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All Posts in “SCIENCE”

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How accurate is your light meter?

November 11, 2016 / no comments

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What’s in a light meter? How much do light meters vary? Are the tried and true really as true as we believe?

We decided to explore these questions by challenging our meters, old a new, to a performance test. We digitally controlled light levels in our illuminance testing facility and introduced light situations from powerful LED blow-out down to tightly sealed interior darkness. Lam Labs looked at traditional to contemporary illuminance measuring devices, including the Lumu smartphone plug-in meter and its app, the firm’s trusty standby (a Minolta T-10) and a chunky brown General Electric 214 model circa 1960. Lets see how they stacked up.

Findings

  • Most results remain consistent, and their agreement indicates accuracy – however this was most true in illuminance levels from 0-20 footcandles. Results diverge and become increasingly disparate as the tested illuminance level rises.  
  • The Lam Partner’s standby, the Minolta, T-10 ran largely parallel to the new, high-tech Lumu. New technology and trusted but older technology agree on light levels…proof that different generations can see eye to eye.
  • The older GE 214 ran high for several tests, pulling the mean average up with it. If we ignore this model, there is a larger degree of consistency between all results.

Next Step

If we set the reliable Minolta-T10 as our baseline, how much do the others deviate from its results? The following graphs explain.

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More Findings…

This graph shows each meter’s percentage of variance above or below the standard Minolta T-10 during each light situation.

The HS 1010 runs high consistently, with a 2-7% range for deviation. The Minolta TL-1 runs low consistently, with more variance – between 0 and 9% – and this range gives slightly more reason for distrust.

The Lulu is highly sensitive at lower light levels, suggesting perhaps it picks up light from the iphone screen to which it is attached – which of course can vary by setting for phone model. Alternatively, the Lumu may be finely tuned enough to sense tiny light leaks around doorways in the testing facility.

The GE 214 runs high overall, but reads significantly higher at increased light levels – not a typical trend and therefore this outlier can be tossed out of the runnings for accuracy.

Dr Meter also runs low, but with more uniform results than other meters, from around 2-6% variance, making it a reliable 2nd or 3rd choice after the Minolta T-10 and Lumu which have very similar performance.

The greatest variances – even larger than this graph would comfortably accommodate – are seen at lowest light levels. Those first few moments when a meter is exposed to light are unpredictable, indicating they all could use extra time for calibration and to reach peak performance, and multiple readings until consistent sequential readings are reached.

THE  LIGHT METER ACCURACY AWARD GOES TO:

1st    Minolta T-10 & Lumu

2nd     Dr. Meter

3rd      HS101

4th      Minolta TL-1

5th    GE 214

 

This study was performed by Brittany Lynch and Piper Ainsley in September 2016.

Is LED Street Lighting Bad for Your Health?

June 29, 2016 / no comments

Is LED Street Lighting Bad for Your Health?

Misinterpretation of AMA report distracts from the real problems

The American Medical Association’s (AMA) recently issued report, “Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting,” highlights many important issues regarding the implementation of street lighting to avoid negative environmental and health effects.

Unfortunately, on the subject of potential negative health effects of LED street lighting, the report has been misinterpreted by online media and even by the International Dark-Sky Association (IDA). The report has been boiled down to a sound bite along the lines of: “AMA says LED streetlights are bad for your health! (unless they are 3000K)”. This is really unfortunate, not just because it’s wrong, but because it puts attention solely on the issue of color temperature, distracting from the other very important issues raised in the report.

Jumping to Conclusions

Here are some examples of misinterpretations and misstatements.

  • From NPR:
    • Bright, Bluish-White LED Streetlamps Disrupt Sleep Cycles, AMA Says
  • …Not true. The AMA report does not say this.
  • From takepart.com:
    • LED Streetlights Are Good for the Earth, Bad for Humans and Wildlife
      “Studies have shown that white LED streetlights are five times more powerful at suppressing circadian rhythms than the high-pressure sodium lights they are replacing, the AMA noted.”
  • …Not true. The AMA report does not say this.
  • From the International Dark Sky Association blog:
    • “Not only is blue-rich white LED street lighting five times more disruptive to our sleep cycle than conventional street lighting, according to the report…”
  • …Not true. The AMA report does not say this, either.

