Month: May 2010

Lighting Design Can Reduce Anxiety For Tunnel Drivers

Norwegian researchers have found that good design and lighting can significantly reduce anxiety among travelers driving through tunnels, as reported by EarthSky.org here. The article states: The main point is…

Norwegian researchers have found that good design and lighting can significantly reduce anxiety among travelers driving through tunnels, as reported by EarthSky.org here.

The article states:

The main point is to obtain a good distribution of light, in conjunction with the use of artistic lighting, which turns out to give drivers a feeling of space and of greater security. Modern lighting systems, with two rows of lamps, light sources that illuminate the opposite direction and driving lane, are beginning to be quite common in new Chinese tunnels, and they have also been installed in the tunnel that forms part of the Øresund Link between Denmark and Sweden.

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Product Monday: HessAmerica’s Athens Architectural-Grade Pole-Mounted Luminaire

HessAmerica’s Athens is an architectural-grade pole-mounted luminaire for outdoor pedestrian-scale and area lighting applications. Smartly detailed throughout, the distinctive Euro-form of the luminaire is a blend of curves punctuated by…

HessAmerica’s Athens is an architectural-grade pole-mounted luminaire for outdoor pedestrian-scale and area lighting applications. Smartly detailed throughout, the distinctive Euro-form of the luminaire is a blend of curves punctuated by a functional transition from luminaire to pole.

Click here to learn more.

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ArchitectCES Adds 1-Hour Course on Daylighting

ArchitectCES.com, the American Institute of Architects (AIA) Continuing Education Services (AIA/CES) provider, has added “Introduction to Tubular Daylighting Devices,” delivered by manufacturer Solatube, valued at 1 LU/HSW/SD hour. Students will…

ArchitectCES.com, the American Institute of Architects (AIA) Continuing Education Services (AIA/CES) provider, has added “Introduction to Tubular Daylighting Devices,” delivered by manufacturer Solatube, valued at 1 LU/HSW/SD hour. Students will learn:

  • why daylight is so important and identify the reasons for using daylighting in commercial environments
  • to identify the available daylighting strategies and identify their advantages and disadvantages
  • the three technology zones that make up tubular daylighting device products
  • what tools and resources are available to help you incorporate tubular daylighting devices into projects
  • about projects that have benefited from using tubular daylighting devices

All courses, approved by AIA for distance education and available 24/7, are free if completed on ArchitectCES.com. Students can take a course at their computer, download a slideshow to view at their convenience or download a printable version of the course to read anywhere.

ArchitectCES also offers courses on LEDs (Cree and Acuity) and optical design (Se’lux).

Click here to learn more.

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Controls Friday: Wattstopper’s Dorene Maniccea Assumes Chair of NEMA Lighting Controls Section

Wattstopper has announced that Dorene Maniccia, Director of Policy and Industry Affairs, has been named Chair of the Lighting Controls Section of the National Electrical Manufacturers Association (NEMA). The section’s…

Wattstopper has announced that Dorene Maniccia, Director of Policy and Industry Affairs, has been named Chair of the Lighting Controls Section of the National Electrical Manufacturers Association (NEMA). The section’s focus is to promote the benefits of lighting controls including reducing energy costs and improving occupant satisfaction. Section members share experiences and work to transform the market and widespread use and acceptance of lighting controls and technologies.

Maniccia has 25 years of lighting industry experience, and has been with Wattstopper since 2001. During that time, she has provided the vision and direction for the company’s Best Practices, education and sustainability programs. Before her tenure at Wattstopper, she conducted research in lighting and controls, and was an Assistant Research Professor of Architecture at Rensselaer Institute’s Lighting Research Center. She also has experience as a lighting designer and consulting engineer. She is Lighting Certified as well as LEED-AP. Maniccia graduated from Penn State with a bachelors and masters degree in architectural engineering-illumination.

