People use "IDA certification," "dark sky compliance," and "dark sky ordinance" interchangeably. They are three distinct things with overlapping but different requirements — and an approach that satisfies one may fail the others. A fixture can carry the IDA Fixture Seal of Approval (FSA) and still fail a municipal dark sky ordinance. A project can comply with a local ordinance and still not qualify for IDA certification. And the IDA FSA program, in a decision that surprises almost everyone, dropped all BUG rating requirements and replaced them with the much simpler "no light above 90 degrees" criterion — for a scientifically documented reason that most dark sky guides have never mentioned. This page decodes all three frameworks and explains exactly what each one requires for your landscape lighting.
For years, dark sky compliance was defined partly by BUG ratings — Backlight, Uplight, and Glare maximums from the IES Luminaire Classification System. Then the IDA removed all BUG rating requirements from its Fixture Seal of Approval program. The documented reason from All Things Lighting Association: research presented to the IDA Task Force demonstrated that "we cannot distinguish the resultant differences in sky glow in the night sky" between U0, U1, and U2 uplight ratings. The science didn't support measuring the real-world difference between adjacent BUG uplight ratings, so the IDA replaced the entire BUG requirement with one simple criterion: fixtures must emit no light above 90 degrees vertical. BUG ratings still matter for municipal ordinances and LEED — just not for the IDA FSA program itself.
Before comparing details, establishing what each framework actually is — who runs it, what it governs, and what compliance means — prevents the conceptual confusion that causes most specification errors.
DarkSky International (formerly IDA), a nonprofit organization founded in 1988. Voluntary program, no enforcement authority.
What it governs:Individual luminaire products. Manufacturers apply to have specific fixtures tested and listed as dark sky-friendly. The program has been running since 2002 and as of recent reports certifies products from 97+ participating companies.
What compliance means:The specific fixture model meets IDA's FSA criteria: ≤3000K CCT, no light above 90° (full cutoff), uplight from structure ≤50 lumens total, fixed mount only. This is product-level certification, not site or project certification.
Local government — city council, county commission, zoning authority. Enforceable law with permitting requirements, inspections, and penalties. Enforced by the local AHJ.
What it governs:All outdoor lighting installations within the jurisdiction — new construction, major renovations, sometimes existing lighting at retrofit triggers. Applies to sites and projects, not just individual fixtures.
What compliance means:The entire lighting installation meets the ordinance's requirements for that property's lighting zone. Requirements vary by jurisdiction but typically include CCT limits, shielding, lumen limits by area, light trespass maximums at property lines, and (increasingly) curfew controls. May or may not reference IDA FSA certification specifically.
US Green Building Council (USGBC). Voluntary building certification program. LEED certification is voluntary but provides market value and may be required for certain project types (government, institutional).
What it governs:Outdoor lighting for LEED-certified buildings. One credit in the Sustainable Sites category for light pollution reduction.
What compliance means:BUG ratings are integral to LEED v4 Light Pollution Reduction credit — this is one of the key places where BUG ratings still actively matter despite the IDA FSA removing them from its own program. LEED v4 specifies maximum BUG values by lighting zone (LZ0–LZ4). CCT limits may also apply depending on the credit pathway chosen.
The IDA FSA program has four documented criteria, summarized from the program documentation available via DarkSky International, Border States, AGC Lighting, and Shine Retrofits. Each criterion has specific technical implications for landscape lighting specification.
Fixtures must offer a listed 3000K or lower CCT configuration. This requirement was added in December 2014, when IDA announced new standards on blue light at night. The announcement stated: "FSA approval now requires that products offer a listed correlated color temperature (CCT) configuration of 3000K or lower. Previously approved products will have one year to comply with the new standard."
The important nuance: the 3000K requirement applies to the specific configuration being certified, not necessarily every configuration a fixture offers. Per AGC Lighting documentation: "If other CCTs or mounting options are available for the luminaire, a notation needs to be made on the web page, spec sheets, and order forms that 3000K or warmer, and fixed mounts must be ordered for IDA certification compliance." A manufacturer can make a fixture available in 3000K, 4000K, and 5000K — only the 3000K configuration carries the FSA certification. This means a specifier ordering the wrong CCT version of an "FSA-certified fixture" loses the certification benefit.
