Author: Craig DiLouie

Library Stack Lighting 101

This article describes considerations and techniques for designing book stack lighting, based on the Illuminating Engineering Society’s (IES) RP-4-13, Recommended Practice for Library Lighting.

Below is an application story I contributed to the February issue of tED Magazine. Reprinted with permission.

According to the American Library Association, there are nearly 120,000 libraries in the United States, including school (82 percent), public (8 percent), and other (10 percent) libraries. These buildings feature a variety of spaces and tasks as use of their use has changed. Today’s libraries offer books and artifacts, digital content, computer and Internet access, wireless communications, and a place to meet. A variety of spaces impose common and particular lighting requirements, including entrances, lobbies, retail, office, display, services, multipurpose rooms, and exterior areas.

As library usage shifts to e-books, Internet, and digital content, there is less demand for publicly accessible storage areas. Nonetheless, the most popular type of space remains storage of book collections, called the library or book stack. In typical school and public libraries, this storage takes up 30 to 50 percent of usable floorspace, even more in other library types.

This article describes considerations and techniques for designing book stack lighting, based on the Illuminating Engineering Society’s (IES) RP-4-13, Recommended Practice for Library Lighting.

The library stack

A library stack is a collection storage as opposed to a reading area. In these areas, books are typically stored in shelving units that are often 3 feet wide, 1 foot deep, and 3 to 7.5 feet tall, according to IES. These shelving units connect to form ranges, separated by aisles that are at least 3 feet wide for browsing and 44 inches wide for major circulation and egress paths.

Typically, shelving is vertical, though angled shelves, carrousels, bins, and drawers may be in use for special materials and presentation of books. For older or lesser-used materials storage, high-density storage systems such as rolling stack shelving may be used, in which shelving units rest adjoined and are separated via a floor or ceiling rail using a manual or mechanical method. If rare books and artifacts are stored, these materials may be sensitive to ultraviolet energy and heat produced by electric light and daylight sources, and therefore may need to be isolated.

Image courtesy of Eaton Corporation.

Lighting considerations

In the stack area, the two primary tasks are reading covers and spines on the shelves, requiring vertical illumination from as tall as 90 inches to as low as six inches off the floor; and reading selected materials, requiring horizontal illumination. IES recommends a minimum of about 10 to 40 footcandles of horizontal illumination on the floor and an average of about 15 to 60 footcandles 2.5 feet above the finished floor. IES further recommends about an average 10 to 40 footcandles of vertical illumination on the front face of the shelving 2.5 feet above the finished floor, with a minimum of about half that near the bottom of the shelving. The most desirable light level within these ranges depends on the predominant ages of users, as older people need more light. Regardless, the average-to-minimum vertical and horizontal light level uniformity should be at a 2:1 ratio. High-density book shelving and periodical shelving have similar light level recommendations; consult IES-RP-4-13 to learn more. For high-density book shelving, vacancy sensors can be used to reduce light levels (and save energy) during periods of vacancy during operating hours.

Book spines are typically darker color, resulting in IES estimating an overall reflectance in the aisle of 30 percent or less. As darker materials absorb light, this means a significant amount of light may be absorbed between the top and the bottom of the shelf. Some books are protected by glossy plastic covers, which reflect light and may create a veiling reflection (reflected light that obscures seeing the task) depending on the viewing angle.

Lighting design options

One of the most informative features of IES-RP-4-13 is a stack lighting matrix, which describes lighting design options based on ceiling and shelving height, along with advantages, disadvantages, and design considerations for each.

The options for lower ceiling heights (14 ft.), IES identifies two options, either shelving-mounted direct/indirect or a combination of shelving-mounted direct with ceiling-mounted direct or indirect luminaires.

Image courtesy of Eaton Corporation.

Below, three options for 9- to 14-foot ceilings are summarized:

• Suitable for 3- to 7.5-foot-tall shelving, suspended direct/indirect luminaires, mounted perpendicular to the shelving units, can provide good vertical lighting in the aisles while producing ambient room lighting. Lighting uniformity is improved, and luminaire spacing can be maximized. However, installing these luminaires in continuous rows may result in relatively high lighting power. The direct light component may be shielded to reduce direct glare, while wide direct distribution will improve light level uniformity.
• Suitable for 3- to 7.5-foot-tall shelving, suspended indirect luminaires, mounted perpendicular or parallel to the shelving, can eliminate glare while producing soft ambient lighting. However, as with direct/indirect, mounting in continuous rows may result in higher lighting power. This option is well suited when flexibility is required for future reconfiguration of the shelving layout, or when a reading zone is integrated into the stack area. The luminaires should be mounted as low as possible to maximize the uniformity of illumination on the ceiling and shelves.
• Suitable for 5.5- to 7.5-foot-tall shelving, direct/indirect luminaires mounted on the shelving can provide good vertical lighting in the aisles while eliminating dark areas and producing ambient room lighting. Locating continuous rows on each side of the range may demand more lighting power, and additional lighting may be needed in circulation aisles. Electrical distribution must be provided from the floor to the lighting, which requires coordination and may limit shelving placement.

