Goran Juric Design portfolio | October 2024 | Krijesnica — Firefly Urban Light Concept | Independent Research
A New Generation of Ecologically Responsible Urban Lighting
Krijesnica is a design and technology research project focused on developing urban lighting that interferes less with natural darkness, reduces light pollution, and limits the attraction and disorientation of nocturnal insects.
The concept explores how industrial design, spectral control, precise optical distribution, adaptive operation, and active airflow management can create lighting that responds to human needs while showing greater respect for nocturnal ecosystems.
Krijesnica does not treat a luminaire merely as a source of light. It is conceived as an integrated system in which form, structure, optics, spectrum, airflow, and operating behaviour collectively determine its impact on the surrounding environment.
Light Directed Only Where It Is Needed
The light source is positioned deep within the structure and optically shielded, making it almost invisible from most lateral viewing angles.
Light is directed precisely towards the ground and the intended surface, without unnecessary spill towards the sky, surrounding habitats, building façades, or tree canopies. This spatial control reduces glare, limits direct visibility of the light source, and helps preserve natural darkness outside the area that needs to be illuminated.
The concept is based on a simple principle: high-quality urban lighting does not need to be stronger. It needs to be more precise.
A Spectrum Adapted to the Night Environment
Krijesnica proposes the use of amber or other blue-reduced LED technologies with a minimal proportion of short wavelengths.
Many nocturnal insects are particularly sensitive to ultraviolet, blue, and green regions of the spectrum. Reducing these components can help limit attraction and disorientation while maintaining sufficient visibility for safe human movement.
The spectrum and light intensity can be adapted to different environments. In urban areas, priority may be given to safety, obstacle recognition, and visual comfort. In parks, near waterways, and in ecologically sensitive locations, a narrower amber or red-shifted spectrum and lower illumination levels may be used.
The objective is not to create light that is completely invisible to insects, but to measurably reduce their exposure to artificial illumination, the time they spend around the source, and the disruption of their natural behaviour.
Air Halo – A Gentle Airflow Barrier for Insects
An experimental feature of the Krijesnica concept is an integrated annular airflow system designed to reduce the time insects spend near the optical opening.
Air is generated by a quiet, enclosed brushless blower located inside the luminaire. All moving components are physically separated from the external environment and protected by an intake screen, internal ducting, and the surrounding housing.
Annular airflow system with an integrated BLDC blower
The air is distributed through a circular plenum and released through a narrow annular opening. It is directed downwards and slightly outwards, forming a mild aerodynamic boundary around the deeply recessed light source.
The purpose of the Air Halo is not to trap, strike, injure, or destroy insects. Its function is to make entry into the immediate optical zone more difficult, interrupt repeated circling close to the luminaire, and encourage insects to move away from the illuminated area.
Airflow speed can be adjusted according to location, weather conditions, insect activity, and ecological sensitivity. The system is intended to operate at the lowest effective airflow level and can be reduced or switched off when it is not required.
The Air Halo remains a secondary protective measure. The primary ecological performance of Krijesnica is achieved through low light levels, spectrally adapted illumination, deeply shielded optics, precise spatial distribution, and intelligent operating control.
Enclosed Low-Noise Airflow Technology
Unlike an exposed fan, the Krijesnica airflow system has no externally accessible propeller or rotating components. The brushless blower is fully enclosed within the structure, while air is guided through protected internal channels toward the annular outlet.
This arrangement enables quiet and energy-efficient operation while keeping insects safely separated from all moving parts. It also protects the system from rain, dust, and accidental contact. Airflow can be activated almost instantly, adjusted electronically, and operated continuously, intermittently, or in short pulses, depending on current conditions. Because the blower and air channels are integrated into the structural ring, the system remains visually discreet and can operate only when protective airflow is actually needed.
The annular outlet may also be divided into several independently controlled segments. Individual sections can be activated according to wind direction, weather conditions, seasonal changes, detected insect activity, or the selected operating mode of the luminaire. This segmented control reduces unnecessary energy consumption and allows airflow to be directed more precisely around the optical opening.
Adaptive Operation
Krijesnica is not designed to operate at the same intensity throughout the night.
Integrated sensors can detect pedestrians, vehicles, ambient light levels, temperature, humidity, and other relevant environmental conditions. Based on this information, the system can adjust brightness, spectral composition, operating duration, and the intensity of the Air Halo.
During periods without pedestrians or vehicles, the light can be strongly dimmed or switched off. When a person approaches, illumination can temporarily increase to the level required for safe movement.
The Air Halo may operate only when light output is increased, during warmer seasons, or under conditions associated with greater insect activity. During winter, periods of low insect activity, heavy rain, or strong external wind, the airflow system can remain switched off.
In this way, light and energy are used only where, when, and in the amount in which they are genuinely needed.
Safety and Ecological Validation
The Air Halo is an experimental protective system that requires systematic testing before it can be introduced into public space.
Development must include electrical and mechanical safety, protection against rain, condensation, dust, insects, and accidental contact, as well as long-term testing of the blower, intake screen, internal air channels, and electronic control system.
Particular attention must be given to the design of the air intake. It should be positioned away from the illuminated optical opening and protected by a fine screen and internal labyrinth so that insects cannot reach the blower.
Airflow must remain sufficiently gentle to avoid throwing insects against the ground, surrounding structures, or parts of the luminaire. The objective is to discourage entry into the immediate optical zone rather than to create a powerful air jet.
The effectiveness of the system must be confirmed through comparative laboratory and field testing. Measurements should include the number of insects in the immediate vicinity of the luminaire, their flight paths, the time they spend near the source, and their responses to different spectra, light intensities, airflow velocities, outlet geometries, and operating cycles.
Testing should also compare the luminaire with and without the Air Halo in equivalent environmental conditions.
Krijesnica is therefore presented as a research concept under development rather than as a fully validated final solution.
Organic Structure
The supporting structure is inspired by natural systems of branching, load transfer, and material distribution.
Its organic form is not merely a decorative interpretation of nature. Its geometry follows the paths of structural forces and places material where it is mechanically required.
This approach provides strength and stiffness while reducing mass, visual weight, and the overall amount of material.
The ring supporting the optical system simultaneously functions as a structural element, optical shield, aerodynamic surface, airflow plenum, and carrier of the annular outlet.
Form and technology are therefore not treated as separate layers, but as interconnected parts of a unified system.
Design as an Ecological Tool
Krijesnica explores how industrial design can connect functionality, safety, technological innovation, and ecological responsibility within public infrastructure.
Instead of adding individual ecological features to an existing luminaire, the concept redefines the relationship between the light source, the user, and the nocturnal environment from the beginning.
Each component performs several functions. The ring supports the lighting system, shields the source, distributes air, and shapes the airflow. The organic structure carries loads while reducing material use. Electronic control improves safety while simultaneously limiting unnecessary illumination and energy consumption.
The result is a public-lighting concept that does not attempt to overpower the night, but to become a more considerate part of it.
Philosophy
Krijesnica is an invitation to return light to its natural role — a tool for orientation rather than domination.
It transforms illumination from a symbol of unlimited progress into a gesture of respect. It does not attempt to eliminate the night, turn it into day, or illuminate every part of the environment.
Instead, it provides enough light for safe movement while preserving darkness as an essential part of the natural world.
Krijesnica reconnects the city with natural cycles and restores the quiet poetry of the night.