Fixtures must emit no luminous flux above the horizontal plane (90 degrees from nadir). This is the full-cutoff criterion. Per Border States' documentation of FSA criteria: "A fixture must be fully shielded and emit no light above the horizontal plane. There shall be no sag or drop lenses, side light panels, uplight panels, etc."
The "no sag or drop lenses" specification matters for landscape lighting: many decorative path lights and post top fixtures use globe-style lenses or clear domes that extend below the fixture housing and emit light at all angles — these typically cannot achieve FSA certification regardless of lamp CCT. The fixture body must shield the light source completely from horizontal view.
Even a fully-shielded fixture can produce small amounts of uplight through reflections off its structure, housing, or mounting hardware. The FSA allows an uplight allowance of 0.5% of total output or 50 lumens — whichever is lower — with no more than 10 lumens in the 90–100 degree zone. Per AGC Lighting's documentation: "Allowable uplight as a byproduct of the structure and not the source." This is distinct from deliberate uplight from the source — the tolerance is only for incidental structural reflections. It explains why some technically full-cutoff fixtures with highly reflective housings still fail FSA review.
Fixtures must be mounted at 0 degrees — no tilt allowed. Per Shine Retrofits' documentation: "fixtures have to be mounted at 0 degrees with no tilt — a tilted mounting angle will void Dark Sky compliance." This requirement has direct implications for landscape spotlights and wall packs. A spotlight aimed upward at a tree, sign, or building face cannot be FSA-certified regardless of CCT or shielding, because the tilt directs light upward from the fixture source. FSA certification applies to a fixture in a specific mounting orientation — the horizontal, downward-directed mount only.
This is the least-known and most consequential fact about the current state of dark sky compliance standards. The IDA and IES jointly developed the BUG rating system as part of the 2011 Model Lighting Ordinance — then the IDA subsequently removed all BUG rating requirements from its own FSA program. Understanding why reveals important truths about the limits of what can actually be measured and regulated effectively.
After the BUG rating system was incorporated into the joint IDA/IES Model Lighting Ordinance (2011), researchers conducted studies to measure whether the differences between adjacent uplight ratings — U0, U1, and U2 — produced measurable differences in night sky quality. The results were unexpected.
Per All Things Lighting Association's analysis: "Simply put, not only can we not measure the differences between U0, U1, and U2 ratings in the laboratory with luminaires, we cannot distinguish the resultant differences in sky glow in the night sky. Shortly after these results were presented to the IDA Task Force, the decision was made to remove BUG rating requirements from the IDA Fixture Seal of Approval program."
The underlying physics: sky glow from a single luminaire is determined not just by its uplight rating but by the cumulative effect of many fixtures, their positions relative to residential areas, the atmospheric conditions, and the total lumen output of the installation. At the individual fixture level, the difference between U0 (virtually no uplight) and U1 (very small uplight) could not be detected as a different sky glow outcome. The U rating was too granular for the real-world measurement capabilities available.
The FSA now requires simply that "fixtures must emit no light above 90 degrees" — the full-cutoff criterion. This is a binary requirement (either full-cutoff or not) rather than a graded BUG rating. It is simpler to verify, simpler to communicate to manufacturers and installers, and scientifically defensible as a meaningful criterion since the difference between uplight and no uplight is measurable even if the difference between U0 and U1 is not.
If you are specifying fixtures for IDA FSA compliance specifically: BUG ratings are not required and do not need to be verified. Full-cutoff (no light above 90°), ≤3000K CCT, ≤50 lumens incidental uplight, and fixed mount are the criteria that matter.
If you are specifying fixtures for municipal ordinance compliance: BUG ratings almost certainly still matter, because most ordinances reference the IDA/IES MLO framework which uses BUG rating limits by lighting zone. The IDA removing BUG from its FSA program does not change municipal ordinance requirements that independently specify BUG maximums.
If you are specifying for LEED v4 Light Pollution Reduction credit: BUG ratings are integral and cannot be bypassed. LEED v4 uses BUG rating maximums by lighting zone as its primary compliance mechanism for outdoor lighting. The IDA FSA is "not directly related to LEED v4" per All Things Lighting — they are parallel systems.