What the AMA Really Says

Here is what the AMA report does say (emphasis added):

  • “It is estimated that a “white” LED lamp is at least 5 times more powerful in influencing circadian physiology than a high pressure sodium light based on melatonin suppression. Recent large surveys found that brighter residential nighttime lighting is associated with reduced sleep time, dissatisfaction with sleep quality, nighttime awakenings, excessive sleepiness, impaired daytime functioning, and obesity. Thus, white LED street lighting patterns also could contribute to the risk of chronic disease in the populations of cities in which they have been installed.
    Measurements at street level from white LED street lamps are needed to more accurately assess the potential circadian impact of evening/nighttime exposure to these lights.
    ”

All the AMA report is saying is that it has been estimated that an LED source (of undefined color temperature) could potentially have 5 times the melatonin-suppressing effect as a high-pressure sodium source. (High-pressure sodium was the lamp source commonly used in street lighting before the arrival of LED). What the report neglects to mention is that the exposure to these two sources would have to be of sufficient intensity and duration to have any effect at all. It cites no evidence that the intensity and duration of exposure typically experienced from street lighting is sufficient to have any melatonin-suppressing effect.

The “recent large surveys” mentioned in the report refer to two epidemiological studies which looked for correlations between outdoor light at night, and obesity and sleep disruption. The measurement of outdoor light at night was derived from satellite imagery, with no information on spectral content (“color”) of the light. Since the satellite data used in the studies was from 2001 to 2009, the lighting was most likely high-pressure sodium, and certainly not LED. The studies show an association between obesity and sleep disruption and the level of outdoor lighting, but no causal effect. But even if a causal connection was proven, it can’t be connected to “blue” light, and would have been a problem long before the advent of LED street lighting.

In this RPI/LRC study, computer modeling was used to predict the potential melatonin-suppressing effect of exposure to street lights. The authors estimate that if you stood on the street under 5900K (high “blue” content) LED street lighting for one hour you might experience a small effect.

The AMA report also notes that the percentage of “blue” light in a 4000K LED source is 29%, vs. 21% for a 3000K LED source. Even if exposure to LED streetlights did have a negative health effect, 3000K instead of 4000K probably would not make much difference, based on the marginal difference in percentage of “blue” light.

And most importantly, the AMA says that further study is needed to assess potential health impacts from street lighting. Agreed!

Is Warmer Better?

There are reasons to use 3000K sources in outdoor lighting, such as reduced sky glow (see Ian Ashdown’s Color Temperature and Outdoor Lighting), glare reduction, design aesthetics, or personal/community preference. Until recently, there was a reason to not use 3000K LED, due to significantly lower energy efficacy compared to 4000K LED. But with recent improvements in LED technology, this difference in efficacy is very small, negating the disadvantage.

But, there are also possible reasons to use 4000K sources in some outdoor lighting applications. A study by Clanton & Associates and VTTI showed that 4000K LED street lighting resulted in significantly better ability of drivers to detect pedestrians at greater distances, compared to the other higher and lower color temperatures tested. This might make 4000K the best choice from a safety standpoint on streets with pedestrians and cyclists. Research from RPI shows that perceived outdoor scene brightness is higher with higher color-temperature sources. If you accept the premise that you need less light (fewer photopic lumens) from 4000K street lighting than from 3000K street lighting, then a 4000K street lighting system could use less energy, and create less light pollution than a 3000K system…possibly.

It’s a complex problem with no simple answer. So let’s use 3000K sources for all the good reasons, but not for some presumed public health benefit.

Let’s Keep Our Eyes on the Ball

We should be concentrating our efforts on reducing overall light levels, putting the light only where it’s needed, and controlling glare. This is where we can have a real impact on reducing light pollution and negative environmental impact. I'd hate to see a future where all the streetlights are 3000K, but we are still over-lighting our streets and parking lots.

And when it comes to the effects of light on health, we should be focusing our attention on interior lighting, lighting for shift workers, and light from display screens. This is where there is solid evidence that the quantity and the “color” of light can have negative (and positive) health effects.

For other perspectives on this issue, read the comments from the US Department of Energy and The National Electrical Manufacturers Association, and the detailed analysis from The Lighting Research Center at RPI.

To the AMA: Please Hire a Fact-Checker

A final comment on one blatant error in the AMA report, that is of special interest to me—the report says: “In Cambridge, MA, 4000K lighting with dimming controls was installed to mitigate the harsh blue-rich lighting late at night.”

The truth is that the adaptive dimming system was planned from the beginning of the project to reduce energy use and limit light pollution. The decision to use the adaptive dimming system had nothing to do with mitigating “harsh blue-rich lighting”. I know this because I was intimately involved with the design of the conversion of Cambridge’s street lighting to LED.

The Cambridge lighting control system is still the largest street lighting adaptive dimming system in the US, as far as I know, and is significantly reducing light pollution in our City. Other cities should be following Cambridge’s well-studied lead, and not take media sound bites or one line excerpts from this AMA report as accurate recommendations on how to minimize negative environmental or human health effects.

