent while the whole system, expressed by the gamut, should be oversaturated.

PSU later performed a study also at 3500K and using a different methodology – they opted for an absolute test where participants were exposed to only one lighting scene per day. Interestingly, although the format and methodology were different, preferred light sources fell in the same range as with the PNNL study.

Follow-on research from PNNL sought to explore the effect of changes in chromaticity and exposed participants to light sources that varied between 2700K and 4300K. Similar preference results were observed, independent of chromaticity.

Lastly, in 2017, researchers at Zhejiang University in China showed a total of 164 lighting scenes in four chromaticity groups, ranging from 2800K to 6500K, and drew similar conclusions relative to preference. As the first study taking place outside of the United States, it also demonstrated that preference is not conditioned by the habitual built environment, but that it transcends borders and cultures.

All studies drew similar conclusions that fidelity was not the key determining factor of the pleasance of a light source. Fidelities slightly below the commonly accepted 80 CRI can correlate to a preferred light source when combined with an oversaturation of the gamut of the light source and of the red spectrum.

Specifying a quality light source

The most recent version of the WELL Building Standard™, WELL v2 pilot, defines parameters for Electric Light Quality under Feature L07. It specifies a CRI threshold > 90, or > 80 with R9 > 50. It also incorporates the PNNL targets for a preferable light source with a Fidelity (Rf) ≥ 78, a Gamut (Rg) ≥ 100 and an oversaturation in the red spectrum between 1 and 15 percent using the parameters of TM-30-18.

Light sources meeting those parameters offer the advantage to render colors in a manner that is preferred by humans. Skin tones appear more natural and healthy due to an increase in red content, organic materials such as wood have a warmer, more natural coloration and colors are more vibrant overall, making common objects appear more attractive.

Anthropological, historical, and sociological factors appear to explain this preference for a light source with a slight oversaturation in the red spectrum. Humans have evolved for millennia around fire, which would have shaped our perception of a preferable light source.

We appear to be at a tipping point, where new LED technology is becoming widely available, efficacy gains are translating to incrementally smaller savings year-after-year, new building standards are promoting health and wellness of occupants, and independent studies are converging to define a light that is deemed preferred by humans, independent of cultural backgrounds.

Using this information, specifiers can finally switch the paradigm to the users of a space or add that component in the selection of light sources that will not only be functional, sustainable, and enhance architecture, but also enhance the experience of those who live, work, heal, learn and play under the light sources.

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Focal Point’s Matthew Blakeley on Quantifying Lighting Quality (Part 1)

This is the first of a two-part article addressing advances in light sources and light quality, authored by Matthew Blakeley, Vice President – Product and Business Development for Focal Point as an exclusive contribution to LightNOW. This first article focuses on the evolution of light sources and measurement tools that can accurately describe the quality of the color rendition in a space.

This is the first of a two-part article addressing advances in light sources and light quality, authored by Matthew Blakeley, Vice President – Product and Business Development for Focal Point as an exclusive contribution to LightNOW. This first article focuses on the evolution of light sources and measurement tools that can accurately describe the quality of the color rendition in a space. The second article highlights recent research, which provides a baseline definition of a quality light source that’s preferred by humans, independent of cultural background and familiarity with the habitual built environment.

Light-Emitting Diodes or LEDs are now the common light source installed in commercial spaces. They offer many advantages in terms of efficacy and energy savings (lumens/watt), long useful life, controllability, and integration with building automation systems. As inherently electronic devices, they are an enabler of the IoT, helping transform luminaires from simple light sources to data collection points that support smart building management.

But have LEDs improved the quality of light that all of us live, work, and play under in our daily lives? And how can that light quality be accurately measured?

Until the invention of the Edison blub in 1879, mankind had spent millennia under natural light sources including sunlight, fires, and candles. We became accustomed to that warm glow which the incandescent bulb also produces. One of the complaints often associated with fluorescent lamps and LEDs is their lack of warmth. This is due to the light spectrum distribution of those light sources, which contains more short-wavelength light, thus resulting in a greener and bluer tone. On the positive side, this directly correlates to their higher luminous efficacy which has made them preferred light sources in commercial buildings, starting with fluorescent tubes gaining popularity in the mid-20th century followed by LEDs in the early 2000s.

