I recently had the pleasure of interviewing Don Vendetti, CEO of Evluma. The street and area lighting company has just published a new whitepaper about glare. We also discussed the new ANSI/IES RP-8 standard, as well as the trend toward warming CCTs for streetlights.
Shiller: First, thank you, Don, for agreeing to do this interview. I’ve read the new Evluma whitepaper about Streetlight Glare. It does a great job breaking down discomfort glare versus disability glare, and many of the implications of both types. A big takeaway from this whitepaper is that a well-designed, secondary diffuser / lens can reduce both types of glare. Do a significant percentage of Evluma ROADMAX streetlight customers install the Evluma secondary diffuser optic to reduce glare? Do many install the optional light trespass shields (front-side & house-side)?
Vendetti: David, I appreciate the opportunity to discuss the concept of glare and our ROADMAX product. Before diving into that, I’d like to give some background on Evluma. We’ve been around for about 14 years now as a lighting company, and our founders have decades of LED design experience.
With all of our products, minimizing any possible negative user experience in the switch from HPS or MH to LED has been a key focus. There are several key differences between the technologies that can create this negative experience. These include generally higher CCTs, discrete pixelated light sources, and a high potential for glare due to the use of primary optics.
Our main product until now has been our AREAMAX security light and it is a top competitor, particularly in the rural cooperative electric utilities. Its design includes a diffused glass lens over a single primary optic and LED source. This reduces the intensity of the emitted light, especially at higher angles. While the effect helps to reduce glare, our original intention was to make luminaires that put out a “pleasing light.”
This has been a product design theme for us, including our OMNIMAX retrofit. Our design of the ROADMAX streetlight is implemented in a similar way as AREAMAX specifically targeting glare, while also making the diffused secondary lens optional and installable at the factory, or in the field. We did this to allow customers to decide which version is most acceptable in their roadway application.
To date, there has been strong interest in the diffused lens and many of our sales have included it installed from the factory. We also have a few customers who selected to install the lens in the field during trials to compare the difference. The shields are typically purchased to address specific problem areas where light spill is an issue, so the normal scenario is a much lower quantity of shields purchased versus the luminaires.
Shiller: In some ways, could Evluma’s globes and acorns be considered as secondary diffuser optics to assist in managing glare, for post top lights? Should specifiers think about new globes and acorns as a potential glare control measure?
Vendetti: That’s a very good observation. The OMNIMAX product has several design features itself to help mitigate glare. The first is a silicon lens over the LEDs. This protects the LEDs from direct contact and also contains a light texture to create diffusion of the light directly from the LEDs.
The dimensions of the lamp and location of the LEDs were intended to try to get close to the original size and burn center of the HID lamps being replaced. This design feature leverages the existing globe and acorn optics to put light where it was intended and is particularly important for prismatic globes. A retrofit lamp that has LEDs in vertical rows extending beyond the central prismatic elements is not going to deliver light as expected and will also look much different than the original HID inside the globe.
With any post-top retrofit project, a decision needs to be made about what to do about damaged, dirty or tired-looking fixtures. If they are classic globe or acorn fixtures, they can be easily replaced, creating a clean new look with the retrofit lamp. Additionally, it presents an opportunity to reduce glare versus the legacy fixture by choosing a diffused replacement.
Some of our add-on globes and acorns come in low-glare material, such as LD Acrylic. This is a highly transmissive, translucent material that diffuses the light and provides a fixture with a soft, low-glare glow. We have some nice photos in the Gallery section of our website to illustrate some installations.
Shiller: Do you find Evluma’s streetlight customers to be knowledgeable about glare types and mitigation strategies? Do you see knowledge differences between municipal, utility, and other commercial streetlight customers regarding glare?
Vendetti: We see a large spectrum of customers with vastly different levels of understanding of glare. There are some who rely on outside resources or the luminaire vendors to help them understand it. I suspect understanding glare is an issue in the industry as a whole, not just for our customers.
The topic of glare is complicated and confusing due to there being multiple types of glare: Discomfort and Disability. Most complaints about glare come from the Discomfort side, typically associated with light trespass. It’s easy to grasp that a light is shining where it’s not useful and is annoying due to being overly bright. The light is also typically static and at a fixed location, so it is easy to identify when the glare occurs. However, there is no standard method for measuring it or predicting it with simulation software, so you’re stuck with addressing it when and where it happens.