As with any other lighting application, finding the right stack lighting option requires careful matching to the project characteristics and goals.

Library lighting

Libraries may be changing with the times, but their core role in communities remains the same—providing centers for arts, learning, community-building, and imagination. Using recommended practice, distributors can support their customers in recommending appropriate solutions for their projects.

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Registration Opens for IES Light + Human Health Research Symposium

The Illuminating Engineering Society’s (IES) 2018 Research Symposium, themed, “Light and Human Health,” will be held April 8-10, 2018 at the Crowne Plaza Atlanta and SimTigrate Design Lab in Atlanta, GA. Registration is now open.

The Illuminating Engineering Society’s (IES) 2018 Research Symposium: Light + Human Health will be held April 8-10, 2018 at the Crowne Plaza Atlanta and SimTigrate Design Lab in Atlanta, GA.

The Symposium will present the latest research on how light during the day and night affects our circadian, biological, and behavioral responses. Discussions will include how this research might affect current and future design applications.

Click here to register.

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Lighting for Tomorrow Competition Suspended

The sponsors of the Lighting for Tomorrow product design competition, which recognizes the most advanced energy-saving residential lighting products, will hold a workshop instead of a competition in 2018. Click to learn why.

The sponsors of the Lighting for Tomorrow product design competition, which recognizes the most advanced energy-saving residential lighting products, will hold a constituent workshop instead of a competition in 2018.

Why? Energy regulations are having a big impact on energy efficiency programs, which are seeing the cost-effectiveness of their residential lighting programs decline. The sponsors will hold the workshop to determine how to move forward with the competition and how best to promote the most advanced energy-efficient residential lighting.

The outcome of the workshop will be announced in September 2018.

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Product Monday: Lumu Power Light and Color Meter

Lumu Power by Lumu is a color temperature, illuminance, ambient and flash exposure meter that plugs into iOS devices (iOS 8+) that have a Lightning connector.

Lumu Power by Lumu is a color temperature, illuminance, ambient and flash exposure meter that plugs into iOS devices (iOS 8+) that have a Lightning connector. The dome side measures ambient and flash exposure, performing 750,000 measurements per second. The flat side measures illuminance, color temperature, and chromaticity based on CIE 1931/DIN 5033.

Click here to learn more.

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AIA Consensus Construction Forecast: Nonresidential Construction Spending to Grow 4% in 2018

Construction spending for nonresidential buildings is projected to increase 4% this year and continue at that pace of growth through 2019, according to the American Institute of Architects (AIA) semi-annual Consensus Construction Forecast. Click to see the numbers.

Construction spending for nonresidential buildings is projected to increase 4% this year and continue at that pace of growth through 2019, according to the American Institute of Architects (AIA) semi-annual Consensus Construction Forecast. The commercial construction sectors are expected to generate much of the expected gains this year, and by 2019 the industrial and institutional sectors will dominate the projected construction growth.

“Rebuilding after the record-breaking losses from natural disasters last year, the recently enacted tax reform bill, and the prospects of an infrastructure package are expected to provide opportunities for even more robust levels of activity within the industry,” said AIA Chief Economist, Kermit Baker, PhD, Hon. AIA. “The Architecture Billings Index (ABI) and other major leading indicators for the industry also point to an upturn in construction activity over the coming year.”

Click here to learn more.

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Architecture Billings End year on Positive Note

The Architecture Billings Index (ABI) concluded the year with a score of 52.9, capping three straight months of growth in design billings.

The Architecture Billings Index (ABI) concluded the year in positive terrain, with the December reading capping off three straight months of growth in design billings.

The American Institute of Architects (AIA) reported the December ABI score was 52.9, down from a score of 55.0 in the previous month. This score still reflects an increase in design services provided by U.S. architecture firms (any score above 50 indicates an increase in billings).