The All Things Lighting Association's documented assessment of the FSA program change is notably candid: "It seems, however, that we mostly have come full circle — the International Dark Sky Association no longer makes use of the BUG rating system in its Fixture Seal of Approval program." This is not a criticism — it is recognition that the science-based revision from complex BUG requirements to simple full-cutoff represents genuine calibration of standards to measurement capability. A standard that requires distinguishing U0 from U1 in the field is not a useful standard if the difference cannot be detected in practice.
The IDA's International Dark Sky Places (IDSP) program certifies five distinct types of locations. Each type has different requirements, different scopes, and different implications for what lighting is permitted. Living near, installing lighting near, or developing near a certified IDSP has different practical consequences depending on which type it is.
As of early 2025, DarkSky International has certified more than 200 International Dark Sky Places since Flagstaff, Arizona became the first certified International Dark Sky City in 2001. These places span 22 countries on 6 continents and protect over 160,000 square kilometers of land and night skies.
An incorporated municipality or recognized unincorporated community that has adopted and is actively enforcing a comprehensive outdoor lighting ordinance consistent with IDA guidelines, and demonstrates community commitment through public education and outreach programs.
Requirements include:A formal lighting ordinance with enforcement authority; a resources program (education, incentives, permitting, or regulation) to encourage all new outdoor fixtures to conform to IDA guidelines; examples of conforming lighting installations proportional to population; public outreach program; annual reporting to maintain certification.
Examples:Flagstaff, Arizona (first, 2001); Borrego Springs, California (first in CA, 2009); Dripping Springs, Texas; Wimberley, Texas; Bee Cave, Texas; Sedona, Arizona.
What it means for your lighting:If your property is within a certified IDSC, the community's lighting ordinance — not just IDA's voluntary guidelines — applies to your outdoor lighting. These are legally enforceable requirements. Permitted activities vary by the community's specific ordinance and lighting zone mapping.
A publicly or privately owned land resource — typically a national or state park, nature preserve, or observatory site — with exceptional dark sky quality. The managing authority commits to actively managing lighting on the site to protect the night environment and conducting public education programs.
Requirements include:Exceptional or distinguished quality of starry nights and nocturnal environment within the park boundaries; active management of all artificial lighting on the site to minimize light pollution; formal Lighting Management Plan or Policy for all outdoor fixtures within the park; annual reporting.
Examples:Cherry Springs State Park, Pennsylvania; Death Valley National Park; Big Bend National Park, Texas; Joshua Tree National Park, California.
What it means for adjacent lighting:Properties adjacent to or visible from an IDSP may face stricter requirements under nearby municipal ordinances designed to protect the park's dark sky status. The park itself has no legal authority over adjacent private property, but the certification motivates surrounding municipalities to adopt protective ordinances. See Flagstaff's comprehensive outdoor lighting code as an example of a municipality protecting adjacent parks.
A large region consisting of a core area of exceptional dark sky quality surrounded by a periphery area where policies protect the core's darkness. The reserve framework acknowledges that real-world dark sky protection requires managing both the protected core and the surrounding land that affects it.
Structure:Core area: the darkest, most protected zone with stringent lighting controls. Periphery area: surrounding land where policies exist to limit light pollution affecting the core. Applications must identify both areas with detailed maps and demonstrate coordinated management between core and periphery authorities.
Examples:Exmoor National Park, UK (the world's first, 2011); Central Idaho Dark Sky Reserve (one of the largest, covering 1,400 square miles); Mont-Mégantic Dark Sky Reserve, Canada.
The most remote and darkest places on Earth — areas with typically no permanent population or habitation, often in wilderness regions, that possess extraordinary dark sky quality and are specifically protected for scientific, cultural, and natural heritage value.
Characteristics:Extremely remote locations; typically accessible only to researchers, astronomers, or dedicated stargazers; minimal or no permanent infrastructure; the highest level of natural darkness protection. The certification process requires demonstrating remote access conditions, exceptional darkness measurements, and commitment to maintaining that darkness.
Practical note:Dark Sky Sanctuaries are rarely near developed areas. The certification type is relevant primarily to researchers, astronomers, and policymakers rather than to landscape lighting specifiers.