Disability Glare is much less intuitive and occurs in the dynamic environment of driving (as can Discomfort Glare). While it has a metric and can be predicted and assessed using simulation software, it is difficult to measure. It can also be impacted by changing conditions, such as weather, and is highly influenced by the age of the driver.
From my own research, I have had to try to piece together a picture of glare from available publications. Most of this information is fairly technical and quickly dives into the physiology of our eyes, light adaptation levels, contrast ratios and complicated diagrams using trigonometry. This rarely helps those looking for a quick understanding of Glare or the causes and solutions.
For these reasons, we feel that we need to be a steward in facilitating a better understanding of glare and how to control it. This was the main driver in the creation of our new whitepaper on glare as a step in simplifying the conversation for our customers.
Shiller: Evluma’s website references utilities more than municipalities or commercial end users. Is Evluma primarily focused on the utility streetlight market?
Vendetti: We have historically focused on the utility market for our AREAMAX product, so this is where our most experience is, to date. Our OMNIMAX product appeals to many municipal and commercial customers, due to preserving the investment in often high-priced or difficult to replace decorative fixtures. We expect ROADMAX to have appeal across all segments, including DOTs.
Shiller: The IES recently released their updated ANSI/IES RP-8-21 Recommended Practice for Lighting Roadway and Parking Facilities. Do you see this updated roadway standard impacting the market and Evluma’s business in any way?
Vendetti: Our experience with RP-8 started in 2016 when we introduced a Type III distribution on AREAMAX, and some of our customers wanted to use it as a streetlight. It was then that we got a crash course in understanding the tools and calculations, and how well our product performed against the recommendations. We used these learnings to focus our efforts on our ROADMAX design a few years down the road, and the 2018 version of RP-8 became a major influencer for us.
The 2018 version was a massive unification of several individual IES docs into a more comprehensive discussion. I would call the 2021 release more of an incremental improvement that helped to update and clarify multiple sections, in addition to adding a few more sections that augment roadway recommendations, such as pedestrian lighting.
What we’ve seen in reviews of existing older specifications within utilities or municipalities is that many of them include only partial specification of the RP-8 recommendations. These typically include the average illuminance ratio and the average-to-min uniformity ratio, and some expand to the max-min uniformity value. There is a strong focus on uniformity ratios, and missing in many of the specs is the veiling luminance ratio recommendation. This may be due to the discussion of Glare being essentially an appendix in the RP-8-2014 version, and thus veiling luminance was not a strong area of focus. It also required shifting the thought process from illuminance to luminance, a more difficult concept to grasp and to measure in the field.
In the 2018 version, Glare got its own major section and thus marks a shift in focus. There is also the insistence that all four of the recommended RP-8 parameters, including veiling luminance ratio, should be specified. This helps elevate the importance of paying attention to Disability glare for any new or updated specifications for a new deployment.
This will certainly have a positive impact on the market as a whole and for Evluma. We have attempted to provide a product that achieves strong performance for roadway lighting while also meeting all the recommended metrics, with a major focus on minimizing Disability Glare (aka veiling luminance).
Shiller: There is a quick reference in the white paper to the trend of decreasing CCTs for both human and wildlife health. I see Evluma luminaires and retrofit lamps go down to 2700K CCT. Does Evluma have any opinions on streetlight products beginning to be offered in 1800K, 2200K, and 2500K CCTs? Can you share if Evluma has any plans to offer any CCTs below 2700K?
Vendetti: Our current OMNIMAX post-top product already offers CCTs as low as 2000k and 2200k, so we have been a supporter of low CCTs. We do expect the trend for lower CCTs to occur in streetlights over time as more municipalities weigh the trade-offs and feedback from the communities.
There is still a relatively large efficacy loss at 2700K versus 4000K and it increases significantly as you go lower. For example, moving from 2700K to 2200K has an efficacy drop of 20% or more. This could require going up in luminaire power proportionately to achieve the recommended lighting levels in RP-8, so this needs to be considered.
As far as Evluma plans, our priority is getting our full portfolio of ROADMAX versions to support 250 and 400W HPS replacements later this year and then we’ll shift to focus on additional options, such as lower CCTs.
Shiller: Thank you very much, Don, for sharing your expertise with our readers.
The Evluma glare whitepaper can be downloaded for free, here. Evluma will also be exhibiting at the upcoming IES Street and Area Lighting Conference, October 10-13, in Dallas, Texas. Their booth number is 306.
You must be logged in to post a comment.