The new projects inquiry index was 61.9, up from a reading of 61.1 the previous month, while the new design contracts index decreased slightly from 53.2 to 52.7.

“Overall, 2017 turned out to be a strong year for architecture firms. All but two months saw ABI scores in positive territory,” said AIA Chief Economist, Kermit Baker, Hon. AIA, PhD. “Additionally, the overall strength of the fourth quarter lays a good foundation for healthy growth in construction activity in 2018.”

Key December ABI highlights:

• Regional averages: South (56.3), West (53.0), Midwest (52.9), Northeast (49.4)
• Sector index breakdown: multi-family residential (55.4), commercial / industrial (54.8), institutional (51.2), mixed practice (50.4)
• Project inquiries index: 61.9
• Design contracts index: 53.2

(The regional and sector categories are calculated as a 3-month moving average, whereas the national index, design contracts and inquiries are monthly numbers.)

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Webinar: Lessons Learned from the NGLS Living Lab

On February 13, at 1:00 PM EST, the Department of Energy will host a one-hour webinar to share lessons learned to date from Next Generation Lighting Systems competitions 1 and 2. How did specifier, manufacturer, and installer preconceptions create delays? How did issues related to user interfaces and conflicting control strategies cause confusion? And what can we learn from feedback from lighting experts and users in the classrooms?

On February 13, at 1:00 PM EST, the Department of Energy will host a one-hour webinar to share lessons learned to date from Next Generation Lighting Systems competitions 1 and 2.

Ruth Taylor from Pacific Northwest National Laboratory will provide an inside look at the challenges encountered in the installation and configuration of these lighting systems in working classrooms. How did specifier, manufacturer, and installer preconceptions create delays? How did issues related to user interfaces and conflicting control strategies cause confusion? And what can we learn from feedback from lighting experts and users in the classrooms?

Click here to register.

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California Regulates Incandescent Lamps

On January 1, 2018, new Title 20 regulations went into effect requiring general-service lamps achieve an efficacy of 45 lumens/W. While certain specialty incandescent lamps will continue to be available for sale in the state, consumers will be limited to a choice of LED or CFL for general-service sockets once current inventories of incandescent and halogen lamps are sold.

On January 1, new Title 20 regulations went into effect requiring certain LED lamps, small-diameter directional lamps, and general-service lamps comply with new performance, testing, and marking requirements. Certain lamps must achieve a minimum efficacy level of 45 lumens/W, higher than the current standard imposed by the Energy Independence and Security Act of 2007 (and meeting the backstop provision in the Act going into effect in 2020), and higher than halogen A-lamps currently produce. While certain specialty incandescent lamps will continue to be available for sale in the state, consumers will be limited to a choice of LED or CFL for general-service sockets once current inventories are sold.

Here’s a good fact sheet summarizing the Title 20 regulations. Here’s a good article summarizing the impact of the regulation and the battle behind the scenes.

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Product Monday: Dual Tech Exit by Isolite

Isolite’s new Dual Tech 2.0 exit signs combine LED lighting with photoluminescent materials to increase reliability by eliminating the need for battery backup power.

Isolite’s Dual Tech 2.0 exit signs combine LED lighting with photoluminescent materials to increase reliability by eliminating the need for battery backup power.

During normal power conditions, the sign is illuminated with LED. When the power goes out, a translucent exit stencil diffuser made of photoluminescent material provides illumination, designed for visibility up to 100 feet for a minimum of 90 minutes, the typical standard for electric signs. The photoluminescent material is charged by the LEDs while electric power is provided to the sign; the LEDs are spectrally engineered to emit specific light wavelengths required to optimally charge the material. This hybrid approach facilitates use of photoluminescent while eliminating the need for backup power to the sign.

The Dual Tech 2.0 carries OSHA, NFPA 101 Life Safety Code, NFPA 70-NEC, and UL 924 approvals.

Click here to learn more.

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Masters of Light: Bruce Kirk on How to Light a House of Worship

In “How to Light a Place of Worship,” Bruce Kirk, Light Perceptions talks about about how to balance modern technique and tradition in the lighting of a house of worship.

Episodes of the UK’s LIGHTING Magazine’s “Masters of Light” webcast series are now available for on-demand viewing. In this series, lighting designers, artists and architects talk about their work, methods and philosophy in one-hour retrospectives hosted by the magazine’s editors.

In “How to Light a Place of Worship,” Bruce Kirk, Light Perceptions talks about about how to balance modern technique and tradition in the lighting of a house of worship.

Click here to check it out. Registration required.

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