A place located within or immediately adjacent to a major urban area that takes exceptional steps to protect and celebrate the night environment, creating dark sky oases within highly lit urban contexts. Designed for cities that want to create nighttime nature experiences without being able to achieve the dark sky levels of rural certification types.
Significance:The UNSP designation acknowledges the reality that the majority of the world's population lives in cities where full dark sky conditions are impossible. Urban Night Sky Places create accessible, meaningful nighttime nature experiences and demonstrate best practices for urban lighting. As of the last count, there are only 6 Urban Night Sky Places certified worldwide.
Examples:Zselic Starry Sky Park, Hungary (the first UNSP); Torrey Pines State Natural Reserve, California.
The lighting zone system — LZ0 through LZ4 — is the framework that connects the IDA/IES Model Lighting Ordinance to real-world land use. The zone assigned to a property determines the maximum lumen output allowed, the maximum BUG ratings permitted, curfew requirements, and what types of lighting are allowed at all. Understanding which zone your property is in is the prerequisite for any dark sky ordinance compliance analysis.
When a municipality adopts a dark sky ordinance based on the IDA/IES Model Lighting Ordinance framework, it creates a zone mapping that assigns LZ designations to all properties. This typically follows the existing zoning map: LZ0 for conservation and open space; LZ1 for rural residential and agricultural; LZ2 for suburban residential and low-density commercial; LZ3 for commercial and urban; LZ4 for entertainment and high-activity areas. Some ordinances create overlay districts that override the base zone — a residential property (normally LZ2) within 1,000 feet of an LZ0 natural area might be assigned LZ1 requirements. See the outdoor lighting ordinance guide for the complete framework of how ordinances are structured and adopted.
The MLO vs POLC Research Finding That Changes the Picture for LZ2 and Above: Flagstaff Dark Skies Coalition analysis of the Model Lighting Ordinance vs Flagstaff's own Professional Outdoor Lighting Code (POLC) found a significant gap: "Under MLO standards, outside of MLO LZ 0 and 1, the total lumen allowances, direct uplight allowances, and amount of sky glow are notably greater than expected under POLC standards; in MLO LZ 3 and 4 they are dramatically greater. In LZ 2 and above sky glow impacts are greater than what can be expected even when lighting is unregulated." The IDA/IES Model Lighting Ordinance — the framework most municipalities adopt — is more permissive than the dark sky community expects, particularly in commercial and urban zones. Stricter local codes like Flagstaff's POLC achieve dramatically better dark sky outcomes than the MLO baseline. This is why IDA-certified communities often exceed the MLO requirements in their local ordinances.
Understanding the specific scenarios where IDA FSA certification and municipal dark sky compliance diverge prevents both over-reliance on FSA status and under-specification of FSA requirements.
| Scenario | IDA FSA Status | Municipal Ordinance Status | The Gap |
|---|---|---|---|
| Fixture ordered in 4000K CCT in industrial zone where ordinance allows 4000K | FAILS FSA — FSA requires ≤3000K universally | May PASS — if jurisdiction allows 4000K in industrial LZ3/LZ4 | FSA is more restrictive on CCT than many municipal industrial zones. A compliant industrial installation may not use FSA-certified product configurations. |
| 3000K full-cutoff fixture but no BUG rating documentation, LZ2 ordinance requires B2-U1-G2 max | PASSES FSA — FSA doesn't require BUG ratings | May FAIL ordinance — if fixture BUG rating exceeds municipal maximums | FSA removal of BUG requirements means FSA-approved fixtures can have BUG ratings that exceed municipal ordinance limits. Must verify BUG separately. |
| Tilted landscape spotlight, 2700K, aimed at tree from below | FAILS FSA — tilt void FSA regardless of CCT | DEPENDS — some ordinances permit shielded uplighting, others prohibit all uplighting | FSA's fixed-mount requirement eliminates landscape uplighting from certification eligibility. Municipal compliance depends on ordinance language — some explicitly permit directed accent lighting with shields. |
| Path light with globe lens, 2700K warm white | FAILS FSA — globe lens allows light above 90°, no full cutoff | DEPENDS — if ordinance requires "full cutoff" per FSA definition, fails; if it requires only ≤3000K and full shielding with allowances for decorative fixtures, may pass | Globe and lantern-style path lights are common in residential landscape design and often fail FSA full-cutoff criteria while meeting ordinance shielding requirements that allow limited uplight for decorative fixtures. |
| FSA-certified downlight fixture with lumen output exceeding LZ2 site lumen limit | PASSES FSA — product certification doesn't include site lumen analysis | FAILS ordinance — site lumen limit exceeded regardless of fixture certification | FSA is product-level certification; municipal ordinances regulate total lumen output per site area. Too many FSA-certified fixtures still violates total lumen limits. |
| FSA-certified fixture without automated curfew control in LZ2 jurisdiction requiring curfew | PASSES FSA — FSA doesn't regulate controls | FAILS 2026-era ordinances — automated curfew controls required; manual switch insufficient | FSA certification is fixture-level and includes no controls requirements. Municipal ordinances increasingly mandate automated curfew compliance that FSA doesn't address. |
The most significant regulatory shift in outdoor lighting compliance between 2024 and 2026 is not about CCT or BUG ratings — it's about curfew enforcement and the controls required to achieve it.