New techniques developed by Lam Partners for visualizing Media Display

May 8, 2015 / no comments

Designer Jack Risser and Dan Weissman, Director of Lam Labs, have developed a new workflow for rendering low- and medium-resolution media displays in visualizations. The process includes a multi-application workflow, including Rhinoceros 3D with Grasshopper and the Firefly plugin, and 3Ds Max for rendering. Now that the team has successfully rendered both still and animated images, the next step is validation of the output, compared with reality. To do this, the team is currently finishing an installation of Color Kinetics iColor Flex Gent 2 nodes in  Lam Partners’ office, which will provide a control case to verify lumen output, luminous intensity, and material transmissions. Stay tuned for more about this exciting project.

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Translucent panel 8″ from nodes

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Panel Removed

It's alive! And no we will not keep the rainbow effect... @lampartners @colorkinetics

A video posted by Dan Weissman (@daweissman83) on May 8, 2015 at 10:29am PDT

Student intern from GSD Assists in Daylighting Research

January 29, 2015 / no comments

Rufei Wang, a first year MDesS Energy and Environment student at the Graduate School of Design, joined Lam Partners for two weeks for Harvard GSD’s January Term Externship Program. Rufei worked on a research project with Lam Designer Kera Lagios, studying the relationship between automatic shades and building orientation.

Kera and Rufei will continue the research investigating relationships between daylighting, electric lighting, and energy. Stay tuned.

Redefining White

January 29, 2013 / no comments

I remember my first trip to Paris, The City of Lights. But, because I’m a lighting nerd, I couldn’t help finding the yellow headlights on automobiles particularly striking. Probably because it was so different from the headlights I was used to in the United States at the time. Today, however, I’m seeing more and more headlights in the blue range as opposed to the standard incandescent halogen range of about 2900K. Do we see better under cool light, or is it simply a function of the electric source generating the light? Up until the 1940’s or thereabouts, ‘white light’ for interior architectural applications has had a predominantly warm cast to it, mostly because it was generated by candles or incandescent sources. Since World War II and the widespread use of fluorescent sources, we’ve seen our interiors take on cooler color temperatures. With the advent of LED light sources, it is more efficacious to generate light in the blue range than in the warm range. Are we looking at an even ‘cooler’ future in architectural lighting?

Continue Reading…

Blood, Sweat, and Photons

September 17, 2012 / no comments

A lot of the work we (and all design professionals) do is pretty straightforward. You get plans, discuss the design, produce your layouts, and send it all out for the contractor to build. We walk around the site when it’s all done, but we don’t really get our hands dirty on those jobs, for better or worse. A bit oversimplified perhaps, but that’s the basic process.

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Then there are those other jobs – the jobs where we really are rolling up our sleeves, getting up on lifts, and spending hours on end aiming lighting fixtures. These are the museums and galleries that, without that professional touch, can end up looking like train wrecks if the lighting is not properly aimed. These projects are different from your average office building, school, or hospital in that the lighting design changes throughout the life of the building. You can’t plan to light the Mona Lisa and have the same solution work the next month for a Picasso that’s twice its size and occupies the same space. Where static lighting, like pendants and downlights, is great for a classroom, track is the go-to solution for these evolving spaces. It affords the ability to adapt and change, but it also leaves the door open to lighting chaos at the same time. The contractor can power and hang all those track heads, but who’s going to aim them?

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For galleries and museums, the work is far from done when the contractor is finished. You may think that anyone can get on a ladder and point a track head at a painting, but there’s so much more to it. Is there enough light, too much, good coverage across the piece, enough accent, any unwanted reflections, good fill light, spill onto the adjacent pieces, etc. And the hardest part is that it’s all highly subjective as well. You can easily spend an hour aiming fixtures at one piece of art, nudging, tweaking, lensing, and dimming, to get it just right. Now, imagine doing that 100 or 1000 times and, on top of that, making sure the space looks just as good as the art. This is where a good lighting designer adds value. We work with the curators and technicians to fine tune these installations and bring order to that chaos, to meet their expectations. Our biggest asset is our experience; we know what works and how to do it as efficiently as possible.

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Yes, it means ridiculously long hours spent on ladders and lifts, up near the ceiling where it’s 100+ degrees. We’ve bloodied our knuckles putting lenses on and off and burnt our fingertips grabbing hot lamps because there’s no time to lose. But in the end, it’s all worth it. It just looks so incredibly good when it all comes together and we can actually say, “we did that.”

Photo Credits: Matt Latchford/Lam Partners

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