To achieve efficacy levels that compared to that of fluorescent tubes, hence making them commercially viable, the light spectrum of LEDs had to be tweaked. To maximize the amount of light produced more green content was incorporated, the spectrum that the eye and therefore luminous matching function is most sensitive to.

As a result, the perceived color of objects and natural elements lit by LEDs is different from that lit by incandescent light sources; skin tones don’t appear as healthy, colors are not as vibrant.
The most common way to measure light color quality is CRI – the Color Rendering Index which was developed in the 1960s. It is generally accepted that an 80 CRI LED produces average light, good enough for most commercial environments, while LEDs with a CRI of 90 or above have a higher color quality.

While CRI is an easy-to-understand rule of thumb, it also has limitations. It is a measure of fidelity only: it describes how a light source differs from a reference illuminant, a blackbody radiator, without describing the direction of the change in either chroma or hue. For example, consider a light source with a 20% oversaturation of yellow content and another with a 20% oversaturation of blue content. These two light sources with very different color saturations, assuming the other colors are the same, would both have a similar Color Rendering Index value.

In 2015, the IES launched TM-30-15, an updated technical memorandum that addresses improvements in color control with LEDs. Incremental improvements were made with the current version, TM-30-18.

The main takeaways are that TM-30 measures both shifts in color fidelity and in color gamut from a reference illuminant and provides a color vector graphic which helps visualize the changes in hue and saturation. It divides the color spectrum of the light source in 16 hue bins, clearly denoted on the graph, and for which various data points are reported on when using the IES TM-30-18 calculator.

Going back to the oversaturation in blue versus yellow example, TM-30 would provide a clear depiction of the differences between the light sources, as well as measurements relative to local chroma shift, local hue shift, and local color fidelity for each of the 16 hue bins.

Using TM-30 as a tool to describe the quality of a light source is more accurate than using CRI alone and can support the selection of light sources that will contribute to human comfort and well-being, attributes directly linked to productivity in commercial buildings.

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Chris Cuttle Proposes New Approach to Design

In the Illuminating Engineering Society’s Forum for Illumination Research, Engineering, and Science, designer and educator Christopher (“Kit”) Cuttle, MA, PhD, FCIBSE, FIESANZ, FIESNA, FSLL, proposed a new approach to lighting design that integrates illumination factors beyond workplane light levels.

In the Illuminating Engineering Society’s Forum for Illumination Research, Engineering, and Science, designer and educator Christopher (“Kit”) Cuttle, MA, PhD, FCIBSE, FIESANZ, FIESNA, FSLL, proposed a new approach to lighting design that integrates illumination factors beyond workplane light levels.

The problem with existing technique, he says, is:

Lighting practitioners are poorly served by the illumination metrics that are currently used to specify, measure and predict lighting in buildings. Almost a century has passed since the Lumen Method was introduced, providing a simple tool for enabling a prescribed average illuminance to be provided over the horizontal working plane (HWP). What is truly remarkable is that, to this day, the concepts upon which it is based persist as the basis for specifying illumination levels in lighting standards.

As professional understanding of lighting’s impact developed in the mid twentieth century, this resulted in a segmentation in design between practitioners either engineering workplane light levels or using artistry to go beyond to address lighting’s other impacts:

The lighting profession is now divided between practitioners who use illumination metrics to achieve reliable and efficient compliance with lighting standards, and those who apply lighting to influence the appearance of people’s surroundings and who shun the use of illumination metrics, which they see as inhibiting their creativity and their scope to “think outside the box.”

The answer, Cuttle says, is to combine these approaches into a single set of best practices supported by metrics:

It is proposed here that there is scope for an innovative procedure that combines components from both sides of this division. Lighting’s role in influencing the appearance of people’s surroundings provides a sensible basis for determining the overall illumination quantity to be provided, where surroundings is taken to include all visible surfaces and objects within the space. The appearance of details, which may include anything that deserves attention (including visual tasks), may be crucially affected by illumination distribution within the space, and managing illumination quantity and distribution within an enclosed space calls for competent application of illumination metrics. Application of such a procedure should support the achievement of any set of lighting design objectives without inhibiting innovative design options – as the imposition of the uniformity criterion does.