Per Stars and Stripes Lighting's documented analysis of emerging 2026-era ordinances: "By 2026, many zoning reviews and local ordinances are converging on three baseline requirements for commercial sites: correlated color temperature at or below 3000K, defined shielding or cutoff performance often expressed through BUG ratings, and controls capable of curfew or scheduled light reduction after hours. Installations that meet average illuminance targets but fail these criteria are increasingly subject to correction or rejection."
The curfew requirement is not new — IDA/IES lighting zone definitions have always specified that LZ1 and LZ2 lighting "may be extinguished or reduced as activity levels decline" after curfew. What is new in 2026-era ordinances is the specificity of the controls requirement and the enforcement of it at permit review.
Per Stars and Stripes Lighting: "Key compliance point: Manual switches do not satisfy curfew requirements; automation (time-based, photocell + schedule, or networked controls) is typically required." A lighting system with a manually operated switch technically allows the owner to comply with curfew hours — but manual compliance cannot be verified by inspection and cannot be guaranteed to occur consistently. 2026-era ordinances require automatic reduction or shutoff through time-based controls, photocell-plus-schedule combinations, or networked smart controls.
Real-world example: Malibu, CA's dark sky ordinance requires lighting to "be extinguished by 11:00 PM or when people are no longer present in exterior areas, whichever is later, except for lighting activated by motion sensor which extinguishes 10 minutes after activation." The only exception paths involve automation — either a timer or a motion sensor. A manually controlled system has no compliant pathway unless a person actively turns off all lights by 11:00 PM every night.
For landscape lighting systems, this shift has direct practical implications. Standard landscape lighting transformers include built-in timers and photocell controls. Under 2026-era curfew ordinances:
For the complete transformer timer configuration guide, see the landscape lighting timer settings guide and the transformer guide. For the automation options available on Portfolio transformers, see the Portfolio transformer master guide.
Texas Senate Bill 1090 represents a nationally significant model for how states can enable dark sky protection without mandating it — and it demonstrates a novel approach to linking municipal lighting authority to the IDA certification framework.
Prior to SB 1090, most Texas municipalities had general authority to regulate outdoor lighting within their city limits but limited ability to regulate lighting in their extraterritorial jurisdiction (ETJ) — the unincorporated land surrounding a city. Unincorporated county areas in Texas generally lacked authority to regulate outdoor lighting at all. This created a situation where a dark sky community like Dripping Springs could regulate lighting within the city but couldn't protect the night sky from light pollution originating just outside the city limits.
Per DarkSky Texas and Texas lighting consultants' documentation of SB 1090: "Senate Bill 1090 introduced an important update, allowing cities to regulate lighting if they declare their intent to become an International Dark Sky Association (IDA) certified community. This change permits municipalities to extend lighting regulations into their extraterritorial jurisdiction (ETJ). The bill also shifted enforcement from criminal to civil penalties, with fines for violations capped at $500."