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Specifying Color Quality: A Few Words of Caution

For those specifying color characteristics of light sources, a few words of caution: While color temperature and CRI are important, the true complexities of a light source’s color characteristics cannot…

For those specifying color characteristics of light sources, a few words of caution: While color temperature and CRI are important, the true complexities of a light source’s color characteristics cannot be captured with a few numbers, which is why there is no substitute for seeing the lamps in a given application. A separate mockup with each proposed lamp type is encouraged because color quality is altered by room colors, luminaire characteristics, whether daylight is present, light levels and surface reflectances.

Further, different manufacturers may rate their products very similarly, but when these lamps are seen side by side, there may be slight differences, which is why manufacturers advise against mixing lamps from different manufacturers in the same application. Typically, the human eye cannot discern differences in CRI values that are up to 3-5 points apart.

If task lighting is added to the design, make sure the lamp color matches the general lighting. If the project is a retrofit, the specifier may neglect to specify color characteristics, which can result in poor quality, so even for projects that are driven by energy, lamp color quality should be given due priority and specified. Note the impacts of daylight (does not mix well with warm light sources), color transmission quality of the window glass (can distort color quality in the space), and color shift in the source during normal aging and dimming (such as white-light LED luminaires, which shift in color as they age).

Finally, the proliferation of color temperatures available in fluorescent lighting has made it easy to make mistakes such as mixing warm and cool lamps in the same application, which is why a maintenance plan, which includes a lamp schedule, is important to maintain design integrity.

Besides source color, consider the colors used in the room surface finishes, furnishings, partitions, etc. in the space. Lighter (non-glossy) colors are more reflective (but not glaring), which can raise average light levels and reduce demand on the lighting system. For this reason, lighter colors are recommended for large area surfaces in many typical applications such as offices and schools, while darker finishes are recommended to be limited to accents.

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Light And Color: Rendering Colors and Skin Tones

Light is actually made up of colors. For an object to be perceived a certain color, that color must be present both in the object and the light striking it….

Light is actually made up of colors. For an object to be perceived a certain color, that color must be present both in the object and the light striking it. Because of this, choice of lamp can influence how colors are perceived in a space. This means that perception of objects in the space is, to an extent, controllable.

Color tone

The color temperature of a light source, expressed in kelvins (K), indicates the color tone of the light source itself and the light it emits. Light sources are generally classified as “cool” (>4000K), which appear bluish-white; “neutral” (3000K-4000K), which appear white; or “warm” (<3000K), which appear orangish-white. Warm light sources are more heavily laden with red and orange wavelengths, bringing out some flesh tones and richer content in objects that have warmer colors. Cool light sources are more heavily laden with blue and green wavelengths, enriching the visible color content of blue and green objects. [caption id="attachment_3812" align="alignnone" width="585" caption="Color temperature scale with approximate examples."][/caption]

Color rendering

Color temperature describes the “whiteness,” “bluishness”, etc. of a light source, its warmth or coolness. However, it does not define how natural the color of objects will appear when lighted by the source. Two light sources can have the same color temperature, but render colors differently. The color rendering index (CRI), a rating scale with a maximum of 100, offers a metric to address this. For most common color temperatures, CRI uses the incandescent lamp as the reference for color rendering (100 CRI). Incandescent lamps, however, are not a perfect light source for color rendering. (They are weak in blue.) So the CRI system has its drawbacks. It is, however, the only internationally agreed upon system for expressing a lamp’s color rendering ability. It should only be used as an indicator of relative, not absolute, color rendering ability.

Performance characteristics of major lamp types. Source: LIGHTFAIR 2009 Lamp and Ballast Basics Seminar by Craig A. Bernecker, PhD, FIES, LC.

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NEMA’s CFL Lamp Index Posts Solid Growth During First Quarter of 2010

NEMA’s compact fluorescent lamp (CFL) index reversed a negative trend that dated back to the first quarter 2009, registering a 3% year-over-year increase. Conversely, the incandescent lamps index fell to…

NEMA’s compact fluorescent lamp (CFL) index reversed a negative trend that dated back to the first quarter 2009, registering a 3% year-over-year increase. Conversely, the incandescent lamps index fell to its second lowest level on record showing a year-over-year decline of 2.2% during the first quarter of 2010, which maintains a three and a half year streak of deterioration for this market segment.