Check out the specific of Cuttle’s argument and the solutions he proposes here.

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Lighting for Senior Facilities

Nearly 50 million people aged 65 and over live in the United States, with about 1 million living in more than 30,000 assisted-living communities, according to the National Center for Assisted Living. They can be challenging for lighting design, as the visual system undergoes physiological changes with age that can reduce visual acuity and color discrimination while heightening sensitivity to glare.

Below is an application story I contributed to the November issue of tED Magazine, the official publication of the NAED. Reprinted with permission.

Nearly 50 million people aged 65 and over live in the United States, with about 1 million living in more than 30,000 assisted-living communities, according to the National Center for Assisted Living.

Moving forward, according to the Population Reference Bureau, the 65+ segment of the population is expected to double to nearly 100 million by 2060, increasing its total population share to 24 percent. This will very likely result in increased demand for senior facilities in the future.

These facilities range from retirement housing to assisted-living facilities to nursing homes and hospice, with the average age being 83 to 86. They can be challenging for lighting design, as the visual system undergoes physiological changes with age that can reduce visual acuity and color discrimination while heightening sensitivity to glare.

As a result, a higher percentage of elderly people have vision impairment compared to the rest of the population. Vision in dim lighting, reading small print, distinguishing colors, and transitioning between bright and dim spaces can all be problematic. Eye diseases such as glaucoma and cataracts become more common. Disruption of circadian rhythms may occur, either due to degradation of sight or possibly Alzheimer’s disease or dementia.

Lighting design for these facilities typically emphasizes daylight and higher electric light levels, minimizing glare through indirect light distribution and other means, good uniformity of light distribution, and accent lighting for safety. Transition spaces receive high illumination for visual adaptation. Flicker should be avoided. As people live in these facilities, the lighting should promote circadian entrainment, and the lighting equipment should be pleasant and promote a sense of home.

This article introduces basic lighting design principles for senior facilities, based on two documents. The first is the Facility Guidelines Institute’s 2018 FGI Guidelines for Design and Construction of Residential Health, Care, and Support Facilities. The second is the Illuminating Engineering Society’s (IES) ANSI/IES RP-28-16, Lighting and the Visual Environment for Seniors and the Low Vision Population.

Lighting for Living

Designers should plan the lighting based on the site conditions, building orientation (for daylight), and the needs of the care population. The greater the need for care, the more impact the physical environment can have on quality of life and overall safety. Therefore, the lighting should be verified to be responsive to residents’ daylighting and electric lighting needs.

The design of senior care facilities is not regulated at the national level, with states making the rules. A majority of states have regulations based on the FGI guidelines. For lighting, these guidelines cover various design aspects, while referencing IES RP-28 for minimum recommended light levels, which are typically higher than for other types of applications. Otherwise, the Americans with Disabilities Act (ADA) prohibits wall objects such as sconces projecting more than 4 inches into circulation zones when mounted 27 to 80 inches above the finished floor.

The FGI guidelines require daylighting in common areas such as dining and activity rooms, while recommending it wherever else possible based on its value for light levels, color quality, and circadian entrainment. The guidelines add that if daylight is not available, the electric lighting should promote circadian response, which may be accomplished with intensity and color control in LED luminaires.

Daylight can be balanced with light shelves, skylights, and other methods. To control brightness and minimize glare, daylight apertures should be properly shaded. Similarly, lamps and luminaires should be properly shielded or concealed to minimize glare, while producing lighting patterns free of glare, shadows, and scalloping. This may involve shielded direct lighting or indirect lighting. Daylight, general and task electric lighting, and surface reflectances should combine to produce the desired maintained light levels based on IES recommendations.

A key consideration for senior living is visual adaptation. This is the ability of the eye to adapt from one light level to another so as to maintain the same level of visual acuity. For many elderly people, adaptation between extreme contrasts—such as leaving bright sunshine to enter a dim building—can reduce visual acuity and may even be disorienting. As a result, transition/entry spaces such as lobbies and vestibules require higher light levels to assist with adaptation. If residents will enter a space with a very low light level, seating may be provided to give them time to adjust. Similarly, windows at the end of corridors should be properly shaded.