Key provisions of the framework created by SB 1090:
SB 1090's approach — using IDA certification as both the legal threshold for regulatory authority and the ceiling for regulatory stringency — is a notable policy innovation. It prevents municipalities from using dark sky regulation as a backdoor for excessive lighting controls, while simultaneously empowering municipalities near astronomical observatories or dark sky parks to protect their nighttime environment. Texas cities that have earned IDA certification under this framework — Dripping Springs, Wimberley, Bee Cave — demonstrate that IDA certification standards are practically achievable at the municipal level and create measurable astrotourism economic benefits.
The frameworks above — IDA FSA, municipal ordinances, lighting zones, curfew requirements — have specific practical implications for landscape lighting specification, both residential and commercial. Here is the decision-making sequence for each scenario.
For properties in standard residential areas without dark sky overlay zones, IDA certification is voluntary and municipal ordinances may not apply. The practical guidance for dark sky-conscious residential landscape lighting:
If your property is in Flagstaff, Dripping Springs, Borrego Springs, Wimberley, Bee Cave, or another IDA-certified community, the community's lighting ordinance is legally enforceable. Verify your property's lighting zone under the local ordinance (most certified communities have zone maps available from their building department). For the complete compliance workflow, the dark sky compliance guide provides the step-by-step approach for properties in regulated jurisdictions.
Commercial landscape and site lighting projects typically require photometric plans for permit. In dark sky ordinance jurisdictions, the photometric plan must demonstrate compliance with the applicable lighting zone's requirements: total lumen limits per hardscape area, BUG rating maximums by zone, property line light trespass limits, CCT limits, and curfew control documentation. The IDA FSA certification of specified fixtures is helpful documentation but insufficient alone — site-level compliance must be demonstrated through photometric calculation. See the photometric plan reading guide for how inspectors evaluate compliance at plan review. See the lumen guide for landscape-appropriate lumen output levels by application.
A single fixture specification choice serves all three frameworks simultaneously: amber LEDs with peak wavelengths at 580–590nm. Amber LEDs satisfy IDA FSA CCT requirements (well below 3000K in spectral character); satisfy dark sky ordinance CCT requirements; provide the best available lighting for wildlife-sensitive and sea turtle-sensitive coastal applications (see the turtle-safe lighting codes guide); and minimize attraction of nocturnal insects. The convergence of dark sky, wildlife protection, and lighting code compliance around amber LEDs makes them the highest-value single specification choice for outdoor landscape lighting in any sensitive context. See the wildlife-friendly outdoor lighting guide for the complete wildlife impact framework.
Dark-sky-friendly lighting is not just a fixture label; it depends on whether the system is repaired correctly, aimed correctly, and producing the intended amount of light. Portfolio owners with model, transformer, or part questions can start with the Portfolio Lighting AI assistance tool for guided repair and compatibility help. If an older low-voltage system is dim or unreliable because of green connector corrosion, the green dust lighting connector repair guide explains how restoring clean copper contact can change fixture brightness and beam performance. Once output is restored, the property-line foot-candle light trespass guide helps connect dark-sky intent with measurable spill-light limits.
No — IDA FSA certification is product-level certification of a specific fixture. Dark sky compliance for an installation requires meeting all applicable municipal ordinance requirements, which typically include: the site's total lumen output staying within the lighting zone's lumen limits per unit area; the fixtures' BUG ratings staying within the zone's maximums (even though the FSA no longer requires BUG verification); light trespass at property lines not exceeding maximums; CCT at or below the ordinance limit; and, in 2026-era ordinances, automated curfew controls. An FSA-certified fixture that is ordered in the wrong CCT, that exceeds the site's lumen allocation, that doesn't have automated curfew controls, or that has BUG ratings exceeding the zone's limits can still fail municipal compliance despite its FSA status. FSA certification is useful evidence of product quality and design intent — it is not a substitute for site-level compliance verification.
The IDA FSA program and the IDA/IES Model Lighting Ordinance are separate frameworks developed at different times. The joint MLO (2011) incorporated BUG ratings as its primary fixture performance metric. Subsequently, research demonstrated that the differences between U0, U1, and U2 uplight ratings could not be measured as distinct sky glow differences in real-world conditions. The FSA program responded by replacing BUG requirements with the simpler full-cutoff criterion. The MLO, however, is a separate document that municipalities adopt independently — and municipalities that have adopted MLO-based ordinances still specify BUG rating maximums per lighting zone in their own codes even though the IDA FSA no longer requires them. The FSA is a certification program run by a nonprofit; municipal ordinances are enforceable law. They can and do diverge.
