With all the different terms for light going up in the air from light fittings, as well all the different documents that talk about it, as a customer it is difficult to know what is going on. At some point in the near future there will be a definitive standard that will let us know once and for all what is acceptable, and what is not, but until that time this section of our website will attempt to clear some of the mists, and at least give you some guidance on some sort of best practice for up light control limits.
Holophane and Dark Sky compliance
Dark Sky compliance is not a term we use at Holophane, we defer from using this term, as there is no defined measure of what does or does not comply. We prefer to use the term ‘Nighttime friendly’, and then make a best practice attempt at giving a definition based around existing standards and measures.
Links to ILE (Institution of Lighting Engineers)
- ILE website
- ILE’s guidance notes on ‘Dark Sky Compliance’
Who is the International Dark-Sky Association (IDA)?
The International Dark-Sky Association (IDA) is a US-based non-profit organization incorporated in 1988 by founding members including an astronomer, a medical doctor/amateur astronomer, and an engineer. The mission of IDA is ‘To preserve and protect the nighttime environment and our heritage of dark skies through quality outdoor lighting’. Their principal approach is to raise awareness about the value of dark, star-filled skies and encourage their protection and restoration through education about the problems and solutions, including lighting practices that create less light pollution. In 2008 the organization had about 5000 members in 70 countries.
What do the guys in America do about waste light (IESNA)?
The Illuminating Engineering Society of North America (IESNA) provides, among many other things, classifications for luminaires according to their glare control and high-angle brightness. These classifications include full cutoff, cutoff, semi-cutoff and non cutoff.
Holophane Europe uses Night time Friendly to identify products that reduce negative impacts on the night time environment. Products designated with the Nighttime Friendly logo have controlled and limited upward light and meet at least the IESNA definition (below) for a Semi-cutoff luminaire.
| Classification | Definition | Benefits | Limitations |
| Full Cutoff | Zero intensity at or above horizontal (90° above nadir) and limited to a value not exceeding 10% of lamp lumens at or above 80°. | Limits spill light onto adjacent property, reduces glare. No light is emitted directly from the luminaire into the sky. |
May reduce pole spacing to maintain uniformity and increase pole and luminaire quantities. |
| Cutoff | Intensity at or above 90° (horizontal) no more than 2.5% of lamp lumens, and no more than 10% of lamp lumens at or above 80°. | Small increase in high-angle light allows increased pole spacing. | May allow some uplight from luminaire. Typically a small overall impact on sky glow. |
| Semi-Cutoff | Intensity at or above 90° (horizontal) no more than 5% of lamp lumens and no more than 20% at or above 80°. | High-angle light accents taller vertical surfaces such as buildings. Most light is still directed downward. |
Little control of light at property line. Potential for increased glare when using high wattage luminaires. Typically directs more light into the sky than cutoff. |
| Non-cutoff | No limitations on light distribution at any angle. | Uniform luminous surfaces such as internally illuminated signs or globes. Wattage should be limited. Suitable for sports lighting, facade, landscape or other applications where luminaires are tilted due to limitations in pole or fixture locations. |
Location and aiming are critical. Most likely of all categories to produce offensive brightness and sky glow. |
The Below Table lists all of Holophane Europe Ltd’s products and outlines how they perform in terms of the control of upward light when related to the three above outlined metrics (none of which on their own denote DARK SKY compliance).
The product’s ability to perform to the three metrics outline drives whether or not the product gets our nighttime friendly mark.
| IESNA* | IDA† | ILE‡ | |
| Aeris | FC | YES | E1 |
| QSS | C | E2 | |
| QSM | C | E2 | |
| Dorchester | FC | YES | E1 |
| Vista | C | E2 | |
| Vista Junior | C | E1 | |
| Vista Grande | SC | E2 | |
| Denver Pole | C | E2 | |
| Urbandeco | C | E1 | |
| Signature | C | E2 | |
| Signature II | C | E1 | |
| Petxina | SC | E2 |
* Fittings within range achieve IESNA classification
FC = Full-cutoff
C = Cutoff
SC = Semi-cutoff
NC = Non-Cutoff
† Not certified by the IDA, but fittings within range meet IDA when measured to their metrics.
‡ Achieve required levels of ULR for stated environmental zone.
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