In living spaces, residents should be given easily accessible task lighting. Low-level night lighting should be provided that is mounted no higher than 2 feet above the finished floor. In case the night lighting may be disturbing, it may be portable or able to be switched. Additionally, corridor general lighting should reduce at night using controls.

Regarding color, the IES recommends a minimum light source color rendering index (CRI) rating of 80 for interior spaces at senior facilities—preferably higher in specific spaces such as hobby areas, dining rooms, and elsewhere color accuracy, discrimination, and appearance are important. The IES also recommends a slightly higher correlated color temperature (CCT). A high CRI and slightly higher CCT (e.g., 3000K instead of 2700K), which can help mitigate loss of color discrimination that can occur with age.

Circadian-friendly lighting strategies may be beneficial for residents of senior facilities, including people with Alzheimer’s disease. The LRC’s 24-hour lighting scheme demonstration room provides cycled electric lighting with cool, high light levels during the day and warm, low levels in the evening. Image courtesy of the Lighting Research Center.

 

Image courtesy of the Lighting Research Center.

 

Alzheimer’s and dementia

Alzheimer’s disease is a type of dementia, the incidence of which increases with age. The Alzheimer’s Association estimates that 5.7 million Americans aged 65+ have Alzheimer’s disease—about 10 percent of that age group, and about one-third of people age 85 and over. Because there is no cure, the best outcome is to minimize symptoms. Design can play a role.

Alzheimer’s can affect vision, including negative effects on depth perception, loss of peripheral vision, inability to discern brightness contrast, reduction in visual acuity, and heightened sensitivity to glare and shadows. These problems can contribute to falls and reduced postural stability.

According to the IES, some caregivers have suggested a higher light level than the organization’s recommended minimum. Besides ensuring sufficient illumination, additional steps such as ensuring strong color contrast can improve quality of life.

Providing circadian-friendly lighting may also be beneficial. This may include adjusting light levels and spectral output based on time of day. It may also include incorporating lighting that delivers sufficient light to the eye’s photoreceptors during the day.

In one study published in 2016, the Lighting Research Center (LRC) developed a self-luminous light table to complement customized general lighting. The table delivers a circadian stimulus (CS) of 0.4, above the threshold for circadian stimulus. According to the LRC, the results included significantly improved sleep, reduced depression, and reduced agitation in Alzheimer’s patients. Even after the light intervention was removed, both depression and agitation scores remained lower.

Lighting for seniors

Seniors deserve the best quality of life that good design has to offer, ensuring a physical environment that supports their needs. This includes lighting designed to recommended practice. Good lighting for senior facilities mitigates vision issues that can occur with aging, supporting visual acuity as well as their ability to discern brightness and color contrast.

SIDEBAR: Tunable-White Lighting at ACC Care

In 2015, the Sacramento Municipal Utility District (SMUD) evaluated a trial installation of tunable-white LED lighting at the ACC Care Center, a senior living facility. SMUD and ACC collaborated to learn more about how tunable-white lighting impacts sleep, nighttime safety, and behavior, following guidelines published by the LRC.

At specification time, few tunable-white luminaires were suited to replace the existing fluorescent system. Several luminaires were installed in a corridor, two resident rooms, a nurse’s station, a family common area, and an administrator’s office. Light levels improved in the resident rooms due to the LED lighting, while the spectral output of the lighting in these rooms plus the adjacent corridor and nurse’s station changed throughout the day to support circadian entrainment.

According to the U.S. Department of Energy (DoE), which published the project as a GATEWAY study, the ACC staff captured health-related benefits that may be attributable to the new lighting. These included less agitated behaviors in three studied patients, with a marked reduction in use of psychotropic and sleep medications for one of them. Further, the number of patient falls in the corridor was reduced.

Tunable-white LED lighting in the ACC Care Center corridor, shown at the morning setting (6500K, 66 percent output), afternoon setting (4000K, 66 percent output), and night setting (2700K, 20 percent output). Images courtesy of the Sacramento Municipal Utility District and the U.S. Department of Energy.

 

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