It depends entirely on your jurisdiction. In most US cities without dark sky overlay districts, residential single-family landscape lighting is not regulated by dark sky ordinances. In IDA-certified dark sky communities (Flagstaff, Borrego Springs, Dripping Springs, Wimberley, Bee Cave, and others), the community's outdoor lighting ordinance typically applies to all outdoor lighting including residential landscape lighting. Many of these ordinances apply CCT limits, shielding requirements, and curfew requirements to residential properties, though enforcement often focuses on egregious violations rather than incidental non-compliance. In cities near astronomical observatories (Flagstaff near Lowell Observatory; Palomar-adjacent communities) or near IDA-certified parks, additional overlay requirements may apply. Contact your local building department to determine whether your property is in a regulated zone.
DarkSky International discontinued the Dark Sky Friendly Development of Distinction program as of August 1, 2020. No new nominations are being accepted. This certification was designed for residential subdivisions, master-planned communities, and unincorporated neighborhoods that promoted dark skies but didn't qualify for the full Community designation. Existing certified Developments retain their designation but this certification type has no renewal path and is not being awarded to new applicants. If you are evaluating a residential development that claims "IDA Dark Sky Friendly Development" status, this is legacy documentation from pre-2020 and does not represent a currently maintained active certification program.
IDA requires a maximum of 3000K correlated color temperature for FSA certification, a requirement formalized in December 2014. Amber light sources (which are spectrally below 3000K in effective color temperature) and other warm-spectrum sources are also acceptable. The FSA does not require a minimum color temperature — fixtures could theoretically be at 1800K or 2200K (very warm amber-orange) and satisfy the CCT criterion. The 3000K maximum specifically targets reducing blue-rich white LED light that contributes to sky glow, disrupts wildlife, and impacts human circadian rhythms. Many dark sky advocates recommend 2700K or lower for residential applications where CCT can be selected freely, since lower CCTs produce less short-wavelength (blue) emission. See the color temperature guide for the complete CCT selection framework for landscape applications.
There is a lot of legal info I put on this page so rmember that I am an independent site not affiliated with DarkSky International, USGBC, IES, or any lighting manufacturer. IDA FSA program criteria from DarkSky International (darksky.org), AGC Lighting (agcled.com), Border States (borderstates.com), Shine Retrofits (shineretrofits.com), and the 2014 IDA announcement of 3000K standard (darksky.org/news/ida-issues-new-standards-on-blue-light-at-night). IDA FSA BUG rating removal and full-cutoff replacement documented from All Things Lighting Association (allthingslighting.org). Five IDSP certification types from DarkSky International (darksky.org/what-we-do/international-dark-sky-places/dark-sky-place-types/) and Kūaotunu Dark Sky Community. Dark Sky Friendly Development of Distinction discontinuation from darksky.org (August 2020). LZ0–LZ4 lighting zone definitions from DarkSky International (darksky.org/resources/guides-and-how-tos/lighting-zones/), IDA/IES MLO (2011), Santa Cruz County AZ ordinance, and Energy Code ACE. 2026 curfew enforcement shift from Stars and Stripes Lighting (starsandstripeslighting.com, January 2026). Malibu dark sky ordinance from malibucity.org. Texas SB 1090 analysis from DarkSky Texas (darkskytexas.org), Scenic Texas (scenictexas.org), and Texas Lighting Consultants (texaslightingconsultants.com). MLO vs POLC sky glow comparison from Flagstaff Dark Skies Coalition (flagstaffdarkskies.org). DarkSky International certification count and geographic scope from darksky.org (September 2024 and November 2025). LEED v4 BUG rating integration from All Things Lighting Association. Three-way framework comparison from LED Lighting Supply (ledlightingsupply.com). IDA name change from International Dark-Sky Association to DarkSky International (2022). NEC® is a trademark of NFPA. IDA® and DarkSky International® are trademarks of DarkSky International. LEED® is a trademark of USGBC.
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