The dichotomous growth patterns between residential incandescent lamps and medium screw-base CFLs resulted in CFLs regaining market share, increasing to 24.2% from 22% in 2009Q4. Consumers appear to be more willing to absorb the higher up-front costs of CFLs versus incandescent lamps, possibly due in part to the U.S. economy remaining on a path of recovery. But CFL penetration remains stalled at around 25% penetration.

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Fake Lighting Facts Label Spotted at LIGHTFAIR

LEDs Magazine just reported that the Department of Energy caught a fake Lighting Facts label on an LED lamp displayed at LIGHTFAIR. The lamp was manufactured by Greenlite, based in…

LEDs Magazine just reported that the Department of Energy caught a fake Lighting Facts label on an LED lamp displayed at LIGHTFAIR. The lamp was manufactured by Greenlite, based in Montreal. The company is not an SSL Quality Advocates partner and should not be using the Lighting Facts label.

Be sure to take a little extra time to check the registration number on the label against the product’s listing on the website to ensure you are indeed looking at a genuine and not a counterfeit Lighting Facts label.

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Maximizing Visual Comfort: An Introduction to Glare

Excessive luminances or luminance contrasts may also lead to a visual sensation called glare, which, even though it is also light, can impair or disable vision rather than enable it….

Excessive luminances or luminance contrasts may also lead to a visual sensation called glare, which, even though it is also light, can impair or disable vision rather than enable it. Glare is categorized as several different types according to its effects.

Direct glare is caused by directly viewing a light source, such as a bright window or an unshielded high-brightness lamp. Reflected glare is caused by light reflected from a surface, such as a veiling reflection on a glossy magazine or computer screen.

If the bare lamp is visible to the user’s eye, even if is visible above the natural cutoff angle of the eyebrow, users may find it much more comfortable to shield their eyes with their hand or a baseball cap—a condition called overhead glare. Graphic courtesy of Naomi Miller.

Disability glare is particularly dangerous because vision is virtually disabled. Discomfort glare occurs when glare sources in the field of view produce a sensation of irritation in the eye. One type of discomfort glare that may occur in open office plans, classrooms and similar environments is overhead glare, which, unlike the usual discomfort glare, does not occur within the field of view. Instead, it is caused by people performing heads-up tasks, such as office workers typing on keyboards or students observing a teacher, under recessed 2×4 luminaires. The sensation of brightness fades below the line of sight to the glare source, producing a sensation of glare due to light scattering at eyebrow and cornea of the eye. Light may also be reflected into the eyes from the face around the eyes, such as the nose and cheekbones.

What to do

If glare is present, consider the source, the task and their relationship with each other and the user. Changing one or a combination of these should be able to solve most glare problems.

Regarding the source, avoid direct sunlight penetration into the space. Bright windows can be mitigated by placing light on adjacent walls to reduce contrast or providing shading. Avoid excessively bright lamps in luminaires where the lamps are visible. If bare lamps will be a potential source of glare, consider low-brightness luminaires.

Regarding the task, consider placing light on the task’s surround to reduce contrast. Consider changes to the source/task/eye geometry that may solve the problem, such as relocating or reorienting the task. Reflected glare on computer screens should be less of a problem than it was just a few years ago as computer screens have advanced considerably—larger radius of curvature, improved screen brightness, anti-reflectance technology, flat screens, positive contrast in software, etc.—thereby reducing the risk of unwanted reflections.

Sparkle

While glare is typically best avoided, in some cases it can be welcome, such as tiny points of high brightness, or “sparkle,” used to convey an atmosphere of elegance. Examples include bright highlights on silverware in a fine restaurant or in a chandelier mounted over a grand